Conductive paste, high-thermal-conductivity material, and semiconductor device

Abstract

To provide a conductive paste capable of yielding a cured product (high-thermal-conductivity material) that is excellent in thermal conductivity as well as in adhesion strength and connection reliability.SOLUTION: The conductive paste of the present invention contains: particles having a surface composed of silver; and an adhesion promoter. The adhesion promoter contains a compound represented by the general formula (1) in the figure.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a conductive paste containing an adhesion promoter, a highly thermally conductive material, and a semiconductor device.

Background Art

[0002] Semiconductor devices in which a semiconductor element is mounted on a lead frame and molded with resin are widely used. For example, semiconductor elements such as ICs and LSIs are mounted on a metal piece such as a lead frame, fixed using a conductive paste called a die attach paste, and then the lead portion of the lead frame and the electrodes on the semiconductor element are connected by fine wires (bonding wires). Next, these are housed in a package to form a semiconductor product. In addition, an optoelectronic semiconductor device using a light-emitting diode (LED) or the like that has been put into practical use for various display purposes or the like is manufactured by bonding an optoelectronic semiconductor element to a predetermined portion on a lead frame or a resin substrate with a conductive paste or the like and then sealing it with a transparent encapsulating resin or the like (for example, Patent Document 1).

[0003] Patent Document 2 discloses a resin composition containing polyrotaxane, conductive particles, and a conductive resin composition containing an adhesion promoter, and examples of the adhesion promoter include silane coupling agents.

[0004] Patent Document 3 discloses an adhesive additive containing a triazine compound having a predetermined structure. The document describes that when this adhesive additive is added to a thermosetting resin composition for a sealing material, the adhesion of the cured resin composition to a metal can be improved. In the comparative examples of the document, it is shown that when a specific triazine-based adhesive additive is used, the adhesive force to copper is low.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] However, when joining a semiconductor chip and a metal surface such as copper or nickel using the conductive resin composition described in Patent Document 2, there was room for improvement in thermal conductivity, adhesion strength, and connection reliability. In the prior art, a conductive paste using an adhesion aid sometimes had a reduced thermal conductivity. Further, Patent Document 3 is a technology related to a sealing material and is not described as being used for a conductive paste. [Means for Solving the Problems]

[0007] The present inventors have found that by including a predetermined triazine-based compound in a conductive paste, a cured product excellent in thermal conductivity and having excellent adhesion strength and connection reliability with a metal can be obtained, and have completed the present invention.

[0008] That is, the present invention can be shown as follows. [1] Particles whose surface is made of silver, an adhesion aid, and the adhesion aid contains a compound represented by the following general formula (1), a conductive paste. [Chemical Formula] (In general formula (1), Q is a divalent linking group.) [2] The conductive paste according to [1], further including at least one selected from an epoxy resin and an acrylic resin. [3] The conductive paste according to [1] or [2], further including a curing agent. [4] The conductive paste according to any one of [1] to [3], wherein the die shear strength measured according to the following Measuring Method 1 is 20.0 N / (3 mm × 3 mm) or more and 60.0 N / (3 mm × 3 mm) or less. <Measuring Method 1> Apply the conductive paste onto a silver-plated copper substrate to form a coating film, and place a 3 mm × 3 mm silicon chip with a silver-plated surface on the coating film. Then, raise the temperature from 30°C to 175°C over 30 minutes, and subsequently perform heat treatment at 175°C for 30 minutes. By the above steps, the conductive paste is cured, and the silver-plated surface of the silicon chip is joined to the substrate, which is used as the measurement sample. Thereafter, measure the die shear strength (N / (3 mm × 3 mm)) of the above measurement sample at 260°C using a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000). [5] The conductive paste according to any one of [1] to [3], wherein the die shear strength measured according to the following Measuring Method 2 is 10.0 N / (3 mm × 3 mm) or more and 60.0 N / (3 mm × 3 mm) or less. <Measuring Method 2> Apply the conductive paste onto a silver-plated copper substrate to form a coating film, and place a 3 mm × 3 mm silicon chip with a gold-plated surface on the coating film. Then, raise the temperature from 30°C to 175°C over 30 minutes, and subsequently perform heat treatment at 175°C for 30 minutes. By the above steps, the conductive paste is cured, and the gold-plated surface of the silicon chip is joined to the substrate, which is used as the measurement sample. Thereafter, measure the die shear strength (N / (3 mm × 3 mm)) of the above measurement sample at 260°C using a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000). [6] The conductive paste according to any one of [1] to [3], wherein the die shear strength measured according to the following Measuring Method 3 is 20.0 N / (3 mm × 3 mm) or more and 60.0 N / (3 mm × 3 mm) or less. <Measuring Method 3> Apply a conductive paste onto a copper substrate to form a coating film, and place a 3 mm × 3 mm silicon chip on the coating film. Then, raise the temperature from 30°C to 175°C over 30 minutes, and subsequently perform a heat treatment at 175°C for 30 minutes. By doing so, the conductive paste is cured, and the surface of the silicon chip is joined to the substrate, which is used as a measurement sample. Subsequently, measure the die shear strength (N / (3 mm × 3 mm)) of the above measurement sample at 260°C using a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000). [7] The conductive paste according to any one of [1] to [3], wherein the die shear strength measured according to the following measurement method 4 is 35.0 N / (3 mm × 3 mm) or more and 80.0 N / (3 mm × 3 mm) or less. <Measurement method 4> Apply a conductive paste onto a nickel substrate to form a coating film, and place a 3 mm × 3 mm silicon chip on the coating film. Then, raise the temperature from 30°C to 175°C over 30 minutes, and subsequently perform a heat treatment at 175°C for 30 minutes. By doing so, the conductive paste is cured, and the surface of the silicon chip is joined to the substrate, which is used as a measurement sample. Subsequently, measure the die shear strength (N / (3 mm × 3 mm)) of the above measurement sample at 260°C using a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000). [8] The conductive paste according to any one of [1] to [7], wherein the thermal conductivity measured by the laser flash method is 2.0 W / mK or more and 10.0 W / mK or less. [9] A high thermal conductivity material obtained by curing the conductive paste according to any one of [1] to [8].

[10] A base material, a semiconductor element mounted on the base material via an adhesive layer, and the adhesive layer is formed by curing the conductive paste according to any one of [1] to [8], a semiconductor device.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a conductive paste from which a cured product (high thermal conductivity material) excellent in thermal conductivity and excellent in adhesion strength and connection reliability with a metal can be obtained. In other words, the conductive paste of the present invention is excellent in the balance between thermal conductivity, adhesion strength, and connection reliability. Therefore, a semiconductor device including an adhesive layer made of the conductive paste of the present invention is excellent in product reliability.

