TWI699415B - Thermosetting adhesive composition - Google Patents

Abstract

Provided is a thermosetting adhesive composition and a thermosetting adhesive sheet that can inhibit resin exudation.

The thermosetting adhesive composition of the present invention constituting the thermosetting adhesive sheet 20 contains an acrylic copolymer, a thermosetting epoxy resin, an epoxy resin curing agent, a dendritic conductive filler 21, and an average particle diameter of 3 μm The non-conductive filler 22 is within the range of 15 μm or more. Thereby, since the non-conductive filler 22 is wound around the dendritic conductive filler 21, the flow of the resin component is suppressed to suppress resin exudation, and the metal plate 30 and the terminal 11 are electrically connected.

Description

Thermosetting adhesive composition

The present invention relates to a conductive thermosetting adhesive composition for connecting a ground terminal of a flexible printed wiring board to a metal plate to reinforce the flexible printed wiring board.

Previously, the flexible printed wiring board was reinforced with the metal plate, and the grounding terminal of the flexible printed wiring board was electrically connected to the metal plate to be grounded, thereby performing shielding. In the bonding between the flexible printed wiring board and the metal plate, a conductive thermosetting bonding composition is used.

As conventional technologies, there are, for example, Japanese Patent Application Publication No. 2011-79959 and Japanese Patent Application Publication No. 2013-41869.

In order to perform plating or flow soldering of the circuit pattern of the flexible printed wiring board, there are cases where openings are provided in the metal plate. However, in the conventional thermosetting adhesive composition, there is a situation in which the resin component oozes out in a large amount when heated and pressurized, causing the opening of the metal plate to be blocked.

The present invention is proposed in view of the actual situation of such conventional knowledge, and provides a thermosetting adhesive composition that has conductivity and can inhibit resin bleeding.

The inventors conducted intensive studies and found that by using dendritic conductive fillers and specific average particle diameter non-conductive fillers, resin exudation can be suppressed.

That is, the thermosetting adhesive composition of the present invention is the following thermosetting adhesive composition, which has a resin component containing an acrylic copolymer, a thermosetting epoxy resin with epoxy groups remaining in the molecule, and The epoxy resin hardener for curing the thermosetting epoxy resin; dendritic conductive filler dispersed in the resin component; and non-conductive filler dispersed in the resin component; the non-conductive filler The average particle size is in the range of 3 μm or more and 15 μm or less.

The present invention is a thermosetting adhesive composition in which the non-conductive filler is contained in a range of 4 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the acrylic copolymer.

The present invention is a thermosetting adhesive composition, wherein the non-conductive filler is an organic filler.

The present invention is a thermosetting adhesive composition, wherein the non-conductive filler is an organic filler, and the organic filler is a polyurethane resin particle.

The present invention is a thermosetting adhesive composition, wherein, when the monomer that produces the acrylic copolymer by copolymerization is set to 100wt%, the acrylic copolymer is in the range of 55wt% to 80wt% (Meth) acrylate monomer, 15wt% or more and The monomer of acrylonitrile in the range of 30wt% or less and the monomer of glycidyl methacrylate in the range of 5wt% or more and 15wt% or less are produced by copolymerization.

The present invention is a thermosetting adhesive composition, wherein the epoxy resin curing agent is an organic acid dihydrazide.

The present invention is a thermosetting adhesive composition in which, relative to 100 parts by mass of the acrylic copolymer, the thermosetting epoxy resin contains a liquid in a range of 5 parts by mass to 30 parts by mass The epoxy resin is a liquid thermosetting epoxy resin, and the solid epoxy resin, which is a solid thermosetting epoxy resin, is contained in the range of 10 parts by mass or more and 50 parts by mass or less. 100 parts by mass of the raw material components composed of the copolymer and the above-mentioned epoxy resin contain the above-mentioned epoxy resin hardener in the range of 1 part by mass or more and 50 parts by mass or less.

The present invention is a thermosetting adhesive composition in which the average particle diameter of the dendritic conductive filler is set in the range of 3 μm or more and 20 μm or less.

The present invention is a thermosetting adhesive composition formed into a film shape.

The present invention is a thermosetting adhesive composition, wherein the average particle size of the non-conductive filler is smaller than the average particle size of the dendritic conductive filler.

According to the present invention, since the non-conductive filler of a specific average particle size is wound around the dendritic conductive filler, the flow of the resin component can be suppressed, thereby suppressing resin exudation.

10‧‧‧Flexible printed wiring board

11‧‧‧Terminal

12‧‧‧Substrate

13‧‧‧Wiring

14‧‧‧Next layer

15‧‧‧Protection layer

20‧‧‧Thermosetting adhesive film

21‧‧‧Dendrite conductive filler

22‧‧‧Non-conductive filler

30‧‧‧Metal plate

Figure 1 is used to illustrate the connection method using a thermosetting adhesive sheet The oblique view.

Figure 2 is a cross-sectional view of a connection structure using a thermosetting adhesive sheet.

Fig. 3 is a cross-sectional view of the thermosetting adhesive sheet for explaining the connection method using the thermosetting adhesive sheet.

Figure 4 is a diagram for explaining the shape of the dendritic filler.

Hereinafter, embodiments of the present invention will be described in detail in the following order while referring to the drawings.

1. Thermosetting adhesive composition

2. Thermosetting adhesive sheet

3. Example

<1. Thermosetting adhesive composition>

If the monomer that produces the acrylic resin by polymerization is called the acrylic monomer, the thermosetting adhesive composition of the present invention contains an acrylic polymer obtained by copolymerizing two or more acrylic monomers, that is, an acrylic copolymer (A).

