CN107207923B

CN107207923B - Multilayer adhesive film and connection structure

Info

Publication number: CN107207923B
Application number: CN201680009506.6A
Authority: CN
Inventors: 平山坚一
Original assignee: Dexerials Corp
Current assignee: Dexerials Corp
Priority date: 2015-02-23
Filing date: 2016-02-09
Publication date: 2020-09-04
Anticipated expiration: 2036-02-09
Also published as: TW201638639A; TWI699590B; WO2016136461A1; CN111995956A; KR20170104544A; KR101979526B1; JP2016155887A; JP6608147B2; CN111995956B; CN107207923A

Abstract

The problem is to provide a multilayer adhesive film which contains an anionic polymerization type epoxy curing agent, has sufficient adhesiveness even in low-temperature thermocompression bonding, and has high storage stability. The solution is a multilayer adhesive film, which comprises: a plurality of epoxy layers comprising an uncured epoxy polymeric compound and a latent epoxy curing agent; and a curing agent layer which is sandwiched between the plurality of epoxy layers and contains an anionic polymerization type non-latent epoxy curing agent.

Description

Multilayer adhesive film and connection structure

Technical Field

The present invention relates to a multilayer adhesive film and a connection structure.

Background

In recent years, in the production process of electronic devices, multilayer adhesive films have been widely used for bonding electronic components such as IC chips and liquid crystal panels to substrates and the like.

Such a multilayer adhesive film includes a polymer composition containing an uncured polymer and a curing agent as an adhesive component, and the polymer is cured by thermocompression bonding or the like, thereby bonding the substrate and the electronic component.

Here, when the multilayer adhesive film is bonded, if high-temperature thermocompression bonding is necessary, the electronic component, the substrate, and the like are deformed due to thermal expansion and curing shrinkage, and therefore, the adhesive interface may float or the adhesive strength may be reduced. Therefore, a multilayer adhesive film capable of bonding an electronic component to a substrate or the like even by thermocompression bonding at a relatively low temperature is desired.

For example, patent document 1 below discloses a thermal cationic polymerizable composition that can be bonded by low-temperature thermocompression bonding by including an epoxy polymerizable compound as an adhesive polymer composition and a thermal cationic polymerization type curing agent as a curing agent.

In addition, when reactivity between the epoxy polymer compound and the curing agent in the multilayer adhesive film is improved in order to enable bonding by thermocompression bonding at a low temperature, the epoxy polymer compound may be gradually cured during storage, and adhesiveness of the multilayer adhesive film may be lowered.

Therefore, patent document 2 below discloses a curing agent for epoxy polymers, which is provided with latency by encapsulating an anionic polymerization type curing agent in microcapsules. The curing agent for latent epoxy polymer can be stored stably at room temperature and can rapidly initiate a curing reaction by a predetermined heat, pressure, or the like, thereby improving the storage stability of the multilayer adhesive film.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2013/027541;

patent document 2: international publication No. 2007/037378.

Disclosure of Invention

Problems to be solved by the invention

However, in the case where the surface to be bonded is made of alkali glass, polyimide, or the like, the thermal cationic polymerizable composition disclosed in patent document 1 is not sufficiently cured because of inhibition of polymerization. Therefore, the multilayer adhesive film using the thermal cationic polymerizable composition disclosed in patent document 1 may have reduced adhesiveness depending on the material of the adherend.

In addition, the multilayer adhesive film using the latent curing agent for epoxy polymer disclosed in patent document 2 is not limited by the surface to be adhered, but hot press bonding at high temperature is necessary to obtain sufficient adhesiveness.

In view of the above problems, an object of the present invention is to provide: a novel and improved multilayer adhesive film which contains an anionic polymerization type epoxy curing agent, has high storage stability, and has sufficient adhesion even in low-temperature thermocompression bonding; and a connection structure bonded by the multilayer adhesive film.

Means for solving the problems

In order to solve the above problem, according to an aspect of the present invention, there is provided a multilayer adhesive film including: a plurality of epoxy layers comprising an uncured epoxy polymeric compound and a latent epoxy curing agent; and a curing agent layer which is sandwiched between the plurality of epoxy layers and contains an anionic polymerization type non-latent epoxy curing agent.

The apparatus may further comprise: an interface layer formed between each of the epoxy layers and the curative layer and comprising a cured epoxy polymeric compound.

The non-latent epoxy curing agent may be contained in an amount of 10 mass% or more and 50 mass% or less with respect to the total mass of the curing agent layer.

The non-latent epoxy curing agent may be an imidazole compound.

The latent epoxy curing agent may be a curing agent to which latency is imparted by encapsulating the curing agent in a microcapsule.

At least any one of the plurality of epoxy layers and the curing agent layer may include conductive particles.

The conductive particles may be included in at least any one of the plurality of epoxy layers.

The total film thickness of the multilayer adhesive film may be 4 μm or more and 50 μm or less.

In order to solve the above problem, another aspect of the present invention provides a connection structure in which an electronic component is bonded to another electronic component or a substrate via the above multilayer adhesive film.

At least a part of the bonded surface of the electronic component may be covered with a protective film containing polyimide.

Effects of the invention

As described above, according to the present invention, the non-latent epoxy curing agent having high reactivity diffuses into the layer containing the uncured epoxy polymer compound at the time of thermocompression bonding, and therefore, a multilayer adhesive film having sufficient adhesiveness can be realized even at low temperature thermocompression bonding. Further, according to the present invention, since the layer containing the non-latent epoxy curing agent is separated from the layer containing the uncured epoxy polymer compound, a multilayer adhesive film having high storage stability can be realized.

