Heat conductive paste, semiconductor device, and method of manufacturing semiconductor device

Abstract

To provide a heat conductive paste materializing a heat conductive layer having excellent adhesive property in joining of large area.SOLUTION: A heat conductive paste for use in conductive adhesion is provided, including: a particle of which the at least front surface is a metal; a thermoset resin; and a solvent. Adhesion strength of the heat conductive paste measured by the following conditions of 1 to 5 is 4 N / mm2 or more: 1. a nickel plate and a silicon having a size of 5 mm×5 mm and a thickness of 350 μm is prepared; 2. the heat conductive paste of 1 mm3 or more and 1.5 mm3 or less is coated to the nickel plate; 3. the silicon is arranged in a region where the heat conductive paste of the nickel plate is coated, and the silicon is pressurized to the nickel plate side at a pressure of 0.05 kgf / cm2 f; 4. the heat conductive paste is hardened under a condition of 200°C of heat temperature, and 120 minutes of a heating time; and 5. a weight is added under a condition of 20 mm / min of shearing jig movement speed by using a die share stator, and thus the maximum shearing weight is set to be close adhesion strength.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a thermally conductive paste, a semiconductor device, and a method for manufacturing a semiconductor device. [Background technology]

[0002] In a semiconductor package having a thermal conductor, the use of a thermally conductive layer having a particle-connected structure formed by sintering metal particles by heat treatment is being considered. Patent Document 1 describes a semiconductor package having a substrate, a semiconductor element, a heat spreader, and a heat sink, in which the heat spreader and the heat sink are joined by a thermally conductive layer (thermal conductive material). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 189446 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the use of a thermally conductive layer to bond larger bonding surfaces has been considered. Based on this background, the inventors have found that there is room for improvement in the adhesion of the thermally conductive layer in large-area bonding. [Means for solving the problem]

[0005] According to the present invention, there are provided the following thermally conductive paste, semiconductor device, and semiconductor device.

[0006] [1] 2cm 2 A thermally conductive paste used for conductive bonding in the above area, The method includes the steps of: (a) preparing a mixture of particles having at least a metal surface; a thermosetting resin; and a solvent; The adhesion strength measured under the following condition 1 is 4N / mm 2 That's it, thermal conductive paste. [Condition 1] 1. Prepare a nickel plate and a 5 mm x 5 mm piece of silicon with a thickness of 350 μm. 2.1mm 3 More than 1.5mm 3 The following thermally conductive paste is applied to the nickel plate. 3. Place the silicon on the area of ​​the nickel plate where the thermally conductive paste was applied, and press the silicon under a pressure of 0.05 kgf / cm 2 Then, it is pressed against the nickel plate. 4. The thermally conductive paste is hardened under the following conditions: heating temperature: 200°C, heating time: 120 minutes. 5. In accordance with JIS Z 3198-7, a load is applied using a die shear tester with a shear jig moving speed of 20 mm / min, and the maximum shear load is taken as the adhesion strength. [2] Including thermoplastic resins, [1] The thermal conductive paste according to the present invention. [3] The thermoplastic resin has a melting point of 150° C. or less. [2] The thermal conductive paste according to the present invention. [4] At least a part of the thermoplastic resin has a fibrous shape. The thermal conductive paste according to [2] or [3]. [5] The content of the thermoplastic resin is 0.1 parts by mass or more and 1.0 parts by mass or less per 100 parts by mass of the entire thermal conductive paste. The thermal conductive paste according to [2] or [3]. [6] The content of the solvent is 4 parts by mass or less per 100 parts by mass of the entire thermal conductive paste. A thermally conductive paste according to any one of [1] to [3]. [7] A semiconductor device comprising: a semiconductor element; and a heat spreader bonded to the semiconductor element using the thermally conductive paste according to any one of [1] to [3]. [8] A method for manufacturing a semiconductor device, comprising the step of bonding a heat spreader to a semiconductor element using the thermally conductive paste according to any one of [1] to [3]. Effect of the Invention

[0007] According to the present invention, there is provided a thermally conductive paste that realizes a thermally conductive layer with excellent adhesiveness in large-area bonding.

[0008] The above objects, as well as other objects, features and advantages, will become more apparent from the following preferred embodiments and the accompanying drawings. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an example of a semiconductor device according to an embodiment of the present invention; [Diagram 2] 1 is an SAT image of an adhesive surface using a thermally conductive paste of a comparative example. [Diagram 3] 1 is an SAT image of an adhesive surface using a thermally conductive paste according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all drawings, the same components are given the same reference numerals and the description will be omitted as appropriate. In addition, the drawings are schematic diagrams and do not correspond to the actual dimensional ratio.

