HK1217381B

HK1217381B - Anisotropically conductive film and manufacturing method therefor

Info

Publication number: HK1217381B
Application number: HK16105225.8A
Authority: HK
Inventors: 猿山贤一; 阿久津恭志
Original assignee: Dexerials Corporation
Priority date: 2013-07-31
Filing date: 2014-07-29
Publication date: 2018-08-24

Description

Anisotropic conductive film and method for producing same

Technical Field

The present invention relates to an anisotropic conductive film and a method for manufacturing the same.

Background

Anisotropic conductive films are formed by dispersing conductive particles in an insulating adhesive, and are widely used for mounting electronic components such as IC chips. In recent years, as electronic devices have been miniaturized, mounting components have also been miniaturized, and a pitch of electrodes has been narrowed to a pitch of several tens of μm or the like. When electrodes with a narrowed pitch are connected by an anisotropic conductive film, short circuit due to connection of conductive particles between the electrodes and conduction failure due to absence of conductive particles between the electrodes are likely to occur.

In order to solve these problems, it is studied to arrange conductive particles regularly in an anisotropic conductive film, and for example, there are known: a method in which conductive particles are filled and fixed on one surface of a stretchable film, and the stretchable film is biaxially stretched to arrange the conductive particles at a predetermined center-to-center distance (patent document 1); or a method of aligning conductive particles using a transfer mold having a plurality of holes on the surface (patent document 2).

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4789738

Patent document 2: japanese patent laid-open No. 2010-33793.

Disclosure of Invention

Problems to be solved by the invention

However, in the conventional anisotropic conductive film in which conductive particles are regularly arranged, when an electronic component is mounted by using the anisotropic conductive film, the arrangement of the conductive particles becomes disordered and irregular, and thus, a short circuit due to connection of the conductive particles between electrodes or a conduction failure due to absence of the conductive particles between the electrodes cannot be sufficiently eliminated.

To this end, the main subject of the present invention is: the use of an anisotropic conductive film in which conductive particles are regularly arranged reduces short-circuiting and conduction failure when an electronic component is mounted.

Means for solving the problems

The inventor finds that: in the anisotropic conductive film in which conductive particles are kept in a predetermined arrangement, by controlling the thickness distribution of the insulating resin layer that keeps the conductive particles in a predetermined arrangement state in the vicinity of the conductive particles, the flow direction of the conductive particles can be controlled when an electronic component is mounted using the anisotropic conductive film, thereby reducing short-circuiting and conduction failure; it was also found that: in the case of manufacturing an anisotropic conductive film in which conductive particles are regularly arranged by using a transfer mold, such control of the thickness distribution of an insulating resin layer can be performed by controlling the shape of the transfer mold and filling the transfer mold with an insulating resin to retain the conductive particles in the insulating resin, and the present invention has been conceived.

That is, the present invention provides an anisotropic conductive film having a conductive particle alignment layer in which a plurality of conductive particles are held in a predetermined alignment in an insulating resin layer, wherein the insulating resin layer holding the alignment of the conductive particles has a thickness distribution around each conductive particle in an asymmetric direction with respect to the conductive particle.

The present invention also provides a method for manufacturing the anisotropic conductive film, the method comprising the steps of:

a step of filling conductive particles into a transfer mold having a plurality of openings on the surface,

a step of laminating an insulating resin on the conductive particles, and

a step of forming a conductive particle alignment layer in which a plurality of conductive particles are held in a predetermined alignment in an insulating resin layer and transferred from a transfer mold to the insulating resin layer;

and the following transfer mold was used: the depth distribution of each opening has an asymmetrical direction with respect to a vertical line passing through the center of the deepest portion of the opening.

The present invention further provides a connection structure in which the 1 st electronic component and the 2 nd electronic component are anisotropically conductively connected through the anisotropic conductive film.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the anisotropic conductive film of the present invention, since the thickness distribution of the insulating resin layer that holds the arrangement of the conductive particles has an asymmetric direction with respect to the conductive particles in the periphery of each conductive particle, when an electronic component is mounted using the anisotropic conductive film, the flow direction of the conductive particles depends on the direction in which the amount of resin in the insulating resin layer that holds the arrangement of the conductive particles is small in the periphery of the conductive particles. Therefore, when an electronic component is mounted using the anisotropic conductive film, the flow direction of the conductive particles is not concentrated on a specific portion, and short circuit due to connection of the conductive particles between electrodes or conduction failure due to absence of the conductive particles between electrodes can be reduced. Therefore, the connection structure of the present invention using the anisotropic conductive film has reduced short-circuiting and conduction failure, and is excellent in connection reliability.

Further, according to the method for manufacturing an anisotropic conductive film of the present invention, since the transfer mold having directional depth distribution of the opening is used in manufacturing the anisotropic conductive film of the present invention, the conductive particles are easily filled into the opening of the transfer mold, and aggregation of the conductive particles or falling off of the conductive particles at the opening when the conductive particles are filled into the opening can be prevented, so that occurrence of defects in alignment of the conductive particles in the anisotropic conductive film can be prevented. Thus, according to the anisotropic conductive film obtained by this method, short-circuiting and conduction failure at the time of mounting an electronic component can be further reduced.

In addition, according to the method for manufacturing an anisotropic conductive film of the present invention, after the conductive particle alignment layer is formed using the transfer mold, the operation of peeling the conductive particle alignment layer from the transfer mold becomes easy. The productivity of the anisotropic conductive film is improved.

Drawings

Fig. 1A is a plan view of an anisotropic conductive film 1A according to an embodiment of the present invention.

Fig. 1B is a cross-sectional view of an anisotropic conductive film 1A according to an embodiment of the present invention.

Fig. 1C is a cross-sectional view of an anisotropic conductive film 1A according to an embodiment of the present invention.

Fig. 2A is a perspective view of a transfer mold 10A used in manufacturing an anisotropic conductive film 1A.

Fig. 2B is a plan view of the transfer mold 10A used in the production of the anisotropic conductive film 1A.

Fig. 2C is a cross-sectional view of the transfer mold 10A used in the production of the anisotropic conductive film 1A.

Fig. 3A is a plan view of the transfer mold 10A filled with conductive particles.

Fig. 3B is a sectional view of the transfer mold 10A filled with conductive particles.

Fig. 4A is an explanatory view of a manufacturing process of the anisotropic conductive film 1A.

Fig. 4B is an explanatory view of a manufacturing process of the anisotropic conductive film 1A.

Fig. 4C is an explanatory view of the manufacturing process of the anisotropic conductive film 1A.

Fig. 4D is an explanatory view of the manufacturing process of the anisotropic conductive film 1A.

Fig. 4E is an explanatory view of a manufacturing process of the anisotropic conductive film 1A.

Fig. 4F is an explanatory view of a manufacturing process of the anisotropic conductive film 1A.

Fig. 4G is an explanatory view of a manufacturing process of the anisotropic conductive film 1A.

Fig. 5A is an explanatory view of a manufacturing process of the anisotropic conductive film 1A.

Fig. 5B is an explanatory view of the manufacturing process of the anisotropic conductive film 1A in fig. 5B.

Fig. 5C is an explanatory view of the manufacturing process of the anisotropic conductive film 1A.

Fig. 5D is an explanatory view of the manufacturing process of the anisotropic conductive film 1A.

Fig. 5E is an explanatory view of a manufacturing process of the anisotropic conductive film 1A.

Fig. 6A is an explanatory view of a manufacturing process of the anisotropic conductive film 1A.

Fig. 6B is an explanatory view of a manufacturing process of the anisotropic conductive film 1A.

Fig. 6C is an explanatory view of the manufacturing process of the anisotropic conductive film 1A.

Fig. 6D is an explanatory view of the manufacturing process of the anisotropic conductive film 1A.

Fig. 6E is an explanatory view of a manufacturing process of the anisotropic conductive film 1A.

Fig. 6F is an explanatory view of the manufacturing process of the anisotropic conductive film 1A.

Fig. 6G is an explanatory view of a manufacturing process of the anisotropic conductive film 1A.