Drawings

Fig. 1 is a cross-sectional view schematically showing a cross-section of a multilayer adhesive film according to an embodiment of the present invention cut in a thickness direction.

FIG. 2 is a cross-sectional view of the multilayer adhesive film shown in FIG. 1, in which an interface layer is formed between an epoxy layer and a curing agent layer.

Fig. 3 is a cross-sectional view schematically showing a cross-section of a multilayer adhesive film according to a modification of the same embodiment when cut in a thickness direction.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, the constituent elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description thereof is omitted.

< 1. multilayer adhesive film >

[1.1. construction of multilayer adhesive film ]

First, the structure of a multilayer adhesive film according to an embodiment of the present invention will be described with reference to fig. 1 and 2. Fig. 1 is a cross-sectional view schematically showing a cross-section of a multilayer adhesive film 100 according to the present embodiment cut in a thickness direction. Fig. 2 is a cross-sectional view of the multilayer adhesive film 100A when

interface layers

131 and 132 are formed between the

epoxy layers

111 and 112 and the curing agent layer 120.

As shown in fig. 1, the multilayer adhesive film 100 according to the present embodiment has a laminated structure in which a curing agent layer 120 is sandwiched between a plurality of

epoxy layers

111 and 112.

A release sheet (not shown) for supporting the multilayer adhesive film 100 is provided on either side of the multilayer adhesive film 100. The release sheet is obtained by applying a release agent such as silicone to sheet-shaped PET (polyethylene terephthalate), OPP (Oriented Polypropylene), PMP (Poly-4-methyl pentene-1), PTFE (Polytetrafluoroethylene), or the like, and prevents the multilayer adhesive film 100 from drying while maintaining the shape of the multilayer adhesive film 100. Such a release sheet can be suitably used even when each layer of the multilayer adhesive film 100 is produced.

(epoxy layer)

The

epoxy layers

111, 112 include a film-forming component, an uncured epoxy polymer compound, and a latent epoxy curing agent.

The film-forming component is a resin or the like forming the film shape of the

epoxy layers

111 and 112, and functions as a binder for holding the uncured epoxy polymer compound and the latent epoxy curing agent. The film-forming component may be, for example, a polymer resin having an average molecular weight of 10000 or more, and from the viewpoint of film-forming properties, a polymer resin having an average molecular weight of 10000 or more and 80000 or less is preferable.

Specifically, various resins such as epoxy resin, phenoxy resin, polyester urethane resin, polyester resin, polyurethane resin, acrylic resin, polyimide resin, and butyral resin can be used as the film forming component. These resins may be used alone or in combination of 2 or more. The phenoxy resin is preferably used as the film-forming component in order to improve film-forming properties and adhesion reliability.

In order to obtain good film strength and adhesion reliability, for example, the film forming component is contained preferably at 10 mass% or more and 55 mass% or less, and more preferably at 10 mass% or more and 30 mass% or less, with respect to the total mass of the

epoxy layers

111 and 112.

The uncured epoxy polymer compound is a compound, oligomer or prepolymer having 1 or 2 or more epoxy groups in the molecule, and the multilayer adhesive film 100 is cured by polymerization when it is thermocompression bonded or the like, and functions to bond objects to be bonded to each other. The uncured epoxy polymer compound is polymerized by mixing with a curing agent, and may be solid or liquid as long as it is a curable material.

Examples of the solid epoxy polymer compound include bisphenol a epoxy resins, bisphenol F epoxy resins, novolac epoxy resins, various modified epoxy resins such as rubbers and urethanes, and prepolymers thereof. Examples of the liquid epoxy polymer compound include bisphenol type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, phenol novolac type epoxy resins, stilbene type epoxy resins, triphenol methane type epoxy resins, dicyclopentadiene type epoxy resins, triphenyl methane type epoxy resins, and prepolymers thereof. These compounds may be used alone or in combination of 2 or more.

In order to obtain good film strength and adhesion reliability, for example, the uncured epoxy polymer compound is contained preferably at 15 mass% or more and 65 mass% or less, and more preferably at 30 mass% or more and 50 mass% or less, with respect to the total mass of the

epoxy layers

111, 112.

The latent epoxy curing agent is a curing agent having a latent property and selectively initiating a polymerization reaction with an uncured epoxy polymer compound at the time of thermocompression bonding or the like. Specifically, the latent epoxy curing agent is a curing agent as follows: although not reactive with the epoxy polymer compound at normal temperature (e.g., 25 ℃), the epoxy polymer compound is cured by rapidly acquiring reactivity with the epoxy polymer compound by predetermined heat, light, pressure, or the like. That is, "latent" means that the curing agent is inactive under storage conditions such as room temperature, but is activated under predetermined conditions.

Examples of such a latent epoxy curing agent include: latent epoxy curing agents (NOVACURE, manufactured by asahi chemicals) in which a curing agent is encapsulated in microcapsules and the curing agent is activated by destroying the microcapsules by heat or pressure; latent epoxy hardeners (Amicure (アミキュア) manufactured by the FINE TECHNO Co., Ltd., Fujicure manufactured by Fuji chemical Co., Ltd.) and the like, which are produced by inactivating an amine compound functioning as a curing agent by converting it into an adduct or a salt and decomposing it by heating.

However, in order to improve storage stability and to obtain good adhesion even by pressure bonding at low temperatures, it is preferable to use a microcapsule-type latent epoxy curing agent (NOVACURE, manufactured by asahi chemicals, inc.).

The latent epoxy curing agent is an anionic polymerization type epoxy curing agent. By using the anionic polymerization type latent epoxy curing agent, the multilayer adhesive film 100 according to the present embodiment can exhibit good adhesion even in the case of a cationic polymerization type epoxy curing agent, in the case of an adherend in which polymerization inhibition occurs. In the case of a cationic polymerization type epoxy curing agent, an adherend causing polymerization inhibition is, for example, alkali glass, polyimide, or the like.