[0011] A schematic diagram of an example of a semiconductor device according to this embodiment is shown in Fig. 1. As shown in Fig. 1, the semiconductor device according to this embodiment includes a substrate 10, a semiconductor element 20, a heat spreader 30, a thermally conductive layer 40, a heat sink 50, and a thermally conductive layer 60. The semiconductor element 20 is provided on the substrate 10, the heat spreader 30 surrounds the periphery of the semiconductor element 20, and the thermally conductive layer 40 bonds the semiconductor element 20 and the heat spreader 30. The thermally conductive layer 60 also bonds the heat spreader 30 and the heat sink 50.

[0012] The semiconductor element 20 may be, for example, a logic chip or a memory chip, or may be an LSI chip in which a memory circuit and a logic circuit are combined. The semiconductor element 20 may be configured in a BGA type package.

[0013] The semiconductor element 20 is mounted on the substrate 10 and electrically connected to the substrate 10. The semiconductor element 20 may be flip-chip connected to the substrate 10. In this case, the semiconductor element 20 is solder-connected to the substrate 10 via solder balls 80. An underfill material 70 may be filled in the gap between the semiconductor element 20 and the substrate 10. As the underfill material 70, a known material may be used, but it may also be a sealing material or a die attach material.

[0014] The substrate 10 may be, for example, a printed circuit board. One or more semiconductor elements 20 may be mounted on one surface of the substrate 10. Furthermore, electronic components other than the semiconductor elements 20 or a heat source may be mounted on one surface of the substrate 10. Meanwhile, the other surface of the substrate 10 (the surface opposite to the one surface) may have a connection structure that allows connection to another substrate. The connection structure may be, for example, a solder ball, a pin connector, or the like.

[0015] The heat spreader 30 may be made of any material capable of dissipating heat from a heat generating body such as the semiconductor element 20, and may be made of, for example, a metal material. The metal material may be, for example, one or a combination of two or more materials selected from copper, aluminum, stainless steel, etc. The heat spreader 30 may have a highly thermally conductive material other than a metal material, and may contain, for example, graphite, etc., inside.

[0016] The heat spreader 30 may be formed of a single metal layer made of the above metal material, or may be formed of a laminated structure in which multiple layers are laminated. From the viewpoint of thermal conductivity, it is preferable that at least the surface of the heat spreader 30 that is bonded to the thermal conductive layer 40 has the above metal material exposed, but it may be plated with other metals. For example, the plating film can be formed of nickel, gold, an alloy containing these as main components, or a laminated film of these. This enhances the rust resistance of the heat spreader 30.

[0017] The shape of the heat spreader 30 is not particularly limited as long as it has a lid structure that covers the semiconductor element 20. For example, the heat spreader 30 may be configured as a housing having an opening on the surface facing the semiconductor element 20. In other words, when viewed in a cross-sectional view in the stacking direction of the semiconductor element 20 and the heat spreader 30, the heat spreader 30 may be configured in a substantially U-shape.

[0018] A part of the heat spreader 30 may be bonded to the substrate 10 via an adhesive. For example, the tip of the side wall of the heat spreader 30 may be bonded to one surface of the substrate 10 by an adhesive. Any known adhesive can be used.

[0019] The thermally conductive layer 40 is interposed between one surface of the semiconductor element 20 and the other surface of the heat spreader 30 facing the one surface, and bonds them together. The lower limit of the thermal conductivity of the thermally conductive layer 40 is, for example, 4 W / m·K or more, preferably 10 W / m·K or more, and more preferably 11 W / m·K or more. This can improve the heat dissipation characteristics of the semiconductor device 100. The thermal conductivity can be obtained by measuring in the thickness direction at 25° C. using, for example, a laser flash method.

[0020] The heat sink 50 may be made of any material having excellent heat dissipation properties, and may be made of, for example, the same material as that used for the heat spreader 30. The heat sink 50 may have a plurality of fins.

[0021] The thermally conductive layer 60 is interposed between one surface of the heat spreader 30 and the surface of the heat sink 50 facing the one surface, and bonds them together. The lower limit of the thermal conductivity of the thermally conductive layer 60 is, for example, 4 W / m·K or more, preferably 10 W / m·K or more, and more preferably 11 W / m·K or more. This can improve the heat dissipation characteristics of the semiconductor device 100.