In addition, the thermosetting adhesive composition of the present invention contains a thermosetting epoxy resin (B) in which an epoxy group remains in the molecule and is classified as a prepolymer. The thermosetting epoxy resin (B) is a reactive polymer, and when the polymerization reaction is started by a reaction initiator, it will be cross-linked to form a network-like polymer.

If acrylic copolymer (A) and thermosetting epoxy resin (B) are used as resin components, the thermosetting adhesive composition of the present invention contains resin components, epoxy resin hardener (C), and resin Dendritic conductive filler (D) and non-conductive filler (E).

Hereinafter, each component (A) to (E) of the thermosetting adhesive composition will be described in detail.

[(A) Acrylic copolymer]

The acrylic copolymer of the present invention is one that imparts film forming properties and imparts flexibility and toughness to the cured product during film formation, and is made of alkyl (meth)acrylate monomers and acrylonitrile (AN) monomers And glycidyl methacrylate (GMA) monomer copolymerized. Here, the so-called (meth)acrylate means acrylic acid ester or methacrylic acid ester.

As the (meth)acrylic acid alkyl ester, it can be appropriately selected from the conventional acrylic thermosetting adhesive used in the field of electronic parts and used as a monomer. For example, it can be used as a monomer with 4 carbon atoms. Alkyl (meth)acrylate of an alkyl group of more than and 12 or less. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, (meth) ) 2-ethylhexyl acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, etc., among them One type is used alone, or two or more types are used in combination. Among these, ethyl acrylate (EA), butyl acrylate (BA), and 2-ethylhexyl acrylate (2EHA) are preferably used.

Regarding the amount of (meth)acrylic acid alkyl ester in all the monomers constituting the acrylic copolymer, if it is too small, the basic properties tend to decrease, and if it is too large, the heat resistance tends to decrease, so it is preferably 55wt% or more And below 80wt%.

Also, regarding the acrylonitrile (AN) in all monomers that produce acrylic copolymers If the amount is too small, the heat resistance tends to decrease, and if it is too large, it tends to be difficult to dissolve in the solvent. Therefore, it is preferably 15 wt% or more and 30 wt% or less.

Regarding the amount of glycidyl methacrylate (GMA) in all monomers that form the acrylic copolymer, if it is too small, the heat resistance tends to decrease, and if it is too large, the peel strength tends to decrease, so it is preferable It is 5wt% or more and 15wt% or less.

The polymerization method of the acrylic copolymer is not particularly limited, but from the viewpoint of obtaining a high molecular weight, bead polymerization is preferred. Regarding the weight average molecular weight of the acrylic copolymer, if it is too small, the heat resistance tends to decrease, and if it is too large, the solution viscosity increases and the coatability tends to deteriorate. Therefore, it is preferably 500,000 or more and 700,000 or less, more preferably 550,000 or more And below 650,000

[(B) Thermosetting epoxy resin]

The thermosetting epoxy resin forms a three-dimensional network structure, which gives good heat resistance and adhesion. Among the thermosetting epoxy resins, there are solid thermosetting epoxy resins that are solid at room temperature, and at room temperature Liquid thermosetting epoxy resin which is liquid, among thermosetting epoxy resins contained in the present invention, it is preferable to use a mixture of solid thermosetting epoxy resin and liquid thermosetting epoxy resin.

Here, the "normal temperature" means the temperature range of 5°C to 35°C (5°C or more and 35°C or less) specified in JIS Z 8703.

The liquid thermosetting epoxy resin is not particularly limited as long as it is liquid at room temperature. Examples include bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, A naphthalene type epoxy resin etc. can be used individually by 1 type among these, or in combination of 2 or more types. Especially from the viewpoint of film viscosity and flexibility, it is better to use bisphenol A type Epoxy resin, bisphenol F type epoxy resin.

Regarding the content of the liquid thermosetting epoxy resin, if it is too small, the resin flow tends to decrease, and if it is too large, the room temperature storage property tends to decrease. Therefore, relative to 100 parts by mass of the acrylic copolymer, it is more It is preferably a range of 5 parts by mass or more and 30 parts by mass or less, and more preferably a range of 15 parts by mass or more and 25 parts by mass or less.

The solid thermosetting epoxy resin is not particularly limited as long as it is compatible with the liquid thermosetting epoxy resin and is solid at room temperature. Examples include multifunctional epoxy resins and dicyclopentadiene (DCPD) type epoxy resin, novolac type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, etc., can be used alone or in combination of two or more. Among them, DCPD type epoxy resin is preferably used.

Regarding the content of the solid thermosetting epoxy resin, if it is too small, the heat resistance tends to decrease, and if it is too large, the adhesiveness tends to decrease. Therefore, it is preferably 10 parts by mass or more relative to 100 parts by mass of the acrylic copolymer And the range of 50 parts by mass or less is more preferably the range of 30 parts by mass or more and 50 parts by mass or less.

[(C) Epoxy resin hardener]

As the epoxy resin hardener, a well-known hardener generally used can be used. For example, the organic acid dihydrazine, dicyandiamide, amine compound, polyamide amine compound, cyanate ester compound, phenol resin, acid anhydride, carboxylic acid, tertiary amine compound, imidazole, Lewis acid, Brunste salts, polythiol-based hardeners, urea resins, melamine resins, isocyanate compounds, blocked isocyanate compounds, latent hardeners, etc., can be used alone or combined Use 2 or more in combination. Among these, it is preferable to use organic acid dihydrazide from the viewpoint of room temperature storage properties.