In order to obtain good storage stability and adhesion, for example, the latent epoxy curing agent is contained in an amount of preferably 10% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and 40% by mass or less, based on the total mass of the

epoxy layers

111 and 112.

It is to be noted that the

epoxy layers

111, 112 may contain a silane coupling agent, an inorganic filler, a colorant, an antioxidant, a rust preventive, and the like as other additives.

As the silane coupling agent, known silane coupling agents can be used, and epoxy, amino, mercapto, thioether, and ureide silane coupling agents can be used. When these silane coupling agents are added, the adhesiveness to an inorganic substrate such as a glass substrate can be improved. As the inorganic filler, silica, talc, titanium oxide, calcium carbonate, magnesium oxide, or the like can be used. When these inorganic fillers are added, the fluidity of the

epoxy layers

111, 112 is controlled, and the film strength can be improved.

In order to fill a sufficient epoxy polymer compound in the adhesion of the electronic component to the substrate or the like, the film thickness of the

epoxy layers

111 and 112 is preferably 1 μm or more and 20 μm or less, and more preferably 2 μm or more and 15 μm or less, for example.

(curing agent layer)

The curing agent layer 120 contains a film-forming component and an anionic polymerization type non-latent epoxy curing agent (hereinafter, also simply referred to as a non-latent epoxy curing agent). The curing agent layer 120 does not contain an uncured epoxy polymer compound. This is to avoid: since the curing agent layer 120 contains a non-latent epoxy curing agent having high reactivity with the epoxy polymer compound, the epoxy polymer compound that is not cured during storage reacts with the non-latent epoxy curing agent to be cured.

The film-forming component is a resin or the like in a film shape forming the curing agent layer 120, and functions as a binder for holding the anionic polymerization type non-latent epoxy curing agent. Specifically, the same polymer resin as the film-forming component contained in the

epoxy layers

111 and 112 can be used as the film-forming component, and a phenoxy resin is preferably used in order to improve the film-forming property and the adhesion reliability. The film-forming component contained in the curing agent layer 120 may be the same polymer resin as the film-forming component contained in the

epoxy layers

111 and 112, or may be a different polymer resin.

In order to obtain good film strength and adhesion reliability, for example, the film forming component is contained preferably at 10 mass% or more and 95 mass% or less, and more preferably at 50 mass% or more and 90 mass% or less, with respect to the total mass of the curing agent layer 120.

The anionic polymerization type non-latent epoxy curing agent is a curing agent which does not have a latent property and initiates an anionic polymerization reaction with an epoxy polymer compound. Specifically, the anionic polymerization type non-latent epoxy curing agent means a curing agent other than the latent epoxy curing agent among the anionic polymerization type epoxy curing agents, and for example, an amine compound, an imidazole compound, a polyamide compound, and the like. Further, the anionic polymerization type non-latent epoxy curing agent may also be represented by: the anionic polymerization type curing agent is not encapsulated in microcapsules or the like, and a latent curing agent is not added.

In the multilayer adhesive film 100 according to the present embodiment, since the non-latent epoxy curing agent is anionic polymerization type, it can have good adhesion to the surface to be adhered such as alkali glass or polyimide, which causes polymerization inhibition in the case of cationic polymerization type epoxy curing agent.

The anionic polymerization type non-latent epoxy curing agent may be used alone or in combination of 2 or more. However, in the present embodiment, the anionic polymerization type non-latent epoxy curing agent preferably contains an imidazole compound. In this case, the multi-layer adhesive film 100 can lower the temperature of the thermocompression bonding at the time of bonding and can form a stronger bond.

In the multilayer adhesive film 100 according to the present embodiment, the epoxy layers 111 and 112 are pressed so as to sandwich the curing agent layer 120 during thermocompression bonding, and therefore the non-latent epoxy curing agent in the curing agent layer 120 diffuses into the

epoxy layers

111 and 112. Thus, the epoxy polymer compound in the

epoxy layers

111 and 112 can be cured at a higher curing rate because it undergoes a polymerization reaction with a non-latent epoxy curing agent having a higher reactivity in addition to a polymerization reaction with a latent epoxy curing agent during thermocompression bonding. Therefore, the multilayer adhesive film 100 according to the present embodiment can sufficiently cure the epoxy polymer compound even in the case of thermocompression bonding at a lower temperature, and thus can have sufficient adhesiveness.

In the multilayer adhesive film 100 according to the present embodiment, the curing agent layer 120 containing a highly reactive non-latent epoxy curing agent and the

epoxy layers

111 and 112 containing an uncured epoxy polymer compound are formed separately. Therefore, the highly reactive non-latent epoxy curing agent does not come into direct contact with the uncured epoxy polymer compound except during thermocompression bonding, and therefore the progress of the polymerization reaction of the epoxy polymer compound during storage can be suppressed. Therefore, the multilayer adhesive film 100 according to the present embodiment can have high storage stability.

The anionic polymerization type non-latent epoxy curing agent is preferably contained in an amount of 10 mass% or more and 50 mass% or less based on the total mass of the curing agent layer 120. When the content of the non-latent epoxy curing agent is less than 10% by mass, the curing rate of the

epoxy layers

111 and 112 may decrease, and the adhesiveness may decrease, which is not preferable. When the content of the non-latent epoxy curing agent exceeds 50 mass%, the interface between the

epoxy layers

111 and 112 and the curing agent layer 120 is rapidly cured during thermocompression bonding, and it becomes difficult to sufficiently press the multilayer adhesive film 100, which is not preferable. In particular, as described later, when the multilayer adhesive film 100 is used as an anisotropic conductive film, the multilayer adhesive film 100 is not sufficiently pressed, and thus it is not preferable because it may not be possible to form a reliable anisotropic conductive connection.