[0022] The thermally conductive paste according to this embodiment can be used, for example, to form at least one of the thermally conductive layers 40, 60. Specifically, at least one of the thermally conductive layers 40, 60 can be formed by applying the thermally conductive paste and then heating and curing it. The thermally conductive paste according to this embodiment has an adhesive surface area of ​​2 cm2. 2 This thermal conductive paste is particularly suitable for use in applications where the adhesive surface area is 4 cm 2 In the above cases, and furthermore, the adhesive surface area is 6cm 2 It is preferably used in the above cases.

[0023] [Thermal conductive paste] The thermally conductive paste according to this embodiment contains at least particles having a metal surface (hereinafter referred to as a filler), a thermosetting resin, and a solvent. Each component of the thermally conductive paste will be described in detail below.

[0024] [Thermosetting resin] The thermosetting resin can be one or a combination of two or more selected from the following: epoxy resins; phenolic resins; resins having a triazine ring, such as urea resins and melamine resins; unsaturated polyester resins; maleimide resins, such as bismaleimide compounds; polyurethane resins; allyl resins, such as diallyl phthalate resins and allyl polymers; silicone resins, benzoxazine resins, polyimide resins, polyamide-imide resins; and cyanate ester resins, such as benzocyclobutene resins, novolac-type cyanate resins, bisphenol A-type cyanate resins, bisphenol E-type phenolic resins, and tetramethylbisphenol F-type cyanate resins.

[0025] Specific examples of epoxy resins include bisphenol type epoxy resins such as bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, bisphenol F type epoxy resins, tetramethyl bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol E type epoxy resins, bisphenol M type epoxy resins, bisphenol P type epoxy resins, and bisphenol Z type epoxy resins; novolac type epoxy resins such as phenol novolac type epoxy resins and cresol novolac type epoxy resins; biphenyl type epoxy resins, biphenyl aralkyl type epoxy resins, and aryl alkylene type epoxy resins. One or a combination of two or more selected from epoxy monomers such as naphthalene type epoxy resins, anthracene type epoxy resins, phenoxy type epoxy resins, dicyclopentadiene type epoxy resins, norbornene type epoxy resins, adamantane type epoxy resins, fluorene type epoxy resins, trisphenylmethane type epoxy resins, 4-tert-butylphenyl glycidyl ether, m,p-cresyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, and trimethylolpropane polyglycidyl ether can be used.

[0026] When the entire thermal conductive paste is taken as 100 parts by mass, the lower limit of the content of the thermosetting resin is preferably 5 parts by mass or more, and more preferably 7 parts by mass or more. The upper limit of the content of the thermosetting resin is preferably 15 parts by mass or less, and more preferably 12 parts by mass or less. By keeping the content of the thermosetting resin within the above range, the hardening property of the thermal conductive paste is improved.

[0027] [Filler] The filler is a particle whose surface is at least made of metal. The filler also includes a particle whose entire surface is made of metal. As the metal, for example, one or a combination of two or more selected from silver, copper, copper alloy, aluminum, aluminum alloy, nickel, iron, tin, etc. can be used. Furthermore, the particle whose entire surface is coated with a metal is, for example, a silver-coated particle containing a resin particle such as a silicone resin particle and silver that covers the surface of the resin particle.

[0028] The above-mentioned silver-coated particles are particles (silicone resin particles) made of organopolysiloxane obtained by polymerizing organochlorosilane such as methylchlorosilane, trimethyltrichlorosilane, dimethyldichlorosilane, etc., coated with silver. Alternatively, the above-mentioned organopolysiloxane is further crosslinked three-dimensionally to form a basic skeleton, and the surface of the silicone resin particles made of the silicone resin is coated with silver.

[0029] The shape of the filler is not particularly limited, but may be, for example, spherical, dendritic, string-like, flake-like, aggregated, polyhedral, etc. From the viewpoint of improving the sinterability of the filler and improving the uniformity of sintering, it is preferable that a spherical filler is included. Also, from the viewpoint of reducing costs, it is preferable that a flake-like filler is included.