Fig. 7A is a plan view of an anisotropic conductive film 1A' according to an embodiment of the present invention.

Fig. 7B is a cross-sectional view of an anisotropic conductive film 1A' according to an embodiment of the present invention.

Fig. 7C is a cross-sectional view of an anisotropic conductive film 1A' according to an embodiment of the present invention.

FIG. 8 is a plan view of an anisotropic conductive film 1A '' according to an embodiment of the present invention.

Fig. 9A is a sectional view of a transfer mold 10B filled with conductive particles.

Fig. 9B is a cross-sectional view of the anisotropic conductive film 1B obtained using the transfer mold 10B.

Fig. 10A is a sectional view of a transfer mold 10C filled with conductive particles.

Fig. 10B is a sectional view of the anisotropic conductive film 1C obtained using the transfer mold 10C.

Fig. 11A is a sectional view of a transfer mold 10D filled with conductive particles.

Fig. 11B is a cross-sectional view of the anisotropic conductive film 1D obtained using the transfer mold 10D.

Fig. 12A is a sectional view of a transfer mold 10E filled with conductive particles.

Fig. 12B is a cross-sectional view of the anisotropic conductive film 1E obtained using the transfer mold 10E.

Fig. 13A is a sectional view of a transfer mold 10X of a comparative example filled with conductive particles.

Fig. 13B is a cross-sectional view of the anisotropic conductive film 1X obtained using the transfer mold 10X.

Fig. 14 is an explanatory view of a method for evaluating the adhesive strength between the glass substrate and the IC chip for anisotropic conductive connection.

Detailed Description

The present invention is described in detail below with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same or equivalent components.

(1) Structure of anisotropic conductive film

(1-1) Overall Structure

3 fig. 3 1A 3 is 3a 3 plan 3 view 3, 3 fig. 3 1 3B 3 is 3a 3 sectional 3 view 3a 3- 3a 3, 3 and 3 fig. 3 1 3 c 3 is 3a 3 sectional 3 view 3B 3- 3B 3 of 3 an 3 anisotropic 3 conductive 3 film 3 1A 3 according 3 to 3 an 3 embodiment 3 of 3 the 3 present 3 invention 3. 3

As shown in the figure, the anisotropic conductive film 1A is characterized in that: the insulating resin layer 3 has a conductive particle array layer 4 in which a plurality of conductive particles 2 are directly held in the insulating resin layer 3, and the insulating resin layer 3 has a specific thickness distribution, which will be described later, around each conductive particle 2. One surface of the conductive particle array layer 4 is flat and the other surface has irregularities, the 2 nd insulating resin layer 5 is laminated on the irregular surface of the conductive particle array layer 4, and the 3 rd insulating resin layer 6 is laminated on the flat surface of the conductive particle array layer 4. In the present invention, the 2 nd insulating resin layer 5 and the 3 rd insulating resin layer 6 may be provided as needed in order to improve the adhesiveness between electronic components to be anisotropically conductively connected.

(1-2) conductive particle alignment layer

In the conductive particle alignment layer 4, a plurality of conductive particles 2 are aligned in a single layer in a tetragonal lattice. Each conductive particle 2 is held in the insulating resin layer 3 at the convex portion of each conductive particle alignment layer 4, and the insulating resin layer 3 around each conductive particle 2 has a truncated oblique cone shape with a substantially circular corner.

In the present invention, the arrangement of the conductive particles 2 is not limited to the tetragonal lattice. For example, a hexagonal lattice or the like may be used. The number of conductive particles held in the insulating resin layer 3 in one convex portion of the conductive particle alignment layer 4 is not limited to 1, and may be plural.

In the present invention, the shape of the insulating resin layer 3 forming the convex portion of the conductive particle alignment layer 4 is not limited to the oblique truncated cone shape, and may be a truncated cone shape such as an oblique rectangular truncated cone, for example.

In the anisotropic conductive film 1A, the thickness distribution of the insulating resin layer 3 has a direction X which is asymmetric in the left-right direction with respect to the center axis L1 of the conductive particles 2 (the center axis in the thickness direction of the anisotropic conductive film 1A), and the direction X is uniform in all the conductive particles 2.

3 that 3 is 3, 3 when 3 the 3 anisotropic 3 conductive 3 film 3 1A 3 is 3 cut 3 in 3 the 3 direction 3 X 3 through 3 the 3 center 3 P 3 of 3 any 3 conductive 3 particle 3 2 3, 3 the 3 area 3 of 3 the 3 insulating 3 resin 3 layer 33 3 around 3 q 3 of 3 each 3 conductive 3 particle 3 2 3 is 3 the 3 same 3 as 3 the 3 area 3 of 3 one 3 side 3 q 3 of 3 the 3 conductive 3 particle 3 2 3 in 3 the 3a 3- 3a 3 cross 3 section 3( 3 fig. 3 1 3b 3) 3 of 3 the 3 anisotropic 3 conductive 3 film 3 1A 3_aArea S of_aThan the other side Q_bArea S of_bIs small. Here, the respective guidesThe insulating resin layer 3 around the conductive particles 2Q is a convex region of the insulating resin layer 3 holding each conductive particle 2 in the cross section, that is, a region ranging from a portion where the thickness of the insulating resin layer 3 between the conductive particle 2 and its adjacent conductive particle 2 (the distance between the convex region side surface of the insulating resin layer 3 and the flat surface side region) is the thinnest to a portion where the thickness of the insulating resin layer 3 between the conductive particle 2 and its other adjacent conductive particle 2 is the thinnest.

In the cross section, one side Q of the conductive particle 2_aSide surface 3 of_aIs formed into a cliff shape along the thickness direction of the anisotropic conductive film 1A, and the other side Q is compared with the side surface 3a of one side Qa_bSide surface 3 of_bIs more inclined with respect to the thickness direction of the anisotropic conductive film 1A.

In this way, in the anisotropic conductive film 1A, the thickness distribution of the insulating resin layer 3 around each conductive particle 2 has a direction X asymmetric with respect to the central axis L1 of the conductive particle 2, and in a cross section in the direction X (fig. 1B), one side Q of the conductive particle 2 is located on the side of the conductive particle 2_aArea S of_aThan the other side Q_bArea S of_bSmall, the resin amount of the insulating resin layer 3 holding the conductive particles 2 is one side Qa than the other side Q_bSince the amount is small, when an electronic component is mounted using the anisotropic conductive film 1A, the conductive particles 2 are easily moved in the direction X in which the amount of resin in the insulating resin layer 3 holding the conductive particles 2 is small when heated and pressurized_aFlow (fig. 1A). Therefore, the conductive particles can be prevented from irregularly flowing and concentrating at a specific position due to heating and pressurizing during mounting, and short circuit between electrodes due to connection of the conductive particles or poor conduction due to absence of the conductive particles between the electrodes can be reduced.

When the insulating resin layer is formed to have the thickness distribution, the resin layer on the surface on which the anisotropic conductive film is formed has surface irregularities, and the adhesiveness of the anisotropic conductive film is improved and the adhesiveness is expected to be improved as compared with the case of forming the resin layer with a flat surface.

In the anisotropic conductive film of the present invention, the thickness distribution of the insulating resin layer 3 around each conductive particle 2 may be asymmetric with respect to the conductive particle 2 in at least one direction, and the thickness distribution of the insulating resin layer 3 around the conductive particle 2 may be symmetric with respect to the conductive particle 2 in the other directions. For example, in a B-B cross section in the Y direction perpendicular to the X direction of the anisotropic conductive film 1A, as shown in fig. 1C, the thickness distribution of the insulating resin layer 3 around the conductive particles 2 is symmetrical with respect to the central axis L1 of the conductive particles 2.

(1-3) conductive particles

In the anisotropic conductive film 1A, the conductive particles 2 can be appropriately selected from conductive particles used in conventionally known anisotropic conductive films. Examples thereof include: metal particles such as nickel, cobalt, silver, copper, gold, and palladium, metal-coated resin particles, and the like. More than 2 kinds may be used in combination.