Brief Description of Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Also, for example, "1 to 10" represents "1 or more" to "10 or less" unless otherwise specified.

[0012] The conductive paste of the present embodiment contains particles (A) whose surface is made of silver and an adhesion aid (B).

[0013] [Particles (A) whose surface is made of silver] Particles (A) whose surface is made of silver (hereinafter also referred to as silver-containing particles (A)) can cause sintering (sintering) by appropriate heat treatment and form a particle connection structure (sintering structure).

[0014] In particular, when silver-containing particles (A) are contained in the paste-like composition, a sintering structure is likely to be formed even by heat treatment without pressure and at a relatively low temperature (about 180°C).

[0015] The shape of the silver-containing particles (A) is not particularly limited. A preferred shape is spherical, but non-spherical shapes such as ellipsoidal, flat, plate-like, flake-like, needle-like, scaly, aggregated, and polyhedral shapes may also be used. The silver-containing particles (A) can contain at least one kind of silver-containing particles having these shapes.

[0016] The surface of the silver-containing particles (A) may be treated with a carboxylic acid, a saturated fatty acid having 4 to 30 carbon atoms, or a monovalent unsaturated fatty acid having 4 to 30 carbon atoms, a long-chain alkyl nitrile, or the like.

[0017] The silver-containing particles (A) may be (i) particles consisting essentially of only silver, or (ii) particles consisting of silver and components other than silver. Also, (i) and (ii) may be used in combination as the metal-containing particles.

[0018] In the present embodiment, as the silver-containing particles (A), silver-coated resin particles in which the surface of the resin particles is coated with silver can also be used. Thereby, a paste-like composition capable of obtaining a cured product having excellent thermal conductivity and excellent storage elastic modulus can be prepared.

[0019] Since the silver-coated resin particles have a silver surface and a resin interior, they are considered to have good thermal conductivity and to be softer compared to particles composed only of silver. Therefore, it is considered that by using silver-coated resin particles, it is easy to design the thermal conductivity and storage elastic modulus to appropriate values. In the silver-coated resin particles, it is sufficient that at least a part of the surface of the resin particles is covered with a silver layer. Of course, the entire surface of the resin particles may be covered with silver.

[0020] Specifically, in the silver-coated resin particles, the silver layer preferably covers 50% or more, more preferably 75% or more, and even more preferably 90% or more of the surface of the resin particles. Particularly preferably, in the silver-coated resin particles, the silver layer covers substantially all of the surface of the resin particles.

[0021] Examples of the "resin" in the silver-coated resin particles include silicone resin, (meth)acrylic resin, phenol resin, polystyrene resin, melamine resin, polyamide resin, polytetrafluoroethylene resin, and the like. Of course, resins other than these may also be used. Also, the resin may be only one type, or two or more types of resins may be used in combination. From the viewpoints of elastic properties and heat resistance, the resin is preferably a silicone resin or a (meth)acrylic resin.

[0022] The silicone resin may be particles composed of an organopolysiloxane obtained by polymerizing an organochlorosilane such as methylchlorosilane, trimethyltrichlorosilane, or dimethyldichlorosilane. Also, a silicone resin having a three-dimensionally crosslinked structure of the organopolysiloxane as a basic skeleton may be used.

[0023] (Meta)acrylic resin can be a resin obtained by polymerizing a monomer containing (meta)acrylic acid ester as a main component (50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more). Examples of the (meta)acrylic acid ester include at least one compound selected from the group consisting of methyl (meta)acrylate, ethyl (meta)acrylate, propyl (meta)acrylate, butyl (meta)acrylate, 2-ethylhexyl (meta)acrylate, lauryl (meta)acrylate, stearyl (meta)acrylate, cyclohexyl (meta)acrylate, 2-hydroxyethyl (meta)acrylate, 2-propyl (meta)acrylate, chloro-2-hydroxyethyl (meta)acrylate, diethylene glycol mono(meta)acrylate, methoxyethyl (meta)acrylate, glycidyl (meta)acrylate, dicyclopentanyl (meta)acrylate, dicyclopentenyl (meta)acrylate, and isobornyl (meta)acrylate. Further, a small amount of other monomers may be contained in the monomer component of the acrylic resin. Examples of such other monomer components include styrene-based monomers. For the silver-coated (meta)acrylic resin, refer to, for example, the description in JP-A-2017-126463.

[0024] Various functional groups may be introduced into the silicone resin or (meta)acrylic resin. The functional groups that can be introduced are not particularly limited. For example, epoxy group, amino group, methoxy group, phenyl group, carboxyl group, hydroxyl group, alkyl group, vinyl group, mercapto group, etc. can be mentioned. The resin particle portion of the silver-coated resin particles may contain various additive components, such as a low stress modifier.

[0025] The shape of the resin particle portion in the silver-coated resin particles is not particularly limited. Preferably, a combination of spherical shape and non-spherical shapes such as flat shape, plate shape, needle shape, etc. is preferred.

[0026] When using silver-coated resin particles, the proportion of silver-coated resin particles in the total silver-containing particles (A) is preferably 1 to 50% by mass, more preferably 3 to 45% by mass, and even more preferably 5 to 40% by mass. By appropriately adjusting this proportion, it is possible to further enhance the heat dissipation property while suppressing the decrease in adhesive strength due to heat cycles.

[0027] The median diameter D of the silver-containing particles (A) 50 is, for example, 0.001 to 1000 μm, preferably 0.01 to 100 μm, and more preferably 0.1 to 20 μm. By setting D 50 to an appropriate value, it is easy to achieve a balance among heat conductivity, sinterability, resistance to heat cycles, etc. Also, by setting D 50 to an appropriate value, it may be possible to improve the workability of coating / adhesion. The particle size distribution of the silver-containing particles (horizontal axis: particle diameter, vertical axis: frequency) may be unimodal or multimodal.

[0028] The median diameter D of the silver-containing particles (A) 50 is, for example, 0.5 μm or more, preferably 1.5 μm or more, and more preferably 2.0 μm or more. Thereby, it is easy to set the storage elastic modulus E' to an appropriate value.

[0029] Also, the median diameter D of the silver-containing particles (A) 50 is, for example, 20 μm or less, preferably 15 μm or less, and more preferably 10 μm or less. Thereby, it is easy to make the heat conductivity sufficiently large. Using silver-containing particles (A) with different median diameters D 50 in combination can further improve the uniformity of sintering and is preferable from the viewpoint of heat conductivity.

[0030] The median diameter D of the silver-containing particles (A) 50 can be obtained, for example, by performing particle image measurement using a flow-type particle image analyzer FPIA (registered trademark)-3000 manufactured by Sysmex Corporation. More specifically, the particle diameter of the silver-containing particles (A) can be determined by measuring the volume-based median diameter wet using this apparatus.

