conductive paste

Abstract

Provided are resin particles capable of enhancing gap controllability of a connection structure when exposed to a high temperature environment.　The resin particles according to present invention contain a polymer of polymerizable components. The polymerizable components include divinylbenzene and a (meth)acrylate compound having four or more (meth)acryloyl groups. The resin particles have a compression elastic modulus of 1000 N mm2 or more when compressed by 20% at 200°C.

Description

[Technical Field]

[0001] This invention relates to resin particles containing polymerizable polymer components. Furthermore, this invention relates to metal-coated particles and resin materials using the above-mentioned resin particles. [Background technology]

[0002] Conductive materials such as conductive pastes and conductive films are widely known. In recent years, development has progressed on using these conductive materials for mounting semiconductor chips and the like. From the viewpoint of increasing the amount of current and reliability in thermal cycling, conductive particles such as solder particles are sometimes dispersed in the binder resin of conductive materials.

[0003] The above-mentioned conductive material is used to obtain various connection structures. Examples of connections using the above-mentioned conductive material include connections between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), connections between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), connections between a semiconductor chip and a glass substrate (COG (Chip on Glass)), and connections between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)).

[0004] In such connection structures, a spacer is used as a gap control material to maintain a uniform and constant distance (gap) between the two substrates (connected components). Preferably, the spacer has properties that do not damage the substrate, and preferably, the spacer is not destroyed during mounting. Resin particles may be used as the spacer, or metal-coated particles comprising resin particles and a metal coating layer covering the resin particles may be used.

[0005] As an example of the above resin particles, Patent Document 1 below describes a particle with a 5% weight loss temperature of 350°C or higher and a 10% K value of 100 N / mm² at 25°C. 2 More than 2500N / mm 2The following conditions apply, and the 30%K value at 25°C is 100 N / mm². 2 More than 1500N / mm 2 The following resin particles are disclosed. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] WO2021 / 193911A1 [Overview of the project] [Problems that the invention aims to solve]

[0007] When conventional resin particles are used as spacers, there is a problem in that the compressive modulus of the resin particles cannot be sufficiently increased when exposed to high-temperature environments (e.g., 200°C), and the gap control performance of the resin particles cannot be improved. Furthermore, in connection structures such as electronic components, the connection portion connecting two members to be connected is repeatedly heated and cooled (exposed to thermal cycling conditions). With conventional resin particles, the resin in the resin particles decomposes due to the thermal cycling, resulting in outgassing. If a large amount of outgassing occurs, voids may form at the connection portion of the connection structure, or cracks or delamination may occur between the resin particles and the metal coating layer in metal-coated particles, which can reduce the conductivity reliability of the connection structure. In other words, with conventional resin particles, it is difficult to properly control the gap between substrates when exposed to high-temperature environments and to improve the conductivity reliability of the connection structure after thermal cycling.

[0008] The object of the present invention is to provide resin particles that can improve the gap controllability of connection structures when exposed to high-temperature environments, and to provide the use of said resin particles in solder paste. Another object of the present invention is to provide metal-coated particles and resin materials using the above-mentioned resin particles. [Means for solving the problem]

[0009] This specification discloses the following resin particles, use of the resin particles in solder paste, metal-coated particles, and resin materials.

[0010] Item 1. Resin particles containing a polymer of a polymerizable component, wherein the polymerizable component includes divinylbenzene and a (meth)acrylate compound having four or more (meth)acryloyl groups, and the compression elastic modulus when the resin particles are compressed by 20% at 200 °C is 1000 N / mm 2 or more. Resin particles.

[0011] Item 2. The resin particles according to Item 1, wherein the total content of the divinylbenzene and the (meth)acrylate compound having four or more (meth)acryloyl groups in 100% by weight of the polymerizable component is 80% by weight or more.

[0012] Item 3. The resin particles according to Item 1 or 2, wherein the weight ratio of the content of the divinylbenzene in the polymerizable component to the content of the (meth)acrylate compound having four or more (meth)acryloyl groups in the polymerizable component is 0.40 or more and 1.70 or less.

[0013] Item 4. The resin particles according to any one of Items 1 to 3, wherein the outgassing amount when the resin particles are heated at 250 °C for 10 minutes is 1000 ppm or less.

[0014] Item 5. The resin particles according to any one of Items 1 to 4, wherein the particle diameter of the resin particles is 1 μm or more and 100 μm or less.

[0015] Item 6. The resin particles according to any one of Items 1 to 5 are used to obtain metal-coated particles provided with the metal coating layer by forming a metal coating layer on the surface, or the resin particles have a particle diameter of 5 μm or more and 100 μm or less. <​Item 7. The resin particles are used to obtain metal-coated particles having the metal coating layer by forming a metal coating layer on their surface, or the resin particles are the resin particles according to Item 6, wherein the resin particles have a particle diameter of 20 μm or more and 100 μm or less.

[0017] Item 8. The resin particles according to any one of items 1 to 5, wherein a metal coating layer is formed on the surface of the resin particles to obtain metal-coated particles having the metal coating layer.

[0018] Item 9. The resin particles according to Item 5, wherein the particle size of the resin particles is 5 μm or more and 100 μm or less.

[0019] Item 10. The resin particles according to Item 9, wherein the particle size of the resin particles is 20 μm or more and 100 μm or less.

[0020] Item 11. Metal-coated particles comprising resin particles as described in any one of items 1 to 10, and a metal coating layer disposed on the surface of the resin particles.

[0021] Item 12. The metal-coated particle according to Item 11, wherein the thickness of the metal coating layer is 0.2 μm or more.

[0022] Item 13. A resin material comprising resin particles according to any one of items 1 to 10 and a binder resin, or a resin material comprising metal-coated particles comprising the resin particles and a metal coating layer disposed on the surface of the resin particles and a binder resin, wherein the resin particles or the metal-coated particles are dispersed in the binder resin.

[0023] Item 14. The resin material according to Item 13, wherein the resin material is a solder paste containing solder particles.

[0024] Item 15. Resin particles as described in any one of items 1 to 10, or the resin particles and arranged on the surface of the resin particles. It comprises a metal coating layer. Use of metal-coated particles in solder paste containing solder particles and binder resin. [Effects of the Invention]

[0025] The resin particles according to the present invention are resin particles containing a polymer of a polymerizable component. In the resin particles according to the present invention, the polymerizable component includes divinylbenzene and a (meth)acrylate compound having four or more (meth)acryloyl groups. In the resin particles according to the present invention, the compressive modulus when the resin particles are compressed by 20% at 200°C is 1000 N / mm². 2 This concludes the explanation. The resin particles according to the present invention have the above configuration, which makes it possible to improve the gap controllability of the connecting structure when exposed to high-temperature environments. [Brief explanation of the drawing]

[0026] [Figure 1] Figure 1 is a schematic cross-sectional view showing resin particles according to the first embodiment of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view showing metal-coated particles using resin particles according to the first embodiment of the present invention. [Figure 3] Figure 3 is a cross-sectional view showing an example of a connecting structure obtained using resin particles according to the first embodiment of the present invention. [Figure 4] Figure 4 is a cross-sectional view showing an example of a connecting structure obtained using metal-coated particles with resin particles according to the first embodiment of the present invention. [Modes for carrying out the invention]

[0027] The details of the present invention will be described below.

[0028] (Resin particles) The resin particles according to the present invention are resin particles containing a polymer of a polymerizable component. In the resin particles according to the present invention, the polymerizable component includes divinylbenzene and a (meth)acrylate compound having four or more (meth)acryloyl groups. In the resin particles according to the present invention, the compressive modulus when the resin particles are compressed by 20% at 200°C is 1000 N / mm². 2 That's all.

[0029] When conventional resin particles are used as spacers, there is a problem in that the compressive modulus of the resin particles cannot be sufficiently increased when they are exposed to high-temperature environments (for example, 200°C), and therefore the gap control ability of the resin particles cannot be improved.

[0030] The resin particles according to the present invention have the above configuration, which improves the gap controllability of the connecting structure when exposed to high-temperature environments. In the above connecting structure, the gap on or between the members to be connected can be controlled with high precision by the resin particles.

[0031] Furthermore, in connection structures for electronic components, the connection point connecting two members is repeatedly heated and cooled (exposed to thermal cycling conditions). With conventional resin particles, there is a problem in that the resin in the resin particles decomposes due to thermal cycling, causing outgassing. If a large amount of outgassing occurs, voids may form at the connection point of the connection structure, or cracks or delamination may occur between the resin particles and the metal coating layer in metal-coated particles, which can reduce the conductivity reliability of the connection structure. In other words, with conventional resin particles, it is difficult to properly control the gap between substrates when exposed to high-temperature environments and to improve the conductivity reliability of the connection structure after thermal cycling.

[0032] The resin particles according to the present invention have the above configuration, and therefore can be used in applications where conductivity reliability is required. The resin particles according to the present invention have the above configuration, and therefore can improve the conductivity reliability of the connection structure after the thermal cycle. However, the resin particles according to the present invention can also be used in applications where conductivity reliability is not required.

[0033] The present invention will be described in detail below with reference to the drawings.

[0034] Figure 1 is a schematic cross-sectional view showing resin particles according to the first embodiment of the present invention.

[0035] The resin particles 1 contain a polymer of a polymerizable component. In the resin particles 1, the polymerizable component includes divinylbenzene and a (meth)acrylate compound having four or more (meth)acryloyl groups. In the resin particles 1, the compression elastic modulus when the resin particles 1 are compressed by 20% at 200°C is 1000 N / mm 2 or more.

[0036] The compression elastic modulus (20% K value of the resin particles at 200°C) when the resin particles are compressed by 20% at 200°C is 1000 N / mm 2 or more. The 20% K value of the resin particles at 200°C is preferably 1200 N / mm 2 or more, more preferably 1300 N / mm 2 or more, still more preferably 1500 N / mm 2 or more, particularly preferably 1750 N / mm 2 or more, most preferably 2000 N / mm 2 or more, and preferably 20000 N / mm 2 or less, more preferably 10000 N / mm 2 or less, still more preferably 5000 N / mm 2 or less. When the 20% K value of the resin particles at 200°C is not less than the above lower limit, the gap controllability of the connection structure when exposed to a high-temperature environment can be further enhanced. When the 20% K value of the resin particles at 200°C is not more than the above upper limit, the destruction of the resin particles when exposed to a high-temperature environment can be further prevented.

[0037] The compression elastic modulus (20% K value of the resin particles at 25°C) when the resin particles are compressed by 20% at 25°C is preferably 1000 N / mm 2 or more, more preferably 1500 N / mm 2 or more, still more preferably 2000 N / mm 2 or more, and preferably 20000 N / mm 2 or less, more preferably 10000 N / mm 2 or less, still more preferably 6000 N / mm 2The following applies: If the 20%K value of the resin particles at 25°C is above the lower limit, the gap controllability of the connecting structure when exposed to high-temperature environments can be further improved. If the 20%K value of the resin particles at 25°C is below the upper limit, the resin particles can follow the connected component (substrate, etc.) more closely, further improving the gap controllability.

[0038] The ratio of the compressive modulus of the resin particles when compressed by 20% at 25°C to the compressive modulus of the resin particles when compressed by 20% at 200°C is defined as the ratio (20%K value of the resin particles at 25°C / 20%K value of the resin particles at 200°C). The ratio (20%K value of the resin particles at 25°C / 20%K value of the resin particles at 200°C) is preferably 0.7 or higher, more preferably 0.9 or higher, even more preferably 1.0 or higher, preferably 3.0 or lower, more preferably 2.5 or lower, even more preferably 2.0 or lower, and particularly preferably 1.5 or lower. When the ratio (20%K value of the resin particles at 25°C / 20%K value of the resin particles at 200°C) is above the lower limit and below the upper limit, the gap controllability of the connecting structure when exposed to a high-temperature environment can be further improved.

