KR102577181B1 - Adhesive compositions and structures - Google Patents

Abstract

An adhesive composition containing (a) a thermoplastic resin having a urethane bond, (b) a radically polymerizable compound, (c) a radical polymerization initiator, (d) polyurethane beads, and (e) non-conductive inorganic fine particles.

Description

Adhesive compositions and structures

This disclosure relates to adhesive compositions and structures.

In semiconductor devices and liquid crystal display devices (display display devices), various adhesives have been conventionally used for the purpose of bonding various members in the devices. The properties required for an adhesive cover a variety of things, including adhesiveness, heat resistance, and reliability under high temperature and high humidity conditions. Additionally, the adherends used for adhesion include printed wiring boards, organic substrates (polyimide substrates, etc.), metals (titanium, copper, aluminum, etc.), ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), and IGZO (Indium Gallium). Substrates _with surface states such as Zinc Oxide, _SiN

Conventionally, thermosetting resins (epoxy resins, acrylic resins, etc.) that exhibit high adhesiveness and high reliability have been used in adhesives for semiconductor devices or liquid crystal display devices. As components of adhesives using epoxy resins, epoxy resins and latent curing agents that generate cationic or anionic species reactive to the epoxy resin by heat or light are generally used. The latent curing agent is an important factor that determines the curing temperature and curing speed, and various compounds have been used from the viewpoint of storage stability at room temperature and curing speed when heated. In the actual process, the desired adhesiveness was obtained by, for example, curing under curing conditions of 170 to 250°C and 10 seconds to 3 hours.

Additionally, in recent years, with the increased integration of semiconductor elements and the higher precision of liquid crystal display elements, the pitch between elements and interconnections has become narrower, and there is a risk of adversely affecting surrounding members due to heat during curing. In addition, in order to reduce cost, it is necessary to improve throughput, and low temperature (90 to 170°C) and short-time (within 1 hour, preferably within 10 seconds, more preferably within 5 seconds) adhesion, in other words, low temperature bonding. Adhesion that cures in a short period of time (fast cure at low temperature) is required. In order to achieve this low-temperature, short-time curing, it is necessary to use a thermal potential catalyst with low activation energy, but it is known that it is very difficult to achieve storage stability at around room temperature.

Therefore, in recent years, radical curing adhesives using a combination of (meth)acrylate derivatives and peroxide, which is a radical polymerization initiator, have been attracting attention. In the radical curing system, short-time curing is possible because radicals, which are reactive species, are very reactive, and because peroxides exist stably below the decomposition temperature of the radical polymerization initiator, low-temperature, short-time curing and storage stability (e.g. , storage stability at around room temperature). For example, radical curing adhesive compositions as shown in Patent Documents 1 to 3 below are known.

Japanese Patent Publication No. 2006-22231 Japanese Patent Publication No. 2009-1765 International Publication No. 2009/063827

In recent years, the size of the connection portions of semiconductor elements and liquid crystal display elements has further progressed, and adhesives with sufficient adhesive strength even with smaller connection areas have been required. However, it was found that sufficient adhesive strength could not be obtained with conventional adhesives.

Therefore, the present disclosure aims to provide a radical curing adhesive capable of low-temperature, short-time connection (low-temperature, short-time curing), an adhesive composition that provides sufficient adhesive strength even when the connection area is small, and a structure using the same.

The present inventors focused on polyurethane beads while conducting research. And while the present inventors were examining an adhesive composition containing polyurethane beads, they found that the adhesive strength was particularly high when a resin containing a urethane bond was used as a thermoplastic resin. Additionally, it was found that the adhesive strength was further increased by using non-conductive inorganic fine particles in combination with polyurethane beads.

That is, one aspect of the present disclosure includes (a) a thermoplastic resin having a urethane bond, (b) a radically polymerizable compound, (c) a radical polymerization initiator, (d) polyurethane beads, and (e) a non-conductive An adhesive composition containing inorganic fine particles is provided.

According to the adhesive composition of the present disclosure, high adhesive strength can be obtained even when the connection area is small. In the adhesive composition of the present disclosure, especially by using a combination of (a) a thermoplastic resin having a urethane bond, (d) polyurethane beads, and (e) non-conductive inorganic fine particles, high adhesive strength is achieved even when the connection area is small. Regarding the possible reasons, the present inventors estimate as follows. In other words, the flexibility and polarity of the polyurethane beads improve adhesion to the adherend, and the non-conductive inorganic fine particles provide sufficient strength to the adhesive composition and its cured product, resulting in high adhesion even when the connection area is small. I think I can get it. In addition, since the thermoplastic resin (a) having a urethane bond has a high affinity with the (d) polyurethane beads, by using them in combination, the dispersibility of the (d) polyurethane beads in the adhesive composition is greatly improved, enabling connection. It is believed that excellent adhesive strength can be obtained even when the area is small.

The content of the thermoplastic resin having a urethane bond (a) in the adhesive composition of the present disclosure may be greater than or equal to the content of the polyurethane beads (d) on a mass basis.

The adhesive composition of the present disclosure may further contain (f) conductive particles.

The adhesive composition of the present disclosure may be used for circuit connection (adhesive composition for circuit connection).

Another aspect of the present disclosure provides a structure comprising the adhesive composition or a cured product thereof according to one aspect of the present disclosure.

Another aspect of the present disclosure includes a first circuit member having a first circuit electrode, a second circuit member having a second circuit electrode, and a circuit connection member disposed between the first circuit member and the second circuit member. and wherein the first circuit electrode and the second circuit electrode are electrically connected, and the circuit connection member includes the adhesive composition according to one aspect of the present disclosure or a cured product thereof.

According to the present disclosure, in a radical curing adhesive capable of low-temperature short-time connection (low-temperature short-time curing), an adhesive composition capable of obtaining high adhesive strength even when the connection area is small, and a structure using the same can be provided.

