KR100483106B1 - Adhesive Compositions and Methods of Use - Google Patents

Abstract

The present invention is one or more alkyl acrylates; It is to provide a screen-printable adhesive composition comprising at least one reinforcing comonomer, a polyepoxide resin, and a polyepoxide resin curing agent, which can be applied to a substrate at room temperature. The adhesive composition is substantially solvent free and the composition has a yield point greater than 3 Pascals and a viscosity of less than 6000 centipoise. In another embodiment, the present invention provides a thermally curable electrical conductivity that is a polyepoxide resin, a polyepoxide resin curative, and a substantially solvent-free acrylic polymer further containing an electrically conductive material and / or a thermally conductive material; Or) a thermally conductive adhesive film.

Description

Adhesive Compositions and Methods of Use {Adhesive Compositions and Methods of Use}

The present invention relates to screen-printable adhesives and thermally curable adhesive films.

Screen printing of adhesives is known in the art and is advantageously used to apply the adhesive to selected areas on the substrate. The area where the adhesive is printed or applied can subsequently be used to attach the second substrate. Typical screen-printable adhesives are tacky pressure sensitive adhesives at room temperature, or heat activated adhesives that are tacky at room temperature but become tacky when heated. Examples of screen-printable adhesives are (meth) acrylic polymers and copolymers dispersed in organic solvents or water.

Acrylic adhesives (both pressure sensitive and thermally activated types) are widely used in the industry because they are stable over time and they can be formulated to adhere to a variety of different surfaces. Typical acrylic adhesives are prepared as taught in U.S. Patent RE 24,906 to Ulrich. As stricter environmental regulations have emerged, in general, technology in the field of adhesives has evolved from solvent-based materials to water-based materials and, to some extent, solvent-free materials. Solvent-free acrylate adhesives are known and fall into various treatment categories such as heat activated coatings and radiation curing including E-beam curing, ultraviolet treatment and gamma ray treatment. Solvent-free crosslinked compositions are known in the art, but they are not useful for bonding to other substrates because they are highly crosslinked and do not flow or become tacky even when heated.

UV treated adhesives are described in US Pat. No. 4,181,752 to Martens et al. Known adhesives treated by ultraviolet light have their own utility and advantages, but they are not easily screen printed as they tend to become viscous during screen printing. Accordingly, there is a need for pressure-sensitive and heat activated screen printable adhesives that are solvent-free and screen printable without the use of solvents and that provide good shear and peel strength.

Often an adhesive capable of carefully forming multiple electrical connections between two substrates in close proximity is known as an anisotropic conductive adhesive. Typically, such adhesives contain particles that are sufficiently conductive to provide electrical conductivity through the thickness (z-axis) of the film, while transfer tapes or non-fixed tapes do not provide conductivity to the film plane. In the form of a film. This film type is known as "z-axis adhesive film" or "ZAF". Typical applications of such adhesives are to connect flexible printed circuits with rigid circuits such as flat panel displays or epoxy-glass laminate printed circuit boards.

Several ZAF materials are described in the literature. Some of these ZAF materials use adhesive compositions of a non-reactive hot melted type, such as styrene / butadiene / styrene block copolymers. They provide long shelf life and short bonding times at low temperatures. However, they show weak resistance to elevated temperature and wet aging. Other ZAF materials typically use thermosetting resins that crosslink under the aid of a curing agent or catalyst at the bonding temperature. However, such ZAF materials generally require high bonding temperatures of 170 ° C. or higher and are difficult to use in thermosensitive substrates.

Known ZAF materials are also prepared using solvent softening. Typically, the solvent can be trapped or lost and can result in damage to the substrate and components. In addition, the use of effective catalysts at low temperatures generally reduces the shelf life of ZAF. In addition, the use of photoactivated curing agents in ZAF materials is known. However, such adhesives need to be protected from light to prevent hasty photoactivation. The method of the present invention employs a thermosetting adhesive film that can bond quickly at low temperatures, has a long shelf life at ambient temperature, and provides stable electrical and / or thermal connections over long periods of time.

Summary of the Invention

The present invention

(a) 25 to 100 parts by weight of one or more alkyl acrylate monomers;

(b) 0 to 75 parts by weight of one or more reinforcing comonomers;

(c) 25 to 150 parts by weight of polyepoxide resin per 100 parts of acrylate monomer; And

(d) comprising an effective amount of a thermally activated polyepoxide resin curing agent, wherein the composition or the components are substantially free of solvent, have a yield point greater than 3 Pascals, and a viscosity of less than 6000 centipoise at 25 ° C., described at room temperature Provides a screen-printable adhesive composition that can be applied to a.

In another embodiment, the present invention

(a) 25 to 100 parts by weight of one or more alkyl acrylate monomers;

(b) 0 to 75 parts by weight of one or more reinforcing comonomers; And

(c) providing a screen-printable composition comprising an effective amount of a core-shell polymer or a semicrystalline polymer, said composition and component being substantially solvent free, having a yield point greater than 3 Pascals and less than 6000 centipoise at 25 ° C. It provides a screen-printable adhesive composition having a viscosity of and which can be applied to a substrate at room temperature.

In another embodiment, the present invention

An acrylate polymer comprising a polymerization reaction product of (a) an acrylate monomer, and (ii) a crosslinking agent having an acrylate residue, a polyepoxide resin, an effective amount of a thermally active modified aliphatic amine polyepoxide resin curing agent (Which is insoluble in the adhesive film at 20 ° C.) and a thermally curable electrically conductive adhesive film (substantially free of this composition and the components (i) and (ii)) comprising an effective amount of the electrically conductive material. Applying to the substrate; And

(b) heating the adhesive film at a temperature of 90 to 180 ° C. for 15 seconds to 5 minutes to provide an electrical connection comprising curing the polyepoxide resin in the adhesive film.

In another embodiment, the present invention

An acrylate polymer, polyepoxide resin, comprising a polymerization reaction product of (a) (i) an acrylate monomer, and (ii) a crosslinking agent having an acrylate moiety (these compositions and the individual components being substantially free of solvent). Applying to the substrate a thermally curable thermally conductive adhesive film comprising an effective amount of a thermally active modified aliphatic amine polyepoxide resin curing agent (which is insoluble in the adhesive film at 20 ° C.) and an effective amount of the thermally conductive material; And

(b) heating the adhesive film at a temperature of 90 to 180 ° C. for 15 seconds to 5 minutes to provide a method of providing thermal transfer comprising curing the polyepoxide resin in the adhesive film.

The present invention also provides a tape using the adhesive composition.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or will be understood from the practice of the invention. The objects and other advantages of the invention will be realized and attained by the methods and products particularly pointed out in the written description and claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory, and are intended to provide further explanation of the invention as claimed.

The present invention relates to screen printable adhesive compositions and thermally curable electrically and / or thermally conductive adhesive films.

The screen printable pressure-bonded adhesive of the present invention is a substantially solvent-free acrylic polymer that can be screen printed without the need for a solvent. As used herein, the term "pressing bond" means an adhesive applied to a single surface, which can bind to the second surface under pressure. Screen printable adhesives include pressure sensitive adhesives that are tacky at room temperature and heat activated adhesives that are non-tacky at room temperature but are generally capable of bonding at elevated temperatures in the range of about 25 ° C to 200 ° C.

The thermally curable electrically and / or thermally conductive adhesive film of the present invention is a substantially solvent-free acrylic polymer further containing a polyepoxide resin, a polyepoxide resin curative, and an electrically conductive material and / or a thermally conductive material. . In addition, such a heat curable adhesive film may be pressure bonded as described above.

The term "polyepoxide" as used herein refers to one or more A molecule containing a group is meant.

As used herein, the term "substantially solvent free" refers to an adhesive prepared without using a large amount of solvent, i.e., using less than 5% by weight of the coating composition, preferably less than about 2% by weight of the coating composition. Adhesive, more preferably an adhesive prepared without adding additional solvent. The production of screen printable adhesives and adhesive films includes not only the method used for the polymerization of monomers present in the adhesive, but also the method used to coat the adhesive to produce a finished product, for example a pressure sensitive adhesive tape. The term "solvent" refers to conventional organic solvents used in the industry, including, for example, toluene, heptane, ethyl acetate, methyl ethyl ketone, acetone, and mixtures thereof.

The screen printable adhesives of the present invention are prepared from an adhesive composition comprising about 25 to 100 parts by weight of one or more alkyl acrylate monomers, and correspondingly about 75 to 0 parts by weight of corresponding reinforcing comonomers.

Alkyl acrylate monomers useful in the practice of the present invention which are screen printable are those having a homopolymer glass transition temperature of less than about 0 ° C. Useful alkyl acrylates are unsaturated monofunctional (meth) acrylic acid esters of non-tertiary alkyl alcohols having 2 to 20, preferably 4 to 18 carbon atoms in the alkyl moiety. Examples of useful alkyl acrylate monomers include n-butyl acrylate, hexyl acrylate, octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, decyl acrylate, lauryl acrylate, octadecyl Acrylates, and mixtures thereof, but is not limited thereto. Useful aromatic acrylates include phenoxy ethyl acrylate.

Monoethylenically unsaturated reinforced comonomers having homopolymer glass transition temperatures higher than about 25 ° C. are preferably copolymerized with acrylate monomers in the screen printable adhesives of the present invention. Examples of useful copolymerizable monomers include (meth) acrylic acid, N-vinyl pyrrolidone, N-vinyl caprolactam, substituted (meth) acrylamides such as N, N-dimethyl acrylamide, acrylonitrile, isobor Nyl acrylate, N-vinyl formamide and mixtures thereof, including but not limited to. When using a copolymerizable monomer, the alkyl acrylate is present in the screen printable composition in an amount of about 25 to 99 parts by weight, and the copolymerizable monomer is present in an amount corresponding to 75 to 1 parts by weight (total weight is 100). .

The amount and type of comonomers can be varied to provide the reduced pressure or thermal activation properties required for the end use. Large amounts of comonomers will make the tack less and suitable as heat activated adhesives, while small amounts of comonomers are more suitable for pressure sensitive adhesives. In addition, the type of comonomer can be varied to obtain the desired properties. Polar comonomers, ie comonomers having hydrogen-bonding moieties such as acrylic acid, are useful in amounts of about 1 to about 15 parts by weight for pressure sensitive screen printable adhesives. An amount exceeding about 15 parts by weight is useful as a heat activated screen printable adhesive. Low polar comonomers such as N-vinyl caprolactam, N-vinyl pyrrolidone and isobornyl acrylate provide pressure sensitive properties to screen printable adhesives of less than about 40 parts by weight, while amounts exceeding 40 parts by weight Thermally activated screen printable adhesives can be provided.

The screen printable adhesive compositions of the present invention are prepared such that they have a yield point and viscosity suitable for screen printing. The yield point is the stress required to flow the adhesive. Since the compositions are screen printed on a relatively large surface area, they must be fluid enough to provide a uniformly smooth surface within a short time, ie within minutes after screen printing. The composition is selected to provide a yield point high enough to maintain print resolution after printing on the substrate.

The compositions of the present invention generally have a measured yield point of greater than 3 Pascals, and preferably have a measured yield point of greater than 5 Pascals as measured by the Cassson Model. Casson model is Temple. See, by Pat C. Patton (Paint Flow and Pigment Dispersion, 2nd edition, 1979, pages 355-361), the disclosures of which are incorporated herein by reference. When the adhesive composition is filled with particles, the yield point is generally greater than about 10 pascals to assist in maintaining the particles in suspension.

Shear rate was measured as a function of applied shear stress using a Carri-Med CS Rheometer. The measurements were used in the Casson model to calculate the viscosity at infinite shear forces. The calculated viscosity of the screen printable composition should be low enough for screen printing but high enough to prevent excessive fluidity and maintain resolution. Preferably, the viscosity of the adhesive is less than about 6000 centipoise (cps) at 25 ° C., more preferably less than about 5000 centipoise and most preferably less than about 1500 centipoise. Typically, the viscosity is greater than 50 cps, but there is no specific lower limit when the composition thickens or coalesces when removing the screen. The composition containing the particles preferably has a viscosity of greater than about 100 cps.

Some adhesive compositions, in particular pressure sensitive adhesive compositions, are prone to threading, which makes them undesirable for screen printing. Threading can be reduced or eliminated by adjusting the molecular weight of the polymer and prepolymer in the composition.

In addition, the sagging can be reduced in partially polymerized syrup by adding a chain transfer agent to the monomer prior to polymerization to control the molecular weight.

Chain transfer agents useful in the practice of the present invention include, but are not limited to, carbon tetrabromide, n-dodecyl mercaptan, isooctyl thiol glycolate, and mixtures thereof. The chain transfer agent (s) is present in an amount of about 0.01 to about 1 part by weight, preferably about 0.02 to 0.5 pph per 100 parts by weight of acrylate, ie 100 parts of alkyl acrylate and reinforcing comonomer.

Polymers useful in adhesive compositions, ie syrups, have a weight average molecular weight of about 50,000 to 1,000,000. It is preferred that the molecular weight is from about 100,000 to about 800,000, most preferably from about 150,000 to about 600,000. Lower molecular weights limit the extensible viscosity and reduce the elongation of the adhesive during screen printing.