[0030] The particle diameter D50 of the filler at 50% cumulative frequency in a volume-based cumulative frequency distribution curve measured using a laser diffraction particle size distribution analyzer is preferably 0.1 μm or more, more preferably 1.0 μm or more, and even more preferably 2.0 μm or more. The particle diameter D50 of the filler is preferably 10 μm or less, more preferably 8.0 μm or less, even more preferably 5.0 μm or less, particularly more preferably 5.0 μm or less, and most preferably 4.0 μm or less.

[0031] When the entire thermal conductive paste is taken as 100 parts by mass, the lower limit of the filler content is preferably 75 parts by mass or more, and more preferably 80 parts by mass or more, and the upper limit of the filler content is preferably 95 parts by mass or less, and more preferably 90 parts by mass or less.

[0032] [solvent] Examples of the solvent include methyl carbitol, ethyl carbitol, butyl carbitol, methyl carbitol acetate, ethyl carbitol acetate, butyl carbitol acetate, acetylacetone, methyl isobutyl ketone (MIBK), anone, diacetone alcohol, ethyl cellosolve, methyl cellosolve, butyl cellosolve, ethyl cellosolve acetate, methyl cellosolve acetate, butyl cellosolve acetate, ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, tripropylene glycol mono n-butyl ether, methyl methoxybutanol, α-terpineol, β-terpineol, γ-terpineol, terpineol (mixture of α, β, and γ), dihydroterpineol, hexylene glycol, benzyl alcohol, 2-phenylethyl alcohol, isopalmitoyl alcohol, isostearyl alcohol, lauryl alcohol, ethylene glycol, propylene glycol or alcohols such as glycerin; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol (4-hydroxy-4-methyl-2-pentanone), 2-octanone, isophorone (3,5,5-trimethyl-2-cyclohexen-1-one) or diisobutyl ketone (2,6-dimethyl-4-heptanone); esters such as ethyl acetate, butyl acetate, diethyl phthalate, dibutyl phthalate, acetoxyethane, methyl butyrate, methyl hexanoate, methyl octanoate, methyl decanoate, methyl cellosolve acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, 1,2-diacetoxyethane, tributyl phosphate, tricresyl phosphate or tripentyl phosphate;One or a combination of two or more selected from ethers such as tetrahydrofuran, dipropyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, ethoxyethyl ether, 1,2-bis(2-diethoxy)ethane or 1,2-bis(2-methoxyethoxy)ethane; ester ethers such as 2-(2-butoxyethoxy)ethane acetate; ether alcohols such as 2-(2-methoxyethoxy)ethanol; hydrocarbons such as toluene, xylene, n-paraffin, isoparaffin, dodecylbenzene, turpentine oil, kerosene or light oil; nitriles such as acetonitrile or propionitrile; amides such as acetamide or N,N-dimethylformamide; low molecular weight volatile silicone oil, or volatile organic modified silicone oil, etc. may be used.

[0033] When the entire thermal conductive paste is taken as 100 parts by mass, the lower limit of the solvent content is preferably 1 part by mass or more, and more preferably 2 parts by mass or more. The upper limit of the solvent content is preferably 6 parts by mass or less, and more preferably 4 parts by mass or less. By keeping the solvent content below the upper limit, the cure shrinkage rate of the thermal conductive paste is reduced, and the adhesiveness is improved.

[0034] [Thermoplastic resin] The thermally conductive paste according to the present embodiment may further include a thermoplastic resin, which may be, for example, one or a combination of two or more of (meth)acrylic resin, polycarbonate resin, polyvinyl chloride resin, amorphous polyester resin, amorphous olefin resin, polystyrene resin, AS resin (acrylonitrile, styrene copolymer compound), butyral resin, and butadiene resin such as maleated polybutadiene.

[0035] The melting point of the thermoplastic resin is preferably 150° C. or lower, more preferably 140° C. or lower, and even more preferably 130° C. or lower.

[0036] From the viewpoint of adhesiveness of the thermal conductive paste, the thermoplastic resin preferably has a fibrous shape. More specifically, the average fiber length is preferably 0.05 mm or more, more preferably 0.08 mm or more, and even more preferably 0.10 mm or more. The fiber diameter is preferably 5 μm or more, more preferably 8 μm or more, and even more preferably 10 μm or more.

[0037] Although the details of the mechanism by which the fibrous thermoplastic resin contributes to the adhesiveness of the thermal conductive paste are not clear, the following is thought to be the case. First, when the thermoplastic resin has a fibrous shape, this shape and the property of the thermoplastic resin becoming liquid at high temperatures combine to make it easier to penetrate into the unevenness of the adherend surface. This provides an anchor effect and improves adhesion. In addition, when the thermoplastic resin is fibrous, the thermoplastic resin is more easily dispersed. This improves the toughness of the thermal conductive paste after curing. Furthermore, the thermal conductive paste after curing has a low elastic modulus, and the stress at the interface between the thermal conductive paste after curing and the substrate, etc. is reduced.