The curing agent layer 120 may contain a silane coupling agent, an inorganic filler, a colorant, an antioxidant, a rust inhibitor, and the like as other additives, similarly to the

epoxy layers

111 and 112.

In order to fill a sufficient amount of the anionic polymerization type non-latent epoxy curing agent in the adhesion of the electronic component to the substrate or the like, the film thickness of the curing agent layer 120 is preferably 1 μm or more and 15 μm or less, and more preferably 2 μm or more and 10 μm or less, for example.

Here, as shown in fig. 2, the multilayer adhesive film 100A according to the present embodiment may have

interface layers

131 and 132 formed between the

epoxy layers

111 and 112 and the curing agent layer 120.

The interface layers 131, 132 comprise a cured epoxy polymer compound. The cured epoxy polymer compounds comprised by the interface layers 131, 132 are: the uncured epoxy polymer compound in the

epoxy layers

111 and 112 and the non-latent epoxy curing agent in the curing agent layer 120 are polymerized and cured. The interface layers 131 and 132 containing the cured epoxy polymer compound function as a barrier layer between the

epoxy layers

111 and 112 and the curing agent layer 120, and therefore, diffusion of the non-latent epoxy curing agent in the curing agent layer 120 into the

epoxy layers

111 and 112 can be suppressed during storage. This further improves the storage stability of the multilayer adhesive film 100 having the interface layers 131 and 132 formed thereon.

In order to suppress the diffusion of the non-latent epoxy curing agent into the

epoxy layers

111 and 112, the curing rate of the epoxy polymer compound in the interface layers 131 and 132 is preferably 60% or more, and more preferably 80% or more. The curing rate of the epoxy polymer compound can be calculated as follows: for example, the ratio of epoxy groups in an uncured epoxy polymer compound and the ratio of epoxy groups in a cured epoxy polymer compound are calculated by infrared spectroscopy (IR) measurement, and the degree of reduction of epoxy groups due to curing is calculated.

In order to obtain good storage stability and adhesion in the multilayer adhesive film, the thickness of the interface layers 131 and 132 is preferably 0.1 μm or more and 0.6 μm or less, and more preferably 0.2 μm or more and 0.5 μm or less, for example.

As described above, in the multilayer adhesive film 100 according to the present embodiment, the curing agent layer 120 containing the highly reactive non-latent epoxy curing agent and the

epoxy layers

111 and 112 containing the uncured epoxy polymer compound are formed separately, whereby high storage stability and good adhesion can be achieved at the same time.

In order to obtain good film strength and adhesion reliability, the total film thickness of the multilayer adhesive film 100 according to the present embodiment is preferably 4 μm or more and 50 μm or less.

[1.2. method for producing multilayer adhesive film ]

The multilayer adhesive film 100 according to the present embodiment described above can be produced, for example, as follows.

First, a film-forming component, an epoxy polymer compound and a latent epoxy curing agent are mixed in a suitable solvent at a predetermined ratio. The mixed solution is uniformly mixed by a known mixing method to prepare an epoxy layer-forming composition, and then the composition is applied to a release sheet by a known coating method so as to have a predetermined dry thickness, and dried at 60 to 80 ℃ for 2 to 8 minutes to form

epoxy layers

111 and 112, respectively.

Similarly, a film-forming component and an anionic polymerization type non-latent epoxy curing agent are mixed in a suitable solvent at a predetermined ratio to prepare a curing agent layer-forming composition, and then the composition is applied to a separate release sheet to form a predetermined dry thickness and dried to form a curing agent layer 120.

The formed

epoxy layers

111 and 112 and the curing agent layer 120 are bonded to each other in this order by a known method, so that the multilayer adhesive film 100 according to the present embodiment can be produced.

Here, the method for producing the multilayer adhesive film 100 according to the present embodiment is not limited to the above-described method. For example, instead of forming the

epoxy layers

111 and 112 and the curing agent layer 120 separately and bonding them, the curing agent layer 120 and the epoxy layer 112 may be sequentially applied to the epoxy layer 111. In addition, the multilayer adhesive film 100 can be prepared by laminating the

epoxy layers

111 and 112 and the curing agent layer 120 by combining coating and lamination.

< 2. modification of multilayer adhesive film

Next, a multilayer adhesive film 100B according to a modification of the present embodiment will be described with reference to fig. 3. Fig. 3 is a cross-sectional view schematically showing a cross-section of a multilayer adhesive film 100B according to a modification of the present embodiment when cut in the thickness direction.

As shown in fig. 3, the multilayer adhesive film 100B according to the modification of the present embodiment is a film that contains conductive particles 140 in at least one of the

epoxy layers

111 and 112 and the curing agent layer 120 and can be used as an anisotropic conductive film. In order for the multilayer adhesive film 100B to function as an anisotropic conductive film capable of more reliably performing anisotropic conductive connection, the conductive particles 140 are preferably included in at least one of the

epoxy layers

111 and 112.

The conductive particles 140 are, for example, metal particles or metal-coated resin particles. Specifically, the conductive particles 140 may be metal particles such as nickel, cobalt, copper, silver, gold, or palladium. The conductive particles 140 may be particles obtained by coating the surface of core resin particles such as styrene-divinylbenzene copolymer, benzoguanamine resin, crosslinked polystyrene resin, acrylic resin, or styrene-silica composite resin with a metal such as nickel, copper, gold, or palladium. Further, a gold or palladium thin film, a thin insulating resin thin film to the extent that it is broken at the time of pressure bonding, or the like may be formed on the surface of the conductive particle 140.

