Connection structure, circuit connection member, and adhesive composition

Abstract

The present application provides a connection structure, a circuit connection member, and an adhesive composition. A connection structure 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 electrically connecting the first circuit electrode and the second circuit electrode to each other, the circuit connection member having a linear thermal expansion amount L(t) at a temperature t satisfying a condition of dL(t) / dt < 0 at at least any one of t = 30°C to 12°C.

Description

[0001] The present application is a divisional application of an application No. 2017800627096, filed on September 21, 2017, entitled "Connection Structure, Circuit Connection Member, and Adhesive Composition". TECHNICAL FIELD

[0002] The present application relates to a connection structure, a circuit connection member, and an adhesive composition. BACKGROUND

[0003] In the past, various adhesives have been used in semiconductor elements and display elements for the purpose of bonding various circuit members in the elements to each other. In addition to adhesiveness, the adhesives are required to have various properties such as heat resistance, reliability in a high-temperature high-humidity state, and the like. In addition, since the circuit members use, for example, printed wiring boards, organic substrates such as polyimide, or metals such as titanium, copper, and aluminum, ITO, IZO, IGZO, SiN, SiO2, and the like having various surface states, the material used for the adhesives needs to be molecularly designed according to the circuit members.

[0004] Recently, amorphous (amorphous) ITO films, organic insulating films, and the like are increasingly used in circuit members for the purpose of simplification and low-temperature processing of manufacturing processes of semiconductor elements and display elements. From the physical viewpoint of less surface irregularities and the like, or the chemical viewpoint of low wettability of the surface, the surfaces of these films are not favorable for adhesion.

[0005] On the other hand, in order to firmly bond the circuit connection member obtained by curing the adhesive to the circuit member, an additive such as a coupling agent is sometimes added to the adhesive, which generates interactions such as covalent bonds, hydrogen bonds, and hydrophobic interactions caused by van der Waals forces between the surface of the circuit connection member and the circuit member. As the coupling agent, a silane coupling agent, a coupling agent having a phosphoric acid group, a carboxyl group, and the like can be used. For example, in the case where a resin constituting the circuit connection member has an organic functional group such as an epoxy group, an acryl group, and a vinyl group, and a coupling agent having an alkoxysilane structure, a phosphoric acid group, and the like that generates interactions between the surface of the circuit member and the circuit connection member is used, the circuit member and the circuit connection member can be more firmly bonded (see Patent Documents 1 to 3).

[0006] PRIOR ART DOCUMENTS

[0007] PATENT DOCUMENTS

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-282637

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2003-277694

[0010] Patent Literature 3: Japanese Patent Application Laid-Open No. 2013-191625 SUMMARY

[0011] PROBLEMS TO BE SOLVED BY THE INVENTION

[0012] However, according to the research by the present inventors and others, in the case of using an additive as described above, there is a problem that, in a high-temperature high-humidity environment, depending on the kind of the circuit member, the interaction between the circuit connecting member and the circuit member cannot effectively function, and the circuit connecting member peels from the circuit member.

[0013] Therefore, an object of the present application is to provide a connection structure body in which peeling of a circuit connecting member from a circuit member is suppressed even in a high-temperature high-humidity environment, and a circuit connecting member and an adhesive composition used for the connection structure body.

[0014] MEANS FOR SOLVING THE PROBLEMS

[0015] The present application provides, in one mode, a connection structure body including: a first circuit member having a first circuit electrode; a second circuit member having a second circuit electrode; and a circuit connecting member provided between the first circuit member and the second circuit member and electrically connecting the first circuit electrode and the second circuit electrode to each other, the circuit connecting member having a linear thermal expansion amount L(t) at temperature t satisfying a condition of dL(t) / dt < 0 at at least any temperature t of t = 30°C to 120°C.

[0016] The present application provides, in another mode, a circuit connecting member having a linear thermal expansion amount L(t) at temperature t satisfying a condition of dL(t) / dt < 0 at at least any temperature t of t = 30°C to 120°C.

[0017] The average linear thermal expansion coefficient of the circuit connecting member at 30°C to 120°C is preferably 500 ppm / °C or less.

[0018] The present application provides, in another mode, an adhesive composition, a cured product of which has a linear thermal expansion amount l(t) at temperature t satisfying a condition of dl(t) / dt < 0 at at least any temperature t of t = 30°C to 120°C.

[0019] The average linear thermal expansion coefficient of the cured product at 30°C to 120°C is preferably 500 ppm / °C or less.

[0020] EFFECTS OF THE INVENTION

[0021] According to the present application, a connection structure body capable of suppressing peeling of a circuit connecting member from a circuit member even in a high-temperature high-humidity environment, and a circuit connecting member and an adhesive composition used for the connection structure body can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic cross-sectional view showing one embodiment of a connection structure body.

[0023] Figure 2 is a graph showing one example of the relationship between temperature and linear thermal expansion amount. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present application will be described in detail. However, the present application is not limited to the following embodiments. "(Meth)acrylic acid" means acrylic acid or methacrylic acid, and the same applies to other similar expressions such as "(meth)acrylate".

[0025] Figure 1 is a schematic cross-sectional view showing one embodiment of a connection structure body. As shown in Figure 1 , the connection structure body 1 is provided with a first circuit member 2, a second circuit member 3, and a circuit connecting member 4 disposed between the first circuit member 2 and the second circuit member 3.

[0026] The first circuit member 2 is provided with a first substrate 5 and a first circuit electrode 6 disposed on a main surface of the first substrate 5. The second circuit member 3 is provided with a second substrate 7 and a second circuit electrode 8 disposed on a main surface of the second substrate 7.

[0027] The first circuit member 2 and the second circuit member 3 can be the same as or different from each other, and can be a chip component such as a semiconductor chip, a resistor chip, or a capacitor chip, a substrate such as a printed substrate, or the like. The first substrate 5 and the second substrate 7 can be formed of an inorganic material such as a semiconductor, glass, or ceramic, an organic material such as polyimide or polycarbonate, a composite such as glass / epoxy, or the like. The first circuit electrode 6 and the second circuit electrode 8 can be formed of gold, silver, tin, ruthenium, rhodium, palladium, osmium, indium, platinum, crystalline or amorphous indium tin oxide (ITO), or the like.

[0028] A plurality of circuit electrodes 6, 8 (may be singular depending on the case) are generally provided on the substrates 5, 7 of the circuit members 2, 3. The first circuit member 2 and the second circuit member 3 are arranged so that at least one pair of the first circuit electrode 6 and the second circuit electrode 8 face each other.

[0029] The circuit connecting member 4 contains a cured product 9 of an adhesive component, and electrically conductive particles 10 dispersed in the cured product 9 of the adhesive component. The first circuit electrode 6 and the second circuit electrode 8 are electrically connected to each other via the electrically conductive particles 10 in the circuit connecting member 4 interposed between the first circuit electrode 6 and the second circuit electrode 8 facing each other.