According to the present disclosure, application of the adhesive composition or its cured product to a structure or its production can be provided. According to the present disclosure, application of the adhesive composition or its cured product to circuit connections can be provided. According to the present disclosure, application of the adhesive composition or its cured product to a circuit connection structure or its production can be provided.

1 is a schematic cross-sectional view showing one embodiment of the structure of the present disclosure.
Figure 2 is a schematic cross-sectional view showing another embodiment of the structure of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described, but the present disclosure is not limited to these embodiments at all.

In this specification, “(meth)acrylate” means at least one of acrylate and the corresponding methacrylate. The same applies to other similar expressions such as “(meth)acryloyl” and “(meth)acrylic acid.” Unless otherwise specified, the materials illustrated below may be used individually or in combination of two or more types. The content of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified, when multiple substances corresponding to each component exist in the composition. The numerical range indicated using “to” indicates a range that includes the numerical values written before and after “to” as the minimum and maximum values, respectively. “A or B” may include either A or B, and may include both. “Room temperature” means 25°C.

In the numerical range described in stages in this specification, the upper or lower limit of the numerical range at a certain level may be replaced with the upper or lower limit of the numerical range at another level. In addition, in the numerical range described in this specification, the upper or lower limit of the numerical range may be replaced with the value shown in the examples.

<Adhesive composition>

The adhesive composition of this embodiment includes (a) a thermoplastic resin having a urethane bond (hereinafter also referred to as component (a)), (b) a radically polymerizable compound (hereinafter also referred to as component (b)), and (c) a radical Contains a polymerization initiator (hereinafter also referred to as component (c)), (d) polyurethane beads (hereinafter also referred to as component (d)), and (e) non-conductive inorganic fine particles (hereinafter also referred to as component (e)). It is an adhesive composition that The adhesive composition of this embodiment may further contain (f) conductive particles (hereinafter also referred to as (f) component). The adhesive composition of this embodiment can be suitably used as an adhesive composition for circuit connection. Below, each component is explained.

(thermoplastic resin)

The thermoplastic resin (a) having a urethane bond (hereinafter referred to as polyurethane resin) used in this embodiment can be obtained, for example, by reaction of a polyol and an isocyanate component such as diisocyanate. The weight average molecular weight of the polyurethane resin is preferably 5,000 to 150,000, and more preferably 10,000 to 80,000. If this value is 5,000 or more, film forming properties tend to be good when the adhesive composition is used in the form of a film, and if this value is 150,000 or less, compatibility with other components tends to be good.

Examples of polyols used in the synthesis of polyurethane resins include polyester polyol, polyether polyol, polycarbonate polyol, acrylic polyol, polyurethane polyol, and aromatic polyol (phthalic acid polyol). Specifically, those with ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, etc. as the basic skeleton can be mentioned. These can be used individually or in combination of multiple types.

Examples of the isocyanate component include diisocyanate compounds such as aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate. Specifically, 4,4'-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), and 3-isocyanatomethyl. -3,5,5-trimethylcyclohexyl isocyanate (IPDI), etc. can be mentioned. Additionally, as the isocyanate component, an isocyanurate compound (trifunctional) or a urethedione compound (bifunctional) formed from the diisocyanate monomer can be used. Additionally, as the isocyanate component, terminal isocyanate group polyisocyanate (for example, adduct type polyisocyanate, biuret type polyisocyanate, etc.) can also be used. These can be used individually or in combination of multiple types.

The content of the polyurethane resin in the adhesive composition is preferably greater than or equal to the content of (d) polyurethane beads on a mass basis. When the content of the polyurethane resin is greater than the content of the polyurethane beads, the dispersibility of the polyurethane beads in the adhesive composition tends to be further improved due to the presence of a relatively large amount of polyurethane resin with high affinity to the polyurethane beads. The content of the polyurethane resin is preferably 5 to 90% by mass, based on the total mass of the adhesive component of the adhesive composition (solid content other than (f) conductive particles in the adhesive composition; the same applies hereinafter), and is preferably 6 to 90% by mass. It is more preferable that it is 80 mass %, it is still more preferable that it is 8-70 mass %, and it is especially preferable that it is 10-60 mass %. If the content of the polyurethane resin is 5% by mass or more, the dispersibility of the polyurethane beads improves and the adhesive strength tends to be further improved, and if the content is 90% by mass or less, the fluidity of the adhesive composition tends to be improved.

The adhesive composition of this embodiment can use a combination of known thermoplastic resins other than polyurethane resins. Thermoplastic resins other than polyurethane resins include, for example, one or two types selected from polyimide resin, polyamide resin, phenoxy resin, poly(meth)acrylic resin, polyester resin, and polyvinyl butyral resin. The above resins can be mentioned.

The weight average molecular weight of this thermoplastic resin is preferably 5,000 to 400,000, more preferably 5,000 to 200,000, and still more preferably 10,000 to 150,000. If the weight average molecular weight of such a thermoplastic resin is 5000 or more, the adhesive strength of the adhesive composition tends to be good, and if the weight average molecular weight is 400000 or less, compatibility with other components is good, thereby suppressing the decrease in fluidity of the adhesive. There is a tendency to do it.

As a thermoplastic resin, a rubber component may be used for the purpose of relieving stress and improving adhesion. Rubber components include, for example, acrylic rubber, polyisoprene, polybutadiene, carboxyl terminal polybutadiene, hydroxyl terminal polybutadiene, 1,2-polybutadiene, carboxyl terminal 1,2-polybutadiene, hydroxyl terminal 1,2-poly. Butadiene, styrene-butadiene rubber, hydroxyl-terminated styrene-butadiene rubber, carboxylated nitrile rubber, hydroxyl-terminated poly(oxypropylene), alkoxysilyl-terminated poly(oxypropylene), poly(oxytetramethylene) glycol, polyolefin glycol, and poly -ε-caprolactone can be mentioned. From the viewpoint of improving adhesion, the rubber component preferably has a highly polar group, such as a cyano group or a carboxyl group, as a side chain group or terminal group. These rubber components can be used individually or in combination of two or more types.