When the multilayer adhesive film 100B is thermocompression bonded or the like, the conductive particles 140 are melted and connected to each other, thereby electrically connecting the terminals of the electronic component and the terminals of the substrate or the like bonded through the multilayer adhesive film 100B. On the other hand, the conductive particles 140 are electrically connected only in a region where a higher pressure is applied, such as between the electronic component and the protruding terminals of the substrate, and therefore, the insulating property in the film in-plane direction of the multilayer adhesive film 100B is maintained. That is, the multilayer adhesive film 100B according to the modification of the present embodiment can be used as an anisotropic conductive film.

In order to realize reliable anisotropic conductive connection, the average particle diameter (number average of particle diameters) of the conductive particles 140 is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 5 μm or less. The average particle diameter of the conductive particles 140 can be measured by, for example, a laser diffraction scattering method.

In order to realize a reliable anisotropic conductive connection, for example, the conductive particles 140 are contained preferably at 5 mass% to 30 mass% based on the total mass of the layer including the conductive particles 140, and more preferably at 5 mass% to 20 mass% based on the total mass of the layer including the conductive particles 140.

(method of producing connection Structure)

When the multilayer adhesive film 100B according to the modification of the present embodiment is used as an anisotropic conductive film, for example, terminals of an electronic component and terminals of a substrate can be anisotropically and conductively connected by the following method.

First, the multilayer adhesive film 100B according to the modification of the present embodiment is temporarily attached to the terminal of the substrate so that the layer containing the conductive particles 140 is on the terminal side of the substrate. The method and conditions for temporary bonding may be any known method and conditions, but for example, the multilayer adhesive film 100B may be temporarily bonded by heating and pressing to an extent that it is not completely cured.

Next, the electronic component is placed on the temporarily attached multilayer adhesive film 100B so that the terminals of the electronic component face the terminals of the substrate, and temporarily fixed. The method and conditions for temporary fixing may be any known method and conditions, and for example, the substrate, the multilayer adhesive film 100B, and the electronic component may be temporarily fixed by heating and pressing the multilayer adhesive film 100B to an extent that it is not completely cured.

Next, the temporarily fixed substrate, the multilayer adhesive film 100B, and the electronic component are heated and pressed by the heating and pressing member to be thermocompression bonded, whereby the terminals of the substrate and the terminals of the electronic component are anisotropically and electrically connected to each other to form a connection structure. Here, a known thermocompression bonding apparatus can be used as the method and conditions for thermocompression bonding.

According to the above method, the multilayer adhesive film 100B according to the modification of the present embodiment has sufficient adhesiveness regardless of the material of the surface to be adhered of the substrate and the electronic component, and can form a connection structure in which anisotropic conductive connection is formed.

Examples

< 3. example >

The multilayer adhesive film according to the present embodiment will be described in more detail below with reference to examples and comparative examples. The following examples are examples for showing the applicability and effects of the multilayer adhesive film according to the present embodiment, and the present invention is not limited to the following examples.

[3.1. preparation and evaluation of multilayer adhesive film ]

First, a multilayer adhesive film according to the present embodiment was prepared, and adhesiveness was evaluated.

(example 1)

An epoxy layer-forming composition was prepared by mixing 20 mass% of a phenoxy resin (YP50, manufactured by Nippon iron chemical Co., Ltd.), 40 mass% of a liquid epoxy resin (EP828, manufactured by Mitsubishi chemical Co., Ltd.), 10 mass% of a solid epoxy resin (YD-014, manufactured by Nippon iron chemical Co., Ltd.), and 30 mass% of a latent epoxy curing agent (NOVACURE 3941HP, manufactured by Asahi chemical industries Co., Ltd.). The epoxy layer-forming composition was applied to a release sheet (38 μm thick sheet of silicone treated PET, the same applies hereinafter) so that the film thickness after drying was 6 μm, and dried, thereby forming an epoxy layer.

Subsequently, 90 mass% of phenoxy resin (YP50, manufactured by shiniki chemical corporation) and 10 mass% of imidazole compound (2-methylimidazole, manufactured by shiniki chemical corporation) were mixed to prepare a curing agent layer-forming composition. Further, the curing agent layer-forming composition was applied to a release sheet so that the film thickness after drying became 6 μm, and dried to form a curing agent layer.

Further, the respective layers were peeled off from the release sheet and laminated so that the curing agent layer was sandwiched by 2 epoxy layers, thereby preparing a multilayer adhesive film (total film thickness 18 μm) according to example 1.

Comparative example 1

An adhesive film-forming composition was prepared by mixing 20 mass% of a phenoxy resin (YP50, manufactured by shin-iron chemical corporation), 40 mass% of a liquid epoxy resin (EP828, manufactured by mitsubishi chemical corporation), 10 mass% of a solid epoxy resin (YD-014, manufactured by shin-iron chemical corporation), and 30 mass% of a cationic polymerization type epoxy curing agent (SI-60L, manufactured by shin-iron chemical corporation). Further, an adhesive film forming composition was applied to a release sheet so that the film thickness after drying became 18 μm, and dried, thereby preparing an adhesive film (total film thickness: 18 μm) according to comparative example 1.

(evaluation method and evaluation result)

Using the adhesive films according to example 1 and comparative example 1, a connection structure was produced. Specifically, a polyimide film having a thickness of 0.1mm, the adhesive film according to example 1 or comparative example 1, and a PET (polyethylene terephthalate) film having a thickness of 0.1mm were sequentially laminated, and then thermocompression bonded for 150 ℃ to 1MPa to 5 seconds to prepare a connection structure.