[0038] As the fibrous thermoplastic resin, for example, a commercially available product, Chemivest series (manufactured by Mitsui Fine Co., Ltd.), can be used.

[0039] When the entire thermal conductive paste is taken as 100 parts by mass, the lower limit of the thermoplastic resin content is preferably 0.1 parts by mass or more, and more preferably 0.5 parts by mass or more, and the upper limit of the thermoplastic resin content is preferably 3.0 parts by mass or less, and more preferably 1.0 part by mass or less.

[0040] [Acrylic Monomer] The thermal conductive paste according to this embodiment may further contain an acrylic monomer to improve heat resistance and impact resistance. As the acrylic monomer, a monofunctional acrylic monomer having only one (meth)acrylic group or a polyfunctional acrylic monomer having two or more (meth)acrylic groups may be used. Alternatively, an acrylic acid polymer such as UG-4035 manufactured by Toagosei Co., Ltd. may be used.

[0041] Examples of monofunctional acrylic monomers include 2-phenoxyethyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tridecyl (meth)acrylate, n-stearyl (meth)acrylate, isostearyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, butoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethylhexyl diethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, methoxypoly Ethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenol ethylene oxide modified (meth)acrylate, phenylphenol ethylene oxide modified (meth)acrylate, isobornyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate quaternized, glycidyl (meth)acrylate, neopentyl glycol (meth)acrylic acid benzoate, 1,One or a combination of two or more selected from 4-cyclohexanedimethanol mono(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalic acid, 2-(meth)acryloyloxyethyl acid phosphate, and 2-(meth)acryloyloxyethyl acid phosphate can be used.

[0042] Of the above specific examples, it is preferable to use 2-phenoxyethyl methacrylate as the monofunctional acrylic monomer, as this can improve the adhesion of the thermal conductive paste.

[0043] Specific examples of polyfunctional acrylic monomers include ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, hexane-1,6-diol bis(2-methyl(meth)acrylate), 4,4'-isopropylidenediphenol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,6-bis((meth)acryloyloxy)-2,2,3,3,4,4,5,5-octadecyl acrylate, and the like. One or a combination of two or more selected from the group consisting of fluorohexane, 1,4-bis((meth)acryloyloxy)butane, 1,6-bis((meth)acryloyloxy)hexane, triethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, N,N'-di(meth)acryloylethylenediamine, N,N'-(1,2-dihydroxyethylene)bis(meth)acrylamide, and 1,4-bis((meth)acryloyl)piperazine can be used.

[0044] When the entire thermal conductive paste is taken as 100 parts by mass, the lower limit of the content of the acrylic monomer is preferably 1 part by mass or more, and more preferably 2 parts by mass or more. The upper limit of the content of the acrylic monomer is preferably 5 parts by mass or less, and more preferably 4 parts by mass or less. By keeping the content of the acrylic monomer below the upper limit, the cure shrinkage rate of the thermal conductive paste is reduced, and the adhesiveness is improved.

[0045] [Hardening agent] The thermally conductive paste according to the present embodiment may further include a curing agent. For example, a phenol resin curing agent can be used as the curing agent. In addition, as the phenol resin curing agent, specifically, one or a combination of two or more selected from the following can be used: novolac type phenol resins such as phenol novolac resin, cresol novolac resin, bisphenol A type novolac resin, bisphenol F type novolac resin, and triazine skeleton-containing phenol novolac resin; bisphenol compounds such as bisphenol A and bisphenol F (dihydroxydiphenylmethane); unmodified resol phenol resin; resol type phenol resins such as oil-modified resol phenol resins modified with tung oil, linseed oil, and walnut oil; aralkyl type phenol resins such as phenol aralkyl resin and biphenyl aralkyl type phenol resin; and triphenylmethane type phenol resin.

[0046] When the entire thermal conductive paste is taken as 100 parts by mass, the lower limit of the content of the hardener is preferably 0.5 parts by mass or more, and more preferably 1.0 parts by mass or more. The upper limit of the content of the hardener is preferably 5.0 parts by mass or less, and more preferably 4.0 parts by mass or less. By keeping the content of the hardener within the above range, the hardening property of the thermal conductive paste is improved.