The total content of the thermoplastic resin in the adhesive composition is preferably 20 to 90% by mass, more preferably 20 to 80% by mass, and 30 to 70% by mass, based on the total mass of the adhesive components of the adhesive composition. It is more preferable that it is %. (a) If the content of the thermoplastic resin is 20% by mass or more, the adhesive strength tends to be good while the film forming property of the adhesive composition tends to be improved, and if the content of the thermoplastic resin is 90% by mass or less, the fluidity of the adhesive composition can be improved. There tends to be.

(Radically polymerizable compound)

(b) A radically polymerizable compound is a compound having a functional group capable of radical polymerization. Examples of such radically polymerizable compounds include (meth)acrylate compounds, maleimide compounds, citracone imide resin, and nadiimide resin. “(meth)acrylate compound” means a compound having a (meth)acryloyl group. The radically polymerizable compound may be used in the form of a monomer or oligomer, or a combination of a monomer and an oligomer may be used. A radically polymerizable compound may be used individually by 1 type, or may be used in combination of 2 or more types.

Specific examples of (meth)acrylate compounds include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, ethylene glycol di(meth)acrylate, and di(meth)acrylate. Ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, 2-hydroxy-1,3-di(meth)acryloxypropane, 2,2 -bis[4-((meth)acryloxymethoxy)phenyl]propane, 2,2-bis[4-((meth)acryloxypolyethoxy)phenyl]propane, dicyclopentenyl (meth)acrylate, Tricyclodecanyl (meth)acrylate, tris((meth)acryloyloxyethyl)isocyanurate, urethane (meth)acrylate, isocyanuric acid EO modified di(meth)acrylate, 9,9- Bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene, etc. can be mentioned. As a radically polymerizable compound other than a (meth)acrylate compound, for example, a compound described in Patent Document 3 (International Publication No. 2009/063827) can be suitably used. A (meth)acrylate compound may be used individually by 1 type, or may be used in combination of 2 or more types.

As a radically polymerizable compound, a (meth)acrylate compound is preferable and urethane (meth)acrylate is more preferable from the viewpoint of obtaining more excellent storage stability. From the viewpoint of improving heat resistance, the (meth)acrylate compound preferably has at least one substituent selected from the group consisting of a dicyclopentenyl group, a tricyclodecanyl group, and a triazine ring.

Additionally, as the radically polymerizable compound, it is preferable to use a radically polymerizable compound having a phosphate ester structure represented by the following general formula (1), and the radically polymerizable compound such as a (meth)acrylate compound and the formula ( It is more preferable to use together a radically polymerizable compound having a phosphate ester structure represented by 1). In these cases, since the adhesive strength to the surface of an inorganic material (metal, etc.) is improved, they are suitable for, for example, adhesion between circuit electrodes.

[Wherein, p represents an integer of 1 to 3, and R represents a hydrogen atom or a methyl group.]

The radically polymerizable compound having the phosphoric acid ester structure is obtained, for example, by reacting phosphoric acid anhydride with 2-hydroxyethyl (meth)acrylate. Specific examples of the radically polymerizable compound having the phosphoric acid ester structure include mono(2-(meth)acryloyloxyethyl)acid phosphate, di(2-(meth)acryloyloxyethyl)acid phosphate, etc. . The radically polymerizable compound having a phosphate ester structure represented by Formula (1) may be used individually or in combination of two or more types.

The content of the radically polymerizable compound having a phosphoric acid ester structure represented by formula (1) is the total amount of the radically polymerizable compound (total amount of components corresponding to the radically polymerizable compound. The same applies hereinafter) from the viewpoint of obtaining better adhesive properties. Based on mass, 1 to 100 mass% is preferable, 1 to 50 mass% is more preferable, and 1 to 10 mass% is still more preferable. The content of the radically polymerizable compound having a phosphate ester structure represented by formula (1) is based on the total mass of the radically polymerizable compound and the film forming material (components used as necessary) from the viewpoint of obtaining better adhesiveness. Thus, 0.01 to 50 mass% is preferable, 0.5 to 10 mass% is more preferable, and 0.5 to 5 mass% is still more preferable.

The radically polymerizable compound may contain allyl (meth)acrylate. In this case, the content of allyl (meth)acrylate is preferably 0.1 to 10% by mass, and 0.5 to 5% by mass, based on the total mass of the radically polymerizable compound and the film forming material (components used as necessary). % is more preferable.

The content of the radically polymerizable compound is preferably within the following range based on the total mass of the adhesive components of the adhesive composition from the viewpoint of obtaining better adhesive properties. The content of the radically polymerizable compound is preferably 10% by mass or more, more preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. The content of the radically polymerizable compound is preferably 90% by mass or less, more preferably 80% by mass or less, further preferably 70% by mass or less, particularly preferably 60% by mass or less, and very preferably 50% by mass or less. do. From these viewpoints, the content of the radically polymerizable compound is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, further preferably 30 to 70% by mass, and 40 to 60% by mass. It is especially preferable, and it is very preferable that it is 40 to 50 mass %.

(radical polymerization initiator)

(c) As the radical polymerization initiator, an initiator that generates free radicals by heat (heating), an initiator that generates free radicals by light, an initiator that generates free radicals by ultrasonic waves, electromagnetic waves, etc. can be used.

An initiator that generates free radicals by heat is a compound that decomposes by heat and generates free radicals. Examples of such compounds include peroxides (organic peroxides, etc.) and azo compounds. This radical polymerization initiator is appropriately selected depending on the intended connection temperature, connection time, pot life, etc. From the viewpoint of stability, reactivity and compatibility, peroxides with a 1-minute half-life temperature of 90 to 175°C and molecular weights of 180 to 1000 are preferable. “1-minute half-life temperature” refers to the temperature at which the half-life of peroxide is 1 minute. “Half-life” refers to the time until the concentration of a compound decreases to half the initial value at a given temperature. The half-life temperature for 1 minute is the value published in the catalog (Organic Peroxides (10th edition, February 2015)) published by Nichiyu Corporation.