The peel strength of the prepared connection structure was measured by a T-peel strength test (according to JIS K6853-3) using a Tensilon universal tester (manufactured by Orientec). The results of the measured peel strength are shown in table 1.

[ Table 1]

(Table 1)

	Example 1	Comparative example 1
			Peel strength [ N ]]	13	3

As is clear from the results shown in table 1, example 1 has higher peel strength and higher adhesiveness than comparative example 1. In particular, it is found that in comparative example 1, peeling occurred at the interface between the polyimide film and the adhesive film, and the curing agent of the cationic polymerization type was inhibited by the polyimide, so that the curing became insufficient, and the adhesiveness was lowered.

Therefore, it is understood that the multilayer adhesive film according to the present embodiment exhibits high adhesiveness regardless of the material of the surface to be adhered.

[3.2 preparation and evaluation of Anisotropic conductive film ]

Next, a multilayer adhesive film according to a modification of the present embodiment was prepared, and adhesiveness, storage stability, conductivity, and the like when used as an anisotropic conductive film were evaluated.

(example 2)

First, a phenoxy resin (YP50, manufactured by shin-iron chemical corporation) 20 mass%, a liquid epoxy resin (EP828, manufactured by mitsubishi chemical corporation) 30 mass%, a solid epoxy resin (YD-014, manufactured by shin-iron chemical corporation) 10 mass%, a latent epoxy curing agent (NOVACURE 3941HP, manufactured by asahi chemical materials) 30 mass%, and Conductive particles (AUL-704, manufactured by water-accumulation chemical corporation) 10 mass% were mixed to prepare an ACF (Anisotropic Conductive Film) layer forming composition. Further, an ACF layer-forming composition was applied to a release sheet so that the film thickness after drying became 6 μm, and dried, thereby forming an ACF layer.

Then, a phenoxy resin (YP50, manufactured by shin-iron chemical corporation) 20 mass%, a liquid epoxy resin (EP828, manufactured by mitsubishi chemical corporation) 40 mass%, a solid epoxy resin (YD-014, manufactured by shin-iron chemical corporation) 10 mass%, and a latent epoxy curing agent (NOVACURE 3941HP, manufactured by asahi chemical industries) 30 mass% were mixed to prepare a NCF (non conductive Film) layer forming composition. Further, the NCF layer-forming composition was applied to a release sheet so that the film thickness after drying became 6 μm, and dried, thereby forming an NCF layer.

Further, the cured layer formed as described above was sandwiched between the ACF layer and the NCF layer by peeling from the release sheet and laminating, thereby preparing a multilayer adhesive film (total film thickness 18 μm) according to example 2.

(example 3)

A multilayer adhesive film (total film thickness 18 μm) according to example 3 was prepared in the same manner as in example 2, except that a curing agent layer forming composition was prepared by mixing 60 mass% of a phenoxy resin (YP50, manufactured by shiniki chemical corporation) and 40 mass% of an imidazole compound (2-methylimidazole, manufactured by shiniki chemical corporation).

(example 4)

A multilayer adhesive film (total film thickness 18 μm) according to example 4 was prepared in the same manner as in example 2, except that a curing agent layer forming composition was prepared by mixing 50 mass% of a phenoxy resin (YP50, manufactured by shiniki chemical corporation) and 50 mass% of an imidazole compound (2-methylimidazole, manufactured by shiniki chemical corporation).

(example 5)

A multilayer adhesive film (total film thickness 18 μm) according to example 5 was prepared in the same manner as in example 2, except that a curing agent layer forming composition was prepared by mixing 40 mass% of a phenoxy resin (YP50, manufactured by shiniki chemical corporation) and 60 mass% of an imidazole compound (2-methylimidazole, manufactured by shiniki chemical corporation).

Comparative example 2

A multilayer adhesive film according to comparative example 2 (total thickness 18 μm) was prepared in the same manner as in example 2, except that the NCF layer was formed to a thickness of 12 μm and only the ACF layer and the NCF layer were peeled from the release sheet and bonded.

Comparative example 3

An ACF layer-forming composition was prepared by mixing 20 mass% of a phenoxy resin (YP50, manufactured by Nippon iron chemical Co., Ltd.), 20 mass% of a liquid epoxy resin (EP828, manufactured by Mitsubishi chemical Co., Ltd.), 10 mass% of a solid epoxy resin (YD-014, manufactured by Nippon iron chemical Co., Ltd.), 30 mass% of a latent epoxy curing agent (NOVACURE 3941HP, manufactured by Asahi chemical industries Co., Ltd.), 10 mass% of conductive particles (AUL-704, manufactured by Anhui chemical Co., Ltd.), and 10 mass% of an imidazole compound (2-methylimidazole, manufactured by Sichuan chemical Co., Ltd.). Further, an ACF layer-forming composition was applied to a release sheet so that the film thickness after drying became 6 μm, and dried, thereby forming an ACF layer.

The NCF layer forming composition was applied to a release sheet so that the film thickness after drying was 12 μm, and dried, thereby forming an NCF layer, with the same composition as in example 2.

Further, the ACF layer and the NCF layer were peeled off from the release sheet and bonded to each other, thereby preparing a multilayer adhesive film (total film thickness 18 μm) according to comparative example 3.

Comparative example 4

The ACF layer-forming composition was applied to a release sheet so that the film thickness after drying was 6 μm, and dried, thereby forming an ACF layer, by adjusting the composition to the same composition as in example 2.