[0031] The proportion of silver-containing particles (A) in 100 parts by mass of the paste-like composition is, for example, 1 to 98 parts by mass, preferably 30 to 95 parts by mass, more preferably 50 to 90 parts by mass. By setting the proportion of silver-containing particles (A) to 1% by mass or more, it is easy to enhance the thermal conductivity. By setting the proportion of silver-containing particles (A) to 98% by mass or less, the workability of coating / adhesion can be improved.

[0032] Among the silver-containing particles (A), particles consisting essentially of only silver can be obtained, for example, from DOWA High-Tech Co., Ltd., Fukuda Metal Foil & Powder Co., Ltd., etc. Also, silver-coated resin particles can be obtained, for example, from Mitsubishi Materials Corporation, Sekisui Chemical Co., Ltd., Yamano Corporation, etc.

[0033] [Adhesion promoter (B)] In the present embodiment, the adhesion promoter (B) contains a compound (B1) represented by the following general formula (1).

[0034] [Chemical formula]

[0035] In the general formula (1), Q is a divalent linking group. Et represents an ethyl group. Examples of the divalent linking group include a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, a substituted or unsubstituted arylene group, a substituted or unsubstituted heteroarylene group, a carbonyl group, a carbonyloxy group (-COO-), an oxycarbonyl group (-OCO-), a sulfide group, a disulfide group, a sulfonyl group, an -NH- group, a urethane group (-NHC(=O)O-), a urea group (-NHC(=O)NH-), a thiourethane group (-NHC(=O)S-), and a thiourea group (-NHC(=S)NH-), an ether group (-O-), etc.

[0036] Examples of the alkylene group having 1 to 6 carbon atoms include a methylene group, an ethylene group, a propylene group, an n-butylene group, a t-butylene group, a pentylene group, a hexylene group, a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, and a cyclohexylene group.

[0037] Examples of the substituent of the substituted alkylene group having 1 to 6 carbon atoms include a halogen atom, a carboxyl group, a cyano group, a nitro group, a hydroxyl group, an amino group, and a mercapto group.

[0038] By including the compound (B1) as the adhesion aid (B) together with the particles (A) whose surfaces are made of silver, the conductive paste of the present embodiment can obtain a cured product (high thermal conductivity material) that is excellent in thermal conductivity and has excellent adhesion strength and connection reliability with metals. ”

[0039] The compound (B1) is preferably contained in an amount of 0.05 parts by mass or more and 2.0 parts by mass or less, more preferably 0.1 parts by mass or more and 1.0 parts by mass or less, and still more preferably 0.2 parts by mass or more and 0.8 parts by mass or less with respect to 100 parts by mass of the conductive paste. By containing the compound (B1) within the above range, it is more excellent in thermal conductivity, adhesion strength with metals, and connection reliability, and is more excellent in the balance of these properties.

[0040] The adhesion aid (B) can contain other adhesion aids in addition to the compound (B1).

[0041] As other adhesion aids, for example, silane coupling agents such as amino group-containing silane coupling agents, epoxy group-containing silane coupling agents, (meth)acryloyl group-containing silane coupling agents, mercapto group-containing silane coupling agents, vinyl group-containing silane coupling agents, ureido group-containing silane coupling agents, and sulfide group-containing silane coupling agents can be used.

[0042] Examples of the amino group-containing silane coupling agent include bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldiethoxysilane, N-phenyl-γ-amino-propyltrimethoxysilane, and the like.

[0043] Examples of the epoxy group-containing silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidylpropyltrimethoxysilane, and the like.

[0044] Examples of the (meth)acryloyl group-containing silane coupling agent include γ-((meth)acryloyloxypropyl)trimethoxysilane, γ-((meth)acryloyloxypropyl)methyldimethoxysilane, γ-((meth)acryloyloxypropyl)methyldiethoxysilane, and the like. Examples of the mercapto group-containing silane coupling agent include 3-mercaptopropyltrimethoxysilane, and the like.

[0045] Examples of the vinyl group-containing silane coupling agent include vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, and the like. Examples of the ureido group-containing silane coupling agent include 3-ureidopropyltriethoxysilane, and the like.

[0046] Examples of the sulfide group-containing silane coupling agent include bis(3-(triethoxysilyl)propyl) disulfide, bis(3-(triethoxysilyl)propyl) tetrasulfide, and the like.

[0047] Examples of the acid anhydride-containing silane coupling agent include 3-trimethoxysilylpropyl succinic anhydride, 3-triethoxysilylpropyl succinic anhydride, 3-dimethylmethoxysilylpropyl succinic anhydride, and the like.

[0048] In this embodiment, when the adhesion aid (B) contains the compound (B1) and other adhesion aids, the compound (B1) can be preferably contained in an amount of 10% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 80% by mass or less, in 100% by mass of the adhesion aid (B), and the other adhesion aids can be preferably contained in an amount of 10% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 80% by mass or less.

[0049] [Resin (C)] The conductive paste of this embodiment can further contain a resin (C).

[0050] As the resin (C), for example, one or more selected from the group consisting of cyanate resins, epoxy resins, resins having two or more radical-polymerizable carbon-carbon double bonds in one molecule, and maleimide resins can be used.

[0051] Also, from the viewpoint of low elastic modulus, the resin (C) can preferably contain one or more selected from the group consisting of acrylic resins, imide resins, urethane resins, silicone resins, and ester resins.

[0052] From the viewpoint of the effects of the present invention, the conductive paste of this embodiment preferably contains at least one selected from epoxy resin (C1) and acrylic resin (C2) as the resin (C).

[0053] (Epoxy resin (C1)) The epoxy resin (C1) may be a compound having only one epoxy group in one molecule, or may be a compound having two or more epoxy groups in one molecule.

[0054] Examples of the epoxy resin (C1) include bifunctional or crystalline epoxy resins such as biphenyl type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, stilbene type epoxy resin, and hydroquinone type epoxy resin; novolak type epoxy resins such as cresol novolak type epoxy resin, phenol novolak type epoxy resin, and naphthol novolak type epoxy resin; phenol aralkyl type epoxy resins such as phenylene skeleton-containing phenol aralkyl type epoxy resin, biphenylene skeleton-containing phenol aralkyl type epoxy resin, and phenylene skeleton-containing naphthol aralkyl type epoxy resin; alicyclic epoxy resins such as cyclohexane type epoxy resin and cyclohexanedimethanol type epoxy resin; trifunctional epoxy resins such as triphenolmethane type epoxy resin and alkyl-modified triphenolmethane type epoxy resin; modified phenol type epoxy resins such as dicyclopentadiene-modified phenol type epoxy resin and terpene-modified phenol type epoxy resin; heterocyclic ring-containing epoxy resins such as triazine nucleus-containing epoxy resin; and the like.