Specific examples of initiators that generate free radicals by heat include diacyl peroxide, peroxydicarbonate, peroxy ester, peroxy ketal, dialkyl peroxide, hydroperoxide, and silyl peroxide.

As a radical polymerization initiator, from the viewpoint of suppressing corrosion of electrodes (circuit electrodes, etc.), an initiator whose concentration of chlorine ions and organic acids contained is 5000 ppm or less is preferable, and an initiator with less organic acid generated after thermal decomposition is more preferable. Specific examples of such initiators include peroxyester, dialkyl peroxide, hydroperoxide, silyl peroxide, etc., and peroxyester is more preferable from the viewpoint of obtaining high reactivity.

As a radical polymerization initiator, for example, 1,1,3,3-tetramethylbutylperoxyneodecanoate, di(4-t-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl) Peroxydicarbonate, cumyl peroxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, dilauroyl peroxide, 1-cyclohexyl-1-methylethylperoxyneo Decanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexa Noate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate , t-butylperoxyneoheptanoate, t-amylperoxy-2-ethylhexanoate, di-t-butylperoxyhexahydroterephthalate, t-amylperoxy-3,5,5-trimethylhexa. Noate, 3-hydroxy-1,1-dimethylbutylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-amylperoxyneodecano ate, t-amylperoxy-2-ethylhexanoate, 3-methylbenzoyl peroxide, 4-methylbenzoyl peroxide, di(3-methylbenzoyl)peroxide, dibenzoyl peroxide, di(4-methylbenzoyl) ) Peroxide, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobis(1-acetoxy-1-phenylethane), 2,2'-azobisisobutyro Nitrile, 2,2'-azobis(2-methylbutyronitrile), dimethyl-2,2'-azobisisobutyronitrile, 4,4'-azobis(4-cyanovaleric acid), 1, 1'-azobis(1-cyclohexanecarbonitrile), t-hexylperoxyisopropylmonocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate , t-butylperoxylaurate, 2,5-dimethyl-2,5-di(3-methylbenzoylperoxy)hexane, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxy Benzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxybenzoate, dibutylperoxytrimethyl adipate, t-amylperoxynormal octoate, t-amylper It is one or more compounds selected from oxyisononanoate and t-amylperoxybenzoate.

An initiator that generates free radicals by light is a compound that is decomposed by light and generates free radicals. As such an initiator, a compound that generates free radicals when irradiated with light with a wavelength of 150 to 750 nm can be used. As such compounds, for example, from the viewpoint of high sensitivity to light irradiation, Photoinitiation, Photopolymerization, and Photocuring, J.-P. The α-acetoaminophenone derivatives and phosphine oxide derivatives described in Fouassier, Hanser Publishers (1995), pages 17 to 35 are preferred.

A radical polymerization initiator may be used individually by 1 type, or may be used in combination of 2 or more types. An initiator, a decomposition accelerator, a decomposition inhibitor, etc. may be used together. Additionally, the initiator may be microencapsulated by coating it with a polyurethane-based or polyester-based polymer material. Microencapsulated initiators are preferred because their pot life is extended.

The content of the radical polymerization initiator is preferably 1 to 15 parts by mass, and more preferably 2.5 to 10 parts by mass, based on 100 parts by mass of the total amount of component (a) and component (b).

(polyurethane beads)

The (d) polyurethane beads used in this embodiment are spherical organic fine particles containing crosslinked urethane resin.

Polyurethane beads can be synthesized by reacting a polyol component and an isocyanate component. Polyols are mainly difunctional, but trifunctional or higher polyols may be used in combination. When trifunctional or more functional substances are used together, the degree of crosslinking of polyurethane beads can be increased.

Examples of the polyol component include polyester polyol, polyether polyol, polycarbonate polyol, acrylic polyol, polyurethane polyol, aromatic polyol (phthalic acid polyol), etc. Among these, polycarbonate polyol or aromatic polyol is preferable in terms of improved hydrolysis resistance. Additionally, as the polyol, a polyfunctional polyol is preferred because it increases the degree of crosslinking of the polyurethane beads and improves elastic recovery. Examples of polyfunctional polyols include trifunctional polycaprolactone-based polyols. The greater the weight average molecular weight of a multifunctional polyol, the higher the flexibility. These can be used individually or in combination of multiple types.

The isocyanate component may be any of yellow-modified, non-yellowing-modified, or egg-yolk-modified. Examples of the isocyanate component include diisocyanate compounds such as aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate. Specifically, for example, 4,4'-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), 3-iso Cyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), etc. can be mentioned. Additionally, as the isocyanate component, an isocyanurate compound (trifunctional) or a urethedione compound (bifunctional) formed from the diisocyanate monomer can be used. Additionally, as the isocyanate component, terminal isocyanate group polyisocyanate (for example, adduct type polyisocyanate, biuret type polyisocyanate, etc.) can also be used. These can be used individually or in combination of multiple types.

The average particle diameter of the polyurethane beads is not particularly limited, but is preferably 50 nm to 10 μm, more preferably 70 nm to 6 μm, and still more preferably 70 nm to 5 μm. Since it may be technically difficult to produce polyurethane beads less than 50 nm, it is preferable that they are 50 nm or more from the viewpoint of ease of availability. In addition, in the case of 10 μm or less, aggregation is unlikely to occur when mixed with other adhesive compositions, and even if aggregation occurs, deterioration of filterability tends to be suppressed. The average particle diameter can be confirmed by, for example, SEM.

The content of polyurethane beads is preferably less than the content of polyurethane resin as component (a). And, based on the total mass of the adhesive components of the adhesive composition, it is preferably 3 to 50% by mass, more preferably 4 to 40% by mass, more preferably 5 to 30% by mass, and 8 to 25% by mass. It is especially preferable that it is mass %. When the content is 3% by mass or more, sufficient adhesive strength tends to be easily obtained, and when the content is 50% by mass or less, there is a tendency to suppress a decrease in the fluidity of the adhesive.