A phenoxy resin (YP50, manufactured by Nippon Tekknika Co., Ltd.), a liquid epoxy resin (EP828, manufactured by Mitsubishi chemical Co., Ltd.), a solid epoxy resin (YD-014, manufactured by Nippon Tekknika chemical Co., Ltd.) and 10 mass% of a latent epoxy curing agent (NOVACURE 3941HP, manufactured by Asahi chemical industries Co., Ltd.) were mixed with 10 mass% of an imidazole compound (2-methylimidazole, manufactured by Sikko chemical Co., Ltd.) to prepare an NCF layer-forming composition. Further, the NCF layer-forming composition was applied to a release sheet so that the film thickness after drying became 12 μm, and dried, thereby forming an NCF layer.

Further, the ACF layer and the NCF layer were peeled off from the release sheet and bonded to each other, thereby preparing a multilayer adhesive film (total film thickness 18 μm) according to comparative example 4.

Comparative example 5

First, an ACF layer-forming composition was prepared by mixing 20 mass% of a phenoxy resin (YP50, manufactured by shin-iron chemical corporation), 30 mass% of a liquid epoxy resin (EP828, manufactured by mitsubishi chemical corporation), 10 mass% of a solid epoxy resin (YD-014, manufactured by shin-iron chemical corporation), 30 mass% of a cationic polymerization type epoxy curing agent (SI-60L, manufactured by shin-iron chemical corporation), and 10 mass% of conductive particles (AUL-704, manufactured by water-accumulation chemical corporation). Further, an ACF layer-forming composition was applied to a release sheet so that the film thickness after drying became 6 μm, and dried, thereby forming an ACF layer.

Next, a composition for forming an NCF layer was prepared by mixing 20 mass% of a phenoxy resin (YP50, manufactured by Nippon Tekken chemical Co., Ltd.), 40 mass% of a liquid epoxy resin (EP828, manufactured by Mitsubishi chemical Co., Ltd.), 10 mass% of a solid epoxy resin (YD-014, manufactured by Nippon Tekken chemical Co., Ltd.), and 30 mass% of a cationic polymerization type epoxy curing agent (SI-60L, manufactured by Sanxin chemical Co., Ltd.). Further, the NCF layer-forming composition was applied to a release sheet so that the film thickness after drying became 12 μm, and dried, thereby forming an NCF layer.

Further, the ACF layer and the NCF layer were peeled off from the release sheet and bonded to each other, thereby preparing a multilayer adhesive film (total film thickness 18 μm) according to comparative example 5.

(confirmation of interface layer)

First, in the multilayer adhesive films according to examples 2 to 5, it was confirmed that an interface layer was formed between the curing agent layer and the ACF layer and the NCF layer. Specifically, in examples 2 to 5, the curing rates of the ACF layer and the NCF layer in the vicinity of the interface with the curing agent layer were calculated separately in the thickness direction, and it was confirmed that an interface layer containing a cured epoxy polymer compound was formed.

The curing rate was calculated by calculating the ratio of epoxy groups present by IR measurement. Specifically, the ratio of epoxy groups to methyl groups in the ACF layer and the ratio of epoxy groups to methyl groups in the measurement region were measured by IR measurement, and the ratio of decrease in the ratio of epoxy groups in the measurement region was calculated as the cure rate.

The calculated curing rate is shown in table 2. The calculated change in the curing rate in the thickness direction was not significantly different in examples 2 to 5.

[ Table 2]

(Table 2)

The results in table 2 were referenced to confirm that: in both the ACF layer and the NCF layer, an interface layer containing a cured epoxy polymer compound having a curing rate of 80% or more is formed at a distance of 0 to 0.2 [ mu ] m from the interface with the curing agent layer.

When the distance from the interface with the curing agent layer is 0.5 μm or more, the curing rate is 3% or less. This is believed to be due to: by causing the interface layer to function as a barrier layer, diffusion of the non-latent epoxy curing agent into the ACF layer and the NCF layer is suppressed, and curing of the ACF layer and the NCF layer is suppressed. Therefore, the thickness of the interface layer is considered to be about 0.4 μm in each of the ACF layer and the NCF layer.

(evaluation method and evaluation result)

Using the anisotropic conductive films of examples 2 to 4 and comparative examples 2 to 4, connection structures were produced. Specifically, a polyimide substrate having a thickness of 0.3mm and a Ti/Al coating layer formed thereon, and an IC (Integrated Circuit) chip having a gold-plated bump with a height of 15 μm and a planar area of 30 μm × 85 μm, a planar area of 1.8mm × 20mm, and a thickness of 0.3mm were thermocompression bonded to the anisotropic conductive films according to examples 2 to 4 and comparative examples 2 to 4. The conditions for the thermocompression bonding are 190 ℃ to 60MPa to 5 seconds (high temperature condition) or 150 ℃ to 60MPa to 5 seconds (low temperature condition).

The prepared connection structure was evaluated by the following evaluation method.

The curing rate was evaluated as follows: the ratio of epoxy groups to methyl groups in the ACF layer before thermocompression bonding and the ratio of epoxy groups to methyl groups in the ACF layer after thermocompression bonding were measured by infrared spectroscopy (IR) measurement, and the ratio of decrease in the ratio of epoxy groups before and after thermocompression bonding was calculated as the curing rate.

The warpage amount was evaluated as follows: the surface roughness of the substrate side after thermocompression bonding was measured using a surface roughness measuring instrument (manufactured by Okaguchi research Co., Ltd.).

The on-resistance value was evaluated as follows: the resistance value between the polyimide substrate and the IC chip was measured using a digital multimeter (manufactured by yokawa electric corporation). For evaluation of reliability, the on-resistance value was measured at the initial stage after the pressure bonding and after leaving the pressure bonding for 500 hours in an environment of 85 ℃ and 85% humidity.