[0055] Also, as the epoxy group-containing compound, it may include monofunctional epoxy group-containing compounds such as 4-tert-butylphenyl glycidyl ether, m,p-cresyl glycidyl ether, phenyl glycidyl ether, and cresyl glycidyl ether.

[0056] As the epoxy resin (C1), cyclohexane type epoxy resin and bisphenol type epoxy resin are preferable, and 1,4-diglycidylcyclohexane type epoxy resin, bisphenol F type epoxy resin, and acetal-modified bisphenol A type epoxy resin are more preferable. In 100% by mass of the conductive paste of the present embodiment, the amount of the epoxy resin (C1) is preferably 2 to 30% by mass, more preferably 5 to 20% by mass.

[0057] (Acrylic resin (C2)) Specific examples of the monomer constituting the acrylic resin (C2) include, for example, monofunctional (meth)acrylate, difunctional (meth)acrylate, polyfunctional (meth)acrylate having three or more functional groups, epoxy (meth)acrylate, and urethane (meth)acrylate.

[0058] Examples of monofunctional (meth)acrylates include aliphatic (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, butoxyethyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octylheptyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate; alicyclic (meth)acrylates such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isobornyl (meth)acrylate, 3-methyl-3-oxetanylmethyl (meth)acrylate, 1-adamantyl (meth)acrylate; aromatic (meth)acrylates such as phenyl (meth)acrylate, nonylphenyl (meth)acrylate, p-cumylphenyl (meth)acrylate, o-biphenyl (meth)acrylate, 1-naphthyl (meth)acrylate, 2-naphthyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-3-(o-phenylphenoxy)propyl (meth)acrylate, 2-hydroxy-3-(1-naphthoxy)propyl (meth)acrylate, 2-hydroxy-3-(2-naphthoxy)propyl (meth)acrylate;Examples of heterocyclic (meth)acrylates include 2-tetrahydrofurfuryl (meth)acrylate, N-(meth)acryloyloxyethylhexahydrophthalimide, and 2-(meth)acryloyloxyethyl-N-carbazole.;

[0059] Examples of bifunctional (meth)acrylates include aliphatic (meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 2-methyl-1,3-propanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, glycerin di(meth)acrylate, and tricyclodecane dimethanol (meth)acrylate; alicyclic (meth)acrylates such as cyclohexane dimethanol (meth)acrylate, tricyclodecane dimethanol (meth)acrylate, hydrogenated bisphenol A di(meth)acrylate, and hydrogenated bisphenol F di(meth)acrylate; aromatic (meth)acrylates such as bisphenol A di(meth)acrylate, bisphenol F di(meth)acrylate, bisphenol AF di(meth)acrylate, and fluorene-type di(meth)acrylate; and heterocyclic (meth)acrylates such as isocyanuric acid di(meth)acrylate.

[0060] Examples of polyfunctional (meth)acrylates having three or more functional groups include aliphatic (meth)acrylates such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; and heterocyclic (meth)acrylates such as isocyanuric acid tri(meth)acrylate.

[0061] Examples of epoxy (meth)acrylate include compounds obtained by reacting an epoxy group of an epoxy resin with a carboxyl group of a compound having a carboxyl group and a (meth)acryloyl group to form an ester bond.

[0062] Examples of urethane (meth)acrylate include those obtained by reacting a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound such as a polyester type or a polyether type with a polyvalent isocyanate compound with a (meth)acrylate having a hydroxy group. Here, examples of the polyvalent isocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and diphenylmethane-4,4-diisocyanate. Examples of the (meth)acrylate having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and polyethylene glycol (meth)acrylate.

[0063] In 100% by mass of the conductive paste of this embodiment, the amount of the acrylic resin (C2) is preferably 2 to 30% by mass, more preferably 5 to 20% by mass.

[0064] The resin (C) preferably contains an epoxy resin (C1) and an acrylic resin (C2). In 100% by mass of the resin (C), the epoxy resin (C1) is preferably contained in an amount of 5 to 20% by mass, preferably 7 to 15% by mass, and the acrylic resin (C2) can be preferably contained in an amount of 1 to 15% by mass, preferably 2 to 10% by mass.

[0065] [Hardener (D)] When the conductive paste according to this embodiment contains the epoxy resin (C1), the conductive paste according to this embodiment preferably contains a hardener (D). Thereby, the epoxy resin can be cured and shrunk, and the silver-containing particles (A) can be aggregated. The conductive paste according to this embodiment can use a known hardener within the range where the effects of the present invention are exhibited, and preferably a phenolic hardener can be used.

[0066] Examples of the phenolic hardener include novolak-type phenolic resins such as phenol novolak resin, cresol novolak resin, bisphenol novolak resin, and phenol-biphenyl novolak resin; polyvinylphenol; polyfunctional phenolic resins such as triphenylmethane-type phenolic resin; modified phenolic resins such as terpene-modified phenolic resin and dicyclopentadiene-modified phenolic resin; phenol aralkyl resins having a phenylene skeleton and / or a biphenylene skeleton, and phenol aralkyl-type phenolic resins such as naphthol aralkyl resins having a phenylene and / or a biphenylene skeleton; bisphenol compounds such as bisphenol A and bisphenol F (dihydroxydiphenylmethane); and compounds having a biphenylene skeleton such as 4,4'-biphenol.

[0067] From the viewpoint of improving adhesion, the content of the hardener in the conductive paste of this embodiment can be preferably 0.5 parts by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 8 parts by mass or less when the conductive paste is 100 parts by mass.

[0068] [Other components] The conductive paste of the present embodiment may contain a curing accelerator, a radical polymerization initiator, etc. as other components.

[0069] (Curing accelerator) The conductive paste according to the present embodiment may contain a curing accelerator (curing catalyst) that accelerates the reaction between the epoxy resin and the curing agent.

[0070] Examples of the curing accelerator include imidazole-based curing accelerators; phosphorus atom-containing compounds such as organic phosphines, tetra-substituted phosphonium compounds, phosphobetaine compounds, adducts of phosphine compounds and quinone compounds, and adducts of phosphonium compounds and silane compounds; amidines such as dicyandiamide, 1,8-diazabicyclo[5.4.0]undecene-7, and benzyldimethylamine, and tertiary amines; nitrogen atom-containing compounds such as quaternary ammonium salts of the above amidines or the above tertiary amines, and the like.