Fillers useful in the present invention include fumed silica that thickens the monomer mixture of monomers described above or syrup of monomers. Silica provides thixotropy to the mixture to thicken the mixture after the pressure in screen printing is removed.

It is also possible to add a thermoplastic polymer or a copolymer of suitable molecular weight, or a macropolymer to the monomer mixture or syrup of acrylates described above to obtain a solution having a useful viscosity that does not show slack. The polymer, copolymer or macropolymer preferably has a weight average molecular weight of less than about 100,000. Useful thermoplastic polymers include acrylic polymers such as poly (iso-butylmethacrylate) such as ELVACITE 2045 (manufactured by ICI Americas). Useful copolymers include block copolymers such as styrene butadiene copolymers and acrylic copolymers. Useful macropolymers are those copolymerizable with acrylate monomers, which are described in US Pat. No. 4,554,324 to Husman et al., The disclosure of which is incorporated herein by reference, and is commercially available from IC Americas. (ELVACITE 1010).

Other useful thermoplastic polymers or copolymers include semi-crystalline polymers that are sufficiently thickened and form yield stress in the adhesive composition to prevent the adhesive composition from flowing after screen printing the adhesive composition. Useful semicrystalline polymers can also be dissolved in acrylate monomers at temperatures of about 80 ° C. and form clear solutions. Examples of useful semicrystalline polymers include ethylene / ethyl acrylate / glycidyl methacrylate terpolymers available from Elf Atochem North America, Philadelphia, PA, and Cincinnati, Ohio. Ethylene / butyl acrylate / glycidyl methacrylate terpolymer, marketed under the trade name ENATHENE ™ from Quantum Chemicals, USA, and DuPont Company, Wilmington, Delaware, USA. Ethylene / Ethyl Acrylate / Carbon Monooxide Terpolymer. The semicrystalline polymer preferably comprises more than 20% by weight of non-ethylenic comonomer and preferably has a melt index in the range of about 75 g / min at 190 ° C (ASTM D1238).

In the practice of the invention, the polymer, copolymer, semicrystalline polymer, or macropolymer is dissolved in acrylate monomer or syrup. This can be done on conventional equipment such as roller mills, ball mills and the like. The monomer or syrup may be heated to about 80 ° C., for example, to increase dissolution of the polymer or macropolymer. Screen printable adhesive compositions of the invention using semicrystalline polymers do not require additional thixotropic agents to obtain the yield point required when the semicrystalline polymer is separated into crystalline and amorphous regions, and is suitable for screen printing. Provided is a tropic adhesive composition.

Semicrystalline polymers are used in screen printable adhesive compositions in amounts of about 3 to 20% by weight and preferably 5 to 15% by weight.

Another embodiment of the screen printable adhesive composition of the present invention contains a polyepoxide resin or a mixture of polyepoxide resins. Polyepoxide resins may be added to the monomer mixtures or syrups of the acrylates described above to control the viscosity of the adhesive composition and to prevent laminar sagging. Useful polyepoxide resins include resins selected from the group of compounds containing an average of at least one, preferably at least two, epoxide groups per molecule. The polyepoxide resin can be solid, semisolid or liquid at room temperature. Combinations of different kinds of polyepoxide resins can also be used to achieve the desired viscosity.

Representative polyepoxide resins include phenolic polyepoxide resins, bisphenol polyepoxide resins, hydrogenated polyepoxide resins, aliphatic polyepoxide resins, halogenated bisphenol polyepoxide resins, novolac polyepoxide resins and mixtures thereof do. Preferred polyepoxide resins include diglycidyl ethers of bisphenol A. Examples of useful polyepoxide resins commercially available include resins of EPON ™ 164, EPON 825, EPON 828 and EPON 1002, available from Shell Chemical Co., Houston, Texas. Preferred polyepoxide resins have a molecular weight of about 300-2000.

Polyepoxide resins are used in the compositions of the present invention in an effective amount capable of providing a screen printable viscosity (at room temperature) with little or no stretching of the composition. The polyepoxide resin may be used in the screen printable adhesive composition of the present invention in an amount of about 25 parts to about 150 parts per 100 parts of acrylate monomer. Preferably, the amount of polyepoxide resin used is about 60 to about 120 parts, more preferably about 65 to about 110 parts, per 100 parts of acrylate monomer.

In practical use, polyepoxide resins are mixed into acrylate monomers or acrylate syrups using conventional mixing techniques such as gentle rolling, roller and ball milling, and the like. In addition, the acrylate monomer or syrup may be heated to about 80 ° C. to enhance mixing of the polyepoxide resin.

The polyepoxide resin is cured with any kind of polyepoxide curing agent and is preferably cured using a heat activated curing agent. Useful polyepoxide curing agents may be acid or base curing agents. Preferably, the polyepoxide curing agent used is a base curing agent, is insoluble in the polyepoxide resin at a temperature of about 20 ° C., and is soluble in the polyepoxide resin when the polyepoxide resin is heated to a temperature of about 60 ° C. or more. The polyepoxide resin is cured at elevated temperatures, for example at temperatures exceeding 160 ° C. "Insoluble" means that there is no substantial hardening of the polyepoxide over a long time at room temperature. Examples of useful curing agents for curing polyepoxide resins at elevated temperatures include dicyandiamides used in combination with the accelerators described below.

If the oven cure temperature is not sufficient to sufficiently cure the polyepoxide resin when using the curing agent, it may be used in the screen printable adhesive composition prior to screen printing to allow the resin to cure at a lower temperature or within a shorter time. It is useful to include accelerators. Imidazole and urea derivatives are particularly preferred as accelerators because they do not reduce the shelf life of the screen printable adhesive compositions of the present invention. Examples of useful imidazoles include 2,4-diamino-6- (2'-methyl-imidazoyl) -ethyl-s-triazine isocyanurate, 2-phenyl-4-benzyl-5-hydroxymethyl Imidazole, 2,4-diamino-6 (2'-methyl-imidazoyl) -ethyl-s-triazine, hexakis (imidazole) nickel phthalate and toluene bisdimethylurea. The accelerator may be used in the adhesive composition of the present invention in an amount of about 20 parts by weight or less per 100 parts by weight of acrylate monomer.

In the case of adhesive compositions of the present invention which are screen printed on polymeric substrates, in particular thin polymer substrates which may be deformed upon prolonged exposure to high temperatures or moderately high temperatures, the preferred polyepoxide curing agents are those of the polyepoxide resin at relatively low temperatures. To induce rapid curing and / or to cure polyepoxide resins. Such hardeners include modified amines. Examples of modified amines include addition products of amines with epoxy resins, alkylene epoxides or acrylonitrile, and condensation reaction products of amines with fatty acids or Mannich bases. Generally, the modified amine curing agent cures the polyepoxide resin when the composition is exposed to 90 to 180 ° C. and has a curing time of 15 seconds to 5 minutes. Preferably, the polyepoxide resin is cured at a temperature of 110 to 160 ° C., and the curing time is 15 seconds to 3 minutes. More preferably, the polyepoxide resin is cured within 15 to 90 seconds at a curing temperature of 120 to 150 ° C. Preferred modified amine polyepoxide curing agents are reaction products of novolak polyepoxide resins with aliphatic di-primary amines. Examples of such modified amine curing agents are those sold under the trade names ANCAMINE, such as ANCAMINE 2337S and 2014 curing agents, from Air Products and Chemicals, Inc. and from Ajinimoto, Japan. Which include Ajicure AJICURE ™ PN23 and MY23.

In practical use, the polyepoxide resin curing agent is dispersed in the polyepoxide resin / acrylate monomer or syrup composition under conventional suitable mixing, for example using a paddle mixer or the like. Preferably, the curing agent is dispersed in the epoxide or adhesive composition containing the component (s).

Preferably, the polyepoxide curing agent is included in the adhesive composition in an amount sufficient to act on the curing of the polyepoxide resin under heating. Generally, the heat activated polyepoxide curing agent is used in an amount of about 0.1 to about 20 parts by weight, preferably about 0.5 to about 10 parts by weight per 100 parts by weight of the total adhesive composition.

Another embodiment of the screen printable adhesive composition of the present invention contains crosslinked polymer particles that are swellable in acrylate monomers and are known as "core-shell" polymers. Core-shell polymers are polymer particles having an elastomer or rubber core substantially surrounded by a shell material, which is generally a thermoplastic polymer. The core is formed from polymeric diene or acrylic rubber, and the shell material is generally a polyacrylate or polymethacrylate polymer. Preferred core-shell polymers are those that can be completely dispersed in the acrylate monomer, ie, to provide a visually smooth dispersion as measured by, for example, a Hegman gauge.

Preferred core-shell polymers have a particle size of less than 5 microns, more preferably less than 1 micron. In general, core-shell particles are added to the acrylate monomers in an amount that provides viscosity and yield stress suitable for screen printing. If too much core-shell polymer is added to the composition, the polymer will not disperse properly. If it is added in a small amount to the composition, the composition will not have the yield stress required for screen printing. Examples of commercially available core-shell polymers include KANE ACE M901, available from Kaneka Co., Japan, and PARALOID, available from Rohm & Haas, Philadelphia, PA. ) EXL-2691 and PARALOID EXL-2691A.

The core-shell polymer is present in the screen printable composition in an amount of 5 to 25% by weight, preferably 10 to 20% by weight of the screen printable composition.

In practical use, the core-shell polymer is added to and dispersed in an acrylate monomer, wherein the particles swell with the acrylate monomer to form a thixotropic composition having a viscosity suitable for screen printing.

In a preferred embodiment, the adhesive composition may comprise a thixotropic agent, such as silica, to impart thixotropy to the composition if necessary. The viscosity of the thixotropic composition is reduced when subjected to shear stress, such that it flows during screen printing. Once the shear stress is removed, the viscosity of the thixotropic material increases rapidly so that the printed adhesive does not substantially flow once printed on the substrate. Suitable silicas are the trade name CAB-O-SIL (trade name) (e.g. M-5 and TS-720) available from Cabot Corporation and AEROSIL (trade name) 972 silica available from DeGussa Corporation. to be.

In another preferred embodiment, the screen printable adhesive composition may comprise an electrically conductive material. Such materials include metal particles and spheres such as aluminum, nickel, gold, copper or silver, and coated copper, nickel, conductive coatings such as aluminum, gold, silver, copper or nickel and polymers coated with glass Including but not limited to spheres and particles. Also useful are brazed particles (commercially available from Sheritt Gordon Limited, Canada), such as lead / tin alloys, in which the amount of each metal is different. Examples of commercially available electrically conductive particles include conductive nickel spheres commercially available from Novamet, Inc., Wykov, NJ. Electrically conductive materials are commercially available from Japan Chemicals Inc., Japan, Potters Industries Inc., Parsippany, NY, and Sherit Gordon.

The amount of electrically conductive material used in the screen printable adhesive composition of the present invention depends on the type of substrate to be bonded and the purpose of use thereof. For example, in order to connect a flexible circuit to a circuit board or a liquid crystal display (LCD) where anisotropic or "z" axial electrical conductivity is required, the screen printable adhesive composition may be in the range of 1-20, preferably 1-10 vol%. It contains an electrically conductive material. When shielding or grounding, for example, printed circuit boards to a heat sink or bonding for electromagnetic interference (EMI) shielding, the screen printable adhesive composition may be from 1 to 80, preferably from 1 to 70 volume percent of electrically conductive material. It contains.

In addition, the screen printable composition of the present invention preferably includes a free radical initiator. Initiators are known in the art and are preferably photoactivated. In a preferred embodiment, the initiator is a photoinitiator, for example substituted acetophenones such as 2,2-dimethoxy-2-2-phenylacetophenone, benzoin ethers such as benzoin methyl ether, substituted Benzoin ethers such as anisoin methyl ether, substituted alpha-ketols such as 2-methyl-2-hydroxypropiophenone, phosphine oxide and polymerizable photoinitiators. Photoinitiators are IRGACURE (trade name) of Ciba Geigy Corp., for example IRGACURE 184, IRGACURE 651, IRGACURE 369, IRGACURE 907, ESCACURE (trademark) of Sartomer and BASF. LUCIRIN (trade name) Commercially available as TPO.

The photoinitiator may be used in an amount of about 0.001 to about 5 pph depending on the type and molecular weight of the photoinitiator. Generally, low molecular weight materials are used in amounts of about 0.001 to about 2 pph and high molecular weight polymer photoinitiators are used in amounts of about 0.1 to about 5 pph.

Crosslinking agents can be added to the screen printable adhesive composition to improve the adhesion of the adhesive.

Useful crosslinking agents include polyfunctional acrylates, such as those described in Heilman, US Pat. No. 4,379,201, for example 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, 1,2-ethylene Glycol diacrylates, pentaerythritol tetraacrylates and mixtures thereof, copolymerizable aromatic ketone comonomers as described in Kellen U.S. Pat.No. 4,737,559, U.S. Patent 4,329,384 to Vesley et al., Photoactive triazines, organosilanes, benzophenones and isocyanates as described in US Pat. Nos. 4,330,590 and 4,391,687, but are not limited thereto. Thermally activated organic peroxides such as di-t-butyl peroxide can also be used for thermal crosslinking. Other useful crosslinkers include EBECRYL® 230, EBECRYL 3605 and EBECRYL 8804 from UCB Radcure Inc., Smina, GA, USA, and CN under the trade name CN from Sartomer, Exton, Pa. Examples include urethane and epoxy diacrylate oligomers available under the trade name 104.