The adhesive interface was visually checked for floating, and those with floating were evaluated as poor (B) and those without floating were evaluated as good (a). For the evaluation of reliability, the floating of the bonding interface was evaluated in the initial stage after the pressure bonding and after the pressure bonding was left for 500 hours in an environment of 85 ℃ and 85% humidity.

The storage stability was evaluated as follows: after the curing acceleration test at 50 ℃ for 12 hours, the ratio of epoxy groups to methyl groups in the ACF layer was measured by the method described above, and the reduction ratio of the ratio of epoxy groups to methyl groups in the ACF layer immediately after thermocompression bonding was calculated.

The above evaluation results are shown in table 3.

[ Table 3]

In Table 3, "high temperature" in the column of "conditions" means hot press bonding under high temperature conditions of 190 ℃ to 60MPa to 5 seconds, and "low temperature" means hot press bonding under low temperature conditions of 150 ℃ to 60MPa to 5 seconds.

As is clear from the results shown in Table 3, in examples 2 to 5, the curing rate was high and no floating occurred in the bonded interface even when thermocompression bonding was performed under the low temperature condition of 150 to 60MPa to 5 seconds. In addition, in examples 2 to 5, even after the curing acceleration test at 50 ℃ for 12 hours, the curing rate was suppressed to 8% or less, and the storage stability was excellent.

Furthermore, it is clear that examples 2 to 4 also have a low on-resistance value, and a suitable anisotropic conductive connection is formed between the substrate and the IC. However, it is found that in example 5 in which the content of the imidazole compound as the non-latent epoxy curing agent is 60 mass%, the curing speed of the curing agent layer, the ACF layer and the NCF layer is fast, and the ACF layer and the NCF layer cannot be sufficiently pressed during thermocompression bonding, and therefore, the on-resistance value becomes high, and a suitable anisotropic conductive connection cannot be formed. Therefore, it is found that the content of the non-latent epoxy curing agent in the curing agent layer is preferably 10 mass% or more and 50 mass% or less with respect to the total mass of the curing agent layer.

On the other hand, in comparative example 2, since the curing agent layer was not formed, in the case of performing the thermocompression bonding under the low temperature condition of 150 to 60MPa to 5 seconds, the curing rate was lowered and floating was observed at the bonding interface. It is understood that comparative example 2, in which thermocompression bonding was performed under a high temperature condition of 190 to 60MPa to 5 seconds, exhibited a sufficient curing rate, but was not preferable because the amount of warpage increased.

In comparative examples 3 and 4, since the ACF layer or the NCF layer contains an imidazole compound which is a non-latent epoxy curing agent, the curing rate was more than 30% in the curing acceleration test at 50 ℃ for 12 hours, and the storage stability was low.

In comparative example 5, since a cationic polymerization type epoxy curing agent was used, polymerization was inhibited by the polyimide on the surface to be bonded, and the curing rate was lowered, and floating was observed at the bonding interface after leaving. Therefore, it is understood that in comparative example 5, the adhesiveness is lowered depending on the material of the surface to be adhered.

As described above, in the multilayer adhesive film 100 according to the present embodiment, the epoxy polymer compound can be polymerized with the latent epoxy curing agent and also with the non-latent epoxy curing agent having higher reactivity during thermocompression bonding. Therefore, the multilayer adhesive film 100 according to the present embodiment can have sufficient adhesiveness even by thermocompression bonding at a low temperature.

epoxy layers

111 and 112 containing an uncured epoxy polymer compound are formed separately. Therefore, the multilayer adhesive film 100 according to the present embodiment can have high storage stability.

In addition, the multilayer adhesive film 100 according to the present embodiment can be suitably used as an anisotropic conductive film by including conductive particles in any one layer.

While the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to the above-described examples. It is obvious that a person having ordinary knowledge in the art to which the present invention pertains can conceive various modifications and alterations within the scope of the technical idea described in the claims, and it is needless to say that these modifications and alterations fall within the technical scope of the present invention.

Description of the symbols

100. 100A, 100B multilayer adhesive film

111. 112 epoxy layer

120 layer of curing agent

131. 132 interfacial layer

140 conductive particles

Claims

1. A multilayer adhesive film comprising:

a plurality of epoxy layers formed using an uncured epoxy polymer compound and a latent epoxy curing agent; and

and a curing agent layer sandwiched by the plurality of epoxy layers, the curing agent layer being formed using an anionic polymerization type non-latent epoxy curing agent.

2. The multilayer adhesive film according to claim 1, further comprising:

an interface layer formed between each of the epoxy layers and the curative layer, the interface layer comprising a cured epoxy polymeric compound.

3. The multilayer adhesive film according to claim 1 or 2, wherein the non-latent epoxy curing agent is contained in an amount of 10 mass% or more and 50 mass% or less with respect to the total mass of the curing agent layer.

4. The multilayer adhesive film of claim 1 or 2, wherein the non-latent epoxy curing agent is an imidazole compound.

5. The multilayer adhesive film according to claim 1 or 2, wherein the latent epoxy curing agent is a curing agent to which latency is imparted by encapsulating the curing agent in a microcapsule.

6. The multilayer adhesive film of claim 1 or 2, wherein at least any one of the epoxy layers and the curing agent layer comprises conductive particles.

7. The multilayer adhesive film of claim 6, wherein the conductive particles are contained in at least any one of the plurality of epoxy layers.

8. The multilayer adhesive film according to claim 1 or 2, wherein the total film thickness of the multilayer adhesive film is 4 μm or more and 50 μm or less.

9. A connection structure obtained by bonding an electronic component to another electronic component or a substrate via the multilayer adhesive film according to any one of claims 1 to 8.

10. The connection structure according to claim 9, wherein at least a part of the bonded surface of the electronic component is covered with a protective film containing polyimide.