[0030] The circuit connecting member 4 is a circuit connecting member in which the linear thermal expansion amount L(t) pm of the circuit connecting member 4 at a temperature t°C satisfies the condition of dL(t) / dt < 0 at at least any temperature t of t = 30°C to 120°C from the viewpoint of suppressing peeling of the circuit connecting member 4 from the circuit members 2, 3 and the circuit electrodes 6, 8.

[0031] The linear thermal expansion amount L(t) of the circuit connecting member 4 is determined as follows: using a thermal mechanical analysis device, under the conditions of a length 10 mm, a width 4 mm, and a thickness 0.1 mm of a sample, a load 5 gf (0.4 mm 2 The linear thermal expansion amount at a temperature t°C is determined every 0.1°C when the linear thermal expansion amount at a temperature t = 0°C is set to L(0) = 0 pm. The linear thermal expansion amount here refers to the linear thermal expansion amount in the length direction of the sample.

[0032] The linear thermal expansion amount L(t) of the circuit connecting member 4 satisfies the condition of dL(t) / dt < 0 at at least any temperature t of t = 30°C to 120°C, preferably the condition of dL(t) / dt < -0.01, more preferably dL(t) / dt < -0.1, and further preferably dL(t) / dt < -0.5, from the viewpoint of suppressing peeling of the circuit connecting member 4 from the circuit members 2, 3 and the circuit electrodes 6, 8.

[0033] The linear thermal expansion amount L(t) of the circuit connecting member 4 satisfies the condition of dL(t) / dt at at least any temperature t of preferably t = 30°C to 100°C, more preferably t = 30°C to 90°C, and further preferably t = 30°C to 80°C, from the viewpoint of suppressing peeling of the circuit connecting member 4 from the circuit members 2, 3 and the circuit electrodes 6, 8.

[0034] The average linear thermal expansion coefficient of the circuit connecting member 4 at 30°C to 120°C is preferably less than or equal to 500 ppm / °C, more preferably less than or equal to 250 ppm / °C, and further preferably less than or equal to 150 ppm / °C, from the viewpoint of suppressing peeling of the circuit connecting member 4 from the circuit members 2, 3 and the circuit electrodes 6, 8.

[0035] The linear thermal expansion coefficient (ppm / °C) of the circuit connecting member 4 is defined as the linear thermal expansion amount (μm) of a 1 m length of the circuit connecting member 4 per 1 °C rise in temperature. The average linear thermal expansion coefficient α of the circuit connecting member 4 at 30°C to 120°C L is calculated as follows: the change in the linear thermal expansion amount L(t) [unit: μm / 10 mm] of the circuit connecting member 4 at t = 30°C to 120°C, which is measured by the above method, is converted into the linear thermal expansion amount (μm) of a 1 m length of the circuit connecting member 4, and the average value per 1 °C rise in temperature is calculated from this converted value (i.e., calculated according to the following equation).

[0036] α L = {L(t = 120°C) - L(t = 30°C)} x 100 / (120 - 30)

[0037] The cured product 9 of the adhesive component and the electrically conductive particles 10 that constitute the circuit connecting member 4 are selected in such a manner that the circuit connecting member 4 has the above-described properties. The circuit connecting member 4 is obtained, for example, by curing an adhesive composition containing the adhesive component and the electrically conductive particles 10. From the viewpoint of suppressing peeling of the circuit connecting member 4 from the circuit members 2, 3 and the circuit electrodes 6, 8, the adhesive composition is preferably an adhesive composition whose cured product satisfies the condition that the linear thermal expansion amount l(t) of the cured product of the adhesive composition at temperature t satisfies dl(t) / dt < 0 at at least any temperature t from t = 30°C to 120°C. The cured product of the adhesive composition can be, for example, a cured product obtained by molding the adhesive composition into a film-shaped adhesive having a thickness of 100 ± 20 μm and curing the film-shaped adhesive by heating it at 180°C for 1 hour.

[0038] The linear thermal expansion amount l(t) of the cured product of the adhesive composition is measured as follows: using a thermal mechanical analysis device, under the conditions that the length, width and thickness of the sample are 10 mm, 4 mm and 0.1 mm, respectively, the load is 5 gf (cross-sectional area of the sample per 0.4 mm 2 at t = 0°C is set to l(0) = 0 μm, and the linear thermal expansion amount (μm) at temperature t°C is measured every 0.1 °C in the temperature range from t = 0°C to 200°C. The linear thermal expansion amount here refers to the linear thermal expansion amount in the length direction of the sample.

[0039] From the viewpoint of suppressing peeling of the cured product of the adhesive composition (circuit connecting member 4) from the circuit members 2, 3 and the circuit electrodes 6, 8, the linear thermal expansion amount l(t) of the cured product of the adhesive composition satisfies the condition that dl(t) / dt ≤ -0.01, more preferably dl(t) / dt ≤ -0.1, and further preferably dl(t) / dt ≤ -0.5 at at least any temperature t from t = 30°C to 120°C.

[0040] From the viewpoint of suppressing peeling of the cured product of the adhesive composition (circuit connecting member 4) from the circuit members 2, 3 and the circuit electrodes 6, 8, the linear thermal expansion amount l(t) of the cured product of the adhesive composition at at least any one temperature t of t = 30 to 100°C, more preferably t = 30 to 90°C, further preferably t = 30 to 80°C satisfies the condition of dl(t) / dt described above.

[0041] From the viewpoint of suppressing peeling of the cured product of the adhesive composition (circuit connecting member 4) from the circuit members 2, 3 and the circuit electrodes 6, 8, the average linear thermal expansion coefficient of the cured product of the adhesive composition at 30 to 120°C is preferably 500 ppm / °C or less, more preferably 250 ppm / °C or less, further preferably 150 ppm / °C or less.

[0042] The linear thermal expansion coefficient (ppm / °C) of the cured product of the adhesive composition is defined as the linear thermal expansion amount (pm) of 1 m length of the cured product of the adhesive composition per 1°C rise in temperature. The average linear thermal expansion coefficient a of the cured product of the adhesive composition at 30 to 120°C is calculated from the linear thermal expansion amount l(t) of the cured product of the adhesive composition at t = 30 to 120°C [unit: pm / 10 mm] measured by the above method. l The average value per 1°C rise in temperature is calculated from the change amount of the linear thermal expansion amount l(t) of the cured product of the adhesive composition at t = 30 to 120°C [unit: pm / 10 mm] measured by the above method, converted to the linear thermal expansion amount (pm) of 1 m length of the cured product of the adhesive composition, from this converted value.