The average particle diameter of the conductive particles 2 is preferably 1 to 10 μm, more preferably 2 to 6 μm, because it is not able to absorb the height variation of the wiring of the anisotropic conductive connection and tends to increase the resistance, and too large it tends to cause short circuit.

Since the number of particles in the anisotropic conductive film 1A is too small, the particle capture number decreases, the anisotropic conductive connection becomes difficult, and too large, short-circuiting may occur, it is preferably 50 to 50000, more preferably 200 to 40000, and still more preferably 400 to 30000 per 1 square mm.

(1-4) insulating resin layer

As the insulating resin layer 3 for holding the conductive particles 2, a known insulating resin layer can be suitably used. For example, the following may be used: a photoradical polymerization type resin layer containing an acrylate compound and a photoradical polymerization initiator, a thermal radical polymerization type resin layer containing an acrylate compound and a thermal radical polymerization initiator, a thermal cation polymerization type resin layer containing an epoxy compound and a thermal cation polymerization initiator, a thermal anion polymerization type resin layer containing an epoxy compound and a thermal anion polymerization initiator, and the like. These resin layers may be resin layers obtained by polymerization, respectively, as necessary.

Among them, a photoradical polymerization type resin layer containing an acrylate compound and a photoradical polymerization initiator is preferably used as the insulating resin layer 3. The photo-radical polymerizable resin layer is irradiated with ultraviolet rays to be photo-radical polymerized, whereby the conductive particle alignment layer 4 in which the conductive particles 2 are fixed to the insulating resin layer 3 can be formed. In this case, as will be described later, when the photo-radical polymerizable resin layer is irradiated with ultraviolet rays from the conductive particle 2 side and photo-radical polymerized before the second insulating resin layer 5 is formed, the region 3 of the insulating resin layer 3 located between the flat surface of the conductive particle alignment layer 4 and the conductive particles 2 can be formed as shown in fig. 4D_mIs higher than the curing ratio of the region 3 of the insulating resin layer 3 between the mutually adjacent conductive particles 2_nThe curing rate of (2) is low. Therefore, in the insulating resin layer 3, the region 3 having a low curing rate and located directly below the conductive particles 2 can be formed_mHas a lowest melt viscosity ratio of a region 3 having a higher solidification rate and located around the conductive particle 2_nHas a low minimum melt viscosity, and when anisotropic conductive connection is performed, the conductive particles 2 are easily pushed into the conductive layer without being displaced in the horizontal direction. Therefore, the particle capture efficiency can be improved, the on-resistance value can be reduced, and good on-reliability can be realized.

Here, the curing ratio is a numerical value defined as a reduction ratio of a functional group (e.g., vinyl group) contributing to polymerization. Specifically, if the amount of vinyl groups present after curing is 20% of that before curing, the cure rate is 80%. The amount of vinyl groups present can be determined by characteristic absorption analysis of vinyl groups by infrared absorption spectroscopy. Region 3 of insulating resin layer 3 having low curing rate_mThe curing rate of (3) is preferably 40 to 80%, and the region 3 having a high curing rate_nThe curing rate of (3) is preferably 70 to 100%.

The minimum melt viscosity of the insulating resin layer 3 can be measured by a rheometer, and when it is too low, the particle capture efficiency tends to decrease, and when it is too high, the on-resistance value tends to increase, and therefore, it is preferably 100 to 100000mPa · s, and more preferably 500 to 50000mPa · s.

The minimum melt viscosity of the insulating resin layer 3 is preferably higher than the minimum melt viscosity of each of the 2 nd insulating resin layer 5 and the 3 rd insulating resin layer 6. Specifically, if the value of [ minimum melt viscosity (mPa · s) of the insulating resin layer 3 ]/[ minimum melt viscosity (mPa · s) of the 2 nd insulating resin layer 5 or the 3 rd insulating resin layer 6) ] is too low, the particle capture efficiency tends to decrease and the probability of short circuit occurrence tends to increase, and if it is too high, the conduction reliability tends to decrease. Therefore, it is preferable to set the value of [ the lowest melt viscosity (mPa · s) of the insulating resin layer 3 ]/[ the lowest melt viscosity (mPa · s) of the 2 nd insulating resin layer 5 or the 3 rd insulating resin layer 6) ] to 1 to 1000, more preferably 4 to 400.

The minimum melt viscosity of the 2 nd insulating resin layer 5 and the 3 rd insulating resin layer 6 is preferably 0.1 to 10000mPa · s, more preferably 1 to 1000mPa · s, because when too low, resin bleeding tends to occur when wound on a roll, and when too high, on-resistance tends to be high.

As the acrylate compound used for the insulating resin layer 3, conventionally known radical polymerizable acrylate can be used. For example, monofunctional (meth) acrylates (herein, (meth) acrylates include acrylates and methacrylates), and polyfunctional (meth) acrylates having two or more functions can be used. In the present invention, in order to make the insulating resin layer 3 thermosetting, it is preferable to use a polyfunctional (meth) acrylate for at least a part of the acrylic monomer.

Examples of monofunctional (meth) acrylates are: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-methylbutyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate, 2-methylhexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-butylhexyl (meth) acrylate, isooctyl (meth) acrylate, isoamyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenoxy (meth) acrylate, phenylglycidyl (meth) acrylate, N-nonyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, morpholin-4-yl (meth) acrylate, and the like. Examples of difunctional (meth) acrylates are: bisphenol F-EO-modified di (meth) acrylate, bisphenol A-EO-modified di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, dicyclopentadiene (meth) acrylate, and the like. Examples of trifunctional (meth) acrylates are: trimethylolpropane tri (meth) acrylate, trimethylolpropane PO-modified (meth) acrylate, isocyanuric acid EO-modified tri (meth) acrylate, and the like. Examples of the tetrafunctional or higher (meth) acrylate include: dipentaerythritol penta (meth) acrylate, pentaerythritol hexa (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetraacrylate, and the like. In addition, a polyfunctional urethane (meth) acrylate may also be used. Specifically, the following may be mentioned: m1100, M1200, M1210, M1600 (Toyo Synthesis Co., Ltd.), AH-600, AT-600 (Kyoeisha chemical Co., Ltd.), and the like.

When the content of the acrylate compound in the insulating resin layer 3 is too small, it tends to be difficult to obtain the lowest melt viscosity difference from the insulating resin layer 2, and when too large, curing shrinkage increases, which tends to lower workability, and therefore, it is preferably 2 to 70% by mass, and more preferably 10 to 50% by mass.

specifically, the acetophenone-based photopolymerization initiator includes 2-hydroxy-2-cyclohexylacetophenone (IRGACURE 184, manufactured by BASF Japan K.K.), α -hydroxy- α, α' -dimethylacetophenone (DARUR 1173, manufactured by BASF Japan K.K.), 2-dimethoxy-2-phenylacetophenone (IRGACURE 651, manufactured by BASF Japan K.K.), 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone (DAROCUR 2959, manufactured by BASF Japan K.K.), 2-hydroxy-1- {4- [ 2-hydroxy-2-methylpropyl ] -benzyl } phenyl } -2-methyl-propane-1-one (IRGACURE 127, manufactured by BASF Japan K.K.K.), 2-hydroxy-1- {4- [ 2-hydroxy-2-methylpropyl ] -benzyl } phenyl } -2-methylpropane-1-one (IRGACURE, BASF 127, BASF Japan K.K.K.K.K., benzophenone, 4-benzoylbenzophenone, 4-dichlorobenzophenone (IRGACURE), benzophenone, bis (IRGACURE) and the like, and the photopolymerization initiator includes 2-hydroxy-4-benzoylbenzophenone, bis (IRGACURE) and the like, and the photopolymerization initiator can be prepared by BASF-4-bis (IRGACURE 4-4, 4-benzoylbenzophenone, 4-benzoylbenzophenone, 4-bis (IRGACURE) and the like, and the like

TPO, manufactured by BASF Japan K.K.).