The crosslinking binder is included in an amount of about 0.002 pph (parts per 100 parts of acrylate monomer, ie alkyl acrylate and optional comonomer) to about 2 pph, preferably about 0.01 pph to about 0.5 pph. The amount used will depend on the functional groups and molecular weight of the crosslinker and the desired properties of the adhesive. In the case of an electrically conductive screen printable adhesive, the amount of crosslinker and chain transfer agent is preferably limited to flow sufficiently during bonding of the adhesive so that the conductive particles contact each other or contact the conductive portion of the substrate to provide a conductive path. Preferred thermally activated electrically conductive screen printable adhesives have a tanδ greater than 1, measured at 1 radian / second above 140 ° C. At this temperature, the adhesive has a fluidity similar to a viscous liquid.

In addition, an adhesive may be added to the syrup of the screen printable composition to increase adhesion to certain low energy surfaces such as olefin substrates. Useful tackifiers include hydrogenated hydrocarbon resins, phenol modified terpenes, poly (t-butyl styrene), rosine esters, vinyl cyclohexane, and the like. Suitable adhesive resins are commercially available and include, for example, REGALREZ ™ and FORAL ™ in Hercules, for example REGALREZ 1085, REGALREZ 1094, REGALREZ 6108, REGALREZ 3102 and FORAL 85.

In use, the pressure-sensitive adhesive may be used in an amount of about 1 to about 100 pph, preferably 2 to 60 pph, more preferably 3 to 50 pph.

Other auxiliaries may be included in the screen printable composition before and after the preparation of the syrup in the amounts required for the desired properties, so long as they do not affect the polymerization and the desired properties. Useful auxiliaries include, for example, dyes, pigments, fillers, coupling agents and thermally conductive materials.

Screen printable adhesives are useful in the manufacture of pressure sensitive adhesive coating articles such as tapes and sheets. The tape generally has a narrow width relative to its length. Sheets are generally substantially the same length and width and can be made in the same way as tape. The tape can be made as a transfer tape, generally provided with a screen printable adhesive on a liner coated on both sides with a release coating. The tape can also be made by permanently attaching the adhesive to the back side. Tapes permanently attached to the backing may be prepared by laminating the adhesive of the transfer tape on the back or coating the composition on the back and curing the adhesive on the back. The tape may also be a double coated tape with both sides of the back side having an adhesive layer thereon. Useful backing materials are polymer films such as cast and oriented polyesters, cast and oriented polypropylenes, films made of polyethylene, paper, metal foils, wovens and nonwovens, and foams such as polyolefins and acrylic products. Foams. Examples of suitable acrylic foams are those described in US Pat. No. 4,415,615 to Esmay et al. Suitable polyolefin foams include crosslinked polyethylene and polyethylene / EVA foams.

The screen printable adhesives of the present invention are particularly useful for performing screen printing directly on a substrate when it is desired to have the adhesive only on selected areas of the surface. One example of such a substrate is a flexible electrical circuit. Flexible electrical circuits generally include a polymer film coated with an electrically conductive metal such as copper that is etched to provide an electrically conductive circuit line. Polymer films are also polyimide, although other types of films such as polyester are also used. Suitable flexible circuits are commercially available from Minnesota Mining and Manufacturing Company, St. Paul, Minn., USA and Nippon Graphite, Ltd. Flexible circuits are also described in US Pat. Nos. 4,640,981, 4,659,872, 4,243,455, and 5,122,215. For this kind of use, preferred screen-printable compositions for adhesives comprise about 25-99 parts of alkyl acrylate monomers and 75-1 part of one or more reinforcing monomers free of acid, and 1-10% by volume of electrically conductive particles. It includes. Preferably the comonomer is isobornyl acrylate and the electrically conductive particles are present in an amount of about 1 to 5 vol%.

Flexible electrical circuits are used, for example, in electronic devices where electrical interconnections must exist between two circuit boards or between a circuit board and a liquid crystal display (LCD). Such connectors are useful for a variety of electronic products such as calculators, computers, pagers, mobile phones, and the like.

In addition, screen printable adhesives are usefully used as damping polymers. The polymer may be used as a free layer damper in which adhesive is used alone or as a restraining layer damper. In the constraint layer damper, the adhesive is attached to a material having a higher modulus of elasticity than the adhesive. Examples of useful constraint layers include, but are not limited to, metals such as aluminum, stainless steel, cold rolled steel, and the like. In practical use, the adhesive of the present invention can be screen printed directly onto the restraint layer. If the adhesive material is not pressure sensitive, the adhesive may be attached to the restraining layer, for example by heating to 70 ° C. and applying pressure on the adhesive.

In the practice of the invention, the syrup is formed by partially polymerizing a mixture of alkyl acrylates, optional comonomers, free radical initiators and chain transfer agents. Free radical initiators useful in preparing syrups include thermal initiators and photoinitiators as described above. Suitable thermally activated free radical initiators are commercially available from DuPont Company under the name VAZO. Specific examples are VAZO 64 (2,2'-azobis (isobutyronitrile)) and VAZO 52. Useful amounts may vary from about 0.01 to about 2 pph. Preferably partial polymerization is carried out by means of an ultraviolet lamp with a photoinitiator. More preferably, the partial polymerization has most emission spectra between about 280 and 400 nm and peak emission at about 350 nm at an intensity of less than 20 mW / cm 2. The composition comprising the syrup, additional photoinitiator, optional crosslinker (s) and any other preferred auxiliaries is mixed, optionally degassed and coated on the substrate. Suitable substrates include, for example, polymeric films such as polyester films, paper, metals, ceramics, glass, flexible electrical circuits, and the like. The substrate is optionally treated with a release coating such as a silicone release agent, TEFLON ™ coating, perfluoropolyether coating, and the like. The coated composition is then exposed to a low oxygen atmosphere, ie an ultraviolet lamp containing less than about 500 ppm, preferably less than about 200 ppm, to cure the composition with the pressure-bonding adhesive. Optionally, the cured screen printable adhesive can further crosslink the adhesive by exposure to other energy sources such as heat, electron beam, high intensity ultraviolet light, and the like.

In other methods of making screen printable adhesives, acrylate monomers, optional comonomers, free radical initiators, optional crosslinkers, optional thixotropic agents, and (1) polyepoxide resins and polyepoxide curing agents, (2 ) The core-shell polymer, (3) semicrystalline polymer or (4) amorphous thermoplastic, and any other preferred auxiliaries are mixed to form a homogeneous mixture. After coating the mixture onto the substrate, the acrylate is polymerized as described above. When the screen printable adhesive contains a polyepoxide resin and a polyepoxide curing agent, the polyepoxide resin is cured as described above.

In another embodiment of the present invention, a thermally curable adhesive composition comprising an acrylate monomer, a crosslinking agent (defined below), a polyepoxide resin, a polyepoxide resin curative and an electrically conductive material and / or a thermally conductive material is selected from And / or thermally conductive and thermally curable adhesive films. Electrically conductive thermosetting adhesive films are useful for bonding and interconnecting electrical substrates at connection and grounding. Thermally conductive thermosetting adhesive films are useful for bonding thermally transfer substrates. Preferably, the thermally curable adhesive film of the present invention may contain photoinitiators and may include polymeric modifiers or property enhancing materials, such as core-shell materials and thermoplastic polymers.

Thermally curable adhesive films may be tacky or non-tacky upon contact, and screen printability is not required. Surprisingly, the electrically conductive thermally curable adhesive film of the present invention provides acceptable electrical conductivity and bond strength performance as the degree of cure of a low polyepoxide resin of 50%. For example, in products with a resistance of less than 5 ohms, the resistance remains stable even after time passes. That is, the resistance is less than 3 ohms, preferably less than 1 ohm, during its use. Unexpectedly, the heat curable adhesive film of the present invention can be suitably cured at a relatively low temperature and a relatively short time. In addition, the heat curable adhesive film of the present invention is stable for a period of up to 16 months at room temperature.

Preferred thermally curable electrically conductive adhesive films include a) an acrylic polymer comprising a reaction product of an acrylate monomer, a crosslinking agent having an acrylate residue, and a photoinitiator; b) polyepoxide resin; c) a polyepoxide curing agent and d) an electrically conductive material.

Preferred thermally curable thermally conductive adhesive films include a) an acrylic polymer comprising a reaction product of an acrylate monomer, a crosslinking agent having an acrylate residue, and a photoinitiator; b) polyepoxide resin; c) a polyepoxide curing agent and d) a thermally conductive material.

Generally, the polyepoxide resin is present in the adhesive film composition in a polyepoxide resin: acrylate monomer weight ratio of 30:70 to 70:30. Preferred polyepoxide: acrylate monomer weight ratios are 40:60 to 60:40.

Generally, the crosslinking agent is present in the adhesive film composition in a crosslinker: acrylate monomer weight ratio of 20:80 to 0.1: 99.9. Preferred crosslinker: acrylate monomer weight ratios are from 10:90 to 2:98.

Generally, the polyepoxide curing agent is present in the adhesive film composition in a weight ratio of curing agent: polyepoxide resin of 30: 100 to 60: 100. Preferred curing agents: polyepoxide resin weight ratios are from 35: 100 to 50: 100.

Generally, the free radical initiator is present in the adhesive film composition in an initiator: total acrylate weight ratio of 0.1: 99.9 to 2:98. Preferred initiator: total acrylate weight ratio is from 1:99 to 0.3: 99.7.

Useful polyepoxide resins for use in the thermally curable adhesive films of the present invention include phenolic polyepoxide resins, halogenated bisphenol polyepoxide resins, novolac polyepoxide resins, and mixtures thereof. Includes references to The polyepoxide resin can be liquid or solid as long as acceptable adhesive coating properties and film processing properties are maintained. Preferred polyepoxide resins include polyfunctional novolac polyepoxide resins (equivalent to about 200 to 240) and liquid bisphenol A polyepoxide resins (equivalent to about 172 to 192). Preferred commercially available polyepoxide resins include EPON ™ 164, EPON 825 and EPON 828 available from Shell Chemical Co., Houston, Texas.

Useful acrylate monomers used in the heat curable adhesive films of the present invention include monofunctional (meth) acrylic acid esters of non-tertiary alkyl alcohols having 2 to 20, preferably 4 to 18 carbon atoms in the alkyl moiety. And those mentioned for the screen printable adhesive composition. In embodiments of the heat curable adhesive film of the present invention, useful acrylate monomers may include the acrylate monomers mentioned above as reinforcing comonomers for use in screen printable adhesive compositions. Preferred acrylate monomers or combinations of acrylate monomers are those which are miscible with the polyepoxide resin and do not dissolve the polyepoxide curing agent prior to the polymerization of the acrylate. Preferred acrylate monomers include phenoxyethyl acrylate and isobornyl acrylate.

In addition, the heat curable adhesive film composition of the present invention contains at least one crosslinking agent for crosslinking the acrylate component of the adhesive composition. In general, crosslinkers include difunctional compounds having two or more ethylenically unsaturated residues and compounds having two or more ethylenically unsaturated residues. Useful crosslinking agents include the polyfunctional acrylates and difunctional epoxide-acrylates mentioned above for screen printable adhesive compositions. Preferred crosslinking agents are those which are miscible with the polyepoxide resin and do not dissolve the polyepoxide curing agent prior to the polymerization of the acrylate. Preferred crosslinkers include urethane and epoxy diacrylate oligomers. Examples of useful crosslinkers commercially available include the trade names EBECRYL 230, EBECRYL 3605, EBECRYL 8804 from Smirna, Georgia, USA, and the trade name CN 104 from Sartomer, Exton, Pa.

The heat curable adhesive film of the present invention contains a heat activated polyepoxide curing agent. Preferably, the heat activated curing agent is a modified aliphatic amine curing agent that is insoluble in the adhesive composition matrix at room temperature. In general, modified aliphatic amines include addition products of amines and epoxy resins, alkylene epoxides or acrylonitrile and condensation reaction products of fatty amines with fatty acids or Mannich bases. Preferably, the polyepoxide curing agent is insoluble in the polyepoxide resin at a temperature of about 20 ° C. and is soluble in the polyepoxide resin when the polyepoxide resin is heated to about 60 ° C. "Insoluble polyepoxide curing agent" means a curing agent that does not cause substantial curing of the polyepoxide at room temperature for extended periods of time. Insolubility of the curing agent in the adhesive composition matrix at ambient temperature provides an adhesive film of the invention that is storage stable for less than about 16 months. Preferred modified aliphatic amine curing agents are reaction products of novolac polyepoxide resins and di-tertiary aliphatic amines. Preferred polyepoxide curing agents are those sold by Air Products and Chemicals, Inc., Allentown, PA, under the trade name "ANCAMINE 2337S". In practice, insoluble curing agents are uniformly dispersed throughout the adhesive composition. In addition, accelerators for the polyepoxide curing reaction may optionally be added to the adhesive composition of the present invention. Useful promoters include those listed above for use in screen-printable adhesive compositions.