[0043] a = {l(t = 120°C) - l(t = 30°C)} x 100 / (120 - 30) l = {l(t = 120°C) - l(t = 30°C)} x 100 / (120 - 30)

[0044] The adhesive composition having such properties contains, for example, two or more kinds of resin components having mutually different glass transition temperatures (Tg), components that easily generate phase separation from each other, components having a skeleton that easily orient, a filler component having a negative linear thermal expansion coefficient, and the like. As the combination of components that easily generate phase separation from each other, combinations of components having a large difference in molecular weight from each other, combinations of components having a large difference in polarity from each other, and the like can be given. The combination of components that easily generate phase separation from each other can be, specifically, a combination of an acrylic resin and an epoxy resin, a combination of a polyurethane resin and a phenoxy resin, a combination of an acrylic rubber and a phenoxy resin, a combination of an acrylic rubber and an epoxy resin, and the like. As the component having a skeleton that easily orient, components containing an alkyl chain, components containing a phenyl group, and the like can be given. The present inventors and the like believe that, by the adhesive composition containing the components as described above, in the cured product (circuit connection member 4) of the obtained adhesive composition, shrinkage (volume phenomenon) accompanying temperature rise occurs due to the reduction of minute voids, the re-orientation of molecular chains, the re-arrangement of filler components, and the like caused by temperature rise.

[0045] The adhesive composition preferably contains, in one embodiment, (a) a thermoplastic resin (hereinafter also referred to as "(a) component"), (b) a radically polymerizable compound (hereinafter also referred to as "(b) component"), and (c) a radical polymerization initiator (hereinafter also referred to as "(c) component").

[0046] As the (a) component, there is no particular limitation, and, for example, one or two or more kinds of resin selected from among a polyimide resin, a polyamide resin, a phenoxy resin, a poly(meth)acrylic resin, a polyester resin, a polyurethane resin, a polyester polyurethane resin, and a polyvinyl butyral resin can be given.

[0047] From the viewpoint of easily obtaining a cured product (circuit connection member 4) of the adhesive composition having a desired linear thermal expansion amount, the adhesive composition preferably contains two or more kinds of the above-described thermoplastic resins, and more preferably contains two or more kinds of thermoplastic resins having different Tg from each other. As a suitable combination of resins, for example, combinations of a phenoxy resin and a poly(meth)acrylic resin, a phenoxy resin and a polyester resin, a phenoxy resin and a polyester polyurethane resin, and a phenoxy resin and a polyimide resin can be given.

[0048] In the case where the adhesive composition contains two or more kinds of thermoplastic resins having different Tgs, the ratio of the content (mass ratio: high Tg / low Tg) of the thermoplastic resin having a higher Tg to the thermoplastic resin having a lower Tg is preferably 90 / 10 to 10 / 90, more preferably 90 / 10 to 20 / 80, and further preferably 90 / 10 to 30 / 70, from the viewpoint of easily obtaining a cured product (circuit connection member 4) of the adhesive composition having a desired linear thermal expansion amount. In the case where the adhesive composition contains three or more kinds of thermoplastic resins having different Tgs, the adhesive composition preferably contains the thermoplastic resin having the highest Tg and the thermoplastic resin having the lowest Tg in the above-mentioned ratio.

[0049] The weight average molecular weight of the thermoplastic resin is preferably greater than or equal to 5,000, more preferably greater than or equal to 10,000, and is preferably less than or equal to 400,000, more preferably less than or equal to 200,000, and further preferably less than or equal to 150,000. If the weight average molecular weight of the thermoplastic resin is greater than or equal to 5,000, there is a tendency that the adhesive force of the adhesive composition increases. If the weight average molecular weight of the thermoplastic resin is less than or equal to 400,000, there is a tendency that the compatibility with other components is excellent and the flowability of the adhesive increases. The weight average molecular weight in the present application refers to the weight average molecular weight (standard polystyrene conversion value) measured by GPC (gel permeation chromatography).

[0050] The adhesive composition can also contain a rubber component as the thermoplastic resin from the viewpoint of further improving stress relaxation and adhesiveness. Examples of the rubber component include silicone rubber, acrylic rubber, polyisoprene rubber, polybutadiene rubber, carboxyl-terminated polybutadiene rubber, hydroxyl-terminated polybutadiene rubber, 1,2-polybutadiene rubber, carboxyl-terminated 1,2-polybutadiene rubber, hydroxyl-terminated 1,2-polybutadiene rubber, styrene-butadiene rubber, hydroxyl-terminated styrene-butadiene rubber, acrylonitrile-butadiene rubber, carboxylated nitrile rubber, hydroxyl-terminated poly(oxypropylene) rubber, alkoxysilyl-terminated poly(oxypropylene) rubber, poly(oxytetramethylene) glycol rubber, polyolefin glycol rubber, and poly-ε-caprolactone rubber. The rubber component preferably has a cyano group or a carboxyl group as a side chain group or a terminal group as a highly polar group from the viewpoint of further improving adhesiveness. These rubber components can be used alone or in combination of two or more kinds.

[0051] The rubber component can also be formed into particles. The average particle diameter of the rubber particles is preferably 2 times or less the average particle diameter of the electrically conductive particles 10, for example, 0.01 to 100 μm. The storage modulus of the rubber particles at room temperature (25°C) is preferably 1 / 2 or less the storage modulus of the electrically conductive particles 10 and the adhesive composition at room temperature, for example, 0.1 to 100 MPa. From the viewpoint of excellent solvent resistance and easy dispersion in the adhesive composition, the rubber particles are preferably three-dimensionally crosslinked rubber particles.

[0052] The content of the (a) component is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and further preferably 35 parts by mass or more, and is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and further preferably 65 parts by mass or less, relative to 100 parts by mass of the total amount of the (a) component and the (b) component. If the content of the (a) component is 20 parts by mass or more, there is a tendency for the adhesive force to further increase and for the film formability of the adhesive composition to improve, and if the content is 80 parts by mass or less, there is a tendency for the flowability of the adhesive to improve.

[0053] The (b) component is not particularly limited and can be, for example, the compounds (monomers) described below, or can be an oligomer of the compounds, or can contain both.

[0054] The (b) component is preferably a multifunctional (meth)acrylate compound having two or more (meth)acryloyloxy groups. As such (meth)acrylate compounds, there can be mentioned epoxy (meth)acrylates, urethane (meth)acrylates, polyether (meth)acrylates, polyester (meth)acrylates, trimethylolpropane tri(meth)acrylate, polyethylene glycol di(meth)acrylate and the like polyalkylene glycol di(meth)acrylates; dicyclopentenyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, neopentyl glycol di(meth)acrylate, dipentaerythritol hexa(meth)acrylate, isocyanurate-modified difunctional (meth)acrylate, isocyanurate-modified trifunctional (meth)acrylate and the like. As epoxy (meth)acrylates, there can be mentioned epoxy (meth)acrylates obtained by adding (meth)acrylic acid to both glycidyl groups of a bisphenol fluorene diglycidyl ether, compounds obtained by introducing a (meth)acryloyloxy group into a compound obtained by adding ethylene glycol and / or propylene glycol to both glycidyl groups of a bisphenol fluorene diglycidyl ether, and the like. Of these (meth)acrylate compounds, from the viewpoint of obtaining better adhesiveness by having a urethane bond, it is preferable to use a urethane (meth)acrylate. These compounds can be used singly or in combination of two or more.