[0039] The 20%K values ​​of the above resin particles at 25°C and 200°C can be measured as follows.

[0040] Using a microcompression testing machine, resin particles are compressed under the conditions of 25°C or 200°C and a maximum test load of 90 mN applied for 30 seconds using the smooth end face of a cylindrical diamond indenter (50 μm in diameter). The load value (N) and compression displacement (mm) are measured at this time. From the obtained measurements, the compressive modulus can be calculated using the following formula. Examples of microcompression testing machines used include the Fischerscope H-100 from Fischer GmbH and the ENT-5 from Elionix Corporation.

[0041] 20%K value (N / mm 2 )=(3 / 2 1 / 2 )·F·S -3 / 2 ·R -1 / 2 F: Load value (N) when resin particles are compressed and deformed by 20% S: Compression displacement (mm) when resin particles are compressed by 20% R: Radius of resin particles (mm)

[0042] Methods for adjusting the 20%K values ​​of the resin particles at 25°C and 200°C, and the ratio (20%K value of the resin particles at 25°C / 20%K value of the resin particles at 200°C) to a preferred range include using preferred polymerizable components described later, adjusting the molecular weight of the polymerizable components, using preferred crosslinking agents described later, adjusting the polymerization temperature and polymerization time, applying pressure during polymerization, adjusting the porosity (specific surface area) of the resin particles, and washing away unreacted polymerizable components (monomers).

[0043] From the viewpoint of further improving the effects of the present invention, the compression recovery rate of the resin particles at 25°C is preferably 20% or more, more preferably 25% or more, even more preferably 30% or more, preferably 95% or less, more preferably 90% or less, and even more preferably 85% or less. The compression recovery rate of the resin particles at 25°C may also be 70% or less, 60% or less, or 55% or less.

[0044] The above compression recovery rate can be measured as follows.

[0045] Resin particles are scattered onto a sample stage. For each scattered resin particle, a microcompression tester is used to apply a load (reverse load value) at 25°C using the smooth end face of a cylindrical (100 μm diameter, diamond) indenter, towards the center of the resin particle, until the particle is compressed and deformed by 40%. Then, the load is removed to the origin load value (0.40 mN). The load-compression displacement during this time is measured, and the compression recovery rate can be calculated using the following formula. The loading speed is set to 0.33 mN / sec. Examples of microcompression testers used include the Fischerscope H-100 from Fischer GmbH and the ENT-5 from Elionix Corporation.

[0046] Compression recovery rate (%) = (L2 / L1) × 100 L1: Compressive displacement from the origin load value to the reverse load value when a load is applied. L2: Unloading displacement from the reversal load value when the load is released to the origin load value.

[0047] Further details about the resin particles are described below. In the following description, "(meth)acrylic" means either or both "acrylic" and "methacrylic," and "(meth)acrylate" means either or both "acrylate" and "methacrylate."

[0048] The above-mentioned resin particles are resin particles formed from resin.

[0049] Various organic materials are suitably used as the resin material for the above-mentioned resin particles. Examples of resins that can be used as the material for the above-mentioned resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl (meth)acrylate and polyisobornyl (meth)acrylate; polyalkylene terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamideimide, polyetheretherketone, polyethersulfone, and polymers obtained by polymerizing one or more polymerizable monomers having ethylenically unsaturated groups. Since the hardness of the resin particles can be easily controlled within a suitable range, the resin used to form the above-mentioned resin particles is preferably a polymer obtained by polymerizing one or more polymerizable monomers having multiple ethylenically unsaturated groups.

[0050] The above resin particles contain a polymer of a polymerizable component. Preferably, the polymerizable component contains a polymerizable monomer having an ethylenically unsaturated group. Examples of polymerizable monomers having an ethylenically unsaturated group include non-crosslinked monomers and crosslinked monomers.

[0051] The above non-crosslinked monomers include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride; methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate. Examples include alkyl (meth)acrylate compounds such as acrylate; oxygen atom-containing (meth)acrylate compounds such as 2-hydroxyethyl (meth)acrylate, glycerol (meth)acrylate, polyoxyethylene (meth)acrylate, and glycidyl (meth)acrylate; nitrile-containing monomers such as (meth)acrylonitrile; and halogen-containing monomers such as trifluoromethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene.

[0052] The above crosslinkable monomers include tetramethylolmethane tetra(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, glycerol tri(meth)acrylate, glycerol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly) Examples include polyfunctional (meth)acrylate compounds such as pyrene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; and silane-containing monomers such as triallyl(iso)cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallylacrylamide, diallyl ether, γ-(meth)acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane.

[0053] The polymerizable component described above comprises divinylbenzene and a (meth)acrylate compound having four or more (meth)acryloyl groups. The polymer of the polymerizable component may include a copolymer of divinylbenzene and a (meth)acrylate compound having four or more (meth)acryloyl groups, or it may include a homopolymer of divinylbenzene and a homopolymer of a (meth)acrylate compound having four or more (meth)acryloyl groups. From the viewpoint of exhibiting the effects of the present invention more effectively, it is preferable that the polymer of the polymerizable component described above includes a copolymer of divinylbenzene and a (meth)acrylate compound having four or more (meth)acryloyl groups.

[0054] The above (meth)acrylate compound having four or more (meth)acryloyl groups may have four, five or more, or six or more (meth)acryloyl groups. The above (meth)acrylate compound having four or more (meth)acryloyl groups may have 20 or fewer (meth)acryloyl groups, 10 or fewer (meth)acryloyl groups, 8 or fewer (meth)acryloyl groups, or 6 or fewer (meth)acryloyl groups. The range of the number of (meth)acryloyl groups in the above (meth)acrylate compound having four or more (meth)acryloyl groups can be set by appropriately selecting the above lower limit and upper limit. The above (meth)acrylate compound having four or more (meth)acryloyl groups may be used by one type only, or by two or more types in combination.

[0055] From the viewpoint of exhibiting the effects of the present invention more effectively, it is particularly preferable that the (meth)acrylate compound having four or more (meth)acryloyl groups has four to six (meth)acryloyl groups. From the viewpoint of exhibiting the effects of the present invention more effectively, it is preferable that the (meth)acrylate compound having four or more (meth)acryloyl groups is a tetrafunctional (meth)acrylate compound, a pentafunctional (meth)acrylate compound, or a hexafunctional (meth)acrylate compound. The (meth)acrylate compound having four or more (meth)acryloyl groups may contain a tetrafunctional (meth)acrylate compound, a pentafunctional (meth)acrylate compound, or a hexafunctional (meth)acrylate compound.

[0056] Examples of (meth)acrylate compounds having four (meth)acryloyl groups (tetrafunctional (meth)acrylate compounds) include pentaerythritol tetra(meth)acrylate, pentaerythritol alkoxytetra(meth)acrylate, alkoxy-modified pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and tetramethylolmethane tetra(meth)acrylate.

[0057] Examples of (meth)acrylate compounds having five (meth)acryloyl groups include dipentaerythritol hydroxypenta(meth)acrylate and alkoxylated dipentaerythritol hydroxypenta(meth)acrylate.

[0058] Examples of (meth)acrylate compounds having six (meth)acryloyl groups include dipentaerythritol hexa(meth)acrylate (such as dipentaerythritol hexaacrylate) and alkoxylated dipentaerythritol hexa(meth)acrylate (such as alkoxylated dipentaerythritol hexaacrylate).

[0059] From the viewpoint of exhibiting the effects of the present invention more effectively, the above (meth)acrylate compound having four or more (meth)acryloyl groups preferably includes a (meth)acrylate compound having four (meth)acryloyl groups, and more preferably includes pentaerythritol tetra(meth)acrylate. From the viewpoint of exhibiting the effects of the present invention more effectively, the above polymerizable component preferably includes divinylbenzene and a (meth)acrylate compound having four (meth)acryloyl groups, and more preferably includes divinylbenzene and pentaerythritol tetra(meth)acrylate. From the viewpoint of exhibiting the effects of the present invention more effectively, the polymer (resin particles) of the above polymerizable component preferably includes a copolymer of divinylbenzene and a (meth)acrylate compound having four (meth)acryloyl groups, and more preferably includes a copolymer of divinylbenzene and pentaerythritol tetra(meth)acrylate.

[0060] The polymerizable components described above may or may not contain other polymerizable components other than divinylbenzene and (meth)acrylate compounds having four or more (meth)acryloyl groups (hereinafter sometimes referred to as "other polymerizable components").

[0061] Other polymerizable components mentioned above include polymerizable monomers having ethylenically unsaturated groups as described above. Only one of these other polymerizable components may be used, or two or more may be used in combination.

[0062] When obtaining resin particles using the above-mentioned crosslinkable monomer, a crosslinking agent can be used. Examples of the above-mentioned crosslinking agent include (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate. The above-mentioned crosslinking agent may be used alone or in combination of two or more.

[0063] From the viewpoint of exhibiting the effects of the present invention more effectively, it is preferable that the polymerizable component includes a crosslinking agent. From the viewpoint of exhibiting the effects of the present invention more effectively, it is preferable that the polymerizable component (crosslinking agent) includes (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, or 1,4-butanediol di(meth)acrylate. From the viewpoint of exhibiting the effects of the present invention more effectively, it is preferable that the polymerizable component (crosslinking agent) is (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, or 1,4-butanediol di(meth)acrylate.

[0064] The above-mentioned polymerizable monomer having an ethylenically unsaturated group can be polymerized by known methods to obtain the resin particles. Examples of such methods include suspension polymerization in the presence of a radical polymerization initiator, and polymerization by swelling the monomer together with a radical polymerization initiator using non-crosslinked seed particles.

[0065] The viscosity of the polymerizable component mixture (before polymerization) is preferably 50 mPa·s or more, more preferably 100 mPa·s or more, even more preferably 500 mPa·s or more, particularly preferably 1000 mPa·s or more, most preferably 1200 mPa·s or more, preferably 7000 mPa·s or less, more preferably 5000 mPa·s or less, and even more preferably 4000 mPa·s or less. If the viscosity of the polymerizable component mixture (before polymerization) is above the lower limit, the particle size of the resin particles can be easily controlled. If the viscosity of the polymerizable component mixture (before polymerization) is below the upper limit, the molecular weight of the resulting polymer of the polymerizable component can be increased, and the 20%K values ​​of the resin particles at 25°C and 200°C can be easily adjusted to a preferred range, further improving the gap controllability of the connecting structure when exposed to high-temperature environments. The polymerizable component mixture (before polymerization) contains the polymerizable compound used for the resin particles in the weight ratio used for the resin particles.

[0066] The viscosity of the above polymerizable component mixture (before polymerization) is measured, for example, using an E-type viscometer at 25°C and 5 rpm. Examples of such E-type viscometers include the "VISCOMETER TV-22" manufactured by Toki Sangyo Co., Ltd.