Since the organic acid dihydrazide is solid at room temperature, it can improve the room temperature storage properties of the thermosetting adhesive composition. As the organic acid dihydrazine, for example, dihydrazine adipate, dihydrazine oxalate, dihydrazine malonate, dihydrazine succinate, dihydrazine iminodiacetate, and dihydrazine pimelate can be cited. Dihydrazine, dihydrazine suberate, dihydrazine azelate, dihydrazine sebacate, dihydrazine dodecanedioate, dihydrazine hexadecanedioate, dihydrazide maleate , Dihydrazine fumarate, diglycolic acid dihydrazine, dihydrazine tartrate, dihydrazine malate, dihydrazine isophthalate, dihydrazine terephthalate, 2,6-naphthalene Dihydrazine formate, 4,4'-biphenyldihydrazine, 1,4-naphthoate dihydrazine, Amicure VDH, Amicure UDH (trade name, manufactured by Ajinomoto), trihydrazine citrate, etc. , Can be used alone or in combination of two or more of them. Among them, it is preferable to use dihydrazine adipate in terms of relatively low melting point, excellent curing property balance, and easy availability.

In addition, the average particle diameter of the organic acid dihydrazine is preferably in the range of 0.5 μm or more and 15 μm or less, and more preferably in the range of 1 μm or more and 5 μm or less. If the average particle size is too small, there is a tendency that when an organic solvent is used for coating the thermosetting adhesive composition, the organic acid dihydrazine particles will dissolve, resulting in reduced storage at room temperature; if the average particle size is too large, heat The coating properties of the curable adhesive composition are reduced, and because of the large particle size, it is difficult to sufficiently mix with the acrylic copolymer or the thermosetting epoxy resin.

Regarding the content of the epoxy resin hardener, if the content of the epoxy resin hardener is too small, unreacted epoxy groups will remain, and the crosslinking will not be sufficient, so there is a tendency for heat resistance and adhesiveness to decrease. If too much, the excess hardener will not react. It remains in the same state, so there is a tendency for heat resistance and adhesiveness to decrease. Therefore, it is preferable that the total amount of acrylic copolymer and thermosetting epoxy resin is 100 parts by mass, and it is more than 1 part by mass and less than 50 parts by mass. Range of use, more preferably more than 5 parts by mass And use in the range of 30 parts by mass or less.

[(D) Dendritic conductive filler]

The knock tightness of the dendritic conductive filler is preferably in the range of 1.0 g/cm ³ or more and 1.8 g/cm ³ or less, more preferably 1.1 g/cm ³ or more and 1.6 g/cm ³ . If the tapping tightness is too small, the resin overflow (overflow) of the thermosetting adhesive composition caused by heating and pressing will increase. If the tapping tightness is too large, the filling of the conductive filler will become too dense, resulting in a high temperature environment The tendency of the conduction stability to decrease under high temperature and high humidity environment.

Here, the so-called dendritic crystal is also called dendritic crystal. As shown in FIG. 4, "dendritic" means the shape of the branches of a tree. The dendritic conductive filler 21 has main branches 31 and side branches 32, 33 . The dendritic conductive filler 21 because the main branch 31 and the side branches 32 and 33 are easily entangled with each other, it can prevent the dendritic conductive filler 21 in the conductive layer from being separated due to bending or deformation, so as to maintain even if bent or deformed Electric connection. In addition, the knock tightness is measured by the method specified in JIS Z 2512. Specifically, put a prescribed amount of powder in the container, use a tapping device to tap until the volume of the powder no longer decreases, divide the mass of the powder by the volume of the tapped powder to obtain the density. The density is set as the knock tightness.

The dendritic conductive filler 21 can be obtained, for example, by forming main branches 31 and side branches 32 and 33 on metal powder by electrolysis, liquid phase reduction, or the like.

Examples of the metal powder include copper powder, silver powder, nickel powder, and the like, and examples of the main branch 31 and side branches 32, 33 include copper, silver, and gold. That is, the dendritic conductive filler 21 includes copper-coated copper powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, gold-coated nickel powder, etc. Among them, silver-coated copper powder is preferably used .

The average particle size of the dendritic conductive filler 21 is preferably 3 μm or more and The range of 20 μm or less is more preferably the range of 5 μm or more and 15 μm or less. If the average particle size is too small, the formation of the main branch 31 and the side branches 32 and 33 becomes difficult, and if the average particle diameter is too large, it becomes difficult to thin the film. Here, the average particle size of the dendritic conductive filler 21 is the particle size D50 of 50% of the cumulative fraction under the sieve calculated based on, for example, a particle size distribution measurement result obtained by a laser diffraction scattering method.

Regarding the addition amount of the dendritic conductive filler 21, it is preferably used in the range of 100 parts by mass or more and 300 parts by mass relative to 100 parts by mass of the acrylic copolymer, more preferably 150 parts by mass or more and 250 parts by mass or less The scope of use.

If the addition amount is too small, the conductivity and resin overflow tend to be deteriorated, and if the addition amount is too large, the conduction stability in a high temperature environment or a high temperature and high humidity environment tends to decrease.

In addition, as the conductive filler, non-dendritic conductive fillers such as spherical, flake-shaped, and filament-shaped may be added. In the case of non-dendritic conductive filler, the ratio of dendritic conductive filler in the conductive filler is preferably used in the range of 40wt% or more and 100wt% or less, and more preferably 60wt% Use in the range above and below 100wt%. If the ratio of the dendritic conductive filler 21 is too small, the conduction stability in a high temperature environment or a high temperature and high humidity environment tends to decrease.

[(E) Non-conductive filler]

The average particle diameter of the non-conductive filler is preferably in the range of 3 μm or more and 15 μm or less, more preferably in the range of 5 μm or more and 15 μm or less. If the average particle size is too small, the effect of suppressing the amount of resin bleeding tends to decrease, and if the average particle size is too large, the resistance value tends to increase. Here, the average particle diameter of the conductive filler is defined as the particle diameter D50 of 50% of the cumulative fraction under the sieve calculated from the particle size distribution measurement result by the laser diffraction scattering method.