(Non-conductive inorganic particles)

As the non-conductive inorganic fine particles of component (e), known non-conductive inorganic fine particles can be used without particular restrictions. Examples of non-conductive inorganic fine particles include non-conductive inorganic fine particles such as metal oxide fine particles such as silica fine particles, alumina fine particles, silica-alumina fine particles, titania fine particles, and zirconia fine particles. These can be used individually or in combination of two or more types. In addition, in this embodiment, the (e) non-conductive inorganic fine particles do not have conductivity and do not belong to the (f) conductive particles described later.

The average particle diameter of the non-conductive inorganic fine particles is preferably less than 1 μm, and more preferably 0.1 to 0.5 μm. In addition, the average particle diameter referred to here is the mode diameter in the major axis direction when present in the circuit connection material. Moreover, the average primary particle diameter of component (e) is preferably 100 nm or less, and more preferably 10 to 30 nm. In addition, in this specification, the average particle diameter and average primary particle diameter represent values measured by image analysis.

As non-conductive inorganic fine particles, fine particles whose surface has been modified with an organic group can be suitably used because they have excellent dispersibility. Examples of organic groups include dimethylsiloxane group and diphenylsiloxane group.

The content of non-conductive inorganic fine particles is preferably 1 to 30% by mass, more preferably 2 to 25% by mass, and even more preferably 5 to 20% by mass, based on the total mass of the adhesive components. (e) If the content of the component is within the above range, the effect of the present disclosure is more significantly exhibited.

(conductive particle)

The adhesive composition of this embodiment may further contain (f) conductive particles. Constituent materials of the conductive particles include metals such as gold (Au), silver (Ag), nickel (Ni), copper (Cu), solder, and carbon. Additionally, coated conductive particles may be formed by using a non-conductive resin, glass, ceramic, plastic, etc. as the core and covering the core with the metal (metal particles, etc.) or carbon. Covered conductive particles or heat-fused metal particles are preferable because they have deformability by heating and pressurizing, so they eliminate fluctuations in the height of the circuit electrodes when connected, and the contact area with the electrodes increases during connection, thereby improving reliability. do.

From the viewpoint of excellent dispersibility and conductivity, the average particle diameter of the conductive particles is preferably 1 to 30 μm, more preferably 2 to 25 μm, and still more preferably 3 to 20 μm. The average particle diameter of the conductive particles can be measured, for example, using instrumental analysis such as laser diffraction.

From the viewpoint of excellent conductivity, the content of the conductive particles is preferably 0.1 part by volume or more, and more preferably 1 volume part or more with respect to 100 parts by volume of the total volume of the adhesive component of the adhesive composition. The content of the conductive particles is preferably 50 parts by volume or less, and more preferably 20 parts by volume or less, based on the total volume of the adhesive component of the adhesive composition, from the viewpoint of easily suppressing short circuit of electrodes (circuit electrodes, etc.). , 10 volume parts or less is more preferable, 5 volume parts or less is particularly preferable, and 3 volume parts or less is very preferable. From these viewpoints, the content of the conductive particles is preferably 0.1 to 50 parts by volume, more preferably 0.1 to 20 parts by volume, more preferably 1 to 20 parts by volume, particularly preferably 1 to 10 parts by volume, and particularly preferably 1 to 5 parts by volume. Very preferred, with 1 to 3 parts by volume being highly preferred. In addition, the “volume part” is determined based on the volume of each component before curing at 23°C, and the volume of each component can be converted from mass to volume using specific gravity. In addition, the target component can be added to a container containing a measuring cylinder or the like with an appropriate solvent (water, alcohol, etc.) that well wets the target component without dissolving or swelling the target component, and the increased volume can be obtained as the volume of the target component. .

(Silane coupling agent)

The adhesive composition according to this embodiment may contain a silane coupling agent. The silane coupling agent is preferably a compound represented by the following formula (2).

In formula (2), R ¹ , R ² and R ³ each independently represent a hydrogen atom, an alkyl group with 1 to 5 carbon atoms, an alkoxy group with 1 to 5 carbon atoms, an alkoxycarbonyl group with 1 to 5 carbon atoms, or an aryl group. At least one of R ¹ , R ² and R ³ is an alkoxy group. R ⁴ is (meth)acryloyl group, (meth)acryloyloxy group, vinyl group, isocyanate group, imidazole group, mercapto group, amino group which may be substituted with aminoalkyl group, methylamino group, dimethylamino group, benzylamino group, phenyl It represents an amino group, cyclohexylamino group, morpholino group, piperazino group, ureido group, glycidyl group, or glycidoxy group. a represents an integer from 0 to 10.

As the silane coupling agent of formula (2), for example, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3- (meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane.

The content of the silane coupling agent is preferably 0.1 to 10 parts by mass, and more preferably 0.25 to 5 parts by mass, based on 100 parts by mass of the total amount of component (a) and component (b). If the content of the silane coupling agent is 0.1 parts by mass or more, the effect of suppressing peeling at the interface between the circuit member and the circuit connection material and the generation of bubbles tends to be greater, and if the content of the silane coupling agent is 10 parts by mass or less, the adhesive The pot life of the composition tends to be prolonged.

(Other ingredients)

The adhesive composition of this embodiment may contain a polymerization inhibitor, such as hydroquinone and methyl ether hydroquinone, as needed.

The adhesive composition of this embodiment may further contain a homopolymer or copolymer obtained by polymerizing at least one monomer component selected from the group consisting of (meth)acrylic acid, (meth)acrylic acid ester, and acrylonitrile. The adhesive composition of this embodiment preferably contains acrylic rubber, etc., which is a copolymer obtained by polymerizing glycidyl (meth)acrylate having a glycidyl ether group, from the viewpoint of excellent stress relaxation. The weight average molecular weight of the acrylic rubber is preferably 200,000 or more from the viewpoint of increasing the cohesion of the adhesive composition.