[0067] The particle size of the above resin particles is preferably 0.1 μm or larger, more preferably 1 μm or larger, even more preferably 1.5 μm or larger, still more preferably 2 μm or larger, still more preferably 5 μm or larger, particularly preferably 10 μm or larger, most preferably 20 μm or larger, preferably 300 μm or smaller, more preferably 100 μm or smaller, still more preferably 70 μm or smaller, particularly preferably 50 μm or smaller, and most preferably 30 μm or smaller. If the particle size of the above resin particles is above the lower limit, aggregation becomes less likely when forming a metal coating layer on the surface of the resin particles by electroless plating, and aggregated metal coating particles are less likely to form. If the particle size of the above resin particles is below the upper limit, the gap controllability of the connection structure when exposed to a high-temperature environment can be further improved.

[0068] In particular, when a resin material using resin particles is cured, the occurrence of cracks in the cured product can be suppressed, and when a connecting structure using resin material is exposed to a high-temperature environment, the gap controllability of the connecting structure can be considerably improved, so it is preferable that the particle size of the resin particles be 5 μm or more. This effect is exhibited even more effectively, so it is more preferable that the particle size of the resin particles be 10 μm or more, and even more preferable that it be 20 μm or more. Furthermore, when the resin material is solder paste, this effect is exhibited even more effectively. The particle size of the resin particles is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 100 μm or less, and even more preferable that it be 20 μm or more and 100 μm or less. Moreover, from the viewpoint of considerably improving the conductivity reliability of the connecting structure after a thermal cycle, it is preferable that the particle size of the resin particles be 10 μm or more.

[0069] The inventors have found that in order to more effectively exhibit the effects of the present invention, it is important to 1) use a specific polymerizable component, 2) control the compressive modulus of the resin particles within a specific range, and 3) control the particle size of the resin particles within a specific range; in other words, it is important to combine these three requirements.

[0070] The particle size of the resin particles mentioned above refers to the diameter if the resin particles are spherical, and if the resin particles have a shape other than a perfect sphere, it refers to the diameter assuming they are spherical to the extent of their volume.

[0071] The particle diameter of the above-mentioned resin particles is preferably the average particle diameter, and more preferably the number-average particle diameter. Furthermore, the effect is more effectively realized when the lower and upper limits of the number-average particle diameter of the above-mentioned resin particles satisfy the preferred lower and upper limits of the particle diameter of the above-mentioned resin particles. The particle diameter of the resin particles can be determined, for example, by observing 50 arbitrary resin particles with an electron microscope or optical microscope and calculating the average value of the particle diameter of each resin particle, or by performing laser diffraction particle size distribution measurement. In observation with an electron microscope or optical microscope, the particle diameter of a single resin particle is determined as the particle diameter at the equivalent diameter of a circle. In observation with an electron microscope or optical microscope, the average particle diameter at the equivalent diameter of a circle of any 50 resin particles is approximately equal to the average particle diameter at the equivalent diameter of a sphere. In laser diffraction particle size distribution measurement, the particle diameter of a single resin particle is determined as the particle diameter at the equivalent diameter of a sphere. It is preferable to calculate the above-mentioned particle diameter of the resin particles by laser diffraction particle size distribution measurement.

[0072] From the viewpoint of controlling the gap on or between connected members with even greater precision, it is preferable that the resin particles either do not contain resin particles having a particle diameter of 1.5 times or more the average particle diameter, or contain resin particles having a particle diameter of 1.5 times or more the average particle diameter in an amount of 1000 ppm or less. From the viewpoint of controlling the gap on or between connected members with even greater precision, it is preferable that the content of resin particles having a particle diameter of 1.5 times or more the average particle diameter is 1000 ppm or less, more preferably 100 ppm or less, even more preferably 10 ppm or less, and particularly preferably 0.1 ppm or less. This range includes 0 ppm. From the viewpoint of controlling the gap on or between connected members with even greater precision, it is most preferable that the content of resin particles having a particle diameter of 1.5 times or more the average particle diameter is 0 ppm (not contained).

[0073] The content (ppm) of resin particles with a particle size 1.5 times or larger than the average particle size can be measured as follows: The resin particles are filtered using a filter with a pore size 1.5 times that of the average particle size. The resin particles remaining on the filter are observed using an optical microscope, and the resin particles with a particle size 1.5 times or larger than the average particle size are counted. The content (ppm) of resin particles with a particle size 1.5 times or larger than the average particle size is calculated by dividing the number of counted resin particles by the total number of filtered resin particles.

[0074] From the viewpoint of controlling the gap on or between connected members with even greater precision, the CV value (coefficient of variation) of the particle diameter of the resin particles is preferably 10% or less, more preferably 8.0% or less. The lower limit of the CV value of the particle diameter of the resin particles is not particularly limited. The CV value of the particle diameter of the resin particles may be 0% or more, or 1.0% or more. The range of the CV value of the particle diameter of the resin particles can be set by appropriately selecting the lower limit and upper limit values.

[0075] The coefficient of variation (CV) of the particle size of the above resin particles can be measured as follows.

[0076] CV value (%) of resin particle size = (ρ / Dn) × 100 ρ: Standard deviation of the particle size of resin particles Dn: Average particle size of resin particles

[0077] From the viewpoint of controlling the gap on or between connected members with even greater precision, the aspect ratio of the resin particles is preferably 1.5 or less, more preferably 1.3 or less. The lower limit of the aspect ratio of the resin particles is not particularly limited. The aspect ratio of the resin particles may be 1.0 or more, or 1.1 or more. The aspect ratio represents the major axis / minor axis. Preferably, the aspect ratio is determined by observing 10 arbitrary resin particles with an electron microscope or optical microscope, taking the maximum diameter and minimum diameter as the major axis and minor axis, respectively, and calculating the average value of the major axis / minor axis of each spherical resin particle. The range of the aspect ratio of the resin particles can be set by appropriately selecting the lower limit and upper limit values.

[0078] When the above resin particles are heated at 250°C for 10 minutes, the amount of outgassing is preferably 2000 ppm or less, more preferably 1000 ppm or less, even more preferably 800 ppm or less, particularly preferably 500 ppm or less, and most preferably 300 ppm or less. This range includes 0 ppm. It is most preferable that the amount of outgassing when the above resin particles are heated at 250°C for 10 minutes is 0 ppm (no outgassing occurs). If the amount of outgassing when the above resin particles are heated at 250°C for 10 minutes is below the above upper limit, it is possible to suppress the occurrence of voids in the connection part of the connection structure or cracks and delamination between the resin particles and the metal coating layer in the metal coating particles due to the cold cycle, and the conductivity reliability of the connection structure after the cold cycle can be improved. The lower limit of the amount of outgassing when the above resin particles are heated at 250°C for 10 minutes is not particularly limited. The amount of outgassing when the above resin particles are heated at 250°C for 10 minutes may be 0 ppm or more, 5 ppm or more, or 10 ppm or more. The range of outgassing when the above resin particles are heated at 250°C for 10 minutes can be set by appropriately selecting the above lower limit and upper limit values.

[0079] The amount of outgassing when the above resin particles are heated at 250°C for 10 minutes can be measured, for example, as follows.

[0080] Two samples are prepared: 5 mg of the above-mentioned resin particles and a known weight of toluene (toluene solution of known concentration). Using a thermal desorption apparatus, 5 mg of the above-mentioned resin particles are heated at 250°C for 10 minutes while passing helium gas through at a flow rate of 20 mL / min, and the generated component (A) is adsorbed and collected on a glass tube filled with an adsorbent. While passing helium gas through the glass tube in which component (A) is collected, the glass tube in which component (A) is collected is heated at 350°C for 40 minutes, and the component desorbed from the adsorbent is directly introduced into a gas chromatograph-mass spectrometer and analyzed. Using a thermal desorption apparatus, the known weight of the above-mentioned toluene is heated at 250°C for 10 minutes while passing helium gas through at a flow rate of 20 mL / min, and the generated component (B) is adsorbed and collected on a glass tube filled with an adsorbent. While passing helium gas through the glass tube containing the above-mentioned component (B), the glass tube containing the above-mentioned component (B) is heated at 350°C for 40 minutes. The component detached from the adsorbent is directly introduced into a gas chromatograph-mass spectrometer and analyzed. The peak area values ​​of each component detected when the above-mentioned resin particles are used are compared with the peak area values ​​detected when the above-mentioned known weight of toluene is used to calculate the amount of outgassing when the resin particles are heated at 250°C for 10 minutes.

[0081] The known weight of toluene mentioned above may be 5 mg of toluene.

[0082] The amount of outgassing when the above resin particles are heated at 250°C for 10 minutes is measured in more detail as follows.

[0083] Enclose the sample (5 mg of resin particles or toluene of known weight) in a sample tube, and heat it under heating conditions of 250 °C for 10 minutes while passing helium gas through the sample tube at a flow rate of 20 mL / min. Adsorb and collect the components volatilized by heating in a glass tube filled with a trapping agent (for example, TENAX-TA). While passing helium gas through the glass tube in which the volatilized components have been collected, heat the glass tube under heating conditions of 350 °C for 40 minutes. Introduce the components desorbed from the adsorbent by heating directly into a gas chromatograph mass spectrometer (hereinafter referred to as GC / MS) for analysis (ATD-GC / MS). Examples of the devices and analysis conditions used in the above measurements are as follows.

[0084] [ATD-GC / MS] Thermal desorption device: "TurboMatrix350" manufactured by PerkinElmer GC: "7890A" manufactured by Agilent Technologies MS: "JMS-Q1000GCQ" manufactured by JEOL Ltd. Column: "EQUITY-1 60 m × 0.25 mm I.D. × 0.25 μm" manufactured by SUPELCO

[0085] <Conditions of the thermal desorption device> Heating temperature of the sample tube: 250 °C Heating time: 10 minutes Flow rate of helium gas: 20 mL / min Cold trap temperature: 4 °C Desorption temperature and time from the collection tube (glass tube): 350 °C and 40 minutes Split: inlet; 25 mL / min, outlet; 25 mL / min

[0086] <GC / MS conditions> Carrier gas: helium, contact flow Column flow rate: 1.5 mL Split ratio: 1:30 Initial oven temperature: 40 °C Hold time: 4 minutes Temperature rise rate: 10 °C / min Final temperature: 300 °C Hold time: 10 minutes MS:EI mode, 70eV, transfer line; 250℃, ion source; 230℃

[0087] The sum of the peak area values ​​of each component detected when using the above resin particles is compared with the peak area values ​​detected when using a toluene solution of known concentration (toluene of known weight, for example, "VOCs Mixed Standard Stock Solution III" manufactured by Kanto Chemical Co., Ltd.). This allows the concentration of volatile components (outgassing) from the resin particles to be calculated in toluene equivalent. In this invention, the amount of outgassing (ppm) when the resin particles are heated at 250°C for 10 minutes is calculated using the following formula.

[0088] Outgassing amount (ppm) = [(Sum of peak area values ​​of volatile components from resin particles) / (Peak area value of toluene) × Concentration of toluene in toluene solution (μg / g) × Amount of toluene solution measured (g)] / Weight of resin particles

[0089] Methods for adjusting the amount of outgassing when the above resin particles are heated at 250°C for 10 minutes to a preferred range include using the preferred polymerizable components mentioned above, adjusting the molecular weight of the polymerizable components, using the preferred crosslinking agents mentioned above, adjusting the polymerization temperature and polymerization time, applying pressure during polymerization, and washing away unreacted polymerizable components (monomers).