In addition, the amount of the non-conductive filler added is preferably in the range of 4 parts by mass or more and 120 parts by mass relative to 100 parts by mass of the acrylic copolymer, more preferably 10 parts by mass or more and 100 parts by mass or less Range of use. If the amount added is too small, the effect of suppressing the amount of resin bleeding tends to decrease, and if the amount added is too large, the adhesive strength tends to decrease.

(benzoguanamine)樹脂粒子、環氧樹脂粒子等。又，作為無機填料，例如可列舉二氧化矽(SiO₂)、氧化鋁(Al₂O₃)、二氧化鈦(TiO₂)、氧化鉭(Ta₂O₅)、氧化鋯(ZrO₂)等。該等之中，就接著強度(剝離強度)之觀點而言，較佳為有機填料，作為一例，有機填料之中較佳使用聚胺酯樹脂粒子。聚胺酯樹脂粒子可藉由懸浮聚合而製造，特別是根據玻璃轉移溫度低之性質可提高熱硬化性接著組成物之接著強度。 As the non-conductive filler, at least one of organic fillers and inorganic fillers can be used. Examples of organic fillers include polyurethane resin particles, polyimide resin particles, and benzoguanidine.

(benzoguanamine) resin particles, epoxy resin particles, etc. In addition, as the inorganic filler, for example, silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ), tantalum oxide (Ta ₂ O ₅ ), zirconium oxide (ZrO ₂ ), and the like can be cited. Among them, from the viewpoint of adhesive strength (peel strength), organic fillers are preferred. As an example, polyurethane resin particles are preferably used among organic fillers. Polyurethane resin particles can be manufactured by suspension polymerization, and in particular, the adhesive strength of the thermosetting adhesive composition can be improved due to the low glass transition temperature.

In addition, when the thermosetting adhesive composition is formed into a sheet shape to produce a thermosetting adhesive sheet, the average particle size of the non-conductive filler will also be affected by the average particle size of the dendritic conductive filler, or thermal curing In the case of organic fillers, the thickness of the adhesive sheet is preferably in the range of 3 μm or more and 15 μm or less. On the other hand, in the case of inorganic fillers, it is preferably in the range of 3 μm or more and 10 μm or less.

[Other additives]

In addition, as other additives blended into the thermosetting adhesive composition, it is preferable to add nitrile rubber. Nitrile rubber can improve temporary adhesion due to its excellent mechanical properties and elasticity. Regarding the addition amount of the nitrile rubber, it is preferably used in the range of 1 part by mass or more and 20 parts by mass, more preferably in the range of 5 parts by mass or more and 15 parts by mass relative to 100 parts by mass of the acrylic copolymer Make use.

If the amount added is too small, the temporary adhesion tends to decrease, and if the amount added is too large, the on-resistance in a high temperature environment or a high temperature and high humidity environment tends to increase.

In addition, diluting monomers such as thermally conductive particles, film forming resins, various acrylic monomers, fillers, softeners, colorants, flame retardants, thixotropic agents, silane coupling agents, etc. may be blended as necessary.

In the thermosetting adhesive composition composed of such components, if the average particle size of the non-conductive filler is made smaller than the average particle diameter of the dendritic conductive filler contained in the thermosetting adhesive composition, it is specified The non-conductive filler with the average particle size will be entangled with the dendritic conductive filler to inhibit the flow of resin components and also inhibit resin exudation.

In addition, by using organic fillers as non-conductive fillers, the bonding strength can be improved.

<2. Thermosetting adhesive sheet>

A thermosetting adhesive sheet composed of a thermosetting adhesive composition formed into a sheet, containing acrylic copolymer (A), thermosetting epoxy resin (B), and epoxy resin hardener (C) The resin component is dispersed with dendritic conductive filler (D) and non-conductive filler (E). Since each component (A)-(E) is the same as the said thermosetting adhesive composition, description here is abbreviate|omitted.

The above-mentioned components (A) to (E) can be uniformly mixed by a conventional method to prepare a thermosetting adhesive composition of the desired composition.

Next, the prepared thermosetting adhesive composition is coated on the base film using a bar coater or a roll coater so that the dry thickness is in the range of 10 μm or more and 60 μm or less, and dried by a conventional method. This manufacture has the thermosetting property of the layer of thermosetting adhesive composition Then the film.

As the base film, a peeling base obtained by peeling a base material such as a polyethylene terephthalate film and a polyimide film with polysiloxane or the like can be used as needed.

This kind of thermosetting adhesive sheet can be preferably used for bonding and fixing the terminal part of a flexible printed wiring board and a reinforcing sheet used as its substrate. The reinforcing sheet is polyethylene terephthalate. , Polyimide, epoxy glass, stainless steel, aluminum and other materials, with a thickness of 50μm or more and 2mm or less. In addition, since it can be easily adhered to the reinforcing sheet by thermal lamination, the workability can be improved.

Figures 1 to 3 are diagrams showing connection examples using thermosetting adhesive sheets.

The symbol 8 in FIG. 2 indicates a connection structure formed by bonding the flexible printed wiring board 10 and the metal plate 30 with the thermosetting adhesive sheet 20 using a thermosetting adhesive sheet.

First, if the connection structure 8 is described, the flexible printed wiring board 10 is formed by laminating the base material 12, the wiring 13, the adhesive layer 14, and the protective layer 15 in this order, and the terminal 11 is provided at the end. The flexible printed wiring board 10 is composed of, for example, polyimide as the base material 12, copper as the wiring 13, epoxy resin as the adhesive layer 14, and polyimide as the protective layer 15, and the terminal 11 The surface is gilded.

Next, if the manufacturing procedure of the connection structure 8 is described, FIG. 3 shows that the uncured thermosetting adhesive sheet 20 is peeled from the base film as shown in FIG. 1 and placed on the flexible printed wiring board 10 and the metal plate 30 In the state between, and the surface and back of the layer of the thermosetting composition are exposed.