[0047] [Cure accelerator] The thermally conductive paste according to the present embodiment may further include a curing accelerator for accelerating the reaction between the reactive group of the thermosetting resin and the reactive group of the curing agent. The curing accelerator may be one or a combination of two or more selected from the following: imidazole 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 and tertiary amines such as dicyandiamide, 1,8-diazabicyclo[5.4.0]undecene-7, and benzyldimethylamine; and nitrogen atom-containing compounds such as quaternary ammonium salts of the above amidines or tertiary amines.

[0048] In addition, as the imidazole-based curing accelerator, for example, 2-phenyl-1H-imidazole-4,5-dimethanol, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 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, etc. can be used.

[0049] When the entire thermal conductive paste is taken as 100 parts by mass, the lower limit of the content of the hardening accelerator is preferably 0.10 parts by mass or more, and more preferably 0.20 parts by mass or more. The upper limit of the content of the hardening accelerator is preferably 0.50 parts by mass or less, and more preferably 0.40 parts by mass or less. By setting the content of the hardening accelerator within the above range, the hardening property of the thermal conductive paste is improved.

[0050] [Reaction initiator] When the thermally conductive paste according to the present embodiment contains a (meth)acrylic monomer, the thermally conductive paste according to the present embodiment preferably contains a reaction initiator, which causes the (meth)acrylic monomer to cure and shrink, and aggregates the silver-containing particles.

[0051] As the reaction 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.

[0052] Examples of the peroxide include organic peroxides such as diacyl peroxides, dialkyl peroxides, and peroxyketals. 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; di(2-t-butylperoxyisopropyl)benzene and dicumyl peroxide; peroxides such as dialkyl peroxides, 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; and peroxy esters, such as 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-hexyl peroxybenzoate, t-butyl peroxybenzoate, and t-butyl peroxy 2-ethylhexanoate.

[0053] When the entire thermal conductive paste is taken as 100 parts by mass, the lower limit of the content of the reaction initiator is preferably 0.10 parts by mass or more, more preferably 0.15 parts by mass or more, and the upper limit of the content of the reaction initiator is preferably 0.30 parts by mass or less, more preferably 0.25 parts by mass or less.

[0054] [Coupling agent] The thermally conductive paste according to the present embodiment may not further include a coupling agent. However, the thermally conductive paste according to the present embodiment may include a coupling agent. When the thermally conductive paste includes a coupling agent, the flowability of the thermally conductive paste can be increased. As the coupling agent, for example, a silane-based coupling agent, a titanium-based coupling agent, a zirconia-based coupling agent, an aluminum-based coupling agent, or the like can be used.

[0055] When the entire thermal conductive paste is taken as 100 parts by mass, the lower limit of the content of the coupling agent is, for example, more than 0 parts by mass, but is preferably 0.10 parts by mass or more. The upper limit of the content of the coupling agent is preferably 0.30 parts by mass or less, and more preferably 0.20 parts by mass or less. By setting the content of the coupling agent within the above range, the hardening property of the thermal conductive paste is improved.

[0056] Next, the physical properties of the thermally conductive paste according to this embodiment will be described.

[0057] [Adhesion strength] The thermal conductive paste according to this embodiment has an adhesion strength of 4 N / mm 2 It is preferable that the resistance is 6N / mm or more. 2 More preferably, it is 7N / mm 2 More preferably, it is 8 N / mm 2 It is most preferable that the adhesive surface area is 2 cm or more. 2 In the above bonding, sufficient adhesion is obtained. [Condition 1] 1. Prepare a nickel plate and a 5 mm x 5 mm piece of silicon with a thickness of 350 μm. 2.1mm 3 More than 1.5mm 3 The following thermally conductive paste is applied to a nickel plate. 3. Place the silicon on the area of ​​the nickel plate where the thermal conductive paste was applied, and press the silicon under a pressure of 0.05 kgf / cm 2 Then, press it towards the nickel plate. 4. The thermally conductive paste is hardened under the following conditions: heating temperature: 200°C, heating time: 120 minutes. 5. In accordance with JIS Z 3198-7, a load is applied using a die shear tester with a shear jig moving speed of 20 mm / min, and the maximum shear load is taken as the adhesion strength.