[0090] The applications of the above-mentioned resin particles are not particularly limited. The above-mentioned resin particles can be suitably used in a variety of applications. The above-mentioned resin particles are preferably used as spacers. The above-mentioned resin particles are preferably spacer resin particles. The above-mentioned resin particles may also be used as spacers in resin materials. Examples of the above-mentioned spacers include spacers for liquid crystal display elements, gap control spacers, and stress relief spacers. The above-mentioned gap control spacers can be used for gap control of laminated chips to ensure standoff height and flatness, and for gap control of optical components to ensure smoothness of glass surfaces and thickness of adhesive layers. The above-mentioned stress relief spacers can be used for stress relief of sensor chips, and for stress relief of adhesive layers bonding two adherends.

[0091] The above-mentioned resin particles are preferably used as spacers for liquid crystal display elements, and more preferably used in peripheral sealants for liquid crystal display elements. In the peripheral sealant for liquid crystal display elements, the resin particles are preferably used as spacers. Since the above-mentioned resin particles have good compression deformation characteristics, when the above-mentioned resin particles are used as spacers and placed between substrates, the resin particles are efficiently placed between the substrates. Furthermore, since the above-mentioned resin particles can suppress damage to liquid crystal display element components, display defects are less likely to occur in liquid crystal display elements using the above-mentioned spacers for liquid crystal display elements.

[0092] Furthermore, the above-mentioned resin particles can also be suitably used as inorganic fillers, toner additives, shock absorbers, or vibration absorbers. For example, the above-mentioned resin particles can be used as a substitute for rubber or springs. In addition, the above-mentioned resin particles may be used to obtain metal-coated particles, which will be described later.

[0093] In 100% by weight of the above resin particles, the content of the polymerizable component polymer is preferably 80% by weight or more, more preferably 85% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more. When the content of the polymerizable component polymer is above the lower limit, the 20%K values ​​of the resin particles at 25°C and 200°C can be easily adjusted to a preferred range, and the gap controllability of the connecting structure when exposed to a high-temperature environment can be further improved. The upper limit of the content of the polymerizable component polymer in 100% by weight of the above resin particles is not particularly limited. The content of the polymerizable component polymer in 100% by weight of the above resin particles may be 100% by weight (total amount) or less, or less than 100% by weight. The range of the content of the polymerizable component polymer in 100% by weight of the above resin particles can be set by appropriately selecting the lower limit and upper limit values.

[0094] Of the polymerizable components at 100% by weight, the content of divinylbenzene is preferably 20% by weight or more, more preferably 25% by weight or more, even more preferably 30% by weight or more, particularly preferably 40% by weight or more, most preferably 45% by weight or more, preferably 80% by weight or less, more preferably 75% by weight or less, even more preferably 70% by weight or less, particularly preferably 65% ​​by weight or less, and most preferably 60% by weight or less. When the content of divinylbenzene is above the lower limit and below the upper limit, the effects of the present invention can be exhibited more effectively, and the conductivity reliability of the connection structure after the thermal cycle can be further improved. When the content of divinylbenzene is above the lower limit, the heat resistance of the resin particles can be improved. When the content of divinylbenzene is below the upper limit, the amount of unreacted polymerizable components (monomers) remaining can be reduced.

[0095] In 100% by weight of the polymerizable component, the content of the (meth)acrylate compound having four or more (meth)acryloyl groups is preferably 20% by weight or more, more preferably 25% by weight or more, even more preferably 30% by weight or more, still more preferably 35% by weight or more, particularly preferably 40% by weight or more, most preferably 45% by weight or more, preferably 80% by weight or less, more preferably 75% by weight or less, even more preferably 70% by weight or less, still more preferably 65% ​​by weight or less, still more preferably 60% by weight or less, particularly preferably 55% by weight or less, and most preferably 50% by weight or less. When the content of the (meth)acrylate compound having four or more (meth)acryloyl groups is above the lower limit and below the upper limit, the effects of the present invention can be exhibited more effectively, and the conductivity reliability of the connection structure after the thermal cycle can be further improved. When the content of the (meth)acrylate compound having four or more (meth)acryloyl groups is above the lower limit, the degree of crosslinking of the resin particles can be increased. If the content of the (meth)acrylate compound having four or more (meth)acryloyl groups is below the above upper limit, the heat resistance of the resin particles can be improved.

[0096] The total content of the above-mentioned divinylbenzene and the above-mentioned (meth)acrylate compound having four or more (meth)acryloyl groups in 100% by weight of the above-mentioned polymerizable component is preferably 80% by weight or more, more preferably 85% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more. When the total content of the above-mentioned divinylbenzene and the above-mentioned (meth)acrylate compound having four or more (meth)acryloyl groups is above the lower limit above, the effects of the present invention can be exhibited even more effectively. There is no particular upper limit to the total content of the above-mentioned divinylbenzene and the above-mentioned (meth)acrylate compound having four or more (meth)acryloyl groups in 100% by weight of the above-mentioned polymerizable component is 100% by weight or less (total amount), or less than 100% by weight. The range of the total content of the above-mentioned divinylbenzene and the above-mentioned (meth)acrylate compound having four or more (meth)acryloyl groups in 100% by weight of the above-mentioned polymerizable component can be set by appropriately selecting the above-mentioned lower limit and upper limit.

[0097] The weight ratio of the content of divinylbenzene in the polymerizable component to the content of the (meth)acrylate compound having 4 or more (meth)acryloyl groups in the polymerizable component is defined as the weight ratio (content of divinylbenzene / content of the (meth)acrylate compound having 4 or more (meth)acryloyl groups). The weight ratio (content of divinylbenzene / content of the (meth)acrylate compound having 4 or more (meth)acryloyl groups) is preferably 0.30 or higher, more preferably 0.40 or higher, even more preferably 0.50 or higher, still more preferably 0.60 or higher, particularly preferably 0.70 or higher, most preferably 0.80 or higher, preferably 10.00 or lower, more preferably 5.00 or lower, even more preferably 4.00 or lower, still more preferably 3.00 or lower, particularly preferably 2.00 or lower, and most preferably 1.50 or lower. When the above weight ratio (content of divinylbenzene / content of (meth)acrylate compound having 4 or more (meth)acryloyl groups) is above the lower limit and below the upper limit, the effects of the present invention can be exhibited even more effectively. When the above weight ratio (content of divinylbenzene / content of (meth)acrylate compound having 4 or more (meth)acryloyl groups) is above the lower limit, the heat resistance of the resin particles can be increased. When the above weight ratio (content of divinylbenzene / content of (meth)acrylate compound having 4 or more (meth)acryloyl groups) is below the upper limit, the degree of crosslinking of the resin particles can be increased and the amount of unreacted polymerizable components (monomers) remaining can be reduced.

[0098] (metal coated particles) The metal-coated particles according to the present invention comprise the resin particles described above and a metal coating layer disposed on the surface of the resin particles. Because the metal-coated particles according to the present invention have the above configuration, when used as spacers, the gap controllability of the connection structure when exposed to high-temperature environments can be improved, and the conductivity reliability of the connection structure after thermal cycling can be enhanced.

[0099] In particular, it is preferable that the resin particles are used to obtain metal-coated particles having the metal coating layer by forming a metal coating layer on their surface, or that the resin particles have a particle size of 5 μm to 100 μm. In this case, when the resin material using the resin particles or metal-coated particles is cured, the occurrence of cracks in the cured product can be suppressed, and when the connection structure using the resin material is exposed to a high-temperature environment, the gap controllability in the connection structure can be considerably improved. Furthermore, the conductivity reliability of the connection structure after a thermal cycle can be considerably improved. Since these effects are exhibited even more effectively, it is preferable that the resin particles are used to obtain metal-coated particles having the metal coating layer by forming a metal coating layer on their surface, or that the resin particles have a particle size of 10 μm to 100 μm. Since these effects are exhibited even more effectively, it is preferable that the resin particles are used to obtain metal-coated particles having the metal coating layer by forming a metal coating layer on their surface, or that the resin particles have a particle size of 20 μm to 100 μm.

[0100] In particular, the above-mentioned resin particles are preferably used to obtain metal-coated particles having the metal coating layer formed on their surface (use of the above-mentioned resin particles to obtain metal-coated particles having the metal coating layer formed on their surface). In this case, when the resin material using the metal-coated particles is cured, the occurrence of cracks in the cured product can be suppressed, and when the connecting structure using the resin material is exposed to a high-temperature environment, the gap controllability in the connecting structure can be considerably improved. Furthermore, the conductivity reliability of the connecting structure after a thermal cycle can be considerably improved.

[0101] Figure 2 is a schematic cross-sectional view showing metal-coated particles using resin particles according to the first embodiment of the present invention.

[0102] The metal-coated particle 11 shown in Figure 2 has a resin particle 1 and a metal coating layer 2 disposed on the surface of the resin particle 1. The metal coating layer 2 covers the surface of the resin particle 1. The metal-coated particle 11 is a coated particle in which the surface of the resin particle 1 is covered by the metal coating layer 2.

[0103] The compressive modulus (20% K value of the metal-coated particles at 200°C) when the above metal-coated particles are compressed by 20% at 200°C is preferably 1000 N / mm². 2 More preferably, 1500 N / mm 2 More preferably, 2000 N / mm 2 The above is preferable, preferably 20,000 N / mm 2 More preferably, 10,000 N / mm 2 More preferably, 6000 N / mm 2 The following applies: If the 20%K value of the metal-coated particles at 200°C is above the lower limit, the gap controllability of the connecting structure when exposed to high-temperature environments can be further improved. If the 20%K value of the metal-coated particles at 200°C is below the upper limit, the destruction of the metal-coated particles of the connecting structure when exposed to high-temperature environments can be further prevented.

[0104] The compressive modulus (20% K value of the metal-coated particles at 25°C) when the above metal-coated particles are compressed by 20% at 25°C is preferably 1500 N / mm². 2 More preferably, 2000 N / mm 2 More preferably 2500 N / mm 2 The above is preferable, preferably 20,000 N / mm 2 More preferably, 15,000 N / mm 2 More preferably, 8000 N / mm 2 The following applies: If the 20%K value of the metal-coated particles at 25°C is above the lower limit, the gap controllability of the connection structure when exposed to high-temperature environments can be further improved. If the 20%K value of the metal-coated particles at 25°C is below the upper limit, the metal-coated particles can follow the connected component (substrate, etc.) more closely, further improving the gap controllability.

[0105] The ratio of the compressive modulus of the metal-coated particles when compressed by 20% at 25°C to the compressive modulus of the metal-coated particles when compressed by 20% at 200°C is defined as the ratio (20%K value of the metal-coated particles at 25°C / 20%K value of the metal-coated particles at 200°C). The ratio (20%K value of the metal-coated particles at 25°C / 20%K value of the metal-coated particles at 200°C) is preferably 0.7 or higher, more preferably 0.9 or higher, even more preferably 1.0 or higher, preferably 3.0 or lower, more preferably 2.5 or lower, and even more preferably 2.0 or lower. When the ratio (20%K value of the metal-coated particles at 25°C / 20%K value of the metal-coated particles at 200°C) is above the lower limit and below the upper limit, the gap controllability of the connecting structure when exposed to a high-temperature environment can be further improved.

[0106] The 20%K values ​​of the above metal-coated particles at 25°C and 200°C can be measured as follows.

[0107] Using a microcompression testing machine, metal-coated particles are compressed using a smooth indenter end face of a cylindrical (50 μm diameter, diamond) under conditions of 25°C or 100°C and a maximum test load of 90 mN applied for 30 seconds. The load value (N) and compression displacement (mm) are measured at this time. From the obtained measurements, the compressive modulus can be determined by the following formula. Examples of microcompression testing machines used include the Fischerscope H-100 from Fischer GmbH and the ENT-5 from Elionix Corporation.