On the surface of the flexible printed wiring board 10, the protective layer 15 is exposed, and an opening 18 is formed on the terminal 11 of the protective layer 15 to expose the terminal 11 on the bottom surface.

Make one side of the thermosetting adhesive sheet 20 contact the surface of the flexible printed wiring board 10 The protective layer 15 and the surface of the terminal 11 exposed on the bottom surface of the opening 18, and the opposite side is in contact with the metal plate 30, while the flexible printed wiring board 10 and the metal plate 30 are heated, and the metal plate 30 and Either one or both of the flexible printed wiring board 10 is pressed against the thermosetting adhesive sheet 20.

For example, by placing the flexible printed wiring board 10 on a table, heating the metal plate 30 while pressing the metal plate 30, and pressing the thermosetting property between the flexible printed wiring board 10 and the metal plate 30 Then film 20.

The front and back surfaces of the thermosetting adhesive sheet 20 have adhesive force at room temperature, and the flexible printed wiring board 10 and the metal plate 30 are bonded to the thermosetting adhesive sheet 20.

The thermosetting adhesive sheet 20 is heated by heat conduction from the heated metal plate 30 or the heated flexible printed wiring board 10, and is heated and softened. At this time, the flow of the resin component is suppressed by the non-conductive filler 22 and the dendritic conductive filler 21 dispersed in the resin component.

The softened thermosetting adhesive sheet 20 is heated in a state in which it is in contact with the metal plate 30, the protective layer 15 of the flexible printed wiring board 10, and the terminals 11. If the temperature of the thermosetting adhesive sheet 20 rises to a certain temperature, the epoxy resin curing agent reacts with the epoxy groups in the thermosetting epoxy resin to start the polymerization reaction of the thermosetting epoxy resin to form a mesh structure Macromolecular epoxy resin, and thermally hardened.

If the flexible printed wiring board 10, the metal plate 30, and the thermosetting thermosetting adhesive sheet 20 are cooled, the metal plate 30 and the flexible printed wiring board 10 can be obtained by the thermosetting thermosetting adhesive sheet 20. Connected structure 8 (Figure 2).

The thermally hardened thermosetting adhesive sheet 20 is also in contact with the metal plate 30, the protective layer 15 of the flexible printed wiring board 10, and the terminal 11, and is dispersed on the thermally hardened thermosetting adhesive sheet The dendritic conductive filler 21 in 20 is in contact with the adjacent dendritic conductive filler 21, and the thermally hardened thermosetting adhesive sheet 20 has a plurality of dendritic conductive fillers 21 in contact with each other at least in the thickness direction Electrical conductivity. In this example, the thermosetting adhesive sheet 20 also has electrical conductivity in the expansion direction.

The dendritic conductive filler 21 located on the surface of the thermosetting thermosetting adhesive sheet 20 is in contact with the terminal 11 on one side of the thermosetting thermosetting adhesive sheet 20, and the opposite side is in contact with the metal plate 30 Therefore, the metal plate 30 and the terminal 11 are electrically connected by contacting the "multiple dendritic conductive fillers 21 in contact with each other in the thermosetting thermosetting adhesive sheet 20". Therefore, the metal plate 30 and the terminal 11 are electrically connected by The thermosetting thermosetting adhesive sheet 20 is electrically connected.

When the metal plate 30 is set to cover the size of the wiring pattern of the flexible printed wiring board 10 and the terminal 11 is connected to the ground potential, since the metal plate 30 is connected to the ground potential, the wiring pattern of the flexible printed wiring board 10 is shielded , Will not enter harmful electromagnetic waves into the wiring pattern.

In this way, by curing the thermosetting adhesive sheet 20 to adhere the flexible printed wiring board 10 to the metal plate 30, the flexible printed wiring board 10 can be reinforced, and the terminals 11 of the flexible printed wiring board 10 can be electrically connected. Connected to the metal plate 30. In this way, when the terminal 11 is grounded, the flexible printed wiring board 10 can be shielded.

The terminal 11 connected to the metal plate 30 via the cured thermosetting adhesive sheet 20 can also be connected to a potential other than the ground potential of the electronic circuit of the flexible printed wiring board 10.

In the thermosetting adhesive sheet 20 of the present invention, the non-conductive filler 22 of a specific average particle size is wound around the dendritic conductive filler 21 to suppress the flow of resin components, thereby suppressing resin exudation. Therefore, the metal plate 30 can be provided with openings to perform the flexible printed wiring board 10 The yield rate of the circuit pattern plating or soldering is improved.

[Example] <3.1 First Example: Regarding the size of non-conductive filler>

In the first embodiment, a thermosetting adhesive sheet was produced, and the size of the non-conductive filler was verified. The thermosetting adhesive sheet uses the following components to prepare a thermosetting adhesive composition. The thermosetting adhesive composition is applied to a polyethylene terephthalate film (PET) that has been peeled off, and dried in a drying oven at 50 to 130°C to produce a thermosetting adhesive composition with a thickness of 35μm The layer of thermosetting adhesive sheet.

Then, (1) adhesive strength and (2) resin exudation amount were evaluated. Here, the knock tightness of the dendritic conductive filler is measured by the method specified in JIS Z 2512. Specifically, put a prescribed amount of powder in the container, use the tapping device to tap until the volume of the powder no longer decreases, divide the mass of the powder by the volume of the tapped powder to obtain the density, and set the density as Knock tightness. In addition, the average particle size of the conductive filler is set to a particle size D50 of 50% of the cumulative fraction under the sieve calculated based on the particle size distribution measurement result by the laser diffraction scattering method.