The adhesive composition of this embodiment may contain coated fine particles in which the surfaces of the conductive particles are coated with a polymer resin or the like. When such coated fine particles are used in combination with the above-described conductive particles, even when the content of conductive particles increases, short-circuiting due to contact between conductive particles is easily suppressed, and the insulation between adjacent circuit electrodes can be improved. The above-mentioned coated fine particles may be used alone without using conductive particles, or the coated fine particles and conductive particles may be used together. In addition, when the adhesive composition contains coated fine particles, the "adhesive component of the adhesive composition" in this specification means the solid content other than the conductive particles and the coated fine particles in the adhesive composition.

The adhesive composition of this embodiment may contain rubber particles, fillers, softeners, accelerators, anti-aging agents, colorants, flame retardants, thixotropic agents, etc. In addition, the adhesive composition of this embodiment may contain additives such as a thickener, a leveling agent, and a weather resistance improver as appropriate.

The rubber fine particles are preferably particles that have an average particle diameter of 2 times or less than that of the conductive particles and a storage elastic modulus at room temperature of 1/2 or less of the storage elastic modulus at room temperature of the conductive particles and the adhesive composition. In particular, when the material of the rubber particles is silicone, acrylic emulsion, SBR (Styrene-Butadiene Rubber), NBR (Nitril-Butadiene Rubber), or polybutadiene rubber, the rubber particles should be used alone or in a mixture of two or more types. desirable. Three-dimensional crosslinked rubber fine particles have excellent solvent resistance and are easily dispersed in the adhesive composition.

Fillers can improve electrical characteristics (connection reliability, etc.) between circuit electrodes. As the filler, for example, particles having an average particle diameter of 1/2 or less of the average particle diameter of the conductive particles can be suitably used. When non-conductive particles are used in combination with a filler, particles with an average particle diameter smaller than that of the non-conductive particles can be used as the filler. The content of the filler is preferably 0.1 to 60% by mass based on the total amount of adhesive components in the adhesive composition. When the content is 60% by mass or less, the effect of improving connection reliability tends to be more fully achieved. When the content is 0.1% by mass or more, the effect of adding the filler tends to be sufficiently obtained.

The adhesive composition of this embodiment can be used in paste form when it is liquid at room temperature. When the adhesive composition is in a solid state at room temperature, it may be used by heating or may be made into a paste using a solvent. The solvent that can be used is not particularly limited as long as it is not reactive with the components in the adhesive composition and shows sufficient solubility. The solvent is preferably one with a boiling point of 50 to 150°C at normal pressure. If the boiling point is 50°C or higher, the solvent has little volatility at room temperature, so it can be used even in an open system. If the boiling point is 150°C or lower, it is easy to volatilize the solvent, so good reliability is obtained after adhesion.

The adhesive composition of this embodiment may be in a film form. If necessary, an adhesive composition containing a solvent, etc. is applied onto, for example, a fluororesin film, polyethylene terephthalate film, or a peelable substrate (release paper, etc.), and then the solvent, etc. is removed to obtain a film-like adhesive composition. You can. Additionally, a film-like adhesive composition can be obtained by impregnating a substrate such as a non-woven fabric with the solution, placing it on a peelable substrate, and then removing the solvent. When the adhesive composition is used in film form, handling properties, etc. are excellent.

The adhesive composition of this embodiment can be bonded by applying pressure along with heating or light irradiation. By using a combination of heating and light irradiation, bonding can be achieved at a lower temperature and in a shorter time. Light irradiation is preferably irradiated with light in a wavelength range of 150 to 750 nm. As a light source, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp (extra-high pressure mercury lamp, etc.), a xenon lamp, a metal halide lamp, etc. can be used. The irradiation amount may be 0.1 to 10 J/cm2. There is no particular limitation on the heating temperature, but a temperature of 50 to 170°C is preferable. The pressure is not particularly limited as long as it is within a range that does not damage the adherend, but is preferably 0.1 to 10 MPa. Heating and pressurization are preferably performed within the range of 0.5 seconds to 3 hours.

The adhesive composition of this embodiment may be used as an adhesive for the same type of adherend, or may be used as an adhesive for different types of adherends with different thermal expansion coefficients. Specifically, circuit connection materials such as anisotropic conductive adhesive, silver paste, silver film, etc.; It can be used as an elastomer for CSP (Chip Size Package), an underfill material for CSP, and semiconductor device adhesive materials such as LOC (Lead on Chip) tape.

<Structure and its manufacturing method>

The structure of the present embodiment includes the adhesive composition of the present embodiment or a cured product thereof. The structure of this embodiment is, for example, a semiconductor device such as a circuit connection structure. As one form of the structure of this embodiment, the circuit connection structure includes a first circuit member having a first circuit electrode, a second circuit member having a second circuit electrode, and between the first circuit member and the second circuit member. It has an arranged circuit connection member. The first circuit member has, for example, a first substrate and a first circuit electrode disposed on the first substrate. The second circuit member has, for example, a second substrate and a second circuit electrode disposed on the second substrate. The first circuit electrode and the second circuit electrode face each other and are electrically connected. The circuit connection member contains the adhesive composition of this embodiment or its cured product. The structure according to the present embodiment may be provided with the adhesive composition according to the present embodiment or a cured product thereof, and a member (substrate, etc.) without a circuit electrode may be used instead of the circuit member of the circuit connection structure. .

The method for manufacturing the structure of this embodiment includes a step of curing the adhesive composition of this embodiment. As one form of the method of manufacturing the structure of the present embodiment, the method of manufacturing the circuit connection structure includes forming a structure between a first circuit member having a first circuit electrode and a second circuit member having a second circuit electrode. A batch process for arranging the adhesive composition, a heating and pressing process for pressurizing the first circuit member and the second circuit member to electrically connect the first circuit electrode and the second circuit electrode, and heating and curing the adhesive composition. do. In the arrangement process, the first circuit electrode and the second circuit electrode may be arranged to face each other. In the heating and pressing process, the first circuit member and the second circuit member can be pressed in directions opposing each other.