[0071] The conductive paste according to the present embodiment preferably contains an imidazole-based curing accelerator. Examples of the imidazole-based curing accelerator include 2-phenyl-1H-imidazole-4,5-dimethanol, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-methylimidazole, 2-phenylimidazole, 2,4-diamino-6-[2-methylimidazolyl-(1)]-ethyl-s-triazine, 2-undecylimidazole, 2-heptadecylimidazole, 2,4-diamino-6-[2-methylimidazolyl-(1)]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-undecylimidazolium trimellitate, and the like.

[0072] When the content of the curing accelerator in the conductive paste of the present embodiment is based on 100 parts by mass of the conductive paste, it is preferably 0.01 part by mass or more and 5 parts by mass or less, more preferably 0.05 part by mass or more and 1 part by mass or less. Thereby, the adhesiveness becomes better.

[0073] (Radical polymerization initiator) When the conductive paste according to the present embodiment contains an acrylic resin, the conductive paste according to the present embodiment preferably contains a radical polymerization initiator. Thereby, the acrylic resin can be cured and shrunk, and the silver-containing particles can be aggregated.

[0074] As the radical polymerization initiator, for example, an azo compound, a peroxide, etc. can be used. Among the above specific examples, for example, it is preferable to use a peroxide.

[0075] Examples of the peroxide include organic peroxides such as diacyl peroxide, dialkyl peroxide, and peroxyketal. More specifically, ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; peroxyketals such as 1,1-di(t-butylperoxy)cyclohexane and 2,2-di(4,4-di(t-butylperoxy)cyclohexyl)propane; Hydroperoxides such as p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide; Dialkyl peroxides such as di(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-hexyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, and di-t-butyl peroxide; Diacyl peroxides such as dibenzoyl peroxide and di(4-methylbenzoyl)peroxide; Peroxydicarbonates such as di-n-propyl peroxydicarbonate and diisopropyl peroxydicarbonate; Peroxy esters such as 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-hexyl peroxybenzoate, t-butyl peroxybenzoate, and t-butyl peroxy 2-ethylhexanoate can be mentioned.

[0076] When the conductive paste of this embodiment is 100 parts by mass, the content of the radical polymerization initiator in the conductive paste is preferably 0.01 part by mass or more and 3 parts by mass or less, and more preferably 0.05 part by mass or more and 1 part by mass or less. Thereby, the adhesion becomes better.

[0077] As other components of the conductive paste of this embodiment, components such as antioxidants, dispersants, defoamers, and leveling agents can also be added. The content ratios of these components can be appropriately set according to the application for which the conductive paste is applied. The conductive paste according to this embodiment can be obtained by mixing the above-described components and other components as necessary by a conventionally known method.

[0078] [Physical properties] The conductive paste according to this embodiment is preferably in a paste form at 20°C. That is, the conductive paste according to this embodiment can be preferably applied to a substrate or the like like a paste at 20°C. By this, the conductive paste of this embodiment can be preferably used as an adhesive for semiconductor elements or the like. Of course, depending on the applied process or the like, the conductive paste of this embodiment may be in a relatively low-viscosity varnish form or the like.

[0079] The conductive paste according to this embodiment has excellent adhesion to metals (silver), and the die shear strength measured according to the following measurement method 1 is preferably 20.0 N / (3 mm×3 mm) or more and 60.0 N / (3 mm×3 mm) or less, more preferably 25.0 N / (3 mm×3 mm) or more and 55.0 N / (3 mm×3 mm) or less, and still more preferably 30.0 N / (3 mm×3 mm) or more and 50.0 N / (3 mm×3 mm) or less.

[0080] <Measurement method 1> Apply the conductive paste onto a copper substrate plated with silver to form a coating film, and place a 3 mm×3 mm silicon chip with a silver-plated surface on the coating film. Then, heat it from 30°C to 175°C over 30 minutes, and subsequently perform heat treatment at 175°C for 30 minutes. Thus, the conductive paste is cured, and the silver-plated surface of the silicon chip is joined to the substrate, which is used as a measurement sample. Thereafter, measure the die shear strength (N / (3 mm×3 mm)) of the above measurement sample at 260°C using a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000).

[0081] The conductive paste according to this embodiment has excellent adhesion to metals (gold and silver), and the die shear strength measured according to the following measurement method 2 is preferably 10.0 N / (3 mm×3 mm) or more and 60.0 N / (3 mm×3 mm) or less, more preferably 20.0 N / (3 mm×3 mm) or more and 50.0 N / (3 mm×3 mm) or less, and still more preferably 30.0 N / (3 mm×3 mm) or more and 45.0 N / (3 mm×3 mm) or less.

[0082] <Measurement method 2> Apply the conductive paste onto a copper substrate plated with silver to form a coating film, and place a 3 mm×3 mm silicon chip with a gold-plated surface on the coating film. Then, heat it from 30°C to 175°C over 30 minutes, and subsequently perform heat treatment at 175°C for 30 minutes. Thus, the conductive paste is cured, and the gold-plated surface of the silicon chip is joined to the substrate, which is used as a measurement sample. Thereafter, the above measurement sample is measured for die shear strength (N / (3 mm × 3 mm)) at 260°C using a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000).

[0083] The conductive paste according to this embodiment is excellent in adhesion to a metal (copper), and the die shear strength measured according to the following measurement method 3 is preferably 20.0 N / (3 mm × 3 mm) or more and 60.0 N / (3 mm × 3 mm) or less, more preferably 25.0 N / (3 mm × 3 mm) or more and 55.0 N / (3 mm × 3 mm) or less, and still more preferably 30.0 N / (3 mm × 3 mm) or more and 50.0 N / (3 mm × 3 mm) or less.

[0084] <Measurement method 3> The conductive paste is applied onto a copper substrate to form a coating film, and a 3 mm × 3 mm silicon chip is placed on the coating film. Thereafter, the temperature is raised from 30°C to 175°C over 30 minutes, and then heat treatment is continued at 175°C for 30 minutes. Thus, the conductive paste is cured, and the surface of the silicon chip is bonded to the substrate, which is used as a measurement sample. Thereafter, the above measurement sample is measured for die shear strength (N / (3 mm × 3 mm)) at 260°C using a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000).

[0085] The conductive paste according to this embodiment is excellent in adhesion to a metal (nickel), and the die shear strength measured according to the following measurement method 4 is preferably 35.0 N / (3 mm × 3 mm) or more and 80.0 N / (3 mm × 3 mm) or less, more preferably 35.0 N / (3 mm × 3 mm) or more and 60.0 N / (3 mm × 3 mm) or less, and still more preferably 40.0 N / (3 mm × 3 mm) or more and 55.0 N / (3 mm × 3 mm) or less.