The acrylic copolymer obtained by the following method is used: when the total acrylic monomer of the acrylic copolymer obtained by the copolymerization reaction is set to 100wt%, the acrylic monomer contains 66wt% including butyl acrylate (BA) and acrylic acid Ethyl (EA) alkyl (meth)acrylate, 24wt% acrylonitrile (AN), and 10wt% glycidyl methacrylate (GMA) are copolymerized to obtain acrylic copolymer .

In addition, as the thermosetting epoxy resin, a liquid thermosetting epoxy resin (product name "jER828", manufactured by Mitsubishi Chemical Co., Ltd.) and a solid thermosetting epoxy resin are used The DCPD type solid epoxy resin (product name "HP7200L", manufactured by DIC Co., Ltd.), and the epoxy resin hardener (dihydrazine adipate) is used.

The dendritic conductive filler uses dendritic copper powder with a knock compactness of 1.4 g/cm ³ and an average particle size of 10 μm.

As the conductive filler of other shapes, filamentous nickel powder (product name "F-255", manufactured by Vale Co., Ltd.) is used.

The non-conductive filler uses polyurethane particles with an average particle size of 0.7μm, 2.0μm, 3.8μm, 6.0μm, or 15.0μm (product name "Art Pearl", manufactured by Negami Industrial Co., Ltd.) or an average particle size of 0.7μm, 3.0μm, 7.0μm, 10.0μm silicon dioxide particles (product name "FB", manufactured by Denki Kagaku Co., Ltd.).

[(1) Measurement of peel strength]

Cut the thermosetting adhesive sheet into short strips (2cm×5cm), and temporarily attach the layer of thermosetting adhesive composition on one side to a 1.5cm×40cm gold-plated substrate using a laminator set at 140°C. After that, the peeling substrate is removed to expose the layer of the thermosetting adhesive composition on the other side.

A 50μm thick polyimide film of the same size was superimposed on the exposed thermosetting adhesive composition layer from above, using a vacuum press machine (product name "Vacuum Star", manufactured by MIKADO TECHNOS Co., Ltd.) at a temperature of 185°C , The pressure is 4.0MPa, the vacuum holding time is 10 seconds + the pressing time is 90 seconds, and the hot pressing is carried out. After that, it is kept in an oven at 140°C for 60 minutes. Thereafter, a 90-degree peel test was performed on the polyimide film at a peel speed of 50 mm/min, and the force required for peeling was measured as the peel strength. The peel strength is preferably 12 N/cm or more.

[(2) Measurement of resin exudation]

Set the layer utilization of the thermosetting adhesive composition on one side of the thermosetting adhesive sheet to 140 Temporarily attach to a 100μm thick SUS board (2cm×3cm) with a laminating machine at ℃, then remove the peeling substrate to expose the thermosetting adhesive composition layer on the other side, and expose the thermosetting adhesive composition The layer is cut into the same size as the SUS board. The exposed thermosetting adhesive composition layer on the SUS board was temporarily attached to a 175μm thick polyimide film (5cm×5cm) using a laminator set at 140°C, and then a vacuum press machine ( The product name is "Vacuum Star", manufactured by MIKADO TECHNOS Co., Ltd.). It is hot-pressed at a temperature of 185°C, a pressure of 4.0 MPa, a vacuum holding time of 10 seconds + a pressing time of 90 seconds, and then placed in an oven at 140°C Keep it for 60 minutes. Then, the length of the layer of the thermosetting adhesive composition exuded from the SUS end of the test piece was measured with a metal microscope as the amount of resin exudation. The amount of resin bleeding is preferably 200 μm or less.

<Example 1>

As shown in Table 1, 25 parts by mass of acrylic copolymer, 5 parts by mass of liquid thermosetting epoxy resin, 10 parts by mass of solid thermosetting epoxy resin, and 10 parts by mass of dihydrazine adipate were used. A thermosetting adhesive composition of 50 parts by mass of dendritic copper powder and 6 parts by mass of polyurethane particles with an average particle size of 3.8 μm was used to produce a thermosetting adhesive sheet. (1) The peel strength of this thermosetting adhesive sheet was 15.1 N/cm, and (2) the amount of resin exudation was 188 μm.

<Example 2>

As shown in Table 1, a thermosetting adhesive sheet was produced in the same manner as in Example 1, except that 6 parts by mass of polyurethane particles having an average particle diameter of 6.0 μm were blended as a non-conductive filler. (1) The peel strength of this thermosetting adhesive sheet was 15.2 N/cm, and (2) the amount of resin exudation was 106 μm.

<Example 3>

As shown in Table 1, a thermosetting adhesive sheet was produced in the same manner as in Example 1, except that 6 parts by mass of polyurethane particles having an average particle diameter of 15.0 μm were blended as a non-conductive filler. The heat (1) The peel strength of the curable adhesive sheet was 15.3 N/cm, and (2) the resin exudation amount was 95 μm.

<Example 4>

As shown in Table 1, a thermosetting adhesive sheet was produced in the same manner as in Example 1, except that 12 parts by mass of silica particles having an average particle diameter of 3.0 μm were blended as a non-conductive filler. (1) The peel strength of this thermosetting adhesive sheet was 12.4 N/cm, and (2) the resin exudation amount was 195 μm.

<Example 5>

As shown in Table 1, a thermosetting adhesive sheet was produced in the same manner as in Example 1, except that 12 parts by mass of silica particles having an average particle diameter of 7.0 μm were blended as a non-conductive filler. (1) The peeling strength of the thermosetting adhesive sheet was 12.0 N/cm, and (2) the resin exudation amount was 98 μm.

<Example 6>

As shown in Table 1, a thermosetting adhesive sheet was produced in the same manner as in Example 1, except that 12 parts by mass of silica particles with an average particle diameter of 10.0 μm were blended as a non-conductive filler. (1) The peel strength of the thermosetting adhesive sheet was 12.5 N/cm, and (2) the amount of resin exudation was 98 μm.