The amount of the photo radical polymerization initiator used is preferably 0.1 to 25 parts by mass, more preferably 0.5 to 15 parts by mass, because photo radical polymerization tends to be insufficiently performed when the amount is too small and rigidity may be lowered when the amount is too large, relative to 100 parts by mass of the acrylate compound.

When the insulating resin layer 3 is formed of a thermal radical polymerization type resin layer containing an acrylate compound and a thermal radical polymerization initiator, the acrylate compound as described above can be used as the acrylate compound. The thermal radical polymerization initiator may include, for example, organic peroxides and azo compounds, and the azo compounds are preferably used because they decompose during the polymerization reaction to generate nitrogen gas and may cause air bubbles to be mixed into the polymer. Examples thereof include Perhexa 3M (パーヘキサ 3M), PEROYL TCP (パーロイル TCP), and PEROYL L (パーロイル L) manufactured by Nippon fat and oil Co.

examples of the organic peroxide include methyl ethyl ketone peroxide, cyclohexanone peroxide, methylcyclohexanone peroxide, acetylacetone peroxide, 1-bis (t-butylperoxy) 3,3, 5-trimethylcyclohexane, 1-bis (t-butylperoxy) cyclohexane, 1-bis (t-hexylperoxy) 3,3, 5-trimethylcyclohexane, 1-bis (t-hexylperoxy) cyclohexane, 1-bis (t-butylperoxy) cyclododecane, isobutyl peroxide, lauroyl peroxide, succinic peroxide, 3,5, 5-trimethylhexanoyl peroxide, benzoyl peroxide, octanoyl peroxide, stearoyl peroxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-methoxybutyl peroxydicarbonate, bis- (4-t-butylcyclohexyl) peroxydicarbonate, (α, α -bis-neodecanoylperoxy) diisopropylbenzene, cumyl peroxyneodecanoate, octylperoxy-hexyl peroxyneohexanoate, tert-butyl peroxyneohexanoate, tert-butylperoxy, tert-butyl peroxypivalate, tert-butyl peroxyethyl-2-butyl peroxyethyl hexanoate, tert-butyl peroxyethyl-peroxy-2-butyl peroxyhexanoate, 5-ethyl peroxyhexanoate, tert-butyl peroxyethyl hexanoate, 5-peroxyethyl peroxyhexanoate, 5, 5-tert-butyl peroxyethyl peroxyhexanoate, 5-peroxyethyl peroxyhexanoate, 5-peroxyethyl peroxyhexanoate, 5-5, 5-peroxyethyl peroxyhexanoate, and the like.

Examples of the azo compound include: 1, 1-azobis (cyclohexane-1-carbonitrile), 2 ' -azobis (2-methyl-butyronitrile), 2 ' -azobisbutyronitrile, 2 ' -azobis (2, 4-dimethyl-valeronitrile), 2 ' -azobis (2, 4-dimethyl-4-methoxyvaleronitrile), 2 ' -azobis (2-amidino-propane) hydrochloride, 2 ' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ] hydrochloride, 2 ' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ], (methyl-2-imidazolin-2-yl) propane), 2,2 ' -azobis [ 2-methyl-N- (1, 1-bis (2-hydroxymethyl) -2-hydroxyethyl) propionamide ], 2 ' -azobis [ 2-methyl-N- (2-hydroxyethyl) propionamide ], 2 ' -azobis (2-methyl-propionamide) dihydrate, 4 ' -azobis (4-cyano-pentanoic acid), 2 ' -azobis (2-hydroxymethylpropionitrile), dimethyl 2,2 ' -azobis (2-methylpropionate) (dimethanol 2,2 ' -azobis (2-methylpropionate)), cyano-2-propylazoformamide, and the like.

When the amount of the thermal radical polymerization initiator used is too small, thermal radical polymerization tends to be insufficiently performed, and when it is too large, rigidity may be lowered, and therefore, it is preferably 0.1 to 25 parts by mass, more preferably 0.5 to 15 parts by mass, based on 100 parts by mass of the acrylate compound.

when the insulating resin layer 3 is formed from a thermosetting cationically polymerizable resin layer containing an epoxy compound and a thermosetting cationic polymerization initiator, or when the insulating resin layer 3 is formed from a thermosetting anionically polymerizable resin layer containing an epoxy compound and a thermosetting anionic polymerization initiator, the epoxy compound may be a compound or a resin having two or more epoxy groups in the molecule, and these may be liquid or solid, and specifically, bisphenol a, bisphenol F, bisphenol S, hexahydrobisphenol a, tetramethylbisphenol a, diallylbisphenol a, hydroquinone, catechol, resorcinol, cresol, tetrabromobisphenol a, trihydroxybiphenyl, benzophenone, bisresorcinol (bisresorcinol), bisphenol hexafluoroacetone, tetramethylbisphenol a, tetramethylbisphenol F, tris (hydroxyphenyl) methane, biscresol, phenol novolac (phenonol novolac), cresol novolac, etc., glycidyl ether obtained by reacting epichlorohydrin with polyhydric phenol obtained by reacting epichlorohydrin, neopentyl glycol, ethylene glycol, propylene glycol, butylene glycol (チレングリコール), hexanediol, polyethylene glycol, polypropylene glycol, etc., glycidyl ether obtained by reacting an aliphatic polyhydric alcohol with epichlorohydrin to obtain epoxy resin, epoxy naphthalene diol, epoxy urethane, 4' -epoxy urethane, epoxy, urethane, epoxy.

The thermal cationic polymerization initiator is a substance that generates heat to generate an acid that can cationically polymerize the cationically polymerizable compound. The thermal cationic polymerization initiator may be any one known as a thermal cationic polymerization initiator for epoxy compounds, and for example, known iodonium salts, sulfonium salts, phosphonium salts, ferrocene and the like may be used, and aromatic sulfonium salts exhibiting good latency to temperature may be preferably used. Preferable examples of the thermal cationic polymerization initiator include: diphenyliodonium hexafluoroantimonate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroborate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, and triphenylsulfonium hexafluoroborate. Specific examples thereof include: SP-150, SP-170, CP-66 and CP-77 manufactured by ADEKA; CI-2855 and CI-2639 manufactured by Nippon Caoda corporation; San-Aid SI-60(サンエイド SI-60) and SI-80 manufactured by Sanxin chemical industries, Ltd; CYRACURE-UVI-6990, UVI-6974, and the like, manufactured by Union Carbide Corporation (ユニオンカーバイド).

When the amount of the thermal cationic polymerization initiator to be incorporated is too small, thermal cationic polymerization tends to proceed insufficiently, and when it is too large, rigidity may be lowered, so that it is preferably 0.1 to 25 parts by mass, more preferably 0.5 to 15 parts by mass, per 100 parts by mass of the epoxy compound.

The thermal anionic polymerization initiator is a substance that generates heat to generate a base that can anionically polymerize an anionically polymerizable compound. The thermal cationic polymerization initiator may be any one known as a thermal anionic polymerization initiator for epoxy compounds, and examples thereof include: aliphatic amine compounds, aromatic amine compounds, secondary or tertiary amine compounds, imidazole compounds, polythiol compounds, boron trifluoride-amine complexes, dicyandiamide, organic acid hydrazide and the like, and encapsulated imidazole compounds exhibiting good latency to temperature can be preferably used.

When the amount of the thermal anionic polymerization initiator is too small, curing tends to be poor, and when too large, the product life tends to be reduced, and therefore, the amount is preferably from 0.1 to 40 parts by mass, more preferably from 0.5 to 20 parts by mass, based on 100 parts by mass of the epoxy compound.

On the other hand, the 2 nd insulating resin layer 5 and the 3 rd insulating resin layer 6 can be formed by appropriately selecting resins from known insulating resins. The insulating resin layer 3 may be made of the same material as that of the insulating resin layer.