In addition, the heat curable adhesive film of the present invention preferably comprises a free radical initiator that polymerizes the acrylate-containing acrylate component of the adhesive composition. Useful initiators include those described above for use in screen-printable adhesive compositions and are preferably photoinitiators. Useful photoinitiators in the adhesive film compositions of the present invention include those listed above for use in screen-printable adhesive compositions. Examples of preferred photoinitiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and 2-hydroxy-2-methyl And mixtures of -1-phenyl-2-propanone. Useful commercial photoinitiators are commercially available from BASF Corp. of Charlotte, North Carolina under the trade name "LUCIRIN TPO" and CIBA-GIEGY of Terrytown, NY, under the trade designation "CGI." 1700 "is available. Of course, the acrylate component may also be polymerized by exposure to ionizing radiation, such as electron beam radiation known in the art.

The heat curable adhesive film of the present invention may preferably contain an electrically conductive agent or a conductive material. Useful electrically conductive materials include those listed above for screen-printable adhesive compositions comprising metal particles and spheres, and metal or polymeric or ceramic particles and spheres coated with an electrically conductive coating, and also electrically conductive weaving. And nonwoven materials, whiskers, fibers, and flakes. Some of the electrically conductive materials listed also exhibit useful thermal conductivity and include metal particles. Preferred electrically conductive particles include silver coated glass spheres, gold coated nickel particles, and silver coated nickel particles. Preferred electrically conductive particles are commercially available from Potters Industries Inc., Parsippany, NJ under the trade names “CONDUCT-O-FIL S-3000-S-3M” and “S-3000-S-3MM”. And gold-coated nickel particles sold by Novamet Corporation of Yokob, NJ.

The heat curable adhesive film of the present invention may also comprise a thermally conductive electrically insulating material. Thermally conductive electrically insulating materials typically include aluminum oxide, glass, boron nitride, ceramics such as zinc oxide, and nonceramic such as diamonds. This material may be in the same form as listed above for the electrically conductive material. Preferred thermally conductive, electrically insulating materials include aluminum oxide and boron nitride.

The amount of electrically conductive material used in the heat curable adhesive film of the present invention depends on the type of substrate to be bonded and its end use. For example, to interconnect a flexible circuit to a circuit board or a liquid crystal display (LCD) that requires anisotropic or "z" axial electrical conductivity, the thermally curable adhesive film composition may comprise an electrically conductive material of 1 to 20 volumes based on the composition. %, Preferably 1 to 10% by volume. In combination for shielding or grounding, for example, to ground a printed circuit board to a heat sink, or to shield electromagnetic interference (EMI), the thermally curable adhesive film composition may be comprised of 1 to 80% by volume of the electrically conductive material based on the adhesive composition. And preferably 1 to 70% by volume.

For adhesive bonding that requires a thermally curable adhesive film having both thermal and electrical conductivity, the thermally curable adhesive film composition may be selected from about 5 to 80% by volume, preferably 5 to 70% by volume, based on the adhesive composition. It contains. The thermally conductive material is present in an amount of 5 to 80 volume percent, preferably 5 to 70 volume percent, based on the adhesive composition. Alternatively, electrically conductive and thermally conductive materials, such as solid metal particles in the thermally curable adhesive film of the present invention, can be used at 5 to 80% by volume.

For adhesive bonding requiring a thermally curable adhesive film having only thermal conductivity, the adhesive composition contains a thermally conductive electrically insulating material at 5 to 80% by volume, preferably 5 to 70% by volume, based on the adhesive composition.

The heat curable adhesive composition of the present invention may include a material that improves the adhesive composition processability, the adhesive film handleability, and the mechanical properties of the heat cured film. These materials include core-shell impact strength modifiers, including thermoplastic polymers, and core-shell polymers, which are described for use in screen-printable adhesive compositions. Preferred property enhancing materials are methacrylate / butadiene / styrene core-shell impact modifiers, phenoxy thermoplastics, and amorphous linear saturated copolyesters. Examples of commercially available property enhancing materials include "PARALOID® EXL-2691A" core-shell particles from Rohm & Haas Co., Philadelphia, PA, Phenoxy, Rock Hill, SC. "PKHP (R) 200" phenoxy resin particles from Phenoxy Associates and "BOSTIK (R) 7900" copolyester from Bostik, Middleton, MA.

Generally, the thermoplastic polymer is present in the adhesive film composition in a ratio such that the weight ratio of thermoplastic polymer: adhesive composition is from 0: 100 to 10:90, preferably from 0: 100 to 8:92. In general, the core-shell impact strength modifier is present in the adhesive film composition in a ratio where the weight ratio of core-shell: adhesive composition is from 0: 100 to 15:85, preferably from 0: 100 to 10:90.

The heat curable adhesive film of the present invention is generally prepared by first forming a heat curable adhesive composition. Generally, heat curable adhesive compositions are prepared by dissolving and dispersing the components until a homogeneous mixture is obtained. The adhesive composition is then coated onto a substrate, such as a release liner, or between two release liners, as described above for the screen-printable adhesive composition. The heat curable adhesive composition may be coated onto the substrate by a method comprising a knife, knife-over layer, roll and die coating. The acrylate monomer and crosslinker are then polymerized in the presence of polyepoxide resin and other components to form a heat curable adhesive film. The acrylate monomers and crosslinkers are preferably polymerized by exposing the coated adhesive composition to low intensity UV radiation under an oxygen free atmosphere as described above for screen-printable compositions. In addition, the time and the degree of exposure to irradiation do not cause the reaction of the thermally activated curing agent and the polyepoxide resin, and if an ethylenically unsaturated group-containing compound such as acrylate and bifunctional compound are present, they are almost completely polymerized. And sufficient to crosslink. Thermally curable adhesive films may be used in articles or adhesive sheets coated with adhesive, such as single or double-sided tapes, as described above for screen-printable adhesive compositions. Preferably, the heat curable adhesive film is made between two release liners to provide a transferable heat curable adhesive film, or transfer tape.

When a heat curable adhesive is produced between two release liners, one release liner is removed, the heat curable adhesive film is placed on the substrate to be bonded, the second release liner is removed, and the second substrate is heat curable. It is located on the adhesive film.

Once the thermosetting adhesive film is properly positioned relative to the substrate to be bonded, the film is heated at a time and temperature sufficient to cure the polyepoxide resin such that the degree of cure measured by a differential scanning calorimeter is at least about 50%. Substantially time and temperature depend on the particular component in the heat curable adhesive composition and the substrate to be bonded. In general, the adhesive film of the present invention cures for a temperature in the range of 90 to 180 ° C. and a curing time of 15 seconds to 5 minutes. Preferably, the adhesive film is cured for a temperature between 110 and 160 ° C. and a curing time of 15 seconds to 3 minutes or less. More preferably, the adhesive film is cured for 15 to 90 seconds at a curing temperature of 120 to 150 ° C.

The degree of pressure necessary to bond the heat curable adhesive film of the present invention depends on the substrate to be bonded and its end use. Some substrate / adhesive film combinations do not require any applied pressure. For example, to form an electrical interconnect between the substrates, sufficient pressure is applied to fluidize the adhesive sufficient to contact the conductive material with the substrate to form an electrically conductive adhesive bond. For most electrical and thermal applications, sufficient pressure is applied to the heat curable adhesive film to evenly wet the adhesive to the substrate surface. The degree of pressure required (if necessary) will be determined by one skilled in the art without the need for experimentation.

The thermosetting adhesive film can be cured by using any known means of applying heat and, if necessary, pressure, for example hot bar bonds, or by placing the substrate under initial pressure and then heating.

If other auxiliaries do not achieve polymerization of acrylates or curing of polyepoxide resins and the desired final properties, they may be included in the composition in amounts necessary to achieve the desired properties. Useful auxiliaries include dyes, pigments, fillers and coupling agents.

The following non-limiting examples illustrate the specific embodiments of the present invention.

<Test Method-Screen-Printable Adhesives>

Electrical conductivity

This test measures electrical resistance through adhesive bonds and conductive circuits. The resistance value should be less than about 100 ohms, preferably less than about 20 ohms.

3M (trade name) of a flexible circuit coated with a straight 0.2 mm (8 mil) pitch adhesive (Minnesota Mining & Manufacturing Co., St. Paul, Minn.) A test sample is prepared by bonding a heat-sealed connector between a printed circuit board (FR-4 test board) and an ITO coated glass plate (specific resistance 20 ohms / square, Nippon Sheet Glass, Japan). The circuit placement lines of the flexible electrical circuit are parallel to the corresponding placement lines on the circuit board and are joined by passive pressure for pressure sensitive adhesives or by hot bar bonding for heat activated adhesives. Hot bar bonding is performed for 10 seconds using a 3 mm x 25.4 mm thermomode (thermode, TCW125, Palomar Systems, Carlsbad, CA) set at 145 ° C and 800 psi (5516 kPa). The other end of the flexible circuit is bonded to the ITO coated side of the glass plate. In a sample that is overcoated, ie, the adhesive covers the entire flexible circuit, only the area in contact with the thermo mode is bonded to the circuit board. For screen printed samples, only certain areas are printed with adhesive.

The electrical resistance of the interconnections by the adhesive is measured by the four-wire method using the principles described in ASTM B 539-90 such that the net resistance due to the interconnection is minimized to about 150 milliohms. . Results include average resistance (AVG), minimum resistance (MIN), and maximum resistance (MAX). After binding (initial) and at 60 ° C., 95% relative humidity, the samples are tested after aging for 10 days (after aging).

90。 Peel Adhesion

Flexible electrical circuits can be used with adhesive on either FR-4 circuit boards with 20 Ohm / square sheet resistivity or indium tin oxide (ITO) glass plates (Nippon Sheet Glass, Japan). This test is performed by manually or by using a 3 mm x 25.4 mm pulsed thermostat (TCW125, Paloma Systems, Carlsbad, Calif.) Set at 145 ° C and 800 psi (5516 kPa) for 10 seconds. . The circuit board is mounted in the fixture of the lower jaw of the Instron® tensile tester so that the flexible circuit mounted in the upper jaw is peeled off at a 90 ° angle. The width of the flexible circuit is 1.9 x 2.5 cm. Jaw separation rate is 2.54 mm per minute and the results are reported in g / cm. After binding (initial) and at 60 ° C., 95% relative humidity, after 10 days of aging (after aging), the samples are tested and the results are reported in g / cm.

Molecular Weight

The molecular weight of the syrup is determined by typical gel permeation chromatography. Experimental instruments include a Hewlett-Packard model 1090 chromatograph, a Hewlett-Packard model 1047A refractive index detector, and a variable wavelength UV detector set to 254 nm. The chromatograph was equipped with an ASI Permagel 10 micron column. The system was assayed with a polystyrene standard from Pressure Chemical Co. Nelson Analytical hardware and software are used to convert the signals to digital reactions and the molecular weight (weight average) is determined using software from Polymer Labs. GPC assays are described in detail in Modern Size Exclusion Liquid Chromatography: Practice of Gel Permeation Chromatography , John Wiley and Sons, 1979.

Samples are prepared by pretreatment with diazomethane in diethyl ether. After drying, the sample is dissolved in tetrahydrofuran (THF) at a concentration of 2.0 mg / THF ml and filtered through a 0.2 μm TEFLON ™ filter. Samples are injected into the column at a volume of 100 μl and eluted at a rate of 1 ml / min through the column maintained at 21 ° C.

Viscosity, yield point measurements, yield point calculations

Flow characteristics are determined on a carry-med CS flow meter. The flow meter is in the form of cones and plates with a cone angle of 2:00:00 degrees: minutes: seconds and a cone diameter of 4.0 cm. The spacing is 55 microns and the system inertia is 203.3 dyne / cm 2 (20.3 Pascals). The starting and ending temperature is 25 ° C. The starting stress is 10.00 dyne / cm 2 (1.0 pascal) and the ending stress is 1750 dyne / cm 2 (175 pascal). The viscosity at full shear and yield point is measured and the data is recorded as (a) viscosity in centipoise (cps), (b) yield point measurement in pascals, and (c) yield point calculations in pascals. Yield point calculations and viscosities are determined using a Carson model as described above.

<Example 1 and Comparative Example C1>

67 parts isooctyl acrylate (IOA), 33 parts isobornyl acrylate (IBA), benzyl dimethyl ketal photoinitiator (“ESCACURE ™ KB-1” photoinitiator from Sartomer) 0.1 pph (acrylates and comonomers 100 Per part), and 0.1 pph of carbon tetrabromide are mixed in the glass terminal, the glass terminal is evacuated with nitrogen, and at 300 and 400 nm until a viscous syrup is formed whose viscosity is measured from about 2000 to 3000 centipoise. Pressure-sensitive adhesive compositions were prepared by exposure to ultraviolet light from fluorescent black light having a spectral output of at least 90% and peak emission at about 350 nm. To the syrup was added 0.1 pph of 1,6-hexanedioldiacrylate (HDDA) and 0.2 pph of the second photoinitiator ("LUCIRIN TPO" available from BASF). The adhesive was then screen printed onto the polyester film using a 60 mesh screen on a rotating screen printer (X-Cel rotating screen printer from Stoke). The adhesive formed a fairly homogeneous coating on the substrate with some bubbles and with the adhesive somewhat threaded.