[0055] From the viewpoint of adjustment of fluidity or the like, the adhesive composition can contain a monofunctional (meth)acrylate compound as the (b) component. As the monofunctional (meth)acrylate compound, for example, pentaerythritol (meth)acrylate, 2-cyanoethyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-hexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, isobornyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, n-dodecyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-(meth)acryloyloxyethyl phosphate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, a glycidyl group-containing (meth)acrylate obtained by reacting (meth)acrylic acid with one glycidyl group of an epoxy resin having a plurality of glycidyl groups, and (meth)acryloyl morpholine can be exemplified. These compounds can be used alone or in combination of two or more.

[0056] From the viewpoint of increasing the crosslinking rate or the like, the adhesive composition can contain a compound having a radical-polymerizable functional group such as an allyl group, a maleimide group, or a vinyl group as the (b) component. As such a compound, for example, N-vinylimidazole, N-vinylpyridine, N-vinylpyrrolidone, N-vinylformamide, N-vinylcaprolactam, 4,4'-vinylenebis(N,N-dimethyl aniline), N-vinylacetamide, N,N-dimethylacrylamide, N-isopropylacrylamide, and N,N-diethylacrylamide can be exemplified.

[0057] In order to increase the adhesive force, the adhesive composition preferably contains a radical-polymerizable compound having a phosphate ester structure as the (b) component. The radical-polymerizable compound having a phosphate ester structure can be, for example, a compound represented by the following formula (1), (2), or (3).

[0058] [Chemical Formula 1]

[0059]

[0060] In formula (1), R 1 represents a hydrogen atom or a methyl group, R 2 represents a (meth)acryloyloxy group, and a and b each independently represent an integer of 1 to 8. The plurality of R 1 , R 2, a and b can be the same or different from each other.

[0061] [Chemical Formula 2]

[0062]

[0063] In formula (2), R 3 represents a (meth)acryloyloxy group, c and d each independently represent an integer of 1 to 8. A plurality of R 3 , c and d can be the same or different from each other.

[0064] [Chemical Formula 3]

[0065]

[0066] In formula (3), R 4 represents a hydrogen atom or a methyl group, R 5 represents a (meth)acryloyloxy group, e and f each independently represent an integer of 1 to 8. A plurality of R 4 , R 4 , e and f can be the same or different from each other.

[0067] As the radical polymerizable compound having a phosphate structure, for example, (meth)acrylic acid phosphoacryloxyethyl ester, (meth)acrylic acid phosphoacryloxypropyl ester, phosphoacryloxy polyoxyethylene glycol mono(meth)acrylate, phosphoacryloxy polyoxypropylene glycol mono(meth)acrylate, phosphoric acid 2,2'-di(meth)acryloyloxydiethyl ester, EO (ethylene oxide) modified phosphoric acid di(meth)acrylate, phosphoric acid modified epoxy (meth)acrylate, and phosphoric acid vinyl ester can be exemplified.

[0068] The content of the (b) component in the adhesive composition is preferably greater than or equal to 20 parts by mass, more preferably greater than or equal to 30 parts by mass, further preferably greater than or equal to 35 parts by mass, and in addition, is preferably less than or equal to 80 parts by mass, more preferably less than or equal to 70 parts by mass, further preferably less than or equal to 65 parts by mass, relative to 100 parts by mass of the total amount of the (a) component and the (b) component. If the content of the (b) component is greater than or equal to 20 parts by mass, there is a tendency that the heat resistance of the cured product of the adhesive composition (circuit connection member 4) is improved, and if it is less than or equal to 80 parts by mass, there is a tendency that the peeling of the circuit connection member 4 under a high-temperature high-humidity environment can be further suppressed.

[0069] In the case where the adhesive composition contains the radical polymerizable compound having a phosphate structure as the (b) component, the content of the radical polymerizable compound having a phosphate structure is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, with respect to 100 parts by mass of the total amount of the (a) component and the (b) component. If the content of the radical polymerizable compound having a phosphate structure is 0.1 parts by mass or more, there is a tendency that the adhesive strength of the adhesive composition further increases, and if it is 15 parts by mass or less, there is a tendency that the reliability is improved without easily causing a decrease in the physical properties of the cured product (circuit connecting member 4) of the adhesive composition.

[0070] As the (c) component, for example, a compound such as a peroxide and an azo compound can be arbitrarily selected. As the (c) component, from the viewpoints of stability, reactivity, and excellent compatibility, it is preferable to use a peroxide having a 1-minute half-life temperature of 90°C to 175°C and a molecular weight of 180 to 1000. The "1-minute half-life temperature" refers to the temperature at which the half-life of the peroxide is 1 minute. The "half-life" refers to the time until the concentration of the compound decreases to half the initial value at a predetermined temperature.

[0071] The radical polymerization initiator can be, for example, one or more compounds selected from the group consisting of 1,1,3,3-tetramethylbutyl peroxyneodecanoate, di(4-tert-butylcyclohexyl) peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, cumyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, dilauroyl peroxide, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, tert-hexyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, tert-hexyl peroxy-2-ethylhexanoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyneoheptanoate, tert-amyl peroxy-2-ethylhexanoate, di-tert-butyl peroxyhexahydroterephthalate, tert-amyl peroxy-3,5,5-trimethylhexanoate, 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, tert-amyl peroxyneodecanoate, tert-amyl peroxy-2-ethylhexanoate, 3-methylbenzoyl peroxide, 4-methylbenzoyl peroxide, di(3-methylbenzoyl) peroxide, dibenzoyl peroxide, di(4-methylbenzoyl) peroxide, 2,2'-azobis-2,4-dimethylpentane, 1,1'-azobis(1-acetoxy-1-phenylethane), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), dimethyl-2,2'-azobisisobutyronitrile, 4,4'-azobis(4-cyanopentanoic acid), 1,1'-azobis(1-cyclohexanecarbonitrile), tert-hexyl monoperoxycaproate, tert-butyl peroxy maleate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxy laurate, 2,5-dimethyl-2,5-di(3-methylbenzoylperoxy)hexane, tert-butyl peroxy-2-ethylhexyl monocarbonate, tert-hexyl peroxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butyl peroxybenzoate, dimethyl peroxytrimethyladipate, tert-amyl peroxy-n-octanoate, tert-amyl peroxyisononanoate, and tert-amyl peroxybenzoate.