[0058] [Thermal Conductivity] The thermal conductive paste according to this embodiment preferably has a thermal conductivity measured by a laser flash method of 4 W / m·K or more, more preferably 10 W / m·K or more, and even more preferably 11 W / m·K or more.

[0059] The thermal conductivity can be measured using a laser flash thermal constant measurement device known in the art, such as the Laser Flash Thermal Constant Measurement Device LFA447 manufactured by NETZCH.

[0060] [Method of manufacturing thermally conductive paste] The thermal conductive paste according to the present embodiment is prepared, for example, by mixing the above-mentioned raw material components. A known method can be used for mixing, and for example, a three-roll mill or a mixer can be used. The mixture obtained may be further degassed. For example, the mixture may be left under vacuum to degas.

[0061] [Method of manufacturing semiconductor device] The semiconductor device according to the present embodiment can be manufactured using the above-mentioned thermally conductive composition. The manufacturing method of the semiconductor device may include, for example, a step of placing a semiconductor element 20 on one side of a substrate 10 so that the other side faces the substrate 10, a step of applying a thermally conductive paste to the surface of one side of the semiconductor element 20 (the side opposite to the other side), a step of placing a heat spreader 30 so as to contact the thermally conductive paste and cover at least one side of the semiconductor element 20, a step of applying a thermally conductive paste to one side of the heat spreader 30 facing the heat sink 50, a step of placing the heat sink 50 on one side of the heat spreader 30, and a step of heating a structure including the substrate 10, the semiconductor element 20, the thermally conductive composition, the heat spreader 30, and the heat sink 50 to harden the thermally conductive paste, and to bond the semiconductor element 20 and the heat spreader 30, and the heat spreader 30 and the heat sink 50.

[0062] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of the present invention are included in the present invention. EXAMPLES

[0063] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the descriptions of these examples.

[0064] [Thermal conductive paste] The raw material components were mixed according to the blending amounts shown in Table 1 below, and kneaded at room temperature with a three-roll mill to prepare a thermally conductive paste.

[0065] [Table 1]

[0066] Details of the raw material components in Table 1 are shown below. · Thermosetting resin 1: Trimethylolpropane polyglycidyl ether (Denacol EX-321L, manufactured by Nagase ChemteX Corporation) · Thermosetting resin 2: Bisphenol-F-diglycidyl ether · Thermosetting resin 3: Allyl polymer (SBM-8C03, manufactured by Kanto Chemical Co., Inc.) · Acrylic monomer 1: Ethylene glycol dimethacrylate · Curing agent 1: Bisphenol F type phenolic resin (DIC-BPF, manufactured by DIC Corporation) · Curing accelerator 1: Dicyandiamide · Curing accelerator 2: 2-Phenyl-1H-imidazole-4,5-dimethanol · Coupling agent 1: 3-Methacryloxypropylmethyldimethoxysilane · Coupling agent 2: 3-Glycidoxypropyltrimethoxysilane · Thermoplastic resin: Chemvest FDSS-5 (Melting point: 135°), manufactured by Mitsui Chemicals, Inc. · Reaction initiator: Dicumyl peroxide · Silver powder 1: Spherical silver powder, median diameter D50: 0.7 μm (manufactured by DOWA Electronics Co., Ltd.) · Silver powder 2: Flaky silver powder, median diameter D50: 7.6 μm · Silver powder 3: Flake-shaped silver powder, median diameter D50: 6.0 μm · Silver powder 4: Silver-coated particles (SC1050-SSB, manufactured by Mitsubishi Materials Corporation) · Solvent: Tripropylene glycol monomethyl ether n-butyl ether

[0067] [Measurement] Using the obtained thermal conductive paste, the following physical properties were measured. The respective measurement results are shown in Table 1.

[0068] <Adhesion (Ni / Si, 5×5 mm)> The adhesion was measured under the following conditions. [Condition 1] 1. Prepare a nickel plate and a 350-μm-thick silicon with a size of 5 mm × 5 mm. 2. 1 mm 3The thermally conductive paste is applied to a nickel plate. 3. Place the silicon on the area of ​​the nickel plate where the thermal conductive paste was applied, and press the silicon under a pressure of 0.05 kgf / cm 2 Then, press it towards the nickel plate. 4. The thermally conductive paste is hardened under the following conditions: heating temperature: 200°C, heating time: 120 minutes. 5. In accordance with JIS Z 3198-7, a load is applied using a die shear tester with a shear jig moving speed of 20 mm / min, and the maximum shear load is taken as the adhesion strength.