[0108] 20%K value (N / mm 2 )=(3 / 2 1 / 2 )·F·S -3 / 2 ·R -1 / 2 F: Load value (N) when the metal-coated particles are compressed by 20% S: Compressive displacement (mm) when the metal-coated particles are compressed by 20%. R: Radius of metal-coated particles (mm)

[0109] From the viewpoint of further improving the effects of the present invention, the compression recovery rate of the metal-coated particles at 25°C is preferably 20% or more, more preferably 25% or more, even more preferably 30% or more, preferably 95% or less, more preferably 90% or less, and even more preferably 85% or less.

[0110] The above compression recovery rate can be measured as follows.

[0111] Metal-coated particles are scattered on a sample stage. For each scattered metal-coated particle, a microcompression tester is used, applying a load (reverse load value) at 25°C using the smooth end face of a cylindrical (100 μm diameter, diamond) indenter towards the center of the metal-coated particle until the particle is compressed by 40%. Then, the load is removed to the origin load value (0.40 mN). The load-compression displacement during this time is measured, and the compression recovery rate can be calculated using the following formula. The loading speed is set to 0.33 mN / sec. Examples of microcompression testers used include the Fischerscope H-100 from Fischer GmbH and the ENT-5 from Elionix Corporation.

[0112] Compression recovery rate (%) = (L2 / L1) × 100 L1: Compressive displacement from the origin load value to the reverse load value when a load is applied. L2: Unloading displacement from the reversal load value when the load is released to the origin load value.

[0113] The particle size of the metal-coated particles is preferably 0.5 μm or larger, more preferably 1.0 μm or larger, even more preferably 2 μm or larger, still more preferably 5 μm or larger, particularly preferably 10 μm or larger, most preferably 20 μm or larger, preferably 300 μm or smaller, more preferably 100 μm or smaller, still more preferably 70 μm or smaller, particularly preferably 50 μm or smaller, and most preferably 30 μm or smaller. When the particle size of the metal-coated particles is above the lower limit and below the upper limit, aggregated metal-coated particles are less likely to form when forming the metal coating layer, the gap between substrates (connected members) does not become too large, and the metal coating layer is less likely to peel off from the surface of the resin particles.

[0114] In particular, when a resin material using metal-coated particles is cured, the occurrence of cracks in the cured product can be suppressed, and when a connecting structure using the resin material is exposed to a high-temperature environment, the gap controllability of the connecting structure can be considerably improved. Therefore, it is preferable that the particle size of the metal-coated particles be 5 μm or larger. These effects are exhibited even more effectively, so it is more preferable that the particle size of the metal-coated particles be 10 μm or larger, and even more preferable that it be 20 μm or larger. Furthermore, when the resin material is solder paste, these effects are exhibited even more effectively. The particle size of the metal-coated particles is preferably 5 μm to 100 μm, more preferably 10 μm to 100 μm, and even more preferable that it be 20 μm to 100 μm. Moreover, from the viewpoint of considerably improving the conductivity reliability of the connecting structure after a thermal cycle, it is preferable that the particle size of the metal-coated particles be 10 μm or larger.

[0115] The inventors have found that in order to more effectively exhibit the effects of the present invention, it is important to 1) use a specific polymerizable component for the resin particles, 2) control the compressive modulus of the resin particles in the metal-coated particles within a specific range, and 3) control the particle size of the metal-coated particles within a specific range; in other words, it is important to combine these three requirements.

[0116] The particle size of the metal-coated particles mentioned above refers to the diameter if the metal-coated particles are spherical, and if the metal-coated particles have a shape other than a sphere, it refers to the diameter assuming they are spherical to the extent of their volume.

[0117] The particle size of the metal-coated particles is preferably the average particle size, and more preferably the number-average particle size. Furthermore, the effect is more effectively realized when the lower and upper limits of the number-average particle size of the metal-coated particles satisfy the preferred lower and upper limits for the particle size of the metal-coated particles. The particle size of the metal-coated particles can be determined, for example, by observing 50 arbitrary metal-coated particles with an electron microscope or optical microscope and calculating the average particle size of each metal-coated particle, or by performing laser diffraction particle size distribution measurement. In observation with an electron microscope or optical microscope, the particle size of a single metal-coated particle is determined as the particle size at the equivalent diameter of a circle. In observation with an electron microscope or optical microscope, the average particle size at the equivalent diameter of a circle of any 50 metal-coated particles is approximately equal to the average particle size at the equivalent diameter of a sphere. In laser diffraction particle size distribution measurement, the particle size of a single metal-coated particle is determined as the particle size at the equivalent diameter of a sphere. It is preferable to calculate the particle size of the metal-coated particles using laser diffraction particle size distribution measurement.

[0118] The metal used to form the above-mentioned metal coating layer is not particularly limited. Examples of such metals include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, tungsten, molybdenum, and alloys thereof. Other examples of such metals include tin-doped indium oxide (ITO) and solder. From the viewpoint of further improving the reliability of the connection between electrodes, the above-mentioned metal is preferably a tin-containing alloy, nickel, palladium, copper, or gold, and is preferably nickel or palladium.

[0119] As with the metal-coated particles 11, the metal coating layer may be formed by a single layer. The metal coating layer may be formed by multiple layers. That is, the metal coating layer may have a laminated structure of two or more layers. When the metal coating layer is formed by multiple layers, the outermost layer is preferably a gold layer, a nickel layer, a palladium layer, a copper layer, or an alloy layer containing tin and silver, and more preferably a gold layer. When the outermost layer is one of these preferred metal coating layers, the reliability of the connection between electrodes can be further improved. Furthermore, when the outermost layer is a gold layer, corrosion resistance can be further improved.

[0120] The method for forming the metal coating layer on the surface of the resin particles is not particularly limited. Examples of methods for forming the metal coating layer include electroless plating, electroplating, physical vapor deposition, and coating the surface of the resin particles with metal powder or a paste containing metal powder and a binder. From the viewpoint of making the metal coating layer easier to form, electroless plating is preferred. Examples of physical vapor deposition include vacuum deposition, ion plating, and ion sputtering.

[0121] The thickness of the above metal coating layer is preferably 0.005 μm or more, more preferably 0.01 μm or more, even more preferably 0.05 μm or more, still more preferably 0.1 μm or more, particularly preferably 0.15 μm or more, most preferably 0.2 μm or more, preferably 10 μm or less, more preferably 1 μm or less, and still more preferably 0.3 μm or less. The thickness of the above metal coating layer is the total thickness of the metal coating layer if the metal coating layer is multilayered. When the thickness of the above metal coating layer is above the lower limit and below the upper limit, the metal coating particles do not become too hard and the metal coating particles deform sufficiently between the substrates (connected members). In particular, when the thickness of the above metal coating layer is 0.2 μm or more, the effects of the present invention can be exhibited even more effectively, and the conductivity reliability of the connection structure after the thermal cycle can be further improved.

[0122] When the above metal coating layer is formed by multiple layers, the thickness of the outermost metal coating layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, preferably 0.5 μm or less, and more preferably 0.1 μm or less. When the thickness of the outermost metal coating layer is above the lower limit and below the upper limit, the coating by the outermost metal coating layer becomes uniform, corrosion resistance is sufficiently high, and the reliability of the connection between electrodes can be further improved. Also, when the outermost layer is a gold layer, the thinner the gold layer, the lower the cost.

[0123] The thickness of the metal coating layer can be measured, for example, by observing the cross-section of the metal coating particle using a transmission electron microscope (TEM). Preferably, the thickness of the metal coating layer is calculated by taking the average of five arbitrary thickness points of the metal coating layer as the thickness of the metal coating layer of a single metal coating particle, and more preferably by taking the average of the total thickness of the metal coating layer as the thickness of the metal coating layer of a single metal coating particle. Preferably, the thickness of the metal coating layer is the average thickness for 50 arbitrary metal coating particles.

[0124] (Resin materials) The resin material according to the present invention is a resin material comprising the above-described resin particles and a binder resin, or a resin material comprising metal-coated particles comprising the above-described resin particles and a metal coating layer disposed on the surface of the resin particles, and a binder resin. In the resin material according to the present invention, the above-described resin particles or the above-described metal-coated particles are dispersed in the binder resin. Since the resin material according to the present invention is provided with the above-described configuration, the gap controllability of the connection structure when exposed to a high-temperature environment can be improved, and the conductivity reliability of the connection structure after a thermal cycle can be improved.

[0125] The above resin material preferably further contains conductive particles. The above resin material preferably further contains conductive particles different from the above metal-coated particles. The above conductive particles are different from the above resin particles. The above resin material is preferably a conductive material further containing conductive particles. The above resin material is preferably a conductive material. When the above resin material is a conductive material, the above resin material is suitably used for electrical connections between electrodes. The above resin material is preferably a circuit connection material. When the above resin material further contains conductive particles, the above resin material can be used as a conductive paste, a conductive film, etc. When the resin material according to the present invention is a conductive film, a film without conductive particles may be laminated on a conductive film containing conductive particles. The above conductive paste is preferably an isotropic conductive paste. The above conductive film is preferably an isotropic conductive film.

[0126] The above resin particles are preferably used together with conductive particles, and more preferably with solder particles. The above metal-coated particles are preferably used together with conductive particles, and more preferably with solder particles. The above resin material preferably contains the above resin particles or the above metal-coated particles and the above conductive particles, and more preferably contains the above resin particles or the above metal-coated particles and the above solder particles. The above metal-coated particles are preferably different from solder particles, and preferably do not contain solder. By using the above conductive particles (solder particles, etc.) separately from the above resin particles or the above metal-coated particles, the effects of the present invention can be exhibited more effectively, and the conductivity reliability of the connection structure after the thermal cycle can be further improved.

[0127] Furthermore, the following inventions are disclosed herein: the resin particles, or the resin particles and the resin particles arranged on the surface thereof. It comprises a metal coating layer. Use of metal-coated particles in solder paste containing solder particles and binder resin.

[0128] In 100% by weight of the above resin material (solder paste), the content of the above resin particles or the above metal coating particles is preferably 0.1% by weight or more, more preferably 1% by weight or more, even more preferably 2% by weight or more, particularly preferably 5% by weight or more, most preferably 10% by weight or more, preferably 80% by weight or less, more preferably 60% by weight or less, and even more preferably 50% by weight or less. When the content of the above resin particles or the above metal coating particles is above the lower limit and below the upper limit, the effects of the present invention can be exhibited more effectively, and the conductivity reliability of the connection structure after the thermal cycle can be further improved.

[0129] The conductive particles may be solder particles or metal particles. The metal particles may be metal powder. The conductive particles may comprise a base material particle and a conductive portion disposed on the surface of the base material particle. From the viewpoint of further improving the conductivity reliability of the connection structure after the thermal cycle, the conductive particles are preferably solder particles. From the viewpoint of further improving the conductivity reliability of the connection structure after the thermal cycle, the resin material is preferably further comprising solder particles. From the viewpoint of further improving the conductivity reliability of the connection structure after the thermal cycle, the resin material is preferably a solder paste containing solder particles. The solder paste contains the above-mentioned components in the resin material.

[0130] The solder particles described above are particles in which both the central portion and the outer surface are made of solder.