The minimum melt viscosity of the insulating resin layer 3 may be equal to or less than that of the 2 nd and 3 rd insulating resin layers 5 and 6, and when the 2 nd and 3 rd insulating resin layers 5 and 6 are formed of the same material as the insulating resin layer 3, the minimum melt viscosity of the insulating resin layer 3 is preferably higher than that of the 2 nd and 3 rd insulating resin layers 5 and 6.

The thickness of the 2 nd insulating resin layer 5 is 40 μm or less, preferably 5 to 20 μm, and more preferably 8 to 15 μm, because a conduction failure may occur due to insufficient resin filling, and an excessive thickness may cause bleeding of the resin at the time of pressure bonding, thereby contaminating the pressure bonding apparatus. The thickness of the 3 rd insulating resin layer 6 is preferably 0.5 to 6 μm, more preferably 1 to 5 μm, because a bonding failure may occur when temporarily bonded to the 2 nd electronic component, and an excessively thick layer tends to increase the on-resistance value.

In the case of performing anisotropic conductive connection using the anisotropic conductive film 1A, of the 2 nd insulating resin layer 5 (insulating resin layer laminated on the uneven surface of the conductive particle alignment layer 4) and the 3 rd insulating resin layer 6 (insulating resin layer laminated on the flat surface of the conductive particle alignment layer 4), the resin layer having a small layer thickness is generally disposed on the terminal side of the glass substrate such as a solid electrode (ベタ edge) which does not require relatively high alignment accuracy, and the resin layer having a large layer thickness is generally disposed on the terminal side of the IC chip such as a bump (bump) which must be aligned with high positional accuracy. When only one of the 2 nd insulating resin layer 5 and the 3 rd insulating resin layer 6 is provided, the side closer to the conductive particles is the side where the alignment accuracy is relatively low. When both are not provided, there is no particular limitation.

(2) Method for manufacturing anisotropic conductive film

(2-1) transfer mold

The anisotropic conductive film 1A can be produced using, for example, the following transfer mold. That is, fig. 2A is a perspective view of a transfer mold 10A that can be used for manufacturing an anisotropic conductive film 1A, fig. 2B is a plan view of the transfer mold 10A, and fig. 2C is a cross-sectional view of the transfer mold 10A.

The transfer mold 10A has a plurality of openings 11 arrayed in a tetragonal lattice on the surface thereof, and the depth distribution of each opening 11 has a direction X 'asymmetrical with respect to a perpendicular line L1' passing through the deepest portion center R of the opening 11. More specifically, when the transfer mold 10A is cut in the direction X 'through the center R of the deepest portion of the opening 11, one side Q of a perpendicular line L1' passing through the center R of the deepest portion of the opening 11 is located on the cross section (fig. 2C) of the transfer mold 10A_a' area S of opening 11_a' more than the other side Q_bArea S of `_b' Small.

In the transfer mold used in the present invention, the arrangement of the openings is appropriately selected according to the arrangement of the conductive particles in the manufactured anisotropic conductive film, and for example, when the conductive particles are arranged in a hexagonal lattice, the arrangement of the openings of the transfer mold is also in a hexagonal lattice.

The shape of the opposing side walls of the opening 11 in the cross section is the other side Q_b' side wall 11_bRelative to one side Q_a' side wall 11_aAnd (4) inclining. I.e., one side Q_aSide of `Wall 11_aThe other side Q is a cliff standing along the thickness direction of the transfer mold 10A_b' side wall 11_bIs inclined with respect to the thickness direction of the transfer mold 10A.

When filling 1 conductive particle 2 in each opening 11, the depth D1 of the opening 11 is preferably set such that the ratio (W0/D1) of the average particle diameter W0 of the conductive particles 2 filled in the opening 11 to the depth D1 of the opening 11 is 0.4 to 3.0, more preferably 0.5 to 1.5, in view of the balance between the ease of handling to remove the conductive particle alignment layer 4 formed on the transfer mold 10A from the spin mold 10A and the retention of the conductive particles 2.

In the cross section of the transfer mold 10A (fig. 2C) in the direction X' passing through the center R of the deepest portion of the opening 11, regarding the relationship between the opening diameter W1 of the opening 11 and the average particle diameter W0 of the conductive particles 2, in consideration of the ease of filling the opening 11 with the conductive particles 2 and the ease of pushing the insulating resin into the opening 11, the ratio (W1/W0) of the opening diameter W1 of the opening 11 to the average particle diameter W0 of the conductive particles 2 is preferably 1.2 to 5.0, more preferably 1.5 to 3.0.

In this cross section, the relationship between the bottom surface diameter W2 of the opening 11 and the average particle diameter W0 of the conductive particles 2 is preferably such that the ratio (W2/W0) between the bottom surface diameter W2 of the opening 11 and the average diameter W0 of the conductive particles 2 is 0 to 1.9, more preferably 0 to 1.6, from the viewpoint of aligning the flow directions of the conductive particles 2 at the time of thermocompression bonding.

The material for forming the transfer mold 10A may be, for example, an inorganic material such as silicon, various ceramics, metals such as glass and stainless steel, or an organic material such as various resins, and the openings 11 may be formed by a known opening forming method such as photolithography (photolithograph).

(2-2) method for producing Anisotropic conductive film 1

In the method of manufacturing the anisotropic conductive film 1A, first, as shown in fig. 3A and 3B, the openings 11 of the transfer mold 10A are filled with the conductive particles 2. The method for filling the conductive particles 2 is not particularly limited, and for example, dried conductive particles 2 or dried conductive particlesThe dispersion liquid of the conductive particles 2 dispersed in the solvent is scattered or applied on the formation surface of the openings 11 of the transfer mold 10A, and then the formation surface of the openings 11 is wiped with a brush, cloth, or the like. The wiping is along the direction X', from the inclined side wall 11 of the opening 11_bThe bottom portion of (2) is directed upward, whereby the conductive particles 2 can be smoothly fed into the opening portion 11.

As a method of filling the conductive particles 2, the conductive particles 2 may be first dispersed on the surface of the transfer mold 10A on which the openings 11 are formed, and then the conductive particles 2 may be moved into the openings 11 by an external force such as a magnetic field.

Next, as shown in fig. 4A, the insulating resin layers 3 formed on the release film 7 are laminated on the openings 11 filled with the conductive particles 2 in an opposed manner, and the corners of the bottom of the openings 11 are pressed to such an extent that the insulating resin layers 3 do not intrude, whereby the conductive particles 2 are held in the insulating resin layers 3 so that the conductive particles 2 are embedded in the insulating resin layers 3, as shown in fig. 4B. When the transfer mold 10A is taken out, as shown in fig. 4C, the conductive particle alignment layer 4 in which the conductive particles 2 aligned in a tetragonal lattice according to the arrangement of the openings 11 of the transfer mold 10A are held by the insulating resin layer 3 can be obtained on the release film 7.

In the conductive particle array layer 4, the conductive particles 2 may not be completely embedded in the insulating resin layer 3, or may be completely embedded. In order to embed the conductive particles 2 completely in the insulating resin layer 3, the conductive particles 2 positioned at the bottom of the transfer mold 10A may be moved to the side of the opening surface of the transfer mold 10A. The movement may be performed by an external force such as a magnetic force.

Next, as shown in fig. 4D, the surface of the conductive particle alignment layer 4 having surface irregularities is preferably irradiated with ultraviolet light UV. Thereby, the conductive particles 2 can be fixed to the insulating resin layer 3. In addition, since UV irradiation is blocked by the conductive particles 2, the insulating resin layer region 3 directly below the conductive particles 2_mThe curing rate of (a) is relatively lower than that of its surroundings. Therefore, when the anisotropic conductive connection is performed, the conductive particles 2 are easily pressed without being displaced in the horizontal direction. Thus can beThe particle capture efficiency is improved, the on-resistance value is reduced, and good on-reliability is realized.

Next, as shown in fig. 4E, the 2 nd insulating resin layer 5 is laminated on the surface having surface irregularities of the conductive particle alignment layer 4 (i.e., the transfer surface of the conductive particles 2 of the insulating resin layer 3), the release film 7 is peeled off and removed as shown in fig. 4F, and the 3 rd insulating resin layer 6 is laminated on the surface from which the release film 7 is peeled off (i.e., the surface opposite to the transfer surface of the conductive particles 2 of the insulating resin layer 3) as shown in fig. 4G, whereby the anisotropic conductive film 1A shown in fig. 1A, 1B, and 1C can be manufactured.