[0086] <Measurement method 4> Apply the conductive paste onto the nickel substrate to form a coating film, and place a 3 mm × 3 mm silicon chip on the coating film. Then, heat the temperature from 30 °C to 175 °C over 30 minutes, and subsequently perform a heat treatment at 175 °C for 30 minutes. By doing so, the conductive paste is cured, and the surface of the silicon chip is bonded to the substrate, which is used as a measurement sample. After that, measure the die shear strength (N / (3 mm × 3 mm)) of the above measurement sample at 260 °C using a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000).

[0087] The conductive paste according to this embodiment suppresses the decrease in thermal conductivity due to the addition of an adhesion promoter as in the prior art, and the thermal conductivity measured by the laser flash method is preferably 2.0 W / mK or more and 10.0 W / mK or less, more preferably 3.0 W / mK or more and 8.0 W / mK or less, and still more preferably 3.0 W / mK or more and 7.0 W / mK or less.

[0088] As the laser flash method thermal constant measuring device used for measuring the thermal conductivity, a known device can be used. Examples of known devices include the laser flash method thermal constant measuring device LFA467 manufactured by NETZCH.

[0089] <High thermal conductivity material> A high thermal conductivity material can be obtained by sintering the conductive paste of this embodiment. By changing the shape of the high thermal conductivity material, it can be applied to various parts that require heat dissipation in the automotive and electrical fields.

[0090] (Application) The conductive paste according to this embodiment is used, for example, to bond a substrate and a semiconductor element. Here, examples of the semiconductor element include a semiconductor package, an LED, and the like.

[0091] The conductive paste according to this embodiment is excellent in thermal conductivity, adhesion strength to metal, and connection reliability compared to conventional conductive pastes containing an adhesion promoter. Therefore, it can be suitably used for applications in which a semiconductor element with a large heat generation amount is mounted on a substrate. In this embodiment, LED refers to a Light Emitting Diode.

[0092] Specific examples of semiconductor devices using LEDs include bullet-type LEDs, surface mount device (SMD) LEDs, chip on board (COB), power LEDs, and the like.

[0093] Specific examples of the types of the semiconductor packages include CMOS image sensors, hollow packages, mold array packages (MAP), quad flat packages (QFP), small outline packages (SOP), chip size packages (CSP), quad flat non-leaded packages (QFN), small outline non-leaded packages (SON), ball grid arrays (BGA), lead flame BGAs (LF-BGA), flip chip BGAs (FC-BGA), molded array process BGAs (MAP-BGA), embedded wafer-level BGAs (eWLB), fan-in type eWLB, fan-out type eWLB, and the like.

[0094] An example of a semiconductor device using the conductive paste according to this embodiment will be described below. <Semiconductor Device> A semiconductor device can be manufactured using the conductive paste of this embodiment. For example, a semiconductor device can be manufactured by using the conductive paste of this embodiment as an "adhesive" between a base material and a semiconductor element.

[0095] In other words, the semiconductor device of the present embodiment includes, for example, a base material and a semiconductor element mounted on the base material via an adhesive layer obtained by sintering the above-described conductive paste by heat treatment. In the semiconductor device of the present embodiment, the adhesion of the adhesive layer is less likely to deteriorate even by heat cycling. That is, the reliability of the semiconductor device of the present embodiment is high.

[0096] Examples of the semiconductor element include an IC, an LSI, a semiconductor element for power (power semiconductor), and various other elements. Examples of the substrate include various semiconductor wafers, lead frames, BGA substrates, mounting substrates, heat spreaders, heat sinks, and the like.

[0097] Hereinafter, an example of the semiconductor device will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the semiconductor device. The semiconductor device 100 includes a base material 30 and a semiconductor element 20 mounted on the base material 30 via an adhesive layer 10 (die attach material) which is a heat-treated body of the conductive paste of the present embodiment.

[0098] The semiconductor element 20 and the base material 30 are electrically connected via, for example, a bonding wire 40 or the like. Further, the semiconductor element 20 is sealed with, for example, a sealing resin 50.

[0099] The thickness of the adhesive layer 10 is preferably 5 μm or more, more preferably 10 μm or more, and still more preferably 20 μm or more. Thereby, the stress absorption ability of the conductive paste is improved, and the connection reliability can be improved. The thickness of the adhesive layer 10 is, for example, 100 μm or less, preferably 50 μm or less.

[0100] In FIG. 1, the base material 30 is, for example, a lead frame. In this case, the semiconductor element 20 is mounted on the die pad 32 or the base material 30 via the adhesive layer 10. Further, the semiconductor element 20 is electrically connected to the outer lead 34 (base material 30) via, for example, a bonding wire 40.

[0101] The surface of the adhesive layer 10 that contacts the semiconductor element 20 may be provided with a metal plating layer made of silver or gold. The adhesive layer 10 made of the conductive paste of the present embodiment has excellent adhesion to metals, and the connection reliability between the adhesive layer 10 and the semiconductor element 20 is improved. The thickness of the semiconductor element 20 is about 0.05 mm to 0.35 mm.

[0102] The base material 30, which is a lead frame, is composed of, for example, 42 alloy, a Cu frame, etc. The adhesive layer 10 made of the conductive paste of the present embodiment has excellent adhesion to metals, and the connection reliability between the adhesive layer 10 and the base material 30, which is a lead frame, is improved.

[0103] The base material 30 may be an organic substrate or a ceramic substrate. Examples of the organic substrate include those composed of, for example, epoxy resin, cyanate resin, maleimide resin, etc.

[0104] The surface of the base material 30 may be coated with a metal such as silver, gold, copper, nickel, etc. The adhesive layer 10 made of the conductive paste of the present embodiment has excellent adhesion to metals, and the connection reliability between the adhesive layer 10 and the base material 30 is improved. That is, the semiconductor device provided with the adhesive layer made of the conductive paste of the embodiment has excellent product reliability. FIG. 2 is a cross-sectional view showing an example of a semiconductor device 100 different from FIG. 1.

[0105] In the semiconductor device 100 of FIG. 2, the base material 30 is, for example, an interposer. On the surface of the base material 30, which is an interposer, opposite to the surface on which the semiconductor element 20 is mounted, for example, a plurality of solder balls 52 are formed. In this case, the semiconductor device 100 is connected to another wiring board via the solder balls 52. An example of a method for manufacturing a semiconductor device will be described.

[0106] First, a conductive paste is applied onto the base material 30, and then the semiconductor element 20 is disposed thereon. That is, the base material 30, the conductive paste, and the semiconductor element 20 are laminated in this order. The method of applying the conductive paste is not particularly limited. Specifically, dispensing, printing method, inkjet method, etc. can be mentioned.