[0131] The solder described above is preferably a metal with a melting point of 450°C or less (low melting point metal). The solder particles described above are preferably metal particles with a melting point of 450°C or less (low melting point metal particles). The low melting point metal particles described above are particles containing a low melting point metal. The low melting point metal refers to a metal with a melting point of 450°C or less. The melting point of the low melting point metal is preferably 300°C or less, more preferably 220°C or less, and even more preferably 190°C or less.

[0132] The melting point of the solder particles is preferably 100°C or higher, more preferably 105°C or higher, preferably 250°C or lower, and more preferably 245°C or lower. When the melting point of the solder particles is above the lower limit and below the upper limit, the cohesiveness of the solder during conductive connection can be more effectively enhanced. When the melting point of the solder particles is above the lower limit and below the upper limit, the conductivity reliability and insulation reliability can be more effectively enhanced when electrodes are electrically connected using a resin material (conductive material). The range of the melting point of the solder particles can be set by appropriately selecting the lower limit and upper limit values.

[0133] The melting point of the solder particles mentioned above can be determined by differential scanning calorimetry (DSC). Examples of differential scanning calorimetry (DSC) equipment include the "EXSTAR DSC7020" manufactured by SII Corporation.

[0134] Furthermore, the solder particles preferably contain tin. The tin content in 100% by weight of the metal contained in the solder particles is preferably 30% by weight or more, more preferably 40% by weight or more, even more preferably 70% by weight or more, and particularly preferably 90% by weight or more. When the tin content in the solder particles is above the lower limit, the reliability of the connection between the solder and the electrode can be more effectively improved. The tin content in 100% by weight of the metal contained in the solder particles may be 100% by weight or less, or less than 100% by weight. The range of the tin content in 100% by weight of the metal contained in the solder particles can be set by appropriately selecting the lower limit and upper limit values.

[0135] The tin content can be measured using a high-frequency inductively coupled plasma emission spectrometer (Horiba, Ltd. "ICP-AES") or an X-ray fluorescence analyzer (Shimadzu Corporation "EDX-800HS"), etc.

[0136] By using the above-mentioned solder particles, the solder melts and joins to the electrodes, and the soldered portion creates electrical conductivity between the electrodes. For example, because the soldered portion and the electrodes are more likely to make surface contact rather than point contact, the connection resistance is reduced. Furthermore, by using the above-mentioned solder particles, the bonding strength between the soldered portion and the electrodes is increased, resulting in a further reduction in the likelihood of delamination between the soldered portion and the electrodes, thereby more effectively improving conductivity reliability and connection reliability.

[0137] The low-melting-point metal constituting the solder particles described above is not particularly limited. The low-melting-point metal is preferably tin or a tin-containing alloy. Examples of such alloys include tin-silver alloys, tin-copper alloys, tin-silver-copper alloys, tin-bismuth alloys, tin-zinc alloys, and tin-indium alloys. Because of their excellent wettability to electrodes, the low-melting-point metal is preferably tin, a tin-silver alloy, a tin-silver-copper alloy, a tin-bismuth alloy, or a tin-indium alloy. More preferably, the low-melting-point metal is a tin-bismuth alloy or a tin-indium alloy.

[0138] The solder particles described above are preferably filler materials with a liquidus temperature of 450°C or lower, based on JIS Z3001: Welding Terminology. Examples of the composition of the solder particles include metal compositions containing zinc, gold, silver, lead, copper, tin, bismuth, indium, etc. The solder particles are preferably lead-free and contain either tin and indium, or tin and bismuth.

[0139] To further effectively enhance the bonding strength between the solder and the electrode, the solder particles may contain metals such as nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese, chromium, molybdenum, and palladium. Furthermore, from the viewpoint of further enhancing the bonding strength between the solder and the electrode, it is preferable that the solder particles contain nickel, copper, antimony, aluminum, or zinc. From the viewpoint of further effectively enhancing the bonding strength between the solder and the electrode, the content of these metals for enhancing bonding strength is preferably 0.0001% by weight or more, and preferably 1% by weight or less, out of 100% by weight of the metal contained in the solder particles.

[0140] The average particle size of the solder particles is preferably 0.01 μm or more, more preferably 0.03 μm or more. When the average particle size of the solder particles is above the lower limit, the solder can be arranged on the electrode more efficiently. The average particle size of the solder particles may be 10 μm or less, 5 μm or less, or 3 μm or less. The range of the average particle size of the solder particles can be set by appropriately selecting the lower limit and upper limit values.

[0141] The average particle diameter of the solder particles mentioned above is the number-average particle diameter. The average particle diameter of the solder particles can be determined, for example, by observing 50 arbitrary solder particles with an electron microscope or optical microscope and calculating the average particle diameter of each solder particle, or by performing laser diffraction particle size distribution measurement. In observation with an electron microscope or optical microscope, the particle diameter of a single solder particle is determined as the particle diameter at the equivalent diameter of a circle. In observation with an electron microscope or optical microscope, the average particle diameter at the equivalent diameter of a circle of any 50 solder particles is approximately equal to the average particle diameter at the equivalent diameter of a sphere. In laser diffraction particle size distribution measurement, the particle diameter of a single solder particle is determined as the particle diameter at the equivalent diameter of a sphere. It is preferable to calculate the average particle diameter of the solder particles using laser diffraction particle size distribution measurement.

[0142] The coefficient of variation (CV value) of the particle size of the solder particles is preferably 40% or less, more preferably 30% or less. When the coefficient of variation of the particle size of the solder particles is below the upper limit, the solder can be arranged on the electrode more efficiently. The coefficient of variation (CV value) of the particle size of the solder particles may be 0% or more, 1% or more, 5% or more, or 10% or more. However, the CV value of the particle size of the solder particles may be less than 5%. The range of the coefficient of variation of the particle size of the solder particles can be set by appropriately selecting the lower limit and upper limit values.

[0143] The coefficient of variation (CV value) mentioned above can be measured as follows.

[0144] CV value (%) = (ρ / Dn) × 100 ρ: Standard deviation of the particle size of solder particles Dn: Average particle size of solder particles

[0145] The shape of the solder particles is not particularly limited. The shape of the solder particles may be spherical, or it may be a shape other than spherical, such as flattened.

[0146] In 100% by weight of the above resin material (solder paste), the content of the above solder particles is preferably 1% by weight or more, more preferably 2% by weight or more, even more preferably 10% by weight or more, particularly preferably 20% by weight or more, most preferably 30% by weight or more, preferably 80% by weight or less, more preferably 60% by weight or less, and even more preferably 50% by weight or less. When the content of the above solder particles is above the lower limit and below the upper limit, solder can be arranged on the electrodes more efficiently, it is easy to arrange a large amount of solder between the electrodes, and the conductivity reliability of the connection structure after the thermal cycle can be more effectively improved. From the viewpoint of more effectively improving conductivity reliability, a higher content of the above solder particles is preferable.

[0147] The binder resin described above is not particularly limited. Known insulating resins can be used as the binder resin. The binder resin preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably a curable component. Examples of the curable component include photocurable components and thermosetting components. The photocurable component preferably contains a photocurable compound and a photopolymerization initiator. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent. Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. Only one type of binder resin may be used, or two or more types may be used in combination.

[0148] Examples of vinyl resins include vinyl acetate resin, acrylic resin, and styrene resin. Examples of thermoplastic resins include polyolefin resin, ethylene-vinyl acetate copolymer, and polyamide resin. Examples of curable resins include epoxy resin, urethane resin, polyimide resin, and unsaturated polyester resin. The curable resin may be a room-temperature curing resin, a thermosetting resin, a photocuring resin, or a moisture-curing resin. The curable resin may be used in combination with a curing agent. Examples of thermoplastic block copolymers include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, and hydrogenated styrene-isoprene-styrene block copolymer. Examples of elastomers include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

[0149] In addition to the resin particles or metal-coated particles and the binder resin, the above-mentioned resin material may also contain various additives such as fillers, bulking agents, softeners, plasticizers, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents, and flame retardants.

[0150] A conventionally known dispersion method can be used to disperse the resin particles or metal-coated particles in the binder resin. Examples of methods for dispersing the resin particles or metal-coated particles in the binder resin include the following: A method in which the resin particles or metal-coated particles are added to the binder resin and then mixed and dispersed using a planetary mixer or the like. A method in which the resin particles or metal-coated particles are uniformly dispersed in water or an organic solvent using a homogenizer or the like, then added to the binder resin and mixed and dispersed using a planetary mixer or the like. A method in which the binder resin is diluted with water or an organic solvent, then the resin particles or metal-coated particles are added and mixed and dispersed using a planetary mixer or the like.

[0151] The viscosity (η25) of the above resin material at 25°C is preferably 30 Pa·s or more, more preferably 50 Pa·s or more, preferably 400 Pa·s or less, and more preferably 300 Pa·s or less. When the viscosity of the above resin material at 25°C is above the lower limit and below the upper limit, the reliability of the connection between electrodes can be more effectively improved. The viscosity (η25) can be appropriately adjusted depending on the type and amount of the compounding components.

[0152] The viscosity (η25) mentioned above is measured, for example, using an E-type viscometer under conditions of 25°C and 10 rpm. Examples of such E-type viscometers include the "VISCOMETER TV-22" manufactured by Toki Sangyo Co., Ltd.

[0153] In 100% by weight of the above resin material, the content of the above binder resin is preferably 10% by weight or more, more preferably 30% by weight or more, even more preferably 50% by weight or more, particularly preferably 70% by weight or more, preferably 99.99% by weight or less, even more preferably 99.9% by weight or less, even more preferably 99% by weight or less, even more preferably 98% by weight or less, even more preferably 90% by weight or less, even more preferably 80% by weight or less, particularly preferably 70% by weight or less, and most preferably 65% ​​by weight or less. When the content of the above binder resin is above the lower limit and below the upper limit, the effects of the present invention can be exhibited more effectively, and the conductivity reliability of the connection structure after the thermal cycle can be further improved. Furthermore, when the content of the above binder resin is above the lower limit and below the upper limit, conductive particles or metal-coated particles are efficiently arranged between electrodes, and the connection reliability of the connected members connected by the resin material is further improved.

[0154] (Connection structure) By using the aforementioned resin particles to connect the members to be connected, a connecting structure can be obtained.

[0155] The connection structure using the above resin particles comprises a first member to be connected, a second member to be connected, and a connecting portion connecting the first member to be connected and the second member to be connected. In the above connection structure, the connecting portion contains the above resin particles or the above metal-coated particles. In the above connection structure, it is preferable that the connecting portion is formed of the above resin particles or the above metal-coated particles, or formed of a composition containing the above resin particles.

[0156] Furthermore, a connecting structure can be obtained by connecting the members to be connected using a conductive material containing the aforementioned resin particles or metal-coated particles, a binder resin, and conductive particles.

[0157] The above-described connection structure, having the above configuration, can improve the gap controllability of the connection structure when exposed to high-temperature environments, and can also improve the conductivity reliability after thermal cycling.

[0158] The connection structure using the above resin particles or the above metal-coated particles comprises a first connection target member having a first electrode on its surface, a second connection target member having a second electrode on its surface, and a connection portion connecting the first connection target member and the second connection target member. In the above connection structure, the connection portion contains the above resin particles. In the above connection structure, it is preferable that the connection portion is formed of a resin material (conductive material) containing the above resin particles or the above metal-coated particles, conductive particles and a binder resin. It is preferable that the conductive particles are solder particles. It is preferable that the resin material is a solder paste containing solder particles. When the connection portion is formed of a resin material (conductive material) containing the above resin particles or the above metal-coated particles, conductive particles and a binder resin, it is preferable that the first electrode and the second electrode are electrically connected by the conductive particles in the above connection structure. When the above-mentioned connection portion is formed of a resin material (solder paste) containing the resin particles or the metal-coated particles, solder particles, and binder resin, it is more preferable that the first electrode and the second electrode are electrically connected by a solder portion in the connection structure.