Hereinafter, using the drawings, a circuit connection structure and its manufacturing method will be described as one form of this embodiment. 1 is a schematic cross-sectional view showing one embodiment of a structure. The circuit connection structure 100a shown in FIG. 1 includes a circuit member (first circuit member) 20 and a circuit member (second circuit member) 30 that face each other, and the circuit member 20 and the circuit A circuit connection member 10 is disposed between the members 30 to connect them. The circuit connection member 10 contains a cured product of the adhesive composition of this embodiment.

The circuit member 20 includes a substrate (first substrate) 21 and a circuit electrode (first circuit electrode) 22 disposed on the main surface 21a of the substrate 21. In some cases, an insulating layer (not shown) may be disposed on the main surface 21a of the substrate 21.

The circuit member 30 includes a substrate (second substrate) 31 and a circuit electrode (second circuit electrode) 32 disposed on the main surface 31a of the substrate 31. In some cases, an insulating layer (not shown) may be disposed on the main surface 31a of the substrate 31.

The circuit connection member 10 contains an insulating material (cured product of components excluding conductive particles) 10a and conductive particles 10b. The conductive particles 10b are disposed at least between the circuit electrodes 22 and 32 that face each other. In the circuit connection structure 100a, the circuit electrode 22 and the circuit electrode 32 are electrically connected through the conductive particles 10b.

The circuit members 20 and 30 have one or more circuit electrodes (connection terminals). As the circuit members 20 and 30, for example, members having electrodes that require electrical connection can be used. Circuit members include chip components such as semiconductor chips (IC chips), resistor chips, and condenser chips; Substrates such as printed boards and semiconductor mounting boards can be used. Examples of combinations of the circuit members 20 and 30 include a semiconductor chip and a semiconductor mounting substrate. Examples of substrate materials include inorganic materials such as semiconductors, glass, and ceramics; Organic substances such as polyimide, polyethylene terephthalate, polycarbonate, (meth)acrylic resin, and cyclic olefin resin; A composite of glass, epoxy, etc. can be mentioned. The substrate may be a plastic substrate.

Figure 2 is a schematic cross-sectional view showing another embodiment of the structure. The circuit connection structure 100b shown in FIG. 2 has the same configuration as the circuit connection structure 100a except that the circuit connection member 10 does not contain conductive particles 10b. In the circuit connection structure 100b shown in FIG. 2, the circuit electrode 22 and the circuit electrode 32 are electrically connected by direct contact without conductive particles intervening.

The circuit connection structures 100a and 100b can be manufactured, for example, by the following method. First, when the adhesive composition is in a paste form, a resin layer containing the adhesive composition is disposed on the circuit member 20 by applying and drying the adhesive composition. When the adhesive composition is in the form of a film, a resin layer containing the adhesive composition is disposed on the circuit member 20 by attaching the film-shaped adhesive composition to the circuit member 20 . Subsequently, the circuit member 30 is placed on the resin layer disposed on the circuit member 20 so that the circuit electrodes 22 and 32 are opposed to each other. Then, the adhesive composition is cured by heat treatment or light irradiation on the resin layer containing the adhesive composition, and a cured product (circuit connection member 10) is obtained. As a result, the circuit connection structures 100a and 100b are obtained.

Example

Hereinafter, the present disclosure will be described in more detail through examples and comparative examples. However, the present disclosure is not limited to the following examples.

(Synthesis of polyurethane resin)

In a separable flask equipped with a reflux condenser, thermometer, and stirrer, 1000 parts by mass of polypropylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., number average molecular weight Mn=2000), which is a diol having an ether bond, and methyl ethyl ketone (solvent) ) After adding 4000 parts by mass, the reaction solution was prepared by stirring at 40°C for 30 minutes. After heating the reaction solution to 70°C, 0.0127 parts by mass of dimethyltin laurate (catalyst) was added. Next, a solution prepared by dissolving 125 parts by mass of 4,4'-diphenylmethane diisocyanate in 125 parts by mass of methyl ethyl ketone was added dropwise to this reaction solution over 1 hour. Thereafter, stirring was continued at the above temperature until the absorption peak (2270 cm ^-1 ) derived from the isocyanate group was no longer visible by an infrared spectrophotometer (manufactured by Nippon Bunko Co., Ltd.), and the methyl ethyl ketone solution of polyurethane was prepared. got it Next, the amount of solvent was adjusted so that the solid content concentration (polyurethane concentration) of this solution was 30% by mass. The weight average molecular weight of the obtained polyurethane (polyurethane resin) was 320000 (standard polystyrene conversion value) as a result of measurement by GPC (gel permeation chromatography). GPC measurement conditions are shown in Table 1.

(Synthesis of urethane acrylate)

In a 2L (liter) four-necked flask equipped with a thermometer, stirrer, inert gas inlet, and reflux condenser, 4000 parts by mass of polycarbonate diol (manufactured by Aldrich, number average molecular weight 2000) and 2-hydroxyethyl acrylate. A reaction solution was prepared by adding 238 parts by mass, 0.49 parts by mass of hydroquinone monomethyl ether, and 4.9 parts by mass of a tin-based catalyst. 666 parts by mass of isophorone diisocyanate (IPDI) was uniformly added dropwise to the reaction solution heated to 70°C over 3 hours and allowed to react. After completion of dropwise addition, the reaction was continued for 15 hours, and the point when NCO% (NCO content) became 0.2 mass% or less was considered the completion of the reaction, and urethane acrylate was obtained. NCO% was confirmed using a potentiometric automatic titrator (brand name: AT-510, manufactured by Kyoto Denshi Kogyo Co., Ltd.). As a result of analysis by GPC, the weight average molecular weight of urethane acrylate was 8500 (standard polystyrene conversion value). In addition, the analysis by GPC was performed under the same conditions as the analysis of the weight average molecular weight of the polyurethane resin.