[0107] Next, the conductive paste is thermally cured. The thermal curing is preferably performed by pre-curing and post-curing. By the thermal curing, the conductive paste is made into a heat-treated body (cured product). By the thermal curing (heat treatment), the metal-containing particles in the conductive paste aggregate, and a structure in which the interfaces between a plurality of metal-containing particles disappear is formed in the adhesive layer 10. Thereby, the base material 30 and the semiconductor element 20 are adhered via the adhesive layer 10. Next, the semiconductor element 20 and the base material 30 are electrically connected using a bonding wire 40. Next, the semiconductor element 20 is sealed with a sealing resin 50. In this way, a semiconductor device can be manufactured.

[0108] As described above, the embodiments of the present invention have been described, but these are examples of the present invention, and various configurations other than the above can be adopted as long as the effects of the present invention are not impaired.

Example

[0109] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

[0110] [Example 1, Comparative Examples 1 to 3] According to the blending amounts shown in Table 1, the following respective raw material components were mixed to obtain a varnish. Next, using the obtained varnish, it was blended according to the blending amounts shown in Table 1 and kneaded with a three-roll mill at room temperature. Thereby, a conductive paste was produced.

[0111] (Hardener) · Hardener 1: Bisphenol F type phenol resin (Product name: DIC-BPF, manufactured by DIC Corporation)

[0112] (Resin) · Epoxy Resin 1: 1,4 - diglycidylcyclohexane - type epoxy resin, liquid at room temperature (25°C), ZX - 1658GS (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) · Epoxy Resin 2: Bisphenol F - type epoxy resin, SB - 403S (manufactured by Nippon Kayaku Co., Ltd.) · Epoxy Resin 3: Acetal - modified bisphenol A - type epoxy resin, EXA - 4850 - 1000 (manufactured by Dainippon Ink and Chemicals, Incorporated) · Acrylic Resin: Ethylene glycol dimethacrylate, Light Ester EG (manufactured by Kyoeisha Chemical Co., Ltd.)

[0113] (Curing Accelerator) · Curing Accelerator: 2 - phenyl - 4,5 - dihydroxymethylimidazole (2PHZ - PW, manufactured by Shikoku Kasei Co., Ltd.)

[0114] (Radical Polymerization Initiator) · Radical Polymerization Initiator: 1,1 - di(t - butylperoxy)cyclohexane, 10 - hour half - life temperature: 91°C, Perhexa C(s) (manufactured by NOF Corporation)

[0115] (Adhesion Promoter) · Adhesion Promoter 1: Triazine - based compound having an aminotriazine ring and an ethoxysilyl group, melting point 80 - 90°C, VD - 5 (manufactured by Shikoku Kasei Kogyo Co., Ltd.) · Adhesion Promoter 2: Dicyandiamide, EH3636AS (manufactured by ADEKA Corporation) · Adhesion Promoter 3: Tetrasulfide ditoethoxysilane, CABRUS4 (manufactured by Osaka Soda Co., Ltd.)

[0116] (Silver Particles) · Silver Powder 1: Flake - shaped silver powder, HKD - 10A, manufactured by Fukuda Metal Foil & Powder Co., Ltd., average particle size: 8μm · Silver Powder 2: Flake - shaped silver powder, HKD - 38, manufactured by Fukuda Metal Foil & Powder Co., Ltd., average particle size: 4μm)

[0117] (Thermal Conductivity) The obtained conductive paste was applied to a square mold with a thickness of about 1 mm and a side length of 10 mm, heated from 30 °C to 175 °C over 30 minutes, and then continuously heated at 175 °C for 30 minutes to prepare a cured specimen. After preparing the cured specimen, the thermal diffusivity was measured using a laser flash method thermal constant measuring device LFA467 manufactured by NETZCH, and the thermal conductivity was calculated from the specific heat and specific gravity.

[0118] <Adhesion strength 1> The obtained conductive paste was applied onto a silver-plated copper substrate to form a coating film, and a 3 mm × 3 mm silicon chip with a silver-plated surface was placed on the coating film. Then, it was heated from 30 °C to 175 °C over 30 minutes and then continuously heat-treated at 175 °C for 30 minutes. Thus, the conductive paste was cured, and the silver-plated surface of the silicon chip was bonded to the substrate, which was used as a measurement sample. After that, the above measurement sample was used to measure the adhesion strength 1 (die shear strength (N / (3 mm × 3 mm)) at 260 °C using a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000). Also, the fracture mode of the cured conductive paste that was fractured in the die shear strength measurement test was visually confirmed and evaluated according to the following criteria. The results are shown in Table 1. (Criteria) "Chip / paste interface (C / P interface)": Peeling occurs at the interface between the silicon chip and the cured conductive paste. "LF / paste interface (L / P interface)": Peeling occurs at the interface between the copper lead frame and the cured conductive paste. "Aggregation": Cracks have occurred in the cured conductive paste itself.

[0119] <Adhesion strength 2> The obtained conductive paste was applied onto a silver-plated copper substrate to form a coating film, and a 3 mm × 3 mm silicon chip with a gold-plated surface was placed on the coating film. Then, it was heated from 30 °C to 175 °C over 30 minutes and then continuously heat-treated at 175 °C for 30 minutes. Thus, the conductive paste was cured, and the gold-plated surface of the silicon chip was bonded to the substrate, which was used as a measurement sample. Subsequently, the above measurement sample was used with a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000) to measure the die shear strength 2 (die shear strength (N / (3 mm × 3 mm))) at 260°C. Also, the fracture mode of the cured conductive paste that was fractured in the die shear strength measurement test was visually confirmed and evaluated according to the criteria described in Adhesion Strength 1. The results are shown in Table 1.

[0120] <Adhesion Strength 3> The obtained conductive paste was applied onto a copper substrate to form a coating film, and a 3 mm × 3 mm silicon chip was placed on the coating film. Subsequently, the temperature was raised from 30°C to 175°C over 30 minutes, and then heat treatment was carried out at 175°C for 30 minutes. By the above, the conductive paste was cured, and the surface of the silicon chip was bonded to the substrate, which was used as a measurement sample. Subsequently, the above measurement sample was used with a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000) to measure the die shear strength 3 (die shear strength (N / (3 mm × 3 mm))) at 260°C. Also, the fracture mode of the cured conductive paste that was fractured in the die shear strength measurement test was visually confirmed and evaluated according to the criteria described in Adhesion Strength 1. The results are shown in Table 1.