Comparative Example C1 was prepared as prepared in Example 1 except that 0.04 pph KB1 photoinitiator was used in preparing the syrup and no chain transfer agent was used. The resulting adhesive was not satisfactorily screen printed and showed a slack stretch between the screen and the substrate, causing large bubbles and holes in the adhesive coating and the very non-uniform coating.

The examples and comparative examples were cured by exposing the coated adhesive to a medium pressure mercury lamp to form an adhesive. The obtained adhesive was sticky and pressure sensitive.

In addition, the adhesives of both Examples and Comparative Examples were tested for shear viscosity and shear elongation as a function of shear and extrusion rate. Shear viscosity was measured on a Bohlin CS flow meter. Elongational viscosity was measured on an RFX viscometer from Rheometrics. Comparative Example C1 showed an increase in apparent viscosity with increasing non-Newtonian flow type and elongation rate typical for ultraviolet cured adhesives, as evidenced by the shear thinning type. The Troton ratio, defined as elongational viscosity / shear viscosity, increased with increasing tensile rate for C1. Example 1 exhibited a larger Newtonian shear viscosity that remained fairly constant as the shear force increased, and the elongational viscosity and troton ratio were essentially constant as the tensile velocity increased.

<Example 2-3>

A heat activated adhesive was prepared according to the procedure of Example 1 except that the syrup composition was 43 parts of IOA, 57 parts of IBA, 0.1 pph of benzyl dimethyl ketal photoinitiator, and 0.1 pph of carbon tetrabromide. The light exposure time was varied to form a syrup having a viscosity of about 16,000 cps for Example 2 and about 2000 cps for Example 3. Viscosity was measured on a Brookfield RV Viscometer at room temperature with a spindle speed of 5 rpm (Spindle # 5). Additional benzyl dimethyl ketal photoinitiator 0.3 pph and HDDA 0.1 pph were added to each syrup prior to screen printing.

All of the adhesive was screen printed on the AMI 850 screen printer. The screen mesh, rubber roller speed, rubber roller angle, and rubber roller hardness were varied to obtain the best possible coating for each adhesive composition. The target coating thickness was 0.0254 mm (1 mil).

The composition of Example 2 was printable but required a slow rubber roller speed to reduce the number of bubbles in the coating. The composition of Example 3 had smaller bubbles during printing, but flowed after printing to reduce edge resolution. Using 15 watts of two fluorescent black lamps (350 nm black lamp from Sylvania) for about 6 minutes in a nitrogen rich atmosphere, with the sample positioned about 7.62 cm (3 inches) away from the lamp. The coated adhesive was cured. The cured adhesive was essentially viscous at room temperature.

<Example 4>

A heat activated adhesive composition was prepared by mixing 2 parts of the composition of Example 3 and 1 part of the composition of Example 2. The viscosity of the obtained composition was estimated to be about 5000 to 8000 centipoise. The composition provided the highest resolution edge while screen printing easily over a wide range of processing conditions.

<Example 5-6 and Comparative Example C2>

For Example 5, a syrup composition of 40 parts IOA, 60 parts IBA, benzyl dimethyl ketal photoinitiator 0.1 pph, and carbon tetrabromide 0.1 pph and a viscosity of about 7680 cps (spindle # 5 at 5 rpm on a Brookfield viscometer) An activated adhesive syrup was prepared according to the procedure of Example 1.

In Example 6, a pressure sensitive adhesive syrup having a syrup composition of 65 parts IOA, 35 parts IBA, benzyl dimethyl ketal photoinitiator, and 0.1 pph carbon tetrabromide and having a viscosity of about 6240 cps was prepared according to the procedure of Example 1 It was.

For Comparative Example C2, a heat activated adhesive syrup having a viscosity of about 8080 cps was prepared according to the procedure of Example 5 except that no carbon tetrabromide was added.

Prior to coating all syrup compositions further contained 0.05 pph of HDDA and 0.3 pph of "Lucirine TPO" photoinitiator. In addition, Example 6 contained 25 pph of a hydrocarbon tackifier resin ("REGALREZ" 6108 from Hercules).

The adhesive was screen printed. Examples 5 and 6 printed well with excellent corner resolution. Comparative Example C2 was severely slack in the shape of the adhesive, resulting in an unsatisfactory printed image.

Examples 5 and 6 exhibited a similar flow type to Example 1. The shear viscosity of these examples, which is a function of shear rate, remained relatively newtonically below about 100 s ⁻¹ . In Comparative Example C2, the shear viscosity as a function of the shear rate dropped rapidly, ie, to the order of magnitude in the same shear rate range. This type of flow is similar to Comparative Example C1.

<Example 7>

To the syrup was added 2 pph of fumed silica (CAB-O-SIL ™ M5) to prepare a heat activated adhesive composition according to Example 6. The syrup was screen printed and the syrup had improved edge resolution and substantially no coated adhesive flowed before curing.

<Example 8-13 and Comparative Example C3>

A heat activated adhesive composition was prepared according to the procedure of Example 1 using 40 parts of IOA, 60 parts of IBA, 0.1 pph of KB-1, and the amounts (pph units) and type of chain transfer agent (CTA) shown in Table 1. The chain transfer agents used were CBr ₄ (carbon tetrabromide), IOTG (iso-octyl thiol glycolate) and NDDM (n-dodecyl mercaptan). 0.3 pph of TPO photoinitiator as well as crosslinker (HDDA) were added to the syrup in various amounts (pph units). The molecular weight was measured about Example 9, 11 and Comparative Example C3. Examples 9 and 11 were capable of screen printing. The flow profiles, ie shear viscosity, of Examples 10, 12, and 13 were similar to Examples 5 and 6 and screen printing was possible. Comparative Example C3 is expected to be impossible to screen print because its flow profile is similar to Comparative Examples C1 and C2.

Example CTA-quantity / type HDDA TPO Molecular Weight 8 0.02 / CBr ₄ 0.025 0.3 NT ^* 9 0.04 / CBr ₄ 0.05 0.3 453,000 10 0.06 / CBr ₄ 0.025 0.3 NT 11 0.1 / CBr ₄ 0.025 0.3 263,000 12 0.1 / NDDM 0.025 0.3 NT 13 0.1 / IOTG 0.025 0.3 NT C3 none - - 1,570,000 * NT-not measurable

<Example 14>

40 parts of IOA, 60 parts of IBA, 0.1 pph of benzyl dimethyl ketal photoinitiator, and 0.04 pph of carbon tetrabromide were partially polymerized to prepare a thermally activated conductive adhesive syrup according to the procedure of Example 1. The adhesive composition was prepared by mixing these components with syrup until both 0.05 pph HDDA and 0.3 pph TPO photoinitiator (" Lucirin TPO " from BASF) were dissolved. Subsequently, 4 pph of fumed silica (CAB-O-SIL M5) and 20 pph of conductive nickel spheres (CNS, air classification grade -20 / + 10 μm, from Novamet) were dispersed in the composition using a high shear mixer. 20 pph of nickel spheres is 5% by volume of the adhesive composition. Next, a flat screen printer (Roll Edgenearing Co., Ltd.) equipped with a polyester screen of 200 mesh with a 31 ° bias and an emulsion thickness of 0.635 mm (25 mils) and a rubber roller with 60 durometer rounded corners. 3M (trade name) thermally sealed connectors available from Minnesota Mining & Manufacturing Co., Ltd., St. Paul, Minn., Using a "Model 2BS Roll to Roll Screen Press System" from Engineering Ltd. The adhesive composition was screen printed). Print / flow adhesive at 20 psi (138 kPa) rubber roller pressure, 50.8 cm / sec (20 in / sec) and 50.8 cm / sec (20 in / sec) flow blade speeds, and minimum rubber roller angle The composition was printed. The thickness of the adhesive coating was 43 to 53 μm.

The screen printed adhesive was cured by exposing the adhesive to the fluorescent black light described in Example 1 at an intensity of about 4.5 to 5.5 mW / cm 2 and a total energy of 335 to 350 mJ / cm 2. The adhesive obtained was essentially viscous at room temperature but viscous when heated to about 35 ° C. Printed soluble circuits were tested for electrical resistance, ITO glass substrates and peel adhesion to FR-4 circuit boards and both. The test results are shown in Table 2.

<Example 15>

A heat activated conductive adhesive was prepared as in Example 14 except that the amount of HDDA was reduced to 0.035 pph and the conductive nickel spheres were conductive nickel spheres coated with 2% gold. The adhesive was then screen printed to a thickness of about 30 to 40 μm at the ends of the circuit wiring of the flexible circuit. The adhesive was then cured as described above. After this curing was exposed to a mercury arc lamp at 1100 mJ / cm 2. The flexible circuit portion, which was not coated with an adhesive, was coated with a non-adhesive protective cover coat ("ENPLATE" from Enthone-OMI). The obtained soluble circuit was tested for electrical resistance and peel adhesion as described above except that the bonding pressure was reduced from 800 psi (5516 kPa) to 540 psi (3723 kPa), and the recorded aging results were 13 days. The result after aging. The test results are shown in Table 2.

Example 14 Example 15 Early After aging Early After aging resistance Average-Ohm 2.3 9.8 2.2 12.1 Min-ohm 2.1 4.4 2.0 5.9 Max-Ohm 2.6 18.0 4.9 20.6 Peel Adhesion Glass-g / cm 826 1176 617 1883 Substrate-g / cm 1184 2836 834 1250

     The results in Table 2 show that the adhesives of the present invention are suitable for coating flexible circuits to provide electrical connections.

<Example 16>

The solution was mixed by mixing 30.1% by weight of IOA, 34.0% by weight of IBA, 16.02% of isobutyl methacrylate polymer (ELVACITE® 2045, manufactured by ICI Americas), heated at 80 ° C. and stirring until the polymer dissolved. Ready. Their amount was 37.6 parts IOA, 42.4 parts IBA, and 20 parts isobutyl methacrylate by weight. To this solution fumed silica (CAB-O-SIL ™ M5 silica, manufactured by Cabot Corporation) 3.2%, gold coated nickel sphere (described in Example 14), photoinitiator (LUCIRIN Adhesive syrup is added by adding 0.0192% of TPO), 1010 of antioxidant (IRGANOX®), 0.32% of Ciba Geigy Corp., and 0.16% of crosslinking agent (EBECRYL® 230). The composition was prepared. Silica was mixed into the composition using a high shear mixer. The viscosity and yield point were measured with the resulting syrup and the data is presented in Table 3. Flexible circuits were prepared as in Example 15. The resulting circuit was thermally coupled and had a satisfactory electrical resistance.

<Example 17-20>

An adhesive composition was prepared according to the method of Example 16.

Example 17 includes 52 parts of IOA, 28 parts of IBA, 20 parts of styrene butadiene copolymer (K-resin 01, manufactured by Phillips Petroleum), photoinitiator (LUCIRIN® TPO) 0.25%, fumed silica ( CAB-O-SIL M5 silica) 4%, antioxidant (IRGANOX® 1010) 0.3%, and carbon tetrabromide 0.18%.

The composition of Example 18 was prepared as in Example 17 except for including 32 parts of IOA, 48 parts of IBA, and 20 parts of styrene butadiene copolymer.

 The composition of Example 19 was prepared as in Example 16 except that 52 parts of IOA, 28 parts of IBA, and 20 parts of isobutyl methacrylate polymer were included.

The composition of Example 20 was prepared as in Example 19 except that it included 32 parts of IOA, 48 parts of IBA, and 20 parts of isobutyl methacrylate polymer.

Flow test data is presented in Table 3.

Example Viscosity (cps) Yield Point Measurement (Pa) Yield Point Calculation (Pa) 16 968.2 25.5 52.2 17 1038 4.5 61.3 18 1187 29.0 46.4 19 771.2 13.2 26.0 20 1371 20.2 42.8

<Example 21-22>

Semi-crystalline polymers were used to make screen-printable adhesives. The composition of Example 21 is sold as LOTADER 8900 from ELF Atochem, a semicrystalline polymer that is 40 parts IOA, 60 parts IBA, and an ethylene / ethyl acrylate / glycidyl methacrylate terpolymer. ) Has 8.1 parts. The composition of Example 22 has 100 parts of phenoxyethyl acrylate and 8.7 parts of a semicrystalline polymer (ELVALOY 441 from Du Pont Company), which is an ethylene / acrylate / carbon monoxide terpolymer. The composition was prepared by mixing the acrylate monomer with the thermoplastic terpolymer and heating the mixture at about 80 ° C. for several hours until a clear solution was obtained. Upon cooling to room temperature, the solution became opaque and thixotropic. Both solutions were screen printable. Yield points and viscosities are shown in Table 4 below.