[0069] <Elasticity modulus> The thermally conductive paste of each Example and Comparative Example was applied to a mold of 4 mm × 40 mm × 0.3 mm, and the temperature was raised from 30° C. to 200° C. over 60 minutes, and then heated at 200° C. for 120 minutes to obtain a test piece. Using this test piece, the elastic modulus at room temperature and at 260° C. were measured by DMA (dynamic viscoelasticity measurement, SII Nanotechnology DMS6100, tensile mode) in accordance with JIS K 6911 at a heating rate of 5° C. / min and a frequency of 1 Hz.

[0070] <Thermal conductivity> The thermally conductive paste of each Example and Comparative Example was applied to a mold of 10 mm x 10 mm x 1 mm, and the temperature was raised from 30°C to 200°C over 60 minutes, and then heated at 200°C for 120 minutes to obtain a test piece. Using this test piece, the thermal diffusivity was measured using a laser flash thermal constant measurement device LFA467 manufactured by NETZCH, and the thermal conductivity was calculated from the specific heat and specific gravity.

[0071] [evaluation] The adhesiveness of the obtained thermally conductive paste was evaluated by the following evaluation method. The SAT images are shown in Figures 2 and 3. <Evaluation method> 1. Prepare a nickel plate and a 5 mm x 5 mm piece of silicon with a thickness of 350 μm. 2.1mm 3 The thermally conductive paste is applied to a nickel plate. 3. Place the silicon on the area of ​​the nickel plate where the thermal conductive paste was applied, and press the silicon under a pressure of 0.05 kgf / cm 2 Then, press it towards the nickel plate. 4. The thermally conductive paste is hardened under the following conditions: heating temperature: 200°C, heating time: 120 minutes. 5. The adhesive surface was photographed using a thermosonic test (SAT) device to evaluate the adhesiveness.

[0072] The black area in the center of Figures 2 and 3 is the peeled area. As shown in Figures 2 and 3, the adhesive surface using the thermally conductive paste according to this embodiment has fewer peeled areas compared to the comparative example. In this way, it was confirmed that the thermally conductive paste according to this embodiment has excellent adhesiveness. [Explanation of symbols]

[0073] 10 Substrate 20 Semiconductor elements 30 Heat spreader 40 Thermal Conductive Layer 50 Heatsink 60 Thermal Conductive Layer 70 Underfill material

Claims

1. 2 cm ２ A thermally conductive paste used for conductive bonding in the above area, The method includes the steps of: (a) preparing a mixture of particles having at least a metal surface; a thermosetting resin; and a solvent; The adhesion strength measured under the following condition 1 is 4 N / mm ２ That's it, thermal conductive paste. [Condition 1] 1. Prepare a nickel plate and a 5 mm x 5 mm piece of silicon with a thickness of 350 μm. 2.1mm ３ More than 1.5 mm ３ The following thermally conductive paste is applied to the nickel plate.

3. The silicon is placed on the area of ​​the nickel plate where the thermal conductive paste is applied, and the silicon is pressed with a pressure of 0.05 kgf / cm ２ Then, it is pressed against the nickel plate.

4. The thermally conductive paste is hardened under the conditions of a heating temperature of 200° C. and a heating time of 120 minutes.

5. In accordance with JIS Z 3198-7, a load is applied using a die shear tester at a shear jig moving speed of 20 mm / min, and the maximum shear load is regarded as the adhesion strength.

2. Including thermoplastic resins, The thermally conductive paste according to claim 1 .

3. The thermoplastic resin has a melting point of 150° C. or less. The thermally conductive paste according to claim 2 .

4. At least a part of the thermoplastic resin has a fibrous shape. The thermally conductive paste according to claim 2 or 3.

5. The content of the thermoplastic resin is 0.1 parts by mass or more and 1.0 parts by mass or less with respect to 100 parts by mass of the entire thermal conductive paste. The thermally conductive paste according to claim 2 or 3.

6. The content of the solvent is 4 parts by mass or less per 100 parts by mass of the entire thermal conductive paste. The thermally conductive paste according to any one of claims 1 to 3.

7. A semiconductor device comprising a semiconductor element and a heat spreader bonded to the semiconductor element by using the thermally conductive paste according to any one of claims 1 to 3.

8. A method for manufacturing a semiconductor device, comprising the step of bonding a heat spreader to a semiconductor element by using the thermally conductive paste according to any one of claims 1 to 3.

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