[0072] From the viewpoint of suppressing corrosion of the suppressor circuit electrodes 6, 8, the content of chloride ions or organic acids in the radical polymerization initiator is preferably 5000 ppm or less, and more preferably a radical polymerization initiator that generates little organic acid upon decomposition is used. From the viewpoint of improving the stability of the adhesive composition, a radical polymerization initiator that retains 20% by mass or more of the mass after being left in the atmosphere at room temperature (25°C) and at atmospheric pressure for 24 hours is preferably used.

[0073] The content of the (c) component in the adhesive composition is preferably greater than or equal to 1 part by mass, more preferably greater than or equal to 2.5 parts by mass, and in addition, preferably less than or equal to 15 parts by mass, more preferably less than or equal to 10 parts by mass, relative to 100 parts by mass of the total amount of the (a) component and the (b) component.

[0074] The adhesive composition in another embodiment preferably contains: (a) a thermoplastic resin, (d) an epoxy resin (hereinafter also referred to as "(d) component"), and (e) a curing agent (hereinafter also referred to as "(e) component"). The (a) component in the present embodiment is the same component as the (a) component described in the above-described embodiment.

[0075] The (d) epoxy resin is a resin having at least one epoxy group in the molecule. As the epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol F novolak type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, aliphatic chain type epoxy resin, and the like can be exemplified. The (d) epoxy resin can be a halogenated epoxy resin obtained by halogenating the above-described epoxy resin, or a hydrogenated epoxy resin obtained by hydrogenating the above-described epoxy resin. These epoxy resins, halogenated epoxy resins, and hydrogenated epoxy resins can be used alone or in combination of two or more.

[0076] The content of the (d) component in the adhesive composition is preferably greater than or equal to 10 parts by mass, more preferably greater than or equal to 20 parts by mass, further preferably greater than or equal to 30 parts by mass, and in addition, preferably less than or equal to 90 parts by mass, more preferably less than or equal to 80 parts by mass, further preferably less than or equal to 70 parts by mass, relative to 100 parts by mass of the total amount of the (a) component and the (d) component. If the content of the (d) component is greater than or equal to 10 parts by mass, there is a tendency that more excellent adhesiveness can be obtained, and if it is less than or equal to 90 parts by mass, there is a tendency that tackiness is less and workability is improved.

[0077] The (e) curing agent (also referred to as "epoxy polymerization initiator" or "latent type curing agent") is only required to be a curing agent capable of curing the (d) epoxy resin. As the curing agent, a catalyst type curing agent of anionic polymerizability, a catalyst type curing agent of cationic polymerizability, an addition polymerization type curing agent, and the like can be exemplified. They can be used alone or in combination of two or more. From the viewpoint of excellent rapid curing property and not requiring consideration of chemical equivalent, the (e) curing agent is preferably a catalyst type curing agent of anionic polymerizability or cationic polymerizability.

[0078] As the catalyst-type curing agent of an anionic polymerization or a cationic polymerization, there can be mentioned: an imidazole-based curing agent, a hydrazide-based curing agent, a boron trifluoride-amine complex, a sulfonium salt, an onium salt such as a diazonium salt, an amine imide, a diaminomaleonitrile, a melamine and its derivatives, a salt of a polyamine, dicyandiamide, and the like, and modified products thereof can also be used.

[0079] In the case where a compound having a tertiary amino group, an imidazole compound, or the like is used as the catalyst-type curing agent of an anionic polymerization, the epoxy resin is cured by heating at a temperature of 160°C to 200°C for several tens of seconds to several hours. Thus, the pot life of the adhesive composition can be made longer. As the catalyst-type curing agent of a cationic polymerization, for example, a photosensitive onium salt (aromatic diazonium salt, aromatic sulfonium salt, or the like) that cures an epoxy resin by irradiation of energy rays is preferably used. As the catalyst-type curing agent of a cationic polymerization that is activated by heating and cures an epoxy resin, there can be mentioned an aliphatic sulfonium salt, or the like. From the aspect of having a rapid curing property, it is preferable to use these catalyst-type curing agents of an anionic polymerization or a cationic polymerization.

[0080] As the addition polymerization-type curing agent, there can be mentioned a polyamine, a polythiol, a polyphenol, an acid anhydride, and the like.

[0081] From the aspect of obtaining a longer pot life, it is preferable to use a microcapsule-type curing agent in which these curing agents (latent curing agents) are coated with a high molecular compound such as a polyurethane or a polyester, a metal thin film of nickel, copper, or the like, an inorganic substance such as calcium silicate, or the like, and microcapsulated.

[0082] The content of the component (e) in the adhesive composition is preferably greater than or equal to 20 parts by mass, more preferably greater than or equal to 30 parts by mass, and, in addition, preferably less than or equal to 80 parts by mass, more preferably less than or equal to 70 parts by mass, relative to 100 parts by mass of the total amount of the components (a) and (d).

[0083] As the conductive particles 10, metal particles such as Au, Ag, Ni, Cu, and solder; and conductive carbon particles can be given. The conductive particles 10 can be coated conductive particles having a core including non-conductive particles of glass, ceramic, plastic, or the like, and a layer covering the core and composed of the above metal, metal particles, conductive carbon particles, or the like. In the case where the conductive particles 10 are coated conductive particles or metal particles that melt by heat (hot-melt metal particles), the conductive particles 10 are deformed due to heating and pressurization at the time of connection of the circuit, and thus the contact area of the conductive particles 10 with the circuit electrodes 6, 8 increases even if there is a difference in the height of the circuit electrodes 6, 8, and thus good reliability can be obtained. In particular, in the case where the amount of the conductive particles 10 is increased, from the viewpoint of preventing short-circuiting between the conductive particles 10, and improving the insulation between adjacent first circuit electrodes 6, 6 or between adjacent second circuit electrodes 8, 8, the conductive particles 10 can be insulated coated conductive particles having the above conductive particles, and an insulating coating layer formed of an insulating material such as a polymer resin, covering the surface of the conductive particles. These conductive particles, coated conductive particles, and insulated coated conductive particles can be used alone or in combination of two or more.

[0084] The average particle diameter of the conductive particles 10 is preferably 1 μm to 50 μm from the viewpoints of dispersibility and conductivity. The content of the conductive particles is preferably 0.1% by volume or more, and more preferably 30% by volume or less, and even more preferably 10% by volume or less, based on the total amount of the adhesive composition. If the content is 0.1% by volume or more, there is a tendency to further improve the conductivity, and if the content is 30% by volume or less, there is a tendency to be able to suppress short-circuiting between adjacent first circuit electrodes 6, 6 or between adjacent second circuit electrodes 8, 8. The content of the conductive particles 10 is determined based on the volume of each component of the adhesive composition (before curing) at 23°C. The volume of each component can be, for example, a value obtained by converting the weight to volume using the specific gravity. Alternatively, for example, a suitable solvent (water, alcohol, or the like) that does not dissolve or swell the component can be added to a graduated cylinder or the like to sufficiently wet the component, the component can be added thereto, and the added volume can be taken as the volume of the component.