[0159] From the viewpoint of further improving conductivity reliability after thermal cycling and enhancing the dispersibility of each component in the conductive material, it is more preferable that the connection portion of the above-mentioned connection structure is formed of a resin material (conductive material) containing the metal-coated particles, conductive particles, and binder resin. From the viewpoint of further improving conductivity reliability after thermal cycling and enhancing the dispersibility of each component in the conductive material, it is even more preferable that the connection portion of the above-mentioned connection structure is formed of a resin material (solder paste) containing the metal-coated particles, solder particles, and binder resin.

[0160] Figure 3 is a cross-sectional view showing an example of a connecting structure obtained using resin particles according to the first embodiment of the present invention.

[0161] The connecting structure 41 shown in Figure 3 comprises a first member to be connected 42, a second member to be connected 43, and a connecting portion 44 that connects the first member to be connected 42 and the second member to be connected 43. The connecting portion 44 is formed from a resin material (solder paste) containing resin particles 1, solder particles, and binder resin. The resin particles 1 are used as spacers. The resin particles 1 control the distance between the first member to be connected 42 and the second member to be connected 43.

[0162] Figure 4 is a cross-sectional view showing an example of a connecting structure obtained using metal-coated particles with resin particles according to the first embodiment of the present invention.

[0163] The connecting structure 51 shown in Figure 4 comprises a first member to be connected 42, a second member to be connected 43, and a connecting portion 44 that connects the first member to be connected 42 and the second member to be connected 43. The connecting portion 44 is formed from a resin material (solder paste) containing metal-coated particles 11, solder particles, and a binder resin. The metal-coated particles 11 are used as spacers. The distance between the first member to be connected 42 and the second member to be connected 43 is controlled by the metal-coated particles 11.

[0164] In the connecting structures 41 and 51, the connecting portion 44 has a solder portion 3 formed by the aggregation and joining of multiple solder particles, and a resin portion 4 formed by a binder resin. When the binder resin contains a curable component, it is preferable that the resin portion is the cured portion of the binder resin.

[0165] The first connection target member 42 has a plurality of first electrodes 42a on its surface (top surface). The second connection target member 43 has a plurality of second electrodes 43a on its surface (bottom surface). The first electrodes 42a and the second electrodes 43a are electrically connected by the solder portion 3. Therefore, the first connection target member 42 and the second connection target member 43 are electrically connected by the solder portion 3. In the connection portion 44, there is no solder in a region (resin portion 4) different from the solder portion 3 that has accumulated between the first electrodes 42a and the second electrodes 43a. In a region (resin portion 4) different from the solder portion 3, there is no solder separate from the solder portion 3. However, if it is a small amount, solder may be present in a region (resin portion 4) different from the solder portion 3 that has accumulated between the first electrodes 42a and the second electrodes 43a.

[0166] As shown in Figures 3 and 4, in the connection structures 41 and 51, multiple solder particles accumulate between the first electrode 42a and the second electrode 43a. After the multiple solder particles melt, the molten solder particles wet and spread across the surface of the electrodes before solidifying, forming the solder portion 3. As a result, the contact area between the solder portion 3 and the first electrode 42a, and between the solder portion 3 and the second electrode 43a, becomes larger. In other words, by using solder particles, the contact area between the solder portion 3 and the first electrode 42a, and between the solder portion 3 and the second electrode 43a becomes larger compared to the case where conductive particles with a metal outer surface portion such as nickel, gold, or copper are used. Therefore, the conductivity reliability and connection reliability of the connection structures 41 and 51 after the thermal cycle are improved.

[0167] The method for manufacturing the above-mentioned connection structure is not particularly limited. One example of a method for manufacturing the connection structure is to place the resin material (conductive material) between a first connection target member and a second connection target member to obtain a laminate, and then heat and pressurize the laminate. The pressure during pressurization is preferably 40 MPa or more, more preferably 60 MPa or more, preferably 90 MPa or less, and more preferably 70 MPa or less. If the conductive material is a solder paste containing solder particles, the connection structure may be manufactured without pressurizing the laminate. The temperature during heating is preferably 80°C or more, more preferably 100°C or more, preferably 250°C or less, and more preferably 190°C or less.

[0168] The first and second connection targets described above are not particularly limited. Specifically, the first and second connection targets include electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors, and diodes, as well as electronic components such as resin films, printed circuit boards, flexible printed circuit boards, flexible flat cables, rigid-flexible circuit boards, glass epoxy circuit boards, and glass circuit boards. It is preferable that the first and second connection targets are electronic components.

[0169] The above-mentioned resin material is preferably a conductive material for connecting electronic components. The above-mentioned resin material is preferably a paste-like conductive material, and is preferably applied to the members to be connected in a paste-like state.

[0170] The above-mentioned resin particles, resin material, and circuit connection material are also suitably used in touch panels. Therefore, the connection target member is preferably a flexible substrate or a connection target member in which electrodes are arranged on the surface of a resin film. The connection target member is preferably a flexible substrate, and preferably a connection target member in which electrodes are arranged on the surface of a resin film. When the flexible substrate is a flexible printed circuit board or the like, the flexible substrate generally has electrodes on its surface.

[0171] Examples of electrodes provided on the above-mentioned connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the above-mentioned connection target member is a flexible printed circuit board, the electrodes are preferably gold electrodes, nickel electrodes, tin electrodes, silver electrodes, or copper electrodes. When the above-mentioned connection target member is a glass substrate, the electrodes are preferably aluminum electrodes, copper electrodes, molybdenum electrodes, or tungsten electrodes. In the case of aluminum electrodes, the electrodes may be made solely of aluminum, or they may be electrodes in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of materials for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

[0172] Furthermore, the resin particles can be suitably used as spacers for liquid crystal display elements. When the resin particles are used as spacers for liquid crystal display elements, the gap can be effectively controlled, and damage to the substrate can be prevented. The first connection target member may be a first liquid crystal display element member. The second connection target member may be a second liquid crystal display element member. The connection portion may be a sealing portion that seals the outer circumference of the first liquid crystal display element member and the second liquid crystal display element member when the first liquid crystal display element member and the second liquid crystal display element member are facing each other.

[0173] The above resin particles can also be used as a peripheral sealant for liquid crystal display elements. The liquid crystal display element comprises a first liquid crystal display element member and a second liquid crystal display element member. The liquid crystal display element further comprises a sealing portion that seals the outer periphery of the first liquid crystal display element member and the second liquid crystal display element member when the first liquid crystal display element member and the second liquid crystal display element member are facing each other, and liquid crystal disposed inside the sealing portion between the first liquid crystal display element member and the second liquid crystal display element member. In this liquid crystal display element, a liquid crystal drop method is applied, and the sealing portion is formed by heat curing a sealant for the liquid crystal drop method.

[0174] The present invention will be specifically described below with reference to examples and comparative examples. The present invention is not limited to the following examples.

[0175] The following materials were prepared.

[0176] (Polymerizable components) Divinylbenzene (NS Styrene Monomer Co., Ltd. "DVB960") Styrene ("Styrene Monomer" manufactured by NS Styrene Monomer Co., Ltd.) Methyl methacrylate (Mitsubishi Chemical Corporation's "Acryester M", one (meth)acryloyl group) Ethylene glycol dimethacrylate (Mitsubishi Chemical Corporation's "Acryester ED", with two (meth)acryloyl groups) Trimethylolpropane trimethacrylate (manufactured by Tokyo Chemical Industry Co., Ltd., with 3 (meth)acryloyl groups) Pentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., "A-TMMT", with 4 (meth)acryloyl groups) Dipentaerythritol polyacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., "A-DPH", with 5-6 (meth)acryloyl groups)

[0177] (Other components (solvents)) Toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0178] (Polymerization initiator) Benzoyl peroxide (BPO, manufactured by Tokyo Chemical Industry Co., Ltd.)

[0179] (Example 1) (1) Preparation of resin particles 80 parts by weight of divinylbenzene (80% by weight of 100% polymerizable component) was added to 20 parts by weight of pentaerythritol tetraacrylate (20% by weight of 100% polymerizable component) and stirred to obtain a monomer solution. Next, 1 part by weight of a polymerization initiator (benzoyl peroxide) was added to the obtained monomer solution and stirred until homogeneous to obtain a monomer mixture. 200 parts by weight of a 1.0% aqueous solution of polyvinyl alcohol with a molecular weight of approximately 2000 dissolved in pure water was placed in a reaction vessel. The obtained monomer mixture was added to this and stirred until the monomer droplets reached a predetermined particle size. Next, the mixture was heated at 90°C for 9 hours to carry out the polymerization reaction of the monomer droplets and obtain particles. The obtained particles were washed three times with hot water and acetone, respectively, and then the resin particles were recovered by classification.

[0180] (2) Preparation of metal-coated particles 10 parts by weight of the above resin particles were dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of palladium catalyst solution using an ultrasonic disperser, and the resin particles were extracted by filtering the solution. Next, the resin particles were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surface of the resin particles. After thoroughly washing the activated resin particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain dispersion A.

[0181] In addition, a nickel plating solution (1) (pH 8.5) was prepared containing 0.14 mol / L nickel sulfate, 0.46 mol / L dimethylamine borane, and 0.2 mol / L sodium citrate.

[0182] The above dispersion A, containing 10 parts by weight of resin particles, was stirred at 70°C while nickel plating solution (1) was added dropwise at a dropping rate of 30 mL / min for 10 minutes. Subsequently, the solution was added dropwise at a dropping rate of 10 mL / min for 40 minutes, and then dropwise at a dropping rate of 4 mL / min for 80 minutes, thereby controlling the boron content incorporated into the plating film while performing electroless nickel-boron alloy plating. After that, the obtained dispersion was filtered to remove the particles, which were washed with water and dried to obtain metal-coated particles in which a metal coating layer (nickel layer) was arranged on the surface of the resin particles.

[0183] (3) Preparation of resin materials The following materials were mixed to obtain a mixture: 20 parts by weight of resin particles; 21 parts by weight of solder particles (Sn-Bi solder alloy manufactured by Senju Metal Industry Co., Ltd.); 25 parts by weight of bisphenol A type phenoxy resin; 4 parts by weight of fluorene type epoxy resin; 30 parts by weight of phenol novolac type epoxy resin; and SI-60L (manufactured by Sanshin Chemical Industry Co., Ltd.). The obtained mixture was degassed and stirred for 3 minutes to obtain resin material (conductive paste, solder paste) A containing resin particles. Furthermore, resin material (conductive paste, solder paste) B containing metal-coated particles was obtained in the same manner as resin material A, except that the resin particles were replaced with metal-coated particles.

[0184] (4) Fabrication of connecting structures An LGA substrate with a pad size of 0.5 mm x 0.5 mm and a semiconductor chip were prepared. On the LGA substrate, the obtained resin materials (conductive paste and solder paste) A and B were screen printed, respectively, to form a solder paste layer. Next, the semiconductor chip was stacked on the solder paste layer so that the electrodes faced each other. Then, reflow soldering was performed at 160°C to cure the solder paste layer and obtain connection structures A and B. No pressure was applied during the reflow soldering.