(2-3) method for producing Anisotropic conductive film 2

The method for manufacturing the anisotropic conductive film 1A shown in fig. 1A, 1B, and 1C is not limited to the above example. For example, in the above-described manufacturing method, the 3 rd insulating resin layer 6 may be formed instead of the release film 7.

That is, first, as shown in fig. 3A and 3B, the openings 11 of the transfer mold 10A are filled with the conductive particles 2, and then, as shown in fig. 5A, the insulating resin layer 3 to which the 3 rd insulating resin layer 6 is previously bonded is laminated on the openings 11 of the transfer mold 10A filled with the conductive particles 2 in the openings 11.

Next, as shown in fig. 5B, the insulating resin layer 3 is pressed into the surface of the transfer mold 10A on which the openings 11 are formed, and the conductive particles 2 are held by the insulating resin layer 3, thereby forming the conductive particle alignment layer 4.

Then, as shown in fig. 5C, the laminate of the conductive particle alignment layer 4 and the 3 rd insulating resin layer 6 is taken out from the transfer mold 10A, and as shown in fig. 5D, UV is irradiated from the uneven surface side of the insulating resin layer 3 to fix the conductive particles 2 to the insulating resin layer 3.

Next, as shown in fig. 5E, the 2 nd insulating resin layer 5 is laminated on the uneven surface of the insulating resin layer 3. This can produce the anisotropic conductive film 1A shown in fig. 1A, 1B, and 1C.

(2-4) method for producing Anisotropic conductive film 3

In the manufacturing method of the anisotropic conductive film 1A shown in fig. 1A, 1B, and 1C, when the ultraviolet-ray-transmissive transfer mold 10A 'is used, the insulating resin layer 3 holding the conductive particles 2 can be irradiated with ultraviolet rays through the transfer mold 10A'. The ultraviolet-transmitting transfer mold 10A' may be formed of an inorganic material such as ultraviolet-transmitting glass or an organic material such as polymethacrylate.

In this method, first, as shown in fig. 3A and 3B, conductive particles 2 are filled in the opening of an ultraviolet-transmitting transfer mold 10A ', and then, as shown in fig. 6A, a photopolymerizable insulating resin layer 3 formed on a release film 7 is pressed against the opening 11 of the transfer mold 10A' filled with the conductive particles 2 in the opening 11 to such an extent that the insulating resin layer 3 does not intrude into the corners at the bottom of the opening 11, and as shown in fig. 6B, the conductive particles 2 are held in the insulating resin layer 3 so that the conductive particles 2 are embedded in the insulating resin layer 3, thereby forming a conductive particle alignment layer 4. In this case, the conductive particles 2 may be completely embedded in the insulating resin layer 3, or may not be completely embedded.

Next, as shown in fig. 6C, the insulating resin layer 3 is irradiated with ultraviolet rays UV from the rotary stamp 10A'. This can polymerize the photopolymerizable insulating resin layer 3, fix the conductive particles 2 to the insulating resin layer 3, and shield the ultraviolet light UV from the regions 3 of the insulating resin layer where the conductive particles 2 shield the ultraviolet light UV_mIs more cured than the surrounding region 3 of the insulating resin layer_nThe curing rate of (3) is relatively low. Therefore, in the anisotropic conductive connection, the positional displacement of the conductive particles 2 in the horizontal direction can be prevented, and the press-fitting property of the conductive particles 2 can be improved. Therefore, the particle capture efficiency can be improved, the conduction resistance value can be reduced, and good conduction reliability can be realized.

Next, as shown in fig. 6D, the release film 7 is removed from the insulating resin layer 3. Next, as shown in fig. 6E, the 3 rd insulating resin layer 6 is laminated on the surface of the insulating resin layer 3 from which the release film 7 has been removed, and as shown in fig. 6F, the laminate is removed from the transfer mold 10A', and as shown in fig. 6G, the 2 nd insulating resin layer 5 is laminated on the surface of the conductive particle alignment layer 4 having surface irregularities. This makes it possible to produce the anisotropic conductive film 1A shown in fig. 1A, 1B, and 1C.

(3) Variants

(3-1) the thickness distribution of the insulating resin layer around the conductive particles is in an asymmetric direction.

in the anisotropic conductive film of the present invention, with respect to the insulating resin layer 3 directly holding the plurality of conductive particles 2 in a prescribed arrangement, the thickness distribution of the insulating resin layer 3 around each conductive particle 2 may have a plurality of directions asymmetrical with respect to the central axis L1 of the conductive particle 2, for example, the anisotropic conductive film 1A' shown in fig. 7A, 7B, and 7C may make the plan view shape of the insulating resin layer 3 around each conductive particle 2 substantially a sector shape, the asymmetry may take an arbitrary shape according to the opening angle α of the sector shape, and may be a sector shape of α =90 ° (fig. 7A), a semicircular shape of α =180 °, or the like, and, as shown in fig. 8, may be a partial circle of a chord of a circular arc including a central angle α (for example, α =270 °).

More specifically, for example, in the case of the anisotropic conductive film 1A' shown in fig. 7A, 7B, and 7C, the thickness distribution of the insulating resin layer 3 around the conductive particles 2 is asymmetric with respect to the central axis L1 of the conductive particles 2 in each of the X direction and the Y direction shown in fig. 7A. In the heating and pressing for mounting electronic components using the anisotropic conductive film 1A', the conductive particles 2 are easily oriented in two directions X in which the amount of resin holding the conductive particles 2 is small_a、Y_aAnd (4) flowing. Therefore, the conductive particles flow irregularly by heating and pressing at the time of mounting, and connection of the conductive particles between the electrodes due to the portion where the conductive particles are concentrated or conduction failure due to the absence of the conductive particles between the electrodes can be reduced.

In the case of the anisotropic conductive film 1A ″ of fig. 8, the conductive particles 2 easily flow in the direction of the arrows.

In the anisotropic conductive film of the present invention, the thickness distribution of the insulating resin layer 3 around each conductive particle 2 can be made uniform over the entire area of the anisotropic conductive film, and the direction in which the conductive particles 2 easily flow is made uniform for all the conductive particles 2 at the time of anisotropic conductive connection; the thickness distribution of the insulating resin layer 3 around each conductive particle 2 may be different for each predetermined region in the anisotropic conductive film, and the direction in which the conductive particle 2 easily flows may be different for each predetermined region in the anisotropic conductive film at the time of anisotropic conductive connection.

Further, since the thickness distribution of the insulating resin layer 3 around each conductive particle 2 has an asymmetric direction with respect to the central axis L1 of the conductive particle 2, when the conductive particle 2 is made to easily flow in a specific direction in the anisotropic conductive connection, the thickness distribution of the insulating resin layer 3 around the conductive particle 2 may not be uniform over the entire area of the anisotropic conductive film as long as the flow direction is not covered with the adjacent conductive particles.

(3-2) concrete shape of insulating resin layer around conductive particles

In the anisotropic conductive film of the present invention, the insulating resin layer 3 may take various shapes so that the thickness distribution of the insulating resin layer 3 holding a predetermined arrangement of the plurality of conductive particles 2 is asymmetrical in a specific direction around each conductive particle 2. Therefore, the transfer mold used for forming the insulating resin layer 3 may be formed in various shapes such that the depth distribution of the opening 11 has an asymmetric direction X 'with respect to a perpendicular line L1' passing through the center R of the deepest portion of the opening 11.

For example, in the transfer mold 10A shown in fig. 2A, 2B, and 2C, the bottom surface of the opening 11 may be formed on a rough surface having small irregularities. Thereby, the area where the conductive particles 2 contact the transfer mold 10A is reduced, and the operation of removing the conductive particle alignment layer from the transfer mold 10A becomes easy.