[0085] In addition to the (a) component, the (b) component, the (c) component, and the conductive particles 10, or the (a) component, the (d) component, the (e) component, and the conductive particles 10, the adhesive composition can further contain other resins such as phenol resin and melamine resin, fillers (filling agents), softening agents, curing accelerators, anti-aging agents, coloring agents, flame retardants, thixotropic agents, coupling agents, and the like, adhesion improvers, thickening agents, leveling agents, weather resistance improvers, isocyanate compounds, and the like.

[0086] The filler (filler) can be a particle composed of silicon, calcium, zirconium, titanium, aluminum, carbon, bismuth, cobalt, copper, iron, indium, manganese, tin, yttrium, zinc, or a compound containing the same, an organic compound, or the like. The average particle diameter of the particle is preferably 1 / 2 or less of the average particle diameter of the electrically conductive particle 10, for example, 0.005 μm to 25 μm. In the case where the adhesive composition contains a particle (for example, the above-described rubber particle) that does not have electrical conductivity, the average particle diameter of the particle used as the filler can be 1 / 2 or less of the average particle diameter of the particle that does not have electrical conductivity.

[0087] From the viewpoint of further improving the connection reliability between the circuit electrodes 6, 8 and the like, and the electrical characteristics of the cured product (circuit connecting member 4) of the adhesive composition having the desired linear thermal expansion amount, the filler is preferably a filler having a negative average linear thermal expansion coefficient at 30°C to 120°C. As the filler having a negative average linear thermal expansion coefficient at 30°C to 120°C, for example, a particle composed of a zirconium-based compound can be listed.

[0088] The content of the filler is preferably greater than or equal to 5 parts by mass and less than or equal to 60 parts by mass with respect to 100 parts by mass of the adhesive composition. If the content is less than or equal to 60 parts by mass, there is a tendency that the effect of improving the connection reliability can be more sufficiently obtained, and if the content is greater than or equal to 5 parts by mass, there is a tendency that the effect of adding the filler can be sufficiently obtained.

[0089] The coupling agent can be, for example, a silane coupling agent. By using the coupling agent such as a silane coupling agent, the adhesion of the adhesive composition can be further improved. As the silane coupling agent, for example, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, and a condensate thereof can be listed.

[0090] The content of the coupling agent is preferably greater than or equal to 0.1 parts by mass, more preferably greater than or equal to 0.25 parts by mass, and, in addition, preferably less than or equal to 10 parts by mass, more preferably less than or equal to 5 parts by mass, relative to 100 parts by mass of the adhesive components (for example, components (a) to (e)) of the adhesive composition. If the content of the coupling agent is greater than or equal to 0.1 parts by mass, there is a tendency to further inhibit peeling of the circuit member from the circuit connection member. If the content of the coupling agent is less than or equal to 10 parts by mass, there is a tendency for the usable time of the adhesive composition to be longer.

[0091] In the case where the adhesive composition is liquid at 15°C to 25°C, for example, the adhesive composition can be used as a paste-like adhesive composition. In the case where the adhesive composition is solid at room temperature (25°C), the adhesive composition can be used as a paste-like adhesive composition by heating or dissolving in a solvent. As the solvent, there is no particular limitation as long as it is a solvent that has no reactivity with the components contained in the adhesive composition and the components contained in the adhesive composition exhibit sufficient solubility, and a solvent having a boiling point of 50°C to 150°C at atmospheric pressure is preferably used. In the case where the boiling point is greater than or equal to 50°C, the solvent can be inhibited from volatilizing at room temperature (25°C), and use in an open system becomes easy. In the case where the boiling point is less than or equal to 150°C, the solvent can be easily volatilized after the adhesive composition is applied to the circuit members 2 and 3, and reliability after adhesion can be ensured.

[0092] The adhesive composition can also be used as a film-like adhesive. The adhesive composition is, for example, a solution obtained by adding a solvent or the like to the adhesive composition as needed, which is coated on a release substrate such as a fluororesin film, a polyethylene terephthalate film, a release paper, or the like, or is impregnated in a substrate such as a nonwoven fabric, and then is placed on a release substrate, and then the solvent or the like is removed to be shaped into a film. From the viewpoint of workability and the like, a film-like adhesive is suitably used.

[0093] The adhesive composition can be used as a circuit connection material typified by an anisotropic conductive adhesive, a silver paste, a silver film, and the like, and a semiconductor element adhesive material typified by an elastomer for CSP, an underfill material for CSP, an LOC tape, and the like.

[0094] The connection structure 1 can be obtained, for example, by arranging the first circuit member 2 and the second circuit member 3 so that the first circuit electrode 6 and the second circuit electrode 8 face each other, interposing a film-like adhesive between the first circuit member 2 and the second circuit member 3, and heating and pressing them to electrically connect the first circuit electrode 6 and the second circuit electrode 8 to each other.

[0095] The heating temperature at the time of heating is not particularly limited, and is preferably 50°C to 250°C. The pressure at the time of pressure application is not particularly limited as long as it is within a range that does not cause damage to the adherends (circuit members 2, 3), and is preferably 0.1 MPa to 10 MPa. The heating and pressure application are preferably performed for 0.5 seconds to 3 hours.

[0096] When the circuit members 2, 3 are connected to each other, light irradiation can be performed at the same time as the heating and pressure application from the viewpoint of performing the connection at a lower temperature and for a shorter time. The light irradiation preferably uses irradiation light in the wavelength region of 150 nm to 750 nm. The light irradiation can be performed, for example, using a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, or a metal halide lamp, at an irradiation amount of 0.1 J / cm 2 to 10 J / cm 2 .

[0097] The cured product of the adhesive composition (circuit connection member 4) as described above is, for example, as shown in L1 in Figure 2 , a cured product (circuit connection member) in which dl(t) / dt < 0 (dL(t) / dt < 0) at a temperature t = 30°C to 120°C, and thus the amount of thermal expansion of the circuit connection member 4 itself accompanying a temperature increase can be reduced, and the peeling interfacial stress (stress that wants to peel the circuit connection member 4 from the substrates 5, 7 and the circuit electrodes 6, 8) generated at the interface of the circuit connection member 4 with the substrates 5, 7 and the circuit electrodes 6, 8 can be reduced.