<Comparative Example 1>

As shown in Table 1, a thermosetting adhesive sheet was produced in the same manner as in Example 1 except that no non-conductive filler was blended. (1) The peel strength of this thermosetting adhesive sheet was 12.1 N/cm, and (2) the resin exudation amount was 254 μm.

<Comparative Example 2>

As shown in Table 1, a thermosetting adhesive sheet was produced in the same manner as in Example 1, except that 6 parts by mass of polyurethane particles having an average particle diameter of 0.7 μm were blended as a non-conductive filler. (1) The peel strength of this thermosetting adhesive sheet was 15.6 N/cm, and (2) the amount of resin exudation was 240 μm.

<Comparative Example 3>

As shown in Table 1, a thermosetting adhesive sheet was produced in the same manner as in Example 1, except that 6 parts by mass of polyurethane particles having an average particle diameter of 2.0 μm were blended as a non-conductive filler. (1) The peel strength of this thermosetting adhesive sheet was 14.8 N/cm, and (2) the amount of resin exudation was 210 μm.

<Comparative Example 4>

As shown in Table 1, a thermosetting adhesive sheet was produced in the same manner as in Example 1, except that 12 parts by mass of silicon dioxide particles with an average particle diameter of 0.7 μm were blended as a non-conductive filler. (1) The peel strength of the thermosetting adhesive sheet was 12.2 N/cm, and (2) the resin exudation amount was 212 μm.

<Comparative Example 5>

As shown in Table 1, a thermosetting adhesive sheet was produced in the same manner as in Example 2 except that 50 parts by mass of the filamentous nickel powder was blended instead of the dendritic copper powder as the conductive filler. The (2) resin exudation amount of this thermosetting adhesive sheet was 249 μm.

When the conductive filler is not contained as in Comparative Example 1, the amount of resin bleeding is large. In addition, when the average particle size of the non-conductive filler is small as in Comparative Examples 2 to 4, the amount of resin bleeding is also large. In addition, when the filamentous Ni powder was contained in place of the dendritic copper powder as in Comparative Example 5, the amount of resin bleeding was also large.

On the other hand, when the average particle size of the non-conductive filler is 3 to 15 μm as in Examples 1 to 6, the amount of resin bleeding is reduced, and the peel strength is also good. Especially with regard to peel strength, it is better when using polyurethane particles as organic fillers than when using silica particles as inorganic fillers.

<3.2 Second Example: Regarding the blending amount of non-conductive filler>

In the second example, the same non-conductive filler as in Example 2 was blended to produce a thermosetting adhesive composition, and the peeling strength and the amount of resin bleeding were evaluated with respect to the blending amount of the non-conductive filler. In addition, since each blending component and evaluation item are the same as in the first embodiment, the description will be omitted here.

<Comparative Example 6>

As shown in Table 2, a thermosetting adhesive sheet was produced in the same manner as in Example 2 except that 0.5 parts by mass of polyurethane particles having an average particle diameter of 6.0 μm were blended as a non-conductive filler. (1) The peel strength of this thermosetting adhesive sheet was 15.0 N/cm, and (2) the resin exudation amount was 225 μm.

<Example 7>

As shown in Table 2, a thermosetting adhesive sheet was produced in the same manner as in Example 2 except that 1 part by mass of polyurethane particles having an average particle diameter of 6.0 μm was blended as a non-conductive filler. (1) The peel strength of this thermosetting adhesive sheet was 15.1 N/cm, and (2) the amount of resin exudation was 198 μm.

<Example 8>

As shown in Table 2, 3 parts by mass of polyurethane particles with an average particle diameter of 6.0 μm were blended as a non-conductive filler. A thermosetting adhesive sheet was produced in the same manner as in Example 2. The heat The (1) peel strength of the curable adhesive sheet was 14.9 N/cm, and (2) the resin exudation amount was 161 μm.

<Example 9>

As shown in Table 2, a thermosetting adhesive sheet was produced in the same manner as in Example 2 except that 10 parts by mass of polyurethane particles having an average particle diameter of 6.0 μm were blended as a non-conductive filler. (1) The peeling strength of the thermosetting adhesive sheet was 15.5 N/cm, and (2) the resin exudation amount was 86 μm.

<Example 10>

As shown in Table 2, a thermosetting adhesive sheet was produced in the same manner as in Example 2 except that 30 parts by mass of polyurethane particles having an average particle diameter of 6.0 μm were blended as a non-conductive filler. (1) The peeling strength of this thermosetting adhesive sheet was 13.0 N/cm, and (2) the resin exudation amount was 66 μm.

<Comparative Example 7>

As shown in Table 2, except that 50 parts by mass of polyurethane particles with an average particle diameter of 6.0 μm were blended as a non-conductive filler, a thermosetting adhesive sheet was produced in the same manner as in Example 2. (1) The peel strength of this thermosetting adhesive sheet was 9.5 N/cm, and (2) the amount of resin exudation was 47 μm.

In the case where the blending amount of polyurethane particles is small as in Comparative Example 6, the amount of resin exudation is large. In the case where the blending amount of polyurethane particles is large as in Comparative Example 7, the resin exudation amount is small but peeling off Less intensity. On the other hand, when the blending amount of polyurethane particles is 1 to 30 parts by mass as in Examples 2, 7 to 10, the amount of resin exudation is reduced, and the peel strength is also good.

<3.3 Example 3: About the knock tightness of conductive filler>

In the third embodiment, a thermosetting adhesive composition was prepared by blending a conductive filler with a specific knock tightness, and the amount of resin exudation was evaluated for the knock tightness of the conductive filler.