In the transfer mold 10A shown in fig. 2A, 2B, and 2C, the bottom surface of the opening 11 has a predetermined diameter W2 in the cross section (fig. 2C) when the transfer mold 10A is cut in the direction X' passing through the center R of the deepest portion of the opening 11, but the diameter W2 of the bottom surface of the opening 11 may be 0 as in the transfer mold 10B shown in fig. 9A. By using this transfer mold 10B, an anisotropic conductive film 1B having a cross section shown in fig. 9B can be obtained.

In the transfer mold 10A shown in fig. 2A, 2B, and 2C, the adjacent openings 11 are in contact with each other on the upper surface of the transfer mold 10A in the cross section (fig. 2C) obtained when the transfer mold 10A is cut in the direction X' passing through the center R of the deepest portion of the opening 11, but as in the transfer mold 10C shown in fig. 10A, a predetermined distance W3 may be provided between the adjacent openings on the upper surface of the transfer mold. By using this transfer mold 10C, an anisotropic conductive film 1C having a cross section shown in fig. 10B can be obtained.

In the transfer mold 10D shown in fig. 11A, in a cross section when the transfer mold is cut in the direction X' passing through the center R of the deepest portion of the opening 11, one of the opposing side walls of the opening 11 may be raised in a cliff shape along the thickness direction of the transfer mold 10D, and the other may be stepped. By using this transfer mold 10D, an anisotropic conductive film 1D having a cross section shown in fig. 11B can be obtained.

When the side walls of the opening 11 of the transfer mold are formed in a step shape, the number of steps may be changed as appropriate, and for example, the number of steps may be 3 in the transfer mold 10E shown in FIG. 12A. By using this transfer mold 10E, an anisotropic conductive film 1E having a cross section shown in fig. 12B can be obtained.

In the anisotropic conductive films according to the above embodiments, the conductive particles 2 may be partially exposed from the insulating resin layer 3.

As the transfer mold used for manufacturing the anisotropic conductive film of the present invention, a transfer mold in which the depth distribution of each opening is symmetrical in a section including a perpendicular line passing through the center of the deepest portion of the opening in any direction (for example, the entire periphery of the side wall of the opening is in a cliff shape standing up in the thickness direction of the transfer mold) can be used. In this case, the thickness distribution of the insulating resin layer holding the conductive particles in the anisotropic conductive film can be made asymmetric with respect to the conductive particles by adjusting the viscosity of the insulating resin laminated on the conductive particles filled in the opening portion, the pressing distribution to the insulating resin, the irradiation timing or irradiation direction to the insulating resin, or the like.

The conductive particles 2 are likely to flow in a specific direction when the anisotropic conductive films of the present invention are connected to each other by anisotropic conduction. On the other hand, when the opening 11 of the transfer mold 10X is bilaterally symmetric in any direction as shown in fig. 13A, the thickness distribution around the insulating resin layer 3 holding the conductive particles 2 in the obtained anisotropic conductive film 1X is bilaterally symmetric in any direction centering on the conductive particles 2 as shown in fig. 13B, and the flow direction of the conductive particles at the time of anisotropic conductive connection is uncertain. Therefore, it is impossible to avoid the occurrence of short circuit between electrodes due to the connection of conductive particles or poor conduction between electrodes due to the absence of conductive particles.

In the present invention, the above-described modifications of the anisotropic conductive film can be combined as appropriate.

The present invention also includes a connection structure in which a 1 st electronic component and a 2 nd electronic component are anisotropically electrically connected by the anisotropic conductive film of the present invention.

Examples

The present invention is specifically illustrated by the following examples.

Examples 1 to 5 and comparative example 1

(1) Production of anisotropic conductive film

A stamp made of stainless steel having the shapes and dimensions of the following (a) to (f) was prepared as a stamp used in each of examples and comparative examples, and an anisotropic conductive film was produced by the method shown in fig. 4A to 4G.

(a) Example 1: the same shape as that of the transfer mold 10A shown in FIGS. 2A to 2C, and having the dimensions shown in Table 1

(b) Example 2: 3 in 3 the 3 transfer 3 mold 3 10 3A 3 shown 3 in 3 FIGS. 3 2 3A 3 to 3 2 3 C 3, 3 the 3A 3- 3A 3 section 3 is 3 made 3 to 3 be 3 the 3 shape 3 shown 3 in 3 FIG. 3 10 3A 3, 3 having 3 the 3 dimensions 3 shown 3 in 3 Table 3 1 3

(c) Example 3: has the same shape as (b) and has the dimensions shown in Table 1

(d) Example 4: 3 in 3 the 3 transfer 3 mold 3 10 3A 3 shown 3 in 3 FIGS. 3 2 3A 3 to 3 2 3 C 3, 3 the 3A 3- 3A 3 section 3 is 3 made 3 to 3 have 3 the 3 shape 3 shown 3 in 3 FIG. 3 11 3A 3, 3 having 3 the 3 dimensions 3 shown 3 in 3 Table 3 1 3

(e) Example 5: 3 in 3 the 3 transfer 3 mold 3 10 3A 3 shown 3 in 3 FIGS. 3 2 3A 3 to 3 2 3 C 3, 3 the 3A 3- 3A 3 section 3 is 3 made 3 to 3 have 3 the 3 shape 3 shown 3 in 3 FIG. 3 12 3A 3, 3 having 3 the 3 dimensions 3 shown 3 in 3 Table 3 1 3

(f) Comparative example 1: 3 in 3 the 3 transfer 3 mold 3 10 3A 3 shown 3 in 3 FIGS. 3 2 3A 3 to 3 2 3 C 3, 3 the 3A 3- 3A 3 section 3 is 3 made 3 to 3 have 3 the 3 shape 3 shown 3 in 3 FIG. 3 13 3A 3, 3 having 3 the 3 dimensions 3 shown 3 in 3 Table 3 1 3

60 parts by mass of a phenoxy resin (YP-50, new day bronze chemical), 40 parts by mass of an acrylate (EB-600, DAICEL-ALLNEX LTD. (ダイセル, seed オルネクス), and 2 parts by mass of a photoradical polymerization initiator (IRUGACURE369, BASF, japan), were mixed with ethyl acetate or toluene to prepare a mixed solution having a solid content of 50% by mass. On the other hand, a polyethylene terephthalate film (PET film) having a thickness of 50 μm was prepared as a release film, and the mixed solution was applied to the release film so as to have a dry thickness of 5 μm, and dried in an oven at 80 ℃ for 5 minutes, thereby forming a photo radical polymerization type insulating resin layer.

Subsequently, conductive particles (Ni/Au-plated resin particles, AUL703, waterlogging chemical corporation) having an average particle diameter of 3 μm were dispersed in a solvent, applied to the openings of the transfer molds shown in table 1, and wiped with a cloth to fill the openings (fig. 4A).

Next, the opening surface of the transfer mold was opposed to the insulating resin layer, and the conductive particles were pressed into the insulating resin layer by applying pressure from the release film side under conditions of 60 ℃ and 0.5MPa, thereby forming a conductive particle alignment layer 4 in which the conductive particles 2 were held in the insulating resin layer 3 (fig. 4B).

Next, the conductive particle alignment layer 4 was removed from the transfer mold 10A (FIG. 4C), and the surface of the insulating resin layer 3 on which the surface irregularities were formed was irradiated with light having a wavelength of 365nm and a cumulative light amount of 4000mJ/cm²Thereby fixing the conductive particles 2 to the insulating resin layer 3 (fig. 4D).

A mixed solution was prepared from 60 parts by mass of a phenoxy resin (YP-50, Nissan King chemical Co., Ltd.), 40 parts by mass of an epoxy resin (iER828, Mitsubishi chemical Co., Ltd.), and 2 parts by mass of a thermal cationic polymerization initiator (SI-60L, Sanshin chemical Co., Ltd.) in ethyl acetate or toluene so that the solid content concentration was 50% by mass. This mixed solution was coated on a PET film having a thickness of 50 μm so that the dry thickness was 12 μm, and dried in an oven at 80 ℃ for 5 minutes, thereby forming the 2 nd insulating resin layer 5. The 3 rd insulating resin layer 6 having a dry thickness of 3 μm was formed by the same procedure.