(Production of conductive particles)

A nickel layer with a thickness of 0.2 μm was formed on the surface of the polystyrene particles. Additionally, a gold layer with a thickness of 0.04 μm was formed on the outside of this nickel layer. In this way, conductive particles with an average particle diameter of 4 μm were produced.

[Examples 1 to 7 and Comparative Examples 1 to 4]

(Production of film adhesive)

The components shown in Table 2 were mixed in the mass ratio (solid content) shown in Table 2 to obtain a mixture. The above-mentioned conductive particles were dispersed in this mixture at a ratio of 1.5 parts by volume (standard: ratio with respect to 100 parts by volume of the total volume of the adhesive components of the adhesive composition) to obtain a coating liquid for forming a film-like adhesive. This coating liquid was applied to a polyethylene terephthalate (PET) film with a thickness of 50 μm using a coating device. The coating film was dried with hot air at 70°C for 10 minutes to form a film-like adhesive with a thickness of 18 μm.

In addition, the details of each component shown in Table 2 are as follows.

Polyurethane resin: Polyurethane resin synthesized as described above was used.

Phenoxy resin: 40 g of PKHC (manufactured by Union Carbide Co., Ltd., brand name, weight average molecular weight 45000) was used in the form of a 40% by mass solution prepared by dissolving in 60 g of methyl ethyl ketone.

Radically polymerizable compound A: Urethane acrylate synthesized as described above was used.

Radical polymerizable compound B: Isocyanuric acid EO-modified diacrylate (Product name: M-215, Toagosei Co., Ltd.) was used.

Radically polymerizable compound C (phosphoric acid ester): 2-methacryloyloxyethyl acid phosphate (product name: Light Ester P-2M, manufactured by Kyoesha Chemical Co., Ltd.) was used.

Peroxide (radical polymerization initiator): 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (Product name: Perocta O, manufactured by Nichiyu Co., Ltd., half-life temperature for 1 minute: 124.3°C) used.

Polyurethane beads A: 10 g of P-800T (manufactured by Negami Kogyo Co., Ltd., brand name, average particle diameter: 6 ㎛, glass transition temperature: -34°C) dispersed in 90 g of methyl ethyl ketone, used in the form of a 10 mass% solution. did.

Polyurethane beads B: 10 g of JB-800T (manufactured by Negami Kogyo Co., Ltd., brand name, average particle diameter: 6 μm, glass transition temperature: -52°C) dispersed in 90 g of methyl ethyl ketone, used in the form of a 10 mass% solution. did.

Silica fine particles (non-conductive inorganic fine particles): 10 g of R104 (manufactured by Nippon Aerosil Co., Ltd., brand name) was dispersed in a mixed solvent of toluene (45 g) and ethyl acetate (45 g), and was used in the form of a 10% by mass dispersion.

(Production of connection body)

Using the film adhesives of Examples 1 to 7 and Comparative Examples 1 to 4, a flexible circuit board (FPC) having 2200 copper circuits with a line width of 75 μm, a pitch of 150 μm (space 75 μm), and a thickness of 18 μm was produced. , a glass substrate, and a SiN _x substrate (0.7 mm thick) with a thin layer of silicon nitride (SiN _x ) with a thickness of 0.2 μm formed on the glass substrate. The connection was performed by heating and pressurizing at 170°C and 3 MPa for 5 seconds using a thermal compression device (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.). In this way, a connection body (structure) was produced in which the FPC and the SiN _x substrate were connected by a cured film adhesive over a width of 1.5 mm and a width of 1.0 mm. The pressurizing pressure was calculated based on the pressing area being 0.495 cm 2 for a width of 1.5 mm and 0.330 cm 2 for a width of 1.0 mm.

<Measurement of adhesive strength>

The adhesive strength of the obtained connected body was measured by the 90 degree peeling method according to JIS-Z0237. As a measuring device for adhesive strength, Tensilon UTM-4 (manufactured by Toyo Baldwin Co., Ltd., brand name, peel strength 50 mm/min, 25°C) was used. The results are shown in Table 2.

From Table 2, it was confirmed that the film adhesive of the example had a high adhesive strength (8 N/cm or more) even when connected at a width of 1.0 mm compared to the film adhesive of the comparative example. In the film adhesive of Comparative Example 1, high adhesive strength was obtained when making a 1.5 mm wide connection, but sufficient adhesive strength was not obtained when making a 1.0 mm wide connection. In the film adhesives of Comparative Examples 2 to 4, sufficient adhesive strength was not obtained even when connected at a width of 1.5 mm.

10: Circuit connection member
10a: insulating material
10b: Conductive particles
20: first circuit member
21: first substrate
21a: If you give it to me
22: first circuit electrode
30: second circuit member
31: second substrate
31a: If you give it
32: second circuit electrode
100a, 100b: circuit connection structure

Claims (6)

(a) a thermoplastic resin having a urethane bond,
(b) a radically polymerizable compound,
(c) a radical polymerization initiator,
(d) polyurethane beads,
(e) Non-conductive inorganic particles
Contains,
An adhesive composition in which the radically polymerizable compound includes a radically polymerizable compound having a phosphate ester structure represented by the following general formula (1).

[Wherein, p represents an integer of 1 to 3, and R represents a hydrogen atom or a methyl group.] The adhesive composition according to claim 1, wherein the content of the thermoplastic resin having a urethane bond (a) is greater than or equal to the content of the polyurethane beads (d) on a mass basis. The adhesive composition according to claim 1, further comprising (f) conductive particles. The adhesive composition according to claim 1, for circuit connection. A structure comprising the adhesive composition according to any one of claims 1 to 4 or a cured product thereof. a first circuit member having a first circuit electrode;
a second circuit member having a second circuit electrode;
Provided with a circuit connection member disposed between the first circuit member and the second circuit member,
The first circuit electrode and the second circuit electrode are electrically connected,
A structure in which the circuit connection member contains the adhesive composition according to any one of claims 1 to 4 or a cured product thereof.

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