[0185] (Examples 2-12, 14 and Comparative Examples 2-4) Resin particles, metal-coated particles, resin materials A and B, and connecting structures A and B were prepared in the same manner as in Example 1, except that the type and content (weight %) of polymerizable components, the average particle size and CV value of the resin particles, and the type and thickness of the metal coating layer were set as shown in Tables 1 to 4. The average particle size and CV value of the resin particles were adjusted by classification.

[0186] (Example 13) (1) Preparation of resin particles Resin particles were prepared in the same manner as in Example 1, except that the type and content (weight %) of polymerizable components were changed as shown in Table 3.

[0187] (2) Preparation of metal-coated particles Formation of the first metal coating layer: Particle A was obtained in which a first metal coating layer (nickel layer, 100 nm thick) was placed on the surface of a resin particle.

[0188] Formation of the second metal coating layer: Ten parts by weight of the obtained particles A were dispersed in 500 parts by weight of deionized water using an ultrasonic device to obtain suspension B. A tin plating solution (1) (adjusted to pH 8.5 with sodium hydroxide) containing 15 g / L of tin sulfate, 70 g / L of ethylenediaminetetraacetic acid, 30 g / L of sodium gluconate, and 1.5 g / L of phosphinic acid was prepared. In addition, a reducing solution A (adjusted to pH 10.0 with sodium hydroxide) containing 5 g / L of sodium borohydride was prepared.

[0189] The obtained suspension B was stirred at 55°C, and the tin plating solution (1) was gradually added to the suspension B. Electroless tin plating was then performed by reducing the suspension with reducing solution A to form a second metal coating layer. Metal-coated particles were obtained in which a second metal coating layer (tin layer, 100 nm thick) was placed on the surface of the first metal coating layer. Resin materials A and B and connecting structures A and B were fabricated in the same manner as in Example 1, except that the obtained metal-coated particles were used.

[0190] (Comparative Example 1) 44.95 parts by weight of divinylbenzene (50% by weight of polymerizable component out of 100% by weight) was mixed with 44.95 parts by weight of pentaerythritol tetraacrylate (50% by weight of polymerizable component out of 100% by weight) and stirred to obtain a monomer solution. Next, 10.1 parts by weight of solvent (toluene) was added to the obtained monomer solution and stirred until homogeneous to obtain a monomer mixture. 200 parts by weight of a 1.0% aqueous solution of polyvinyl alcohol with a molecular weight of approximately 2000 dissolved in pure water was placed in a reaction vessel. The obtained monomer mixture was added to this and stirred until the monomer droplets reached a predetermined particle size. Next, the mixture was heated at 90°C for 9 hours to carry out the polymerization reaction of the monomer droplets to obtain porous resin particles. Metal-coated particles, resin materials A and B, and connecting structures A and B were prepared in the same manner as in Example 1, except that the obtained resin particles were used.

[0191] (evaluation) (1) Viscosity of the polymerizable mixture The viscosity of the polymerizable component mixture (before polymerization) was measured using an E-type viscometer (VISCOMETER TV-22, manufactured by Toki Sangyo Co., Ltd.) at 25°C and 5 rpm.

[0192] (2) 20%K values ​​of resin particles at 25°C and 200°C The 20%K values ​​of the obtained resin particles at 25°C and 200°C were measured using a micro-compression tester (ENT-5, manufactured by Elionix Corporation) according to the method described above. The ratio (20%K value at 25°C / 20%K value at 200°C) was also calculated.

[0193] (3) Amount of outgassing when resin particles are heated at 250°C for 10 minutes The amount of outgassing of the obtained resin particles was measured when the resin particles were heated at 250°C for 10 minutes using the method described above.

[0194] (4) Gap controllability (resin particles) The connecting structure A, obtained using resin particles, was heated in an oven to 250°C and left at that temperature for 1 hour. The minimum and maximum thicknesses of the connecting portion (cured conductive paste layer) were measured using a scanning electron microscope (SEM). The gap controllability (resin particles) was evaluated according to the following criteria.

[0195] [Criteria for determining gap controllability (resin particles)] ○○○: Maximum thickness is less than 1.1 times the minimum thickness ○○: The maximum thickness is 1.1 times or more but less than 1.3 times the minimum thickness. ○: Maximum thickness is 1.3 times or more but less than 1.5 times the minimum thickness. ×: Maximum thickness is 1.5 times or more than the minimum thickness

[0196] (5) Gap controllability (metal coated particles) The connecting structure B obtained using metal-coated particles was heated to 250°C in an oven and left at that temperature for 1 hour. The minimum and maximum thicknesses of the connecting portion (cured conductive paste layer) were measured using a scanning electron microscope (SEM). The gap controllability (metal-coated particles) was evaluated according to the following criteria.

[0197] [Criteria for determining gap controllability (metal-coated particles)] ○○○: Maximum thickness is less than 1.1 times the minimum thickness ○○: The maximum thickness is 1.1 times or more but less than 1.3 times the minimum thickness. ○: Maximum thickness is 1.3 times or more but less than 1.5 times the minimum thickness. ×: Maximum thickness is 1.5 times or more than the minimum thickness

[0198] (6) Conductivity reliability after thermal cycling (resin particles) A thermal cycling test was conducted on a connection structure A obtained using resin particles, in which the process of heating from -20°C to 100°C and then cooling back to -20°C was repeated 1000 times, with each cycle being considered one cycle. After the thermal cycling, the connection resistance A per connection point between the upper and lower electrodes of connection structure A was measured using the four-terminal method. Note that, from the relationship voltage = current × resistance, the connection resistance can be determined by measuring the voltage when a constant current is flowing. The conductivity reliability (resin particles) after the thermal cycling was judged according to the following criteria.

[0199] [Criteria for determining conductivity reliability (resin particles) after thermal cycling] ○○○: Connection resistance A is 5mΩ or less ○○: Connection resistance A is greater than 5mΩ and less than or equal to 7mΩ. ○: Connection resistance A is greater than 7mΩ and less than or equal to 10mΩ. ×: Connection resistance A exceeds 10mΩ, or a connection failure has occurred.

[0200] (7) Conductivity reliability after thermal cycling (metal-coated particles) A thermal cycling test was conducted on connection structure B obtained using metal-coated particles, in which the process of heating from -20°C to 100°C and then cooling back to -20°C was repeated 1000 times, with each cycle being considered one cycle. After the thermal cycling, the connection resistance B per connection point between the upper and lower electrodes of connection structure B was measured using the four-terminal method. Note that, from the relationship voltage = current × resistance, the connection resistance can be determined by measuring the voltage when a constant current is flowing. The conductivity reliability (metal-coated particles) after the thermal cycling was judged according to the following criteria.

[0201] [Criteria for determining conductivity reliability (metal-coated particles) after thermal cycling] ○○○: Connection resistance B is 5mΩ or less ○○: Connection resistance B is greater than 5mΩ and less than or equal to 7mΩ. ○: Connection resistance B is greater than 7mΩ and less than or equal to 10mΩ. ×: Connection resistance B exceeds 10mΩ, or a connection failure has occurred.

[0202] The composition and results of the resin particles and metal-coated particles are shown in Tables 1 to 4 below.

[0203] [Table 1]

[0204] [Table 2]

[0205] [Table 3]

[0206] [Table 4]

[0207] Furthermore, Examples 6 (particle size 1 μm), 7 (particle size 5 μm), 8 (particle size 10 μm), 3 (particle size 30 μm), and 9 (particle size 50 μm), in which only the particle size of the resin particles was changed, are shown in Table 5 below.

[0208] [Table 5]

[0209] From the results shown in Table 5 above, it can be seen that if 1) a specific polymerizable component is used, and 2) the compressive modulus of the resin particles is within a specific range, and 3A) the particle diameter of the resin particles is 5 μm or larger, the gap controllability of the connecting structure when exposed to high-temperature environments can be further improved compared to the case where the particle diameter of the resin particles is less than 5 μm. Furthermore, if 1) a specific polymerizable component is used, and 2) the compressive modulus of the resin particles is within a specific range, and 3B) the particle diameter of the resin particles is 20 μm or larger, the gap controllability of the connecting structure when exposed to high-temperature environments can be further improved compared to the case where the particle diameter of the resin particles is less than 20 μm.

[0210] Furthermore, while the gap control performance (resin particles) results for both Example 7 (particle size 5 μm) and Example 8 (particle size 10 μm) were "○○", the maximum thickness / minimum thickness values ​​in the evaluation of gap control performance (resin particles) were smaller for Example 8 than for Example 7, indicating that Example 8 had superior gap control performance (resin particles) compared to Example 7. Similarly, while the gap control performance (metal-coated particles) results for both Example 7 (particle size 5 μm) and Example 8 (particle size 10 μm) were "○○", the maximum thickness / minimum thickness values ​​in the evaluation of gap control performance (metal-coated particles) were smaller for Example 8 than for Example 7, indicating that Example 8 had superior gap control performance (metal-coated particles) compared to Example 7.

[0211] Furthermore, the results shown in Table 5 above indicate that if 1) a specific polymerizable component is used, and 2) the compressive modulus of the resin particles is within a specific range, and 3C) the particle size of the resin particles is 10 μm or larger, the conductivity reliability of the connection structure after the thermal cycle can be significantly improved compared to the case where the particle size of the resin particles is less than 10 μm. [Explanation of symbols]

[0212] 1… Resin particles 2...Metal coating layer 3... Soldering section 4… Resin part 11...metal coated particles 41, 51… Connection Structures 42...First connection target member 42a...First electrode 43...Second connection target member 43a...Second electrode 44...Connection part

Claims

1. It is a paste-like conductive paste, It contains metal-coated particles and a binder resin. The metal-coated particles are dispersed in the binder resin. The metal-coated particles are metal-coated particles comprising resin particles containing a polymerizable polymer and a metal coating layer disposed on the surface of the resin particles. The polymerizable component comprises divinylbenzene and a (meth)acrylate compound having four or more (meth)acryloyl groups. The compressive modulus of the aforementioned resin particles when compressed by 20% at 200°C is 1000 N / mm². ２ That's all. A conductive paste wherein the metal coating layer has only one layer, and the one layer is a nickel layer, or has multiple layers, and the outermost layer is a nickel layer.

2. The conductive paste according to claim 1, wherein the total content of the divinylbenzene and the (meth)acrylate compound having four or more (meth)acryloyl groups is 80% by weight or more of the polymerizable component.

3. The conductive paste according to claim 1 or 2, wherein the weight ratio of the content of divinylbenzene in the polymerizable component to the content of the (meth)acrylate compound having four or more (meth)acryloyl groups in the polymerizable component is 0.40 or more and 1.70 or less.

4. The conductive paste according to claim 1 or 2, wherein the amount of outgassing when the resin particles are heated at 250°C for 10 minutes is 1000 ppm or less.

5. The conductive paste according to claim 1 or 2, wherein the particle size of the resin particles is 1 μm or more and 100 μm or less.

6. The conductive paste according to claim 5, wherein the particle size of the resin particles is 5 μm or more and 100 μm or less.

7. The conductive paste according to claim 6, wherein the particle size of the resin particles is 20 μm or more and 100 μm or less.

8. The conductive paste according to claim 1 or 2, wherein the thickness of the metal coating layer is 0.2 μm or more.

9. The conductive paste according to claim 1 or 2, wherein the thickness of the metal coating layer is 0.3 μm or less.

10. The conductive paste according to claim 1 or 2, wherein the conductive paste is a solder paste containing solder particles.

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