<Example 23-24>

Polyepoxide resins were used to make screen-printable adhesives. 12 g (100 parts) of phenoxy ethyl acrylate in a brown jar was added to 8 g (67 parts) of cresol novolac polyepoxide resin (EPON ™ 164, Shell Chemical Co., Houston, TX) ) And the jar was rotated under a sun lamp for about 2 hours until a clear solution was obtained to prepare the composition of Example 23. 2.5 g of methacrylate / butadiene / styrene polymer (PARALOID® EXL 2691, Rohm & Haas, Philadelphia, PA) was used for about 30 minutes using an impeller blade rotating at about 7000 rpm. Dispersed in the solution. Subsequently, 0.8 g of hydrophobic silica (AEROSIL® R812 silica, DeGussa Corporation, Ridgefield Park, NJ) was added and mixed for about 15 minutes with an impeller. During mixing, the mixture was warm when touched. The mixture was cooled to about 20 ° C., 0.1 g of liquid photoinitiator (CGI 1700 (trade name), manufactured by Ciba-Geigy Corporation), glycidylpropyl trimethoxysilane coupling agent (GPMS (trade name), Hulse) ( Huls), Piscataway, NJ) 0.2 g, modified amine polyepoxide curing agent (ANCAMINE ™ 2337S, Air Products and Chemicals, Inc., Allentown, Pennsylvania) Material) 2.75 g, epoxy diacrylate oligomer (EBECRYL ™ 3605, 0.5 g from UCB Radcure, and conductive particles (nickel particles coated with air sorted -20 / + 10 gold, Novamet) 4.0 g was added to the mixture and mixed at a slow speed with a paddle mixer The viscosity and yield point of the resulting adhesive composition are shown in Table 4.

The adhesive composition of Example 23 was applied on a flexible circuit substrate (3M ™ Heat Seal Connector without adhesive, Mining and Mining and Manufacturing, St. Paul, Minn.) Using a 250 mesh polyester screen. Was screen printed on. The printed adhesive composition was cured for about 5 minutes under an ultraviolet black light lamp having an emission spectrum mainly at about 300-400 nm and a maximum emission at about 350 nm. The strength was about 2 GPa / cm ² . The printing adhesive was then bonded to FR4, ITO coated glass and heat cured with a heating bar at a temperature of about 150 ° C. for about 20 seconds. This substrate had a measurement conductivity of 1.26 ohms in the range of 0.64 to 2.0 (two samples, 15 measurements each).

The composition of Example 24 was prepared as in Example 23 with the following exceptions: 8 g of phenoxyethyl acrylate (80 parts), 2 g of isobornyl acrylate (20 parts), polyepoxide resin (EPON (Trade name) 1002, manufactured by Shell Chemicals, 5 g, diglycidyl ether of bisphenol A polyepoxide resin (EPON 825, manufactured by Shell Chemicals) 5 g, methacrylate / butadiene / styrene polymer (PARALOID (Trade name) EXL2691A, manufactured by Rohm and Haas, 5 g, hydrophobic silica thixotropy (AEROSIL (trade name) R812, manufactured by Degusa Corporation) 0.8 g, liquid photoinitiator (CGI 1700, manufactured by Ciba-Geigy Corporation) 0.2 g, Glycidylpropyl trimethoxysilane coupling agent (GPMS, manufactured by Huls) 0.2 g, polyepoxide curing agent (ANCAMINE (trade name) 2337S, manufactured by Air Products and Chemicals) 2.22 g, epoxy diacrylate oligomer (EBECRYL 3605, UCB Rad Q Inc.) 0.5 g, and the conductive particles (air classified the nickel particles) 4.0 g coated with a -20 / + 10 gold. The yield point and viscosity of the resulting adhesive composition are shown in Table 4, which allows screen printing.

<Example 25-26>

The screen-printable adhesives of Examples 25 and 26 were prepared using "core-shell" polymers. 25 parts of methylene / butadiene / styrene core-shell polymer KANE ACE ™ M901 (Kaneka) was added to a mixture of 40 parts of isooctyl acrylate and 60 parts of isobornyl acrylate with an impeller blade rotating at 7000 rpm. The composition of Example 25 was prepared by dispersing and mixing for about 0.5 hours. This solution warmed up during mixing. This adhesive composition was transparent when cooled at room temperature and was thixotropic. The composition of Example 26 was prepared as in the composition of Example 25 with the following exceptions: 40 parts of isooctyl acrylate, 60 parts of isobornyl acrylate, and acrylic acid core-shell polymer (PARALOID ™ KM 330 , Rohm and Haas) 15.6 parts. After cooling, the composition of Example 26 was clear and thixotropic.

Example Yield Point-(Pa) Measurement Calculation Yield Point Regression Calculate Viscosity (cps) 21 - 11.4 0.987 184 22 22.54 24.5 0.994 2820 23 22.54 9.7 0.994 4952 24 83.92 41.5 0.947 1350 25 83.92 16.6 0.996 1053 26 57.61 19.8 0.988 534

General Preparation of Heat-Curable Adhesive Film Compositions

Method 1

Aromatic polyepoxides, monofunctional acrylate monomers and diacrylate oligomers are weighed into 4 ounce clear glass jars, sealed with lids and placed in a forced draft oven at 90 ° C. for 30 minutes and then taken out to completely dissolve the components. (Appears to appear clear in appearance) Stirred for another 15 minutes on a shaker table.

The resulting solution was stirred with a 0.79 inch (20 mm) diameter disk impeller while keeping heated to 100 ° C. (as measured on a thermocouple located at the bottom of the glass jar). The mixing speed was adjusted to about 4000 rpm to create a donut shaped flow pattern around the impeller blades. To avoid clumping, the thermoplastic resin was slowly added to the vortex by dividing by hand and then mixed at 100 ° C. until it dissolved sufficiently. Whether the thermoplastic resin was completely dissolved was determined as the mixture turned from opaque to transparent in appearance. Depending on the roughness of the powder, it is usually completely dissolved in less than 2 hours, with finer powders requiring less time. For example, phenoxy thermoplastics having a particle size of about 200 μm were completely dissolved in less than about 30 minutes, while amorphous linear saturated copolyester thermoplastics with particle sizes much larger than 200 μm required approximately 2 hours.

Next, the photoinitiator required for the acrylate polymerization was polished into fine powder with mortar and pestle, and then added to the polyepoxide / acrylate monomer / crosslinking binder / thermoplastic resin solution at once at room temperature. The jar with the lid containing the mixture was placed on a roller mill for about 2 hours and the photoinitiator was dissolved. During this time, the jar was not exposed to light.

The polyepoxide curing agent powder was then added all at once to the reaction mixture and dispersed with mixing for about 3 to 5 minutes with the Moto / Disc impeller described above. Mixing was carried out at a rate such that the resin temperature below about 40 ° C. was maintained to prevent unwanted reaction of the polyepoxide with the curing agent. Next, the conductive powder was added and dispersed in a similar manner. Finally, a jar with a lid with a dispersion mixture was placed on a roller mill, prevented exposure to light, and rotated overnight to more fully disperse the polyepoxide curing agent and conductive particles. A uniform dispersion with a viscosity of about 5,000 to about 15,000 cps was obtained. The light is blocked until further use.

Method 2

After addition of the aromatic polyepoxide, the acrylate-containing monomer (including the acrylate monomer and crosslinking component) is weighed into a clear glass jar, the jar is covered, placed in a roller mill, and a clear solution is obtained. Rotate for about 1 to 24 hours. When using a solid polyepoxide, approximately 24 hours were required.

In the following order, each of the liquid photoinitiator and the liquid silane coupling agent was added at once. Mix them by hand at room temperature for 15-30 seconds until a clear solution is obtained. Once the photoinitiator was added, all subsequent steps were performed under yellow light.

Subsequently, one spatula portion of core / shell-like particles was added to the solution at one time using the above-mentioned disk impeller and mixed thoroughly at a speed of about 4000 rpm for about 15 to 20 minutes. During this time the mixture was hot when touched. An opaque dispersion was obtained.

The previously described disk impeller was then used at a speed of about 4000 rpm to thoroughly disperse the fumed silica at once by adding it to a very warm mixture with stirring for about 15 to 20 minutes. During this time the mixture was hot when touched.

After cooling the mixture to room temperature, the polyepoxide curing agent powder and the conductive particles were added to the collected fractions, and the above impeller blades were mixed by using the impeller blade for about 10 to 15 minutes at a speed of about 100 to 200 rpm. The components were dispersed. An opaque dispersion with a viscosity of about 1000 to 5000 cps was obtained. The composition was stored at about 40 ° F. (4 ° C.) until further use.

General Preparation of Heat-curable Adhesive Bonding Films

Method 1

An adhesive film was prepared by coating the adhesive composition between two release liners and exposing the coated adhesive to ultraviolet (UV).

More particularly, the adhesive was coated using a 6 inch (15.2 cm) wide bed knife station. The knife was fixed in place to maintain a fixed gap. A knife guage was used to adjust the knife spacing to a height of 63.5 μm (0.0025 inches) thicker than the combined thickness of the two release liners used. The adhesive composition was poured between two 50.8 μm (0.002 inch) silicone-coated polyester release liners and then pulled between the knife and the bed to which the glue was glued.

Low intensity UV radiation on one side of the adhesive coated through the release liner in oxygen-free conditions using two adjacent General Electric FT15T8-BL fluorescent lamps about 1 inch (2.5 cm) away from the release liner. Exposed to. The exposure time for a total dose of 940 mJ / cm 2 was 5 minutes. The intensity was measured using a UVIRAD UV Integral Radiometer (Model UR365CH3, Electronic Instrumention & Technology, Steering, VA). Doses recorded as dose were measured according to the National Institute for Standards and Testing (NIST) method. An adhesive film having a thickness of about 63.5 μm (0.0025 inch) was obtained.

Method 2

An adhesive film was prepared by coating the adhesive composition between two release liners and exposing the coated adhesive to ultraviolet (UV) as described in Method 1 except for the following changes.

The gap gap was used to adjust the knife spacing to a height of 50.8 μm (0.002 inches) thicker than the combined thickness of the two release liners used.

One side of the coated adhesive was exposed to low intensity UV rays through a release liner in oxygen-free conditions using a SYLVANIA ™ fluorescent lamp with a maximum at 351 nm and 90% emission at 300-400 nm. The exposure time for an average intensity of 2 mW / cm 2 with a total dose of 480 mJ / cm 2 was 4 minutes. Doses recorded as dose were measured according to the National Institute of Standards and Testing (NIST). Intensity was measured as described above. A final adhesive film having a thickness of about 38.1 μm (0.0015 inch) was obtained.

Test method of heat-curable adhesive film

Degree of cure of the epoxide (by differential scanning calorimetry)

The heat of reaction was measured using a single cell differential scanning calorimeter (DSC) (Model 220C, Seiko Instruments USA, Inc., Torrance, Calif.) Before and after exposure to various temperatures for several hours. About 3-10 mg of adhesive bond film was placed in a DSC sample pan and welded closed. The adhesive bonding film was immersed in polyamide tweezers and then taken out in a hot oil bath maintained at a selected temperature for a certain time, quenched by soaking in a dry ice / isopropanol bath (about -78 ° C) for about 5 minutes, and then briefly Immersed in dichloromethane, immersed in heptane for a while, and finally wiped dry with paper towels. The samples were then injected under nitrogen purge at a rate of 15 ° C./min at 0-210 ° C. The heat of reaction was calculated as the area under the curve for the exothermic portion of the curve and measured using the software provided with the DSC system. The degree of cure of the polyepoxide was considered as the ratio of the residual heat of reaction of the sample immersed in the oil bath to the residual heat of reaction of the sample not immersed in the oil bath. Recorded values are expressed in% rounded to the nearest integer. If the original samples were not immediately immersed in an oil bath, they were stored in the freezer at below 0 ° C. for later evaluation.

Shelf life

Samples of the adhesive film coated on the release liner as described in Example 30 below were stored in a rolled form, unblocked from ambient roughness, at a temperature of 23 ± 2 ° C. and a relative humidity of about 40-70% for a period of 16 months. . At various times during this period, the tack, stretch and cure exothermic properties were evaluated. In addition, the film samples were used to produce a test circuit for evaluating electrical resistance characteristics after 16 months.

In particular, the stickiness retention was measured by touching the film surface with a finger to determine if there was still a "sticky" feeling. If there was a feeling of "sticky", it was rated "+"; if not, it was rated "-". Elasticity was measured by removing the liner from the adhesive film sample, holding each with a thumb and index finger and gradually increasing it to about 100% from its original size. If the adhesive film did not break, it was rated "satisfied" and if it was broken it was rated "dissatisfied". Residual curing exotherm was measured as described in "Epoxide Curing Degree" Method 1 above. The obtained exothermic value was divided by the initial value to obtain the "residual exothermic%" value. After 16 months, an adhesive film was used to make the test circuit as described in "Electrical Resistance-Method 1" below. The test circuit with the adhesive film was cured at 140 ° C. at 200 psi for 30 seconds and the electrical resistance was evaluated at the beginning and after environmental aging. The environmental aging parameters used are similar to the conditions of “Electrical Resistance-Method 1” below.

Electrical resistance

Method 1

The electrical resistance between the two test circuits bonded with the conductive adhesive bonding film prepared as described in "General Method for Manufacturing Thermo-Adhesive Adhesive Bonding Film-Method 1" was measured before and after environmental aging.