Dendritic copper powder A: knock tightness 0.89g/cm ³ , average particle size 6μm

Dendritic copper powder B: knock compactness 1.18g/cm ³ , average particle size 10μm

Dendritic copper powder C: Knock tightness 1.60g/cm ³ , average particle size 12μm

Dendritic copper powder D: knock tightness 3.28g/cm ³ , average particle size 23μm

In addition, since each blending component and evaluation item are the same as in the first embodiment, the description will be omitted here.

<Example 11>

As shown in Table 3, 100 parts by mass of acrylic copolymer, 10 parts by mass of liquid thermosetting epoxy resin, 30 parts by mass of solid thermosetting epoxy resin, and 10 parts by mass of dihydrazine adipate were used. Nitrile rubber (product name "Nipol 1001", manufactured by Zeon Co., Ltd.) 8 parts by mass, 250 parts by mass of dendritic copper powder A with a tap density of 0.89 g/cm ³ and polyurethane particles with an average particle size of 6 μm 10 Parts by mass of the thermosetting adhesive composition to produce a thermosetting adhesive sheet. (1) The peel strength of this thermosetting adhesive sheet was 15.1 N/cm, and (2) the amount of resin exudation was 194 μm.

<Example 12>

As shown in Table 3, 250 parts by mass of dendritic copper powder B having a tap tightness of 1.18 g/cm ^{3 was} blended as a conductive filler, and a thermosetting adhesive sheet was produced in the same manner as in Example 11 except that it was blended. (1) The peel strength of this thermosetting adhesive sheet was 15.1 N/cm, and (2) the resin exudation amount was 115 μm.

<Example 13>

As shown in Table 3, 250 parts by mass of dendritic copper powder C having a tap tightness of 1.60 g/cm ^{3 was} blended as a conductive filler, and a thermosetting adhesive sheet was produced in the same manner as in Example 11 except that it was blended. (1) The peel strength of this thermosetting adhesive sheet was 15.0 N/cm, and (2) the resin exudation amount was 112 μm.

<Example 14>

As shown in Table 3, 250 parts by mass of dendritic copper powder D with a knock tightness of 3.28 g/cm ^{3 was} blended as a conductive filler, and a thermosetting adhesive sheet was produced in the same manner as in Example 11, except that it was blended. (1) The peel strength of this thermosetting adhesive sheet was 12.1 N/cm, and (2) the amount of resin exudation was 94 μm.

It can be seen that by using dendritic copper powder with a knock compactness of 0.8 g/cm ³ or more as in Examples 11-14, the amount of resin exudation can be reduced. In addition, when the tap tightness of the dendritic conductive filler is in the range of 0.89 g/cm ³ or more and 1.6 g/cm ³ or less, a higher value can be obtained in terms of peel strength.

Furthermore, the aforementioned thermosetting adhesive sheet exhibits adhesion on the surface at room temperature ("adhesion" includes adhesiveness), but the thermosetting adhesive sheet of the present invention may not exhibit adhesion on the surface at room temperature. In order to heat the metal plate and the flexible printed wiring board for bonding, the bonding performance is only expressed when the temperature is raised by heating.

8‧‧‧Connecting structure

10‧‧‧Flexible printed wiring board

11‧‧‧Terminal

12‧‧‧Substrate

13‧‧‧Wiring

14‧‧‧Next layer

15‧‧‧Protection layer

20‧‧‧Thermosetting adhesive film

21‧‧‧Dendrite conductive filler

22‧‧‧Non-conductive filler

30‧‧‧Metal plate

Claims (8)

A thermosetting adhesive composition comprising: a resin component containing: an acrylic copolymer, a thermosetting epoxy resin with epoxy groups remaining in the molecule, and a curing reaction for the thermosetting epoxy resin Epoxy resin hardener; dendritic conductive filler dispersed in the resin component; and non-conductive filler dispersed in the resin component; the average particle size of the non-conductive filler is in the range of 3 μm or more and 15 μm or less, The average particle size of the dendritic conductive filler is set to a range of 3 μm or more and 20 μm or less, and the average particle size of the non-conductive filler is set to be smaller than the average particle size of the dendritic conductive filler. For example, the thermosetting adhesive composition of the first item of the scope of patent application contains the non-conductive filler in a range of 4 parts by mass or more and 120 parts by mass relative to 100 parts by mass of the acrylic copolymer. For example, the thermosetting adhesive composition of item 1 or 2 in the scope of patent application, wherein the non-conductive filler is an organic filler. For example, the thermosetting adhesive composition of item 1 or 2 in the scope of patent application, wherein the non-conductive filler is an organic filler, and the organic filler is a polyurethane resin particle. For example, the thermosetting adhesive composition of item 1 or 2 of the scope of patent application, wherein, when the monomer that generates the acrylic copolymer by copolymerization is set to 100wt%, the acrylic copolymer is 55wt% or more and Alkyl (meth)acrylate in the range below 80wt% The monomer of acrylonitrile in the range of 15wt% or more and 30wt% or less, and the monomer of glycidyl methacrylate in the range of 5wt% or more and 15wt% or less are produced by copolymerization. For example, the thermosetting adhesive composition of item 1 or 2 in the scope of patent application, wherein the epoxy resin hardener is an organic acid dihydrazide. For example, the thermosetting adhesive composition of item 1 or 2 of the scope of patent application, wherein, relative to 100 parts by mass of the acrylic copolymer, the thermosetting epoxy resin is at least 5 parts by mass and 30 parts by mass or less The range contains the liquid epoxy resin, which is a liquid thermosetting epoxy resin, and the solid epoxy resin, which is a solid thermosetting epoxy resin, is contained in a range of 10 parts by mass or more and 50 parts by mass or less, The epoxy resin hardener is contained in the range of 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the raw material components composed of the acrylic copolymer and the epoxy resin. For example, the thermosetting adhesive composition of item 1 in the scope of patent application is formed into a film shape.

Images