On the insulating resin layer 3 of the conductive particle array layer 4 obtained by fixing the conductive particles 2 to the insulating resin layer 3, the 2 nd insulating resin layer 5 was laminated under conditions of 60 ℃ and 0.5MPa (fig. 4E), and then the release film 7 on the opposite side was removed (fig. 4F), and the 3 rd insulating resin layer 6 was laminated on the removed side of the release film 7 in the same manner as the 2 nd insulating resin layer, to obtain an anisotropic conductive film (fig. 4G).

(2) Evaluation of

The anisotropic conductive films obtained in the examples and comparative examples were evaluated for (i) bonding strength, (ii) number of connected particles, and (iii) insulating properties (short-circuit occurrence rate) as follows. The results are shown in Table 1.

(i) Bonding strength

Using the anisotropic conductive films obtained in the examples and comparative examples, a member for evaluation of conduction, including the following IC and glass substrate, was heated and pressed at 180 ℃ and 80MPa for 5 seconds to prepare a mounting sample.

IC: size of 1.8 × 20.0mm, thickness of 0.5mm, bump size of 30 × 85 μm, bump height of 15 μm, and bump pitch of 50 μm

Glass substrate: manufactured by Corning (コーニング) Inc., 1737F, measuring 50X 30mm and having a thickness of 0.5mm

Next, as shown in fig. 14, the probe 22 was brought into contact with the IC21 on the glass substrate 20 by using an adhesion tester manufactured by Daisy (デイジ), and a shear force was applied in the direction of the arrow to measure the force at which the IC21 was peeled off.

(ii) Number of connected particles

40000 μm in the connection region to the mounting sample (excluding the joint portion between terminals)²The maximum value of the number of the connected conductive particles was counted by microscopic observation.

(iii) Insulation property

Using the anisotropic conductive films obtained in the examples and comparative examples, comb-tooth TEG (test element group) patterns having an interval of 7.5 μm were connected to each other under the same bonding conditions as in (i), and the short-circuit occurrence rate was determined. In practice, it is preferably 100ppm or less. The short-circuit occurrence rate was calculated as "the number of occurrences of short-circuits/7.5 μm total interval".

[ Table 1]

As is clear from table 1, the anisotropic conductive films of examples 1 to 5 have a significantly reduced number of connected particles and a reduced short-circuit occurrence rate as compared with the anisotropic conductive film of comparative example 1. Further, the anisotropic conductive films of examples 1 to 5 are excellent in bonding strength as compared with the anisotropic conductive film of comparative example 1, and it is presumed that: in the anisotropic conductive films of examples 1 to 5, the thickness distribution of the insulating resin layer in direct contact with the conductive particles is asymmetric with respect to the conductive particles, and the irregularities of the insulating resin layer affect the irregularities of the surface of the anisotropic conductive film, so that the adhesion of the resin is high.

Industrial applicability

The present invention is useful as a technique for anisotropically and electrically connecting an ionizing member such as an IC chip to a wiring board.

Description of the symbols

1A, 1A '', 1B, 1C, 1D, 1E, 1X anisotropic conductive film

2 conductive particles

3 insulating resin layer

3_a、3_bSide surface

3_m、3_nRegion(s)

4 conductive particle alignment layer

5 nd 2 nd insulating resin layer

6 rd 3 insulating resin layer

7 Release film

10A, 10A', 10B, 10C, 10D, 10E, 10X transfer mold

11 opening part

11_a、11_bSide wall of the opening

20 glass substrate

21 IC

22 Probe

Depth of opening D1

Center axis of L1 conductive particle

L1' perpendicular line passing through center of deepest part of opening part of transfer mold

Center of P conductive particle

Periphery of the Q conductive particle

Q_aOne of the conductive particlesSide surface

Q_bThe other side of the conductive particle

Center of deepest part of opening part of R transfer mold

Sa、Sa’、S_b、S_b' area of

Average particle diameter of W0 conductive particles

Opening diameter of W1 opening

Bottom diameter of W2 opening

Distance between W3 openings

X、X_a、X’、Y、Y_aAnd (4) direction.

Claims

1. An anisotropic conductive film having a conductive particle alignment layer in which a plurality of conductive particles are held in an insulating resin layer in a predetermined alignment, wherein the thickness distribution around each conductive particle of the insulating resin layer in which the alignment of the conductive particles is held has an asymmetric direction with respect to the conductive particle.

2. The acf of claim 1 wherein the asymmetric orientation is uniform for a plurality of conductive particles.

3. The anisotropic conductive film according to claim 1 or 2, wherein when the anisotropic conductive film is cut in the asymmetric direction through the center of the conductive particle, the area of the insulating resin layer around the conductive particle is smaller on one side of the conductive particle than on the other side in the cross section of the anisotropic conductive film.

4. The anisotropic conductive film according to claim 3, wherein when the anisotropic conductive film is cut in the asymmetric direction through the center of the conductive particle, in a cross section of the anisotropic conductive film, one side surface of the insulating resin layer around the conductive particle is raised in a thickness direction of the anisotropic conductive film, and the other side surface is inclined to the thickness direction of the anisotropic conductive film more than the one side surface.

5. The anisotropic conductive film according to claim 3, wherein when the anisotropic conductive film is cut in the asymmetric direction through the center of the conductive particle, one side surface of the insulating resin layer around the conductive particle is raised in the thickness direction of the anisotropic conductive film in a cross section of the anisotropic conductive film and the other side surface is stepped.

6. The anisotropic conductive film according to any of claims 1 to 2 and 4 to 5, wherein one surface of the conductive particle alignment layer is flat, the other surface has irregularities, and the 2 nd insulating resin layer is laminated on the surface having the irregularities.

7. The acf of claim 6 wherein the 3 rd insulating resin layer is laminated on the flat surface of the conductive particle alignment layer.

8. The method for manufacturing an anisotropic conductive film according to claim 1, comprising the steps of:

a step of laminating an insulating resin on the conductive particles, and

and the following transfer mold was used: the depth distribution of each opening has an asymmetrical direction with respect to a perpendicular line passing through the center of the deepest portion of the opening.

9. The production method according to claim 8, wherein when the transfer mold is cut in the asymmetric direction through a center portion of the deepest portion of the opening, an area of the opening on one side of a perpendicular line passing through a center of the deepest portion of the opening is smaller than an area of the opening on the other side in a cross section of the transfer mold.

10. The production method according to claim 8 or 9, wherein when the transfer mold is cut in the asymmetric direction through the center portion of the deepest portion of the opening, one of the opposing side walls of the opening is raised in a cliff shape in the thickness direction of the transfer mold in the cross section of the transfer mold, and the other is inclined more in the thickness direction of the anisotropic conductive film than the one side wall.

11. The production method according to claim 8 or 9, wherein when the transfer mold is cut in the asymmetric direction through a central portion of a deepest portion of the opening, one of opposing side walls of the opening is raised in a cliff shape in a thickness direction of the transfer mold and the other is stepped in a cross section of the transfer mold.

12. The production method according to claim 8 or 9, wherein the insulating resin layer is polymerized in the step of forming the conductive particle alignment layer.

13. The production method according to claim 8 or 9, wherein a photo radical polymerization type resin is used as the insulating resin, and the insulating resin laminated on the conductive particles is polymerized by irradiation of ultraviolet rays.

14. The production method according to claim 8 or 9, wherein the 2 nd insulating resin layer is laminated on the conductive particle transfer surface of the insulating resin layer.

15. The production method according to claim 14, wherein a 3 rd insulating resin layer is laminated on a surface of the insulating resin layer opposite to the transfer surface of the conductive particles.

16. A connection structure in which a 1 st electronic component and a 2 nd electronic component are anisotropically electrically connected by the anisotropic conductive film according to any one of claims 1 to 7.