More specifically, a piece of sample approximately 7.62 cm (3 inches) long and 0.64 cm (0.25 inches) wide is cut into a coated irradiation adhesive sandwich structure, the release liner is removed from one side, and 0.127 mm (0.005 inch) thick. Test circuit pattern at one end of a flexible polyester circuit sample of 46 mm (1.81 inches) long, 40 mm (1.57 inches) wide (Lakeside Nameplate Co., Minneapolis, Minn.) Over the exposed adhesive surface. The test circuit included eight lines of silver ink conductors in a four point probe pattern with a line width of 0.64 mm (0.025 inch) and a line spacing from center to center of 2.5 mm (0.10 inch). Light pressure was applied by hand to the surface of the second release liner on the adhesive film to allow the film to bond with sufficient strength to the flexible substrate for handling. The second release liner was then removed, and a 0.10 cm (0.040 inch) thick FR-4 type composite (glass reinforced epoxy resin; More Than Circuits, Inc., St. Paul, Minn.) The circuit lines on the flexible substrate were visually arranged while matching 35 microns (1 ounce) of copper plated circuit lines by soldering on a thick rigid substrate. After light pressure was applied by hand to the assembly, the bonding force of the adhesive was sufficient to handle without cracking.

High-temperature bar thermomodal binder (model RSM 4000, Todco Generale), which cures the bonding film under a uniform pressure of 200 psi (1.37 MPa) and is equipped with a ceramic thermomod with marks of 50 × 3 mm (1.97 × 0.118 inch). (Toddco General, Inc., San Diego, Calif.) Was used for several hours and at various temperatures. A silicone rubber piece (SARCON ™) 45T, manufactured by Fujipoly America, Cranford, NJ, was placed between the test assembly and the surmod. The curing time was measured as soon as the test assembly reached the desired temperature based on the calibration curve.

A metal foil thermocouple (model C-02-K, manufactured by Omega Engineering, Stamford, Connecticut) is placed between the flexible circuit and the FR-4 substrate of the adhesive film and at the time it takes to reach the set temperature. Assay was plotted by plotting the actual temperature. The final temperature showed a deviation of ± 5 ° C. from the set point during the curing cycle. At the end of the curing cycle, the mode bar and a piece of silicone rubber were removed to remove heat and pressure, and the sample was removed from the stage and cooled.

After cooling for 3 to 24 hours at room temperature, the initial electrical resistance of the bonding samples was evaluated. Keithley Source-Measuring Device (Model 236; Keithley Instruments, Cleveland, Ohio) at about 22 ° C. (72 ° F.) and relative humidity (RH) of about 40 to 70%. Measurements were made on eight bonded lines of each sample using a Caesley scanner (Model 705), and LABVIEW ™ data acquisition software (vol. 3.1, National Instruments, Austin, Texas). . A source voltage of 20 mA was used and the resistance was calculated by dividing the applied voltage by the measured current. A pair of samples was evaluated and the combined resistance ranges of a total of six connection marks were recorded.

The sample was then placed in an environmental chamber (proven below) and exposed to three different protocols.

Condition 1 : 77 ° C./90% RH (Despatch Model EC 503 Environmental Chamber, Despatch Industries, Minneapolis, Minn.)

Condition 2 : Hold at -20 ° C. for 45 minutes, raise to 70 ° C. over 45 minutes, hold at 70 ° C./90% RH for 45 minutes, lower to -20 ° C. over 45 minutes. Total cycle time = 3 hours. Repeat in succession. (Despatch Model EC 603 Environmental Chamber)

Condition 3 : 85 ° C / 85% RH (Despatch Model LEAL 69 Environmental Chamber)

Electrical resistance measurements were made on days 7 and / or 14 and the results obtained were compared with initial resistance values to evaluate the electrical connection stability, for example, with or without resistance.

Method 2

The electrical resistance between the two test circuits bonded together with the conductive adhesive bonding film prepared as described in "General Preparation of Heat-Curable Adhesive Bonding Film Method 2" above was measured before and after environmental aging.

In particular, a rigid FR-4 substrate (Crystal, Minn., TRC Circuits) was preheated for 10 seconds in a hot plate apparatus at about 45 ° C. The FR-4 substrate has a thickness of 0.15 cm (0.060 inch), the test circuit pattern thereon is 50.8 μm (0.002 inch) with a width of 0.20 mm (0.008 inch) and a center-to-center spacing of 0.20 mm (0.008 inch). Consisting of thick plated copper traces. A piece of sample about 2.5 cm (1.0 inches) long and about 0.3 cm (0.12 inches) wide is cut into a coated irradiation adhesive sandwich structure, the release liner is removed from one side, and one end of the test pattern circuit line on the rigid substrate. The exposed adhesive side was placed across the. Using light pressure by hand, the film was joined to a warmed, rigid FR-4 substrate by pressing wood Q-TIP ™ along the length of the second release liner on the adhesive film. The second release liner was then removed after about 10 seconds.

Next, a flexible circuit (adhesive) consisting of a 0.025 mm (0.001 inch) thick polyethylene terephthalate (PET) film substrate having a length of 2.54 cm (1 inch), a width of 0.64 cm (0.25 inch) and having a test pattern on one side. 3M heat seal connector, Minnesota Mining and Manufacturing Company, St. Paul, Minn.) Was bonded to the exposed side of the adhesive bond film. The test pattern of the flexible circuit has a thickness of 0.20 mm (0.008 inch) and has a 3 μm (0.0012 inch) thick copper trace with a center-to-center spacing of 0.20 mm (0.008 inch). The circuit on the flexible substrate was contacted with the adhesive film and arranged in a circuit pattern on the rigid FR-4 substrate. All of the circuit lines on the flexible substrate passed vertically through the circuit lines and were connected by bus bars located opposite the connecting line between the hard substrate and the flexible substrate.

The 1093 series hot stamp bonder ((DCI, Inc.) was cured under a uniform pressure of 28 psi (0.19 MPa) and was equipped with a metal thermostat with marks of (25.4 × 2 mm) (1 × 0.118 inch). .), Orante, Kansas) for several hours and at various temperatures for 35 seconds. A silicone rubber piece (product no. SRG 0607, Mining and Manufacturing Company, Minn., Inc., St. Paul, Minn.) Was placed between the test assembly and the summod. Temperature calibration, curing time, sample cooling and testing were performed as described in Method 1 of “Electrical Resistance” above, except that the number of circuit lines measured for each sample was 15, totaling 30.

The sample was then placed in an environmental chamber (proven below) and exposed to one of two different protocols.

Condition 4 : Hold at -40 ° C for 60 minutes, raise to 85 ° C over 30 minutes, hold at 85 ° C for 60 minutes, lower to -40 ° C over 30 minutes. Total cycle time = 3 hours. Repeat in succession. (Despatch Model 16307 Environmental Chamber)

Condition 5 : 60 ° C / 95% RH (Despatch Model LEAL 69 Environmental Chamber)

The electrical resistance was measured using four wire measurement methods made after the specified time, and the result obtained was compared with the initial resistance value to determine the electrical line stability.

Glossary of Terms

AGEFLEX (trade name) IBOA

Isobornyl acrylate [manufactured by CPS Chemical Co., Old Bridge, NJ, Old Bridge, NJ]

AGEFLEX (trade name) PEA

Phenoxyethyl Acrylate [manufactured by CPS Chemical Co., Old Bridge, NJ, Old Bridge, NJ]

ANCAMINE (trade name) 2337S

Modified aliphatic amines [Products of Air Product and Chemicals, Inc., Pacific Anchor Chemical, Allentown, PA, Allentown, PA]

Au / Ni

Nickel spheres coated with 4% gold with a nominal particle size of 10-20 μm (custom order) [from Novamet, Inc., Wykoff, NJ, Wykov, NJ]

BOSTICK (trade name) 7900

Amorphous Linear Saturated Copolyester [Bostik, Middleton, MA, Middleton, Mass.]

CAB-O-SIL (trade name) M5

Fumed Silica [Cabot Corporation, Tuscola, Ill., Tuscola, Ill.]

CGI 1700 (trade name)

Liquid Free Radical Photoinitiator Mixture of Bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and 2-hydroxy-2-methyl-1-phenyl-2-propanone [New York, USA CIBA GEIGY, Tarrytown, NY products in Terrytown]

CN 104 (trade name)

Liquid Bisphenol A Diacrylate Oligomer [Sartomer Company, Exoton, PA, Exton, PA]

CONDUCT-O-FIL (trade name) S-3000-S-3M

Silver coated solid glass sphere, particle size = 43 ± 4 micrometers, range = 20-60 μm (80%) [manufactured by Potters Industries Inc., Parsippany, NJ, Parsippany, NJ]

CONDUCT-O-FIL (trade name) S-3000-S-3MM

Silver coated solid glass sphere, particle size = 34 ± 4 micrometers, range = 20-50 μm (80%) [Products from Potters Industries Inc., Parsippany, NJ, Parsippany, NJ]

EBECRYL (trade name) 230

Low viscosity aliphatic urethane diacrylate oligomer, MW = 5,000 [manufactured by UCB Radcure Inc., Smyrna, GA, Smyrna, GA, USA]

EBECRYL (trade name) 3605

Partially Acrylate Bisphenol A Epoxy Resin, MW = 450 [UCB Radcure Inc., Smyrna, GA], Smyrna, GA, USA]

EBNECRYL (trade name) 8804

Crystalline semi-solid aliphatic urethane diacrylate oligomer, MW = 1,400 [manufactured by UCB Radcure Inc., Smyrna, GA, Smirna, GA, USA]

EPON (trade name) 164

Solid multifunctional novolac epoxy resin, epoxy equivalent weight = 200-240 [Shell Chemical Co., Houston, TX, Houston, TX]

EPON (trade name) 825

Liquid Bisphenol A Epoxy Resin, Epoxy Equivalent Weight = 172-178 [Shell Chemical Co., Houston, TX, Houston, TX]

EPON (trade name) 828

Liquid Bisphenol A Epoxy Resin, Epoxy Equivalent Weight = 185-192 [Shell Chemical Co., Houston, TX, Houston, TX]

PARALOID (trade name) EXL-2691A

Methacrylate-Butadiene-Styrene Core / Shell Particles [Rhom and Haas Co., Philadelphia, PA, Philadelphia, PA]

G6720 (trade name)

(3-Glycidoxypropyl) trimethyoxysilane [United Chemical Technologies, Inc., Bristol, PA, Bristol, PA]

LUCIRIN (trade name) TPO

2,4,6-trimethylbenzoyldiphenylphosphine oxide free radical photoinitiator [product of BASF Corporation, Charlotte, NC, Charlotte, NC]

PKHP (trade name) 200

Phenoxy resin, molecular weight (weight average) = 50,000-60,000, average particle size: about 200 μm [Phenoxy Associates, Rock Hill, SC, product, Rock Hill, SC]

In the embodiments described below, all amounts are indicated by g unless otherwise indicated.

<Example 27-29>

The compositions of Examples 27-29 having the compositions shown in Table 5 were prepared as described as "General Preparation of Thermosetting Adhesive Compositions" of Method 1 above. In Example 27, core-shell shaped particles were mixed into the solution at one time by one spatula-size using the aforementioned disk impeller. This step was performed after cooling the solution to room temperature and adding thermoplastics. An opaque dispersion was obtained.

Example Polyepoxide ¹ Phenoxyethyl acrylate ² Urethane Diacrylate ³ Urethane Diacrylate ⁴ Phenoxy resin ⁵ Copolyester ⁶ Photoinitiator ⁷ Amine Curing Agents ⁸ Core-Shell Polymer ⁹ Conductive Material ¹⁰ 272829 41.134.432.2 24.633.731.6 2.7-0--0- -0-0.70.6 5.1-0-3.8 -0-6.0-0- 0.080.10.1 16.417.216.1 -0--0-7.6 1088 In Example 27, CONDUCT-O-FIL ™ S-300-3M was used, and in Examples 28 and 29, CONDUCT-O-FIL ™ S-3000-3MM was used. ¹ EPON (trade name) 828 ² AGEFLEX (trade name) PEA ³ EBECRYL (trade name) 230 ⁴ EBECRYL (trade name) 8804 ⁵ PKHP (trade name) 200 ⁶ BOSTIC (trade name) 7900 ⁷ LUCIRIN (trade name) TPO ⁸ ANCAMINE 2337S ⁹ PARALOID Trademark EXL 2691A ¹⁰ CONDUCT-O-FIL S-3000-3M, S-3000-3MM

<Example 30-35>

The composition of Example 27 was converted to a tacky adhesive bond film as described above in "General Preparation of Heat-Curable Adhesive Bond Films-Method 1", except as follows. Using a 9 inch wide knife-over-bed coating station with a dam positioned to provide a 6 inch wide coating area; 0.0035 inch (0.0035 inch) thick polyethylene coated paper is used as a single release liner; Irradiation is carried out using a SYLVANIA ™ fluorescent lamp which emits 90% at 300-400 nm at a maximum of 351 nm under nitrogen filled environment; An average intensity of 4 kPa / cm 2 was maintained for 5 minutes to provide a total dose of 1,392 mJ / cm 2.

This adhesive bond film was used to evaluate the effect of various time / temperature curing cycles on the degree of cure measured using the method described in “A degree of cure (by differential scanning calorimetry)”. The results are shown in Table 6.