[0098] On the other hand, the cured product of the conventional adhesive composition (circuit connection member) is, for example, as shown in L2 in Figure 2 , a cured product (circuit connection member) in which dl(t) / dt ≥ 0 (dL(t) / dt ≥ 0) at a temperature t = 30°C to 120°C, and thus the circuit connection member 4 itself easily undergoes thermal expansion accompanying a temperature increase, resulting in a large peeling interfacial stress at the interface of the circuit connection member 4 with the substrates 5, 7 and the circuit electrodes 6, 8.

[0099] Thus, compared to the cured product of the conventional adhesive composition (circuit connection member), the cured product of the adhesive composition (circuit connection member 4) according to the present embodiment can suppress the peeling of the circuit connection member 4 from the substrates 5, 7 and the circuit electrodes 6, 8 even when it is placed in a high-temperature high-humidity environment. This effect can also be exhibited in the case where the circuit electrodes formed of amorphous ITO or the like that is not favorable for adhesion are used as the circuit electrodes 6, 8.

[0100] Example

[0101] Hereinafter, the present application will be described more specifically based on Examples, but the present application is not limited to the Examples.

[0102] <Synthesis of polyurethane resin>

[0103] In a separable flask equipped with a reflux cooler, a thermometer, and a stirrer, 1000 parts by mass of polypropylene glycol (number average molecular weight: 2000) as a diol having an ether bond and 4000 parts by mass of methyl ethyl ketone as a solvent were stirred at 40°C for 30 minutes. After the solution was warmed to 70°C, 0.127 parts by mass of dimethyl tin laurate as a catalyst was added. Subsequently, to the solution, 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 over 1 hour. Then, stirring was continued at 70°C until an absorption peak derived from the NCO group could not be observed by infrared spectrophotometry, thereby obtaining a methyl ethyl ketone solution of the polyurethane resin. Then, the amount of methyl ethyl ketone was adjusted so that the solid content concentration of the solution (the concentration of the polyurethane resin) would be 30% by mass.

[0104] The glass transition temperature (Tg) of the obtained polyurethane resin was -20°C. The glass transition temperature (Tg) was measured using a thermal mechanical analysis device.

[0105] The weight average molecular weight of the obtained polyurethane resin was 320000. The weight average molecular weight is a standard polystyrene conversion value measured using GPC (gel permeation chromatography). Hereinafter, the analysis conditions of GPC are shown in Table 1.

[0106] [Table 1]

[0107]

[0108] <Synthesis of urethane acrylate>

[0109] In a 2L four-necked flask equipped with a thermometer, a stirrer, a non-active gas inlet, and a reflux cooler, 4000 parts by mass of polycarbonate diol (manufactured by Aldrich Corporation, number average molecular weight: 2000), 238 parts by mass of 2-hydroxyethyl acrylate, 0.49 parts by mass of p-benzene diol monomethyl ether, and 4.9 parts by mass of a tin-based catalyst were put in to prepare a reaction solution. To the reaction solution heated to 70°C, 666 parts by mass of isophorone diisocyanate (IPDI) was added dropwise uniformly over 3 hours to allow the reaction. After the completion of the dropwise addition, the reaction was continued for 15 hours, and the reaction was terminated at the time when the content of the NCO group was confirmed to be less than or equal to 0.2% by mass using a potentiometric automatic titrator (product name AT-510, manufactured by Kyoto Electronic Industrial Co., Ltd.), and a urethane acrylate was obtained. The weight average molecular weight of the urethane acrylate was 8500. Note that the weight average molecular weight of the urethane acrylate was measured in the same manner as the weight average molecular weight of the polyurethane resin described above.

[0110] <Production of film-shaped adhesive>

[0111] An adhesive composition was obtained by mixing the components shown below in the mass ratio shown in Tables 2 and 3.

[0112] (Thermoplastic resin)

[0113] A1: Phenoxy resin (product name: PKHC, manufactured by Union Carbide Corporation, weight average molecular weight: 45,000, Tg: 90°C, bisphenol A skeleton)

[0114] A2: Phenoxy resin (product name: YD-6020, manufactured by Nippon Steel Chemical Co., Ltd., weight average molecular weight: 5,000, Tg: 70°C, bisphenol A / bisphenol F skeleton)

[0115] A3: Phenoxy resin (product name: FX-316, manufactured by Nippon Steel Chemical Co., Ltd., weight average molecular weight: 50,000, Tg: 70°C, bisphenol F skeleton)

[0116] A4: Phenoxy resin (product name: FX-293AT40, manufactured by Nippon Steel Chemical Co., Ltd., Tg: 160°C, high heat resistance skeleton)

[0117] A5: Polyurethane resin synthesized as described above

[0118] A6: Polyester resin (product name: UE-3400, manufactured by Unitika Co., Ltd., Tg: -20°C)

[0119] A7: Polyester resin (product name: UE-3200, manufactured by Unitika Co., Ltd., Tg: 70°C)

[0120] (Radical polymerizable compound)

[0121] B1: Urethane acrylate synthesized as described above

[0122] B2: Isocyanuric acid EO-modified diacrylate (product name: M-215, manufactured by Toagosei Co., Ltd.)

[0123] B3: Acid phosphoric acid 2-methacryloyloxyethyl ester (product name: Light Ester P-2M, manufactured by Kyoeisha Chemical Co., Ltd.)

[0124] Note that, of the above components, as for the solid components, a 40 mass% solution prepared by dissolving 40 g of the solid components in 60 g of methyl ethyl ketone was used.

[0125] (Radical polymerization initiator)

[0126] C1: lauroyl peroxide (product name: PEROYL L, manufactured by Nippon Oil and Fats Corporation, molecular weight 398.6)

[0127] (Filler (filling agent))

[0128] D1: silica microparticles (product name: R104, manufactured by Japan Aerosil Co., Ltd., primary particle diameter: 12 nm)

[0129] (silane coupling agent)

[0130] E1: 3-methacryloyloxypropyltrimethoxysilane (product name: KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0131] Note that, regarding the silica microparticles, a 10 mass% dispersion liquid prepared by dispersing 10 g of the silica microparticles in a mixed solvent of toluene 45 g and ethyl acetate 45 g was used.

[0132] Next, conductive particles having an average particle diameter of 5 μm and a specific gravity of 2.5, and having a nickel layer of 0.2 μm in thickness on the surface of polystyrene particles (core) were prepared. The conductive particles were dispersed in each of the adhesive compositions at a proportion of 1.5% by volume to obtain a coating liquid. Using a coating device, the coating liquid was applied to a polyethylene terephthalate (PET) film having a thickness of 50 μm. The coated film was hot air dried at 70°C for 10 minutes to obtain a film-shaped adhesive having a thickness of 18 μm.