[0121] <Adhesion Strength 4> The obtained conductive paste was applied onto a nickel substrate to form a coating film, and a 3 mm × 3 mm silicon chip was placed on the coating film. Subsequently, the temperature was raised from 30°C to 175°C over 30 minutes, and then heat treatment was carried out at 175°C for 30 minutes. By the above, the conductive paste was cured, and the surface of the silicon chip was bonded to the substrate, which was used as a measurement sample. Subsequently, the above measurement sample was used with a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000) to measure the die shear strength 4 (die shear strength (N / (3 mm × 3 mm))) at 260°C. Also, the fracture mode of the cured conductive paste that was fractured in the die shear strength measurement test was visually confirmed and evaluated according to the criteria described in Adhesion Strength 1. The results are shown in Table 1.

[0122] <Reliability Evaluation (Package Peel Test)> The obtained conductive paste was applied onto a copper lead frame, and a 350-μm-thick silicon chip (SiN on the surface) with a length of 5 mm × width of 5 mm was mounted thereon, and it was made 20 μm thick. Then, the temperature was raised to 175°C in 30 minutes under a nitrogen atmosphere and left for 30 minutes to obtain test pieces. Fourteen test pieces were prepared. Then, it was sealed with an epoxy molding compound (G700LTD) to obtain a package. Then, post-mold cure was performed at 175°C for 4 hours to obtain a package structure. This package structure has a length of 14 mm, a width of 14 mm, and a thickness of 0.8 mm. Then, the obtained package structure was put into the following environment. Environment: Temperature 85°C, Relative Humidity 85%, 168 hours The package structure exposed to the conditions of the above environment was taken out, and further, a 260°C reflow was performed under an N2 atmosphere. The presence or absence of peeling of the silicon chip from the copper frame in the package structure was confirmed. The number of package structures in which peeling was observed is shown in Table 1 as the number of peeled ones.

[0123] In FIGS. 3(a) to 6(a), top surface photographs of the package structure before being exposed to the conditions of the above environment (before the test) are shown, and in FIGS. 3(b) to 6(b), top surface photographs of the package structure after being exposed to the conditions of the above environment (after the test) are shown. In FIGS. 3(b) to 6(b), the blackened parts are the peeled parts.

[0124]

Table 1

[0125] As shown in Table 1, the conductive paste of Example 1 according to the present invention suppressed the decrease in thermal conductivity compared to the conventional adhesion aids (Comparative Examples 2 and 3), and was excellent in thermal conductivity as in Comparative Example 1 without the addition of an adhesion aid. Furthermore, the conductive paste of Example 1 according to the present invention was excellent in adhesion strength and connection reliability with various metals such as silver, gold, copper, and nickel.

Explanation of Signs

[0126] 100 Semiconductor device 10 Adhesive layer 20 Semiconductor element 30 Substrate 32 Die pad 34 Outer lead 40 Bonding wire 50 Encapsulating resin 52 Solder ball

Claims

1. Particles with a silver surface, An adhesion promoter, and The adhesion promoter contains a compound represented by the following general formula (1), a conductive paste. 【Chemical formula 1】 (In general formula (1), Q is a divalent linking group.)

2. Further comprising at least one selected from an epoxy resin and an acrylic resin, the conductive paste according to claim 1.

3. Further comprising a curing agent, the conductive paste according to claim 1.

4. The conductive paste according to claim 1, wherein the die shear strength measured according to the following measurement method 1 is 20.0 N / (3 mm × 3 mm) or more and 60.0 N / (3 mm × 3 mm) or less. <Measurement method 1> Apply the conductive paste on a copper substrate plated with silver to form a coating film, and place a 3 mm × 3 mm silicon chip with a silver-plated surface on the coating film. Then, heat the temperature from 30°C to 175°C over 30 minutes, and subsequently perform heat treatment at 175°C for 30 minutes. In this way, the conductive paste is cured, and the silver-plated surface of the silicon chip is joined to the substrate, and this is used as a measurement sample. Then, the above measurement sample is used to measure the die shear strength (N / (3 mm × 3 mm)) at 260°C using a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000).

5. The conductive paste according to claim 1, wherein the die shear strength measured according to the following measurement method 2 is 10.0 N / (3 mm × 3 mm) or more and 60.0 N / (3 mm × 3 mm) or less. <Measurement method 2> Apply a conductive paste onto a copper substrate plated with silver to form a coating film, and place a 3 mm × 3 mm silicon chip with a surface gold plating on the coating film. Then, heat the temperature from 30 °C to 175 °C over 30 minutes, and subsequently perform a heat treatment at 175 °C for 30 minutes. By the above steps, the conductive paste is cured, and the gold-plated surface of the silicon chip is joined to the substrate, and this is used as a measurement sample. After that, use a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000) to measure the die shear strength (N / (3 mm × 3 mm)) at 260 °C for the above measurement sample.

6. The conductive paste according to claim 1, wherein the die shear strength measured according to the following measurement method 3 is 20.0 N / (3 mm × 3 mm) or more and 60.0 N / (3 mm × 3 mm) or less. <Measurement method 3> Apply a conductive paste onto a copper substrate to form a coating film, and place a 3 mm × 3 mm silicon chip on the coating film. Then, heat the temperature from 30 °C to 175 °C over 30 minutes, and subsequently perform a heat treatment at 175 °C for 30 minutes. By the above steps, the conductive paste is cured, and the surface of the silicon chip is joined to the substrate, and this is used as a measurement sample. After that, use a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., model DAGE-4000) to measure the die shear strength (N / (3 mm × 3 mm)) at 260 °C for the above measurement sample.

7. The conductive paste according to claim 1, wherein the die shear strength measured according to the following measurement method 4 is 35.0 N / (3 mm × 3 mm) or more and 80.0 N / (3 mm × 3 mm) or less. <Measurement method 4> Apply a conductive paste onto a nickel substrate to form a coating film, and place a 3 mm × 3 mm silicon chip on the coating film. Then, heat the temperature from 30 °C to 175 °C over 30 minutes, and subsequently perform a heat treatment at 175 °C for 30 minutes. By the above steps, the conductive paste is cured, and the surface of the silicon chip is joined to the substrate, and this is used as a measurement sample. Thereafter, the above measurement sample is measured for die shear strength (N / (3 mm × 3 mm)) at 260°C using a die shear tester (manufactured by Nordson Advanced Technology Co., Ltd., DAGE-4000 type).

8. The conductive paste according to claim 1, wherein the thermal conductivity measured by the laser flash method is 2.0 W / mK or more and 10.0 W / mK or less.

9. A high thermal conductivity material obtained by curing the conductive paste according to any one of claims 1 to 8.

10. A base material, a semiconductor element mounted on the base material via an adhesive layer, and the adhesive layer is formed by curing the conductive paste according to any one of claims 1 to 8, a semiconductor device.

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