Curing degree Example Composition of Table 5 Curing temperature (℃) Cure Time (sec) Hardness (%) 30a30b 2727 9090 6090 4452 31a31b31c 272727 120120120 306090 567484 32a32b32c32d 27272727 130130130130 10203060 40556683 33a33b33c 272727 140140140 306090 909296 34a34b 2727 150150 15130 84100 35 27 160 15 93

The results in Table 6 show that the degree of cure of 50 to 100% can be achieved in a time of 15 to 130 seconds at a temperature of 90 to 160 ° C. Examples 30a and 32a were cured under conditions providing a degree of cure of less than 50%.

<Example 36-40>

The compositions of Examples 27-29 were subjected to modifications to Example 27, as can be seen in Examples 30-35, respectively, as described in "General Preparation of Heat-Curable Adhesive Bonding Films-Method 1". Likewise, the adhesive adhesive bond film was switched between two release liners. These adhesive bond films were used to prepare cured electrical connection test samples at various times / temperatures and then evaluated electrical resistance properties before and after exposure to environmental conditions as described as “electrical resistance” in Method 1 above. The curing conditions and the obtained resistance values are shown in Table 7.

Electrical resistance stability Example Composition of Table 5 Curing temperature (℃) Cure Time (sec) Environmental aging conditions Initial resistance value (Ohm range) Resistance value after 168 hours (Ohm range) Resistance value after 336 hours (Ohm range) 36a36b 2727 9090 6090 11 0.82-1.020.72-0.89 0.68-0.920.62-0.77 0.77-1.220.75-0.89 37a37b37c37d 27272727 130130130130 10203060 1111 0.94- (open) 0.76-1.990.75-1.460.56-0.69 0.70- (open) 0.54-1.430.71-1.310.48-0.61 0.74- (open) 0.60-1.990.83-1.660.58-0.73 38 27 140 30 3 0.32-0.43 N.D. 0.43-0.79 39a39b 2828 140140 3030 12 0.56-0.720.50-0.69 N.D.N.D. 0.62-0.790.50-0.67 40a40b 2929 140140 3030 12 0.46-0.550.45-0.54 N.D.N.D. 0.49-0.720.44-0.53 1) Open: Resistance value of> 10,000 ohms 2) N.D. : Not measured

The results in Table 7 indicate that acceptable electrical connections were produced in all examples where the curing conditions used provided a polyepoxide cure degree greater than 50%, which is a polyepoxide cure degree based on the results shown in Table 6. These connections remain acceptable after 336 hours (two weeks) of exposure to environmental conditions, i.e. the resistance value does not change more than 1 ohm. Examples 36a and 37a were cured under conditions providing a degree of cure of less than 50%.

<Example 41>

The binder film prepared from the composition of Example 27 was aged for 16 months at ambient conditions and periodically evaluated for a period of time as described in the test method "Storage Life" above to allow acceptable conditions in which the adhesive bond film was uncured. The treatment and polyepoxide curing properties, as well as how long they retained their electrical properties in the cured state, were measured. The results are shown in Table 8.

Shelf life Example Composition of Table 5 Storage period (months) track Shout Residual exotherm (%) Initial resistance value (Ohm range) Resistance value after 336 hours (Ohm range) 41a41b41c41d41e ¹ 2727272727 05111416 +++++ +++++ 100100100100100 N.D.N.D.N.D.N.D.0.56-0.90 N.D.N.D.N.D.N.D.0.56-1.19 ND = not measured ¹ Environmental Aging Condition # 1

The results in Table 8 show that the uncured adhesive bond film made from the composition of Example 27 retains acceptable treatment and polyepoxide curing properties up to 16 months under ambient storage conditions. In addition, these films retained the ability to provide stable electrical connections when cured, even after environmental aging.

<Examples 42 and 43>

Examples 42 and 43 having the compositions shown in Table 9 were prepared as described in "General Preparation of Heat-Curable Adhesive Bonding Films" of Method 2 above, except that Example 43 did not contain core / shell particles. It was.

Example Polyepoxide ¹ Polyepoxide ² Acrylate-Epoxy Resin ³ Epoxy-acrylate ⁴ Core-Shell Polymer ⁵ Isobornyl-acrylate ⁶ Phenoxyethyl acrylate ⁷ Coupling Agents ⁸ Amine Curing Agents ⁹ Photoinitiator ¹⁰ Conductive Particles ¹¹ Au / Ni particles 42 0.0 8.0 0.3 -0- 2.9 -0- 12.3 0.3 2.8 0.1 0.8 4.0 43 2.0 8.0 0.0 0.2 0.0 2.0 8.0 0.3 3.6 0.1 0.8 4.0 Note: Add CN 104 as a 25% solution in PEA ¹ EPON® 825 ² EPON® 164 ³ EBECRYL® 3605 ⁴ CRAYNOR® CN 104 ⁵ PARALOID® EXL 2691A ⁶ AGEFLEX® IBOA ⁷ AGEFLEX (trade name) PEA ⁸ G 6720 (trade name) ⁹ ANCAMINE (trade name) 2337S ¹⁰ CGI 1700 (trade name) ¹¹ CAB-O-SIL (trade name) M5

<Example 44-49>

The compositions of Examples 42 and 43 were converted to non-tacky adhesive bond films between two release liners, respectively, as described in "General Preparation of Heat-Curable Adhesive Bond Films" of Method 2, above.

This adhesive bond film was used to evaluate the effect of various time / temperature cure cycles on the degree of cure measured using the method described in “A degree of cure (by differential scanning calorimetry)” above. The sample was immersed in acetone instead of heptane; The degree of cure of the samples was analyzed using a Model 30 DSC (manufactured by Mettler Instrument Corporation, Highstown, NJ), and the scanned temperature range was -30 to 250 ° C. The results are shown in Tables 10 and 11, respectively.

Curing degree Example Composition of Table 9 Curing temperature (℃) Cure Time (sec) Hardness (%) 44a44b44c 424242 140140140 81828 103559 45a45b45c 424242 150150150 81828 195073 46a46b46c 424242 160160160 81828 215776

Curing degree Example Composition of Table 9 Curing temperature (℃) Cure Time (sec) Hardness (%) 47a47b47c 434343 140140140 81828 132454 48a48b48c 434343 150150150 81828 225358 49a49b49c 434343 160160160 81828 366876

The results in Table 11 show that the polyepoxide curing degree of 50 to 76% can be achieved in a time of 18 to 28 seconds at a temperature of 140 to 160 ℃. Examples 44a, 44b, 45a, 46a, 47a, 47b, 48a and 49a were cured under conditions providing less than 50% degree of cure.

<Example 50-58>

Electrical connection test samples were cured at various times / temperatures using adhesive bonding films made from the compositions of Examples 42 and 43, and then exposed to environmental conditions as described in “Electrical Resistance” of Method 2 above. And afterwards the electrical resistance properties were evaluated. The obtained curing conditions and resistance values are shown in Tables 12 and 13, respectively.

Electrical resistance stability Example Composition of Table 9 Curing temperature (℃) Cure Time (sec) Environmental aging conditions Initial resistance value (Ohm range) Resistance value after 212 hours (Ohm range) 50a50b50c 424242 140140140 81828 444 0.84-1.890.26-1.070.43-1.13 0.93-2.171.03-1.221.02-1.17 51a51b51c 424242 150150150 81828 444 1.11- (open) 0.00-1.190.15-1.18 1.75- (open) 1.08-1.210.87-1.32 52a52b52c 424242 160160160 81828 444 0.93-1.161.00-1.170.92-1.11 1.01-16.641.02-1.210.93-1.23 53a53b53c 424242 140140140 81828 555 0.26-1.430.33-1.150.93-1.04 1.01-25.141.10- (Open) 0.96-1.08 54a54b54c 424242 150150150 81828 555 0.52- (open) 0.32-1.260.63-1.18 1.06- (open) 1.11-2.001.01-1.23 55a55b55c 424242 160160160 81828 555 0.98-9500.40-0.990.96-1.12 1.23-8360.93-1.851.01-1.38 ³ 1) open: resistance value of> 1,000 ohms 2) the given range did not include negative measurements; 3) one of the 30 measurements indicates 5.39, which is believed to be due to the warpage of the substrate.

Electrical resistance stability Example Composition of Table 9 Curing temperature (℃) Cure Time (sec) Environmental aging conditions Initial resistance value (Ohm range) Resistance value after 338 hours (Ohm range) Resistance value after 671 hours (Ohm range) 56a56b56c 434343 140140140 81828 444 0.69-1.350.22-1.041.06-1.16 1.18- (open) 0.94-1.531.08-1.17 1.16-4110.94-1.651.08-1.17 57a57b57c 434343 150150150 81828 444 0.45-1.120.85-1.081.01-1.08 1.17-2601.04-1.471.03-1.13 1.16-381.04-1.550.52-1.17 58a58b58c 434343 160160160 81828 444 0.53-1.290.94-1.170.57-1.12 1.34- (open) 0.94-1.190.93-1.13 1.32- (open) 0.99-1.190.93-1.13 1) Opening: Resistance value of> 1,000 ohms 2) For Comparative Example: The given range does not include negative measured values, which is considered to be due to adjacent openings.

The results in Tables 12 and 13 result in acceptable electrical connections in all examples where the curing conditions used provide a degree of cure of polyepoxides greater than 50%, the degree of polyepoxide cure based on the results shown in Tables 10 and 11. It is displayed. These connections remain acceptable after 671 hours (4 weeks) of exposure to environmental conditions. Examples 50a, 50b, 51a, 52a, 53a, 53b, 54a, 55a, 55b and 57a were cured under conditions providing less than 50% degree of cure.

Various modifications and variations in the methods and articles of the invention will be apparent to those skilled in the art without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (8)

(a) an acrylate polymer comprising a polymerization reaction product of (i) an acrylate monomer, and (ii) a crosslinking agent having an acrylate moiety, a polyepoxide resin, a thermally active modified aliphatic insoluble in an adhesive film at 20 ° C. Applying a thermosetting electrically conductive adhesive film (substantially free of this composition and components (i) and (ii) to the electrically conductive substrate) comprising an effective amount of an amine polyepoxide resin curing agent and an effective amount of an electrically conductive material; And (b) heating the adhesive film at a temperature of 90 to 180 ° C. for 15 seconds to 5 minutes to cure the polyepoxide resin in the adhesive film. Method for providing an electrical connection comprising a. The method of claim 1 wherein the crosslinker is selected from the group consisting of urethane diacrylate oligomers and epoxy diacrylate oligomers. (a) an acrylate polymer comprising a polymerization reaction product of (i) an acrylate monomer, and (ii) a crosslinking agent having an acrylate moiety, a polyepoxide resin, a thermally active modified aliphatic insoluble in an adhesive film at 20 ° C. Applying a thermally curable thermally conductive adhesive film (substantially free of this composition and components (i) and (ii) to the substrate) comprising an effective amount of an amine polyepoxide resin curing agent and an effective amount of a thermally conductive material; And (b) heating the adhesive film at a temperature of 90 to 180 ° C. for 15 seconds to 5 minutes to cure the polyepoxide resin in the adhesive film. Method of providing a thermal transfer medium comprising a. The process of claim 1 or 3, wherein the polyepoxide resin curing agent is the reaction product of a novolak polyepoxide resin and a di-tertiary aliphatic amine. The method of claim 1 or 3, wherein the acrylate monomer is phenoxyethyl acrylate, isobornyl acrylate, or a mixture thereof. (a) a substrate; And (b) an acrylate polymer comprising a polymerization reaction product of (i) an acrylate monomer, and (ii) a crosslinking agent having an acrylate residue, adhered to the substrate, a polyepoxide resin, an adhesive film at 20 ° C. A thermally curable adhesive film comprising an effective amount of a heat-activated modified aliphatic amine polyepoxide resin curing agent and an electrically conductive material effective amount that are insoluble, and wherein the composition and components (i) and (ii) are substantially free of solvent, And the polyepoxide resin in the adhesive film can be cured by heating the adhesive film at a temperature of 90 to 180 ° C. for 15 seconds to 5 minutes. (a) a substrate; And (b) an acrylate polymer comprising a polymerization reaction product of (i) an acrylate monomer, and (ii) a crosslinking agent having an acrylate residue, adhered to the substrate, a polyepoxide resin, an adhesive film at 20 ° C. A heat curable adhesive film comprising substantially an insoluble modified aliphatic amine polyepoxide resin curing agent effective amount and a thermally conductive material effective amount (the composition and components (i) and (ii) are substantially free of solvent), And the polyepoxide resin in the adhesive film can be cured by heating the adhesive film at a temperature of 90 to 180 ° C. for 15 seconds to 5 minutes. (a) an acrylate polymer comprising a polymerization reaction product of (i) an acrylate monomer, and (ii) a crosslinking agent having an acrylate moiety, a polyepoxide resin, a thermally active modified aliphatic insoluble in an adhesive film at 20 ° C. Applying a thermally curable electrically conductive adhesive film (substantially free of this composition and components (i) and (ii) to the substrate) comprising an effective amount of an amine polyepoxide resin curing agent and an electrically conductive material effective amount; And (b) heating the adhesive film at a temperature of 90 to 180 ° C. for 15 seconds to 5 minutes to cure the polyepoxide resin in the adhesive film. Electromagnetic interference shielding method comprising a.