[0133] <Manufacture of connection structure>

[0134] Each of the film-shaped adhesives was disposed between a flexible circuit board (FPC) having a copper circuit electrode of about 2200 lines, 75 μm in line width, 150 μm in pitch, and 18 μm in thickness, and a glass (SiO2) substrate (product name: PreClean Slide S7224, manufactured by Matsunami Glass Ind. Ltd.) or a glass substrate with an amorphous indium tin oxide (ITO) film (manufactured by Geomatec Co., Ltd.), and the FPC was connected to the glass substrate or the glass substrate with amorphous ITO using a hot press bonding device (heating method: constant heating type, manufactured by Toray Engineering Co., Ltd.). The connection was performed by heating and pressurizing at 160°C, 3 MPa, and 5 seconds. The pressure at the time of pressurization was calculated by setting the bonding area to 0.495 cm 2 . Thus, a connection structure in which the FPC was connected to the glass substrate or the glass substrate with amorphous ITO through a cured product of the film-shaped adhesive over the entire 1.5 mm width was obtained.

[0135] <Measurement of linear thermal expansion amount>

[0136] A plurality of the produced film-like adhesive described above was attached with a laminator so as to have a thickness of 100 ± 20 μm, and heated at 180°C for 1 hour using an oven, thereby producing a cured product sample. Regarding the cured product sample, using a thermal mechanical analysis device (manufactured by Shimadzu Corporation), the linear thermal expansion amount l(t) μm at temperatures t = 0°C to 200°C was measured every 0.1°C under conditions of a sample length of 10 mm and a width of 4 mm, a load of 5 gf (0.4 mm of the sample per 1 g), a cross-sectional area, and a temperature increase rate of 5°C / minute. The linear thermal expansion amount l(t) was measured with the linear thermal expansion amount l(0) at temperature t = 0°C as 0 μm. From the measurement results, it was confirmed whether or not there was a temperature region where dl(t) / dt < 0 at temperatures t = 30°C to 120°C (in some cases, the temperature region and the minimum value of dl(t) / dt were confirmed). In addition, from the measurement results, the average linear thermal expansion coefficient (ppm / °C) at 30°C to 120°C was calculated. The results are shown in Tables 2 and 3. 2 The cross-sectional area), a temperature increase rate of 5°C / minute. The linear thermal expansion amount l(t) was measured with the linear thermal expansion amount l(0) at temperature t = 0°C as 0 μm. From the measurement results, it was confirmed whether or not there was a temperature region where dl(t) / dt < 0 at temperatures t = 30°C to 120°C (in some cases, the temperature region and the minimum value of dl(t) / dt were confirmed). In addition, from the measurement results, the average linear thermal expansion coefficient (ppm / °C) at 30°C to 120°C was calculated. The results are shown in Tables 2 and 3.

[0137]

[0138] Regarding the connection structure body produced in the above-described manner, the connection appearance just after connection and after a high-temperature high-humidity test in which a constant-temperature constant-humidity chamber at 85°C, 85% RH was left for 250 hours was observed using an optical microscope, and the peeling generation area of the substrate-resin interface at the interval portion (the portion between the electrode terminals of the FPC) was measured. The case where the peeling generation area of the entire interval was more than 30% was evaluated as "with" peeling, and the case where it was 30% or less was evaluated as "without" peeling. The results are shown in Tables 2 and 3.

[0139] [Table 2]

[0140]

[0141] [Table 3]

[0142]

[0143] From the above, it was confirmed that the circuit connection member of Examples 1 to 7 could suppress the generation of peeling even under high-temperature high-humidity conditions, compared with the circuit connection members of Comparative Examples 1 to 9.

[0144] Explanation of Symbols

[0145] 1: Connection structure body, 2: First circuit member, 3: Second circuit member, 4: Circuit connection member, 6: First circuit electrode, 8: Second circuit electrode, 10: Conductive particles.​

Claims

1. A connection structure comprising: 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 electrically connecting the first circuit electrode and the second circuit electrode to each other. The linear thermal expansion L(t) of the circuit connection component at temperature t satisfies the condition that dL(t) / dt < 0 at at least any temperature t between t = 30℃ and 120℃. The circuit connection component is a cured product of an adhesive composition containing a thermoplastic resin, a free radical polymerizable compound, and a free radical polymerization initiator. The thermoplastic resin comprises phenoxy resin and at least one selected from the group consisting of polyester resin, poly(meth)acrylic resin, polyurethane resin and polyimide resin.

2. The connecting structure according to claim 1, wherein the thermoplastic resin contains two or more thermoplastic resins with different glass transition temperatures, and the ratio of the content of the thermoplastic resin with a higher glass transition temperature to the content of the thermoplastic resin with a lower glass transition temperature is 90 / 10 to 10 / 90.

3. The connection structure according to claim 1 or 2, wherein the average linear thermal expansion coefficient of the circuit connection component at 30℃ to 120℃ is less than or equal to 500ppm / ℃.

4. A circuit connection component, said circuit connection component being a cured product of an adhesive composition comprising a thermoplastic resin, a free radical polymerizable compound, and a free radical polymerization initiator. The thermoplastic resin comprises phenoxy resin and at least one selected from the group consisting of polyester resin, poly(meth)acrylic resin, polyurethane resin and polyimide resin. The linear thermal expansion L(t) of the circuit connection component at temperature t satisfies the condition that dL(t) / dt < 0 at at least any temperature t between t = 30℃ and 120℃.

5. The circuit connection component according to claim 4, wherein the thermoplastic resin contains two or more thermoplastic resins with different glass transition temperatures, and the ratio of the content of the thermoplastic resin with a higher glass transition temperature to the content of the thermoplastic resin with a lower glass transition temperature is 90 / 10 to 10 / 90.

6. The circuit connection component according to claim 4 or 5, wherein the average linear thermal expansion coefficient of the circuit connection component at 30°C to 120°C is less than or equal to 500ppm / °C.

7. An adhesive composition comprising a thermoplastic resin, a free radical polymerizable compound, and a free radical polymerization initiator. The thermoplastic resin comprises phenoxy resin and at least one selected from the group consisting of polyester resin, poly(meth)acrylic resin, polyurethane resin and polyimide resin. The linear thermal expansion l(t) of the cured adhesive composition at temperature t satisfies the condition that dl(t) / dt < 0 at at least any temperature t between t = 30°C and 120°C.

8. The adhesive composition according to claim 7, wherein the thermoplastic resin contains two or more thermoplastic resins with different glass transition temperatures, and the ratio of the content of the thermoplastic resin with a higher glass transition temperature to the content of the thermoplastic resin with a lower glass transition temperature is 90 / 10 to 10 / 90.

9. The adhesive composition according to claim 7 or 8, wherein the cured product has an average linear thermal expansion coefficient of less than or equal to 500 ppm / ℃ at 30℃ to 120℃.

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