Thermally conductive adhesive composition, method for producing the same, and use

Abstract

A thermally conductive composition is provided, comprising, based on the total weight of the thermally conductive adhesive composition, a) 0.5-30 wt%, preferably 2-20 wt%, of an epoxy resin, b) 0.5-30 wt%, preferably 2-20 wt%, of an anhydride, c) 0.1-5 wt%, preferably 0.5-3.5 wt%, of a catalyst, and d) 50-98 wt%, preferably 60-95 wt%, of a metal filler, the catalyst having a core-shell structure in which a shell encases a core, the catalyst core comprising an amine-based compound, and the catalyst shell prepared by reacting at least two of an epoxy resin, an amine-based compound, and a polyisocyanate. A method for producing and using the thermally conductive adhesive composition is also provided.

Description

Technical Field

[0001] The present invention relates to a thermally conductive adhesive composition, a method for producing the same, and use thereof.

Background Art

[0002] Today, electronic components such as semiconductors are designed to be increasingly high-density and highly integrated. Therefore, heat dissipation is an important and difficult problem for electronic assemblies. For conventional adhesives used for joining electronic elements, it is necessary to incorporate a large amount of conductive fillers (for example, silver) in order to achieve high thermal conductivity. However, when a large amount of expensive conductive fillers are used, the production cost of the adhesive increases.

Summary of the Invention

Problems to be Solved by the Invention

[0003] There is a continuing need for a thermally conductive adhesive composition that can achieve high thermal conductivity with a small amount of conductive filler.

Means for Solving the Problems

[0004] In order to solve the above problems, the present inventors have, based on the total weight of the thermally conductive adhesive composition, a) 0.5 to 30% by weight, preferably 2 to 20% by weight of an epoxy resin, b) 0.5 to 30% by weight, preferably 2 to 20% by weight of an anhydride, c) 0.1 to 5% by weight, preferably 0.5 to 3.5% by weight of a catalyst, and d) 50 to 98% by weight, preferably 60 to 95% by weight of a metal filler, A thermally conductive adhesive composition comprising: The catalyst has a core-shell structure in which a shell surrounds a core, the core of the catalyst contains an amine compound, and the shell of the catalyst is prepared by reacting at least two of an epoxy resin, an amine compound, and a polyisocyanate, and provides a thermally conductive adhesive composition.

[0005] The present invention also provides a method for preparing the thermally conductive adhesive composition of the present invention by mixing all components together.

[0006] The present invention further provides the use of the thermally conductive adhesive composition of the present invention for electronic devices, preferably semiconductors and diodes, more preferably for die attachment.

[0007] The inventors have found that by combining specific components in a specific manner, the resin in the thermally conductive adhesive composition aggregates, causing the metal filler to become denser during curing. As a result, the thermally conductive adhesive composition of the present invention achieves excellent thermal conductivity with a small amount of conductive filler. Furthermore, the cured adhesive composition of the present invention exhibits good toughness, which promotes stress relaxation. [Brief explanation of the drawing]

[0008] The attached drawings illustrate embodiments of the present invention and describe the principles and mechanisms of the present invention, but the present invention should not be interpreted as limiting.

[0009] [Figure 1a] Figure 1a is an SEM image of a cured thermally conductive adhesive composition according to an embodiment of the present invention. [Figure 1b] Figure 1b is a schematic representation of the SEM image of Figure 1a, but not scaled to the actual size. [Figure 2] Figure 2 is an optical microscope image of the uncured thermally conductive adhesive composition corresponding to Figure 1a. [Figure 3] Figure 3 is an optical microscope image of the cured thermally conductive adhesive composition corresponding to Figure 1a. [Figure 4] Figure 4 shows an optical microscope image of the cured thermally conductive adhesive composition of the comparative example.

[0010] Now, let us refer in detail to the embodiments of the present invention shown in the attached drawings. [Modes for carrying out the invention]

[0011] In this specification, the terms "thermally conductive adhesive composition" and "adhesive composition" are interchangeable with each other.

[0012] The present invention is based on the total weight of the thermally conductive adhesive composition, a) 0.5 to 30% by weight, preferably 2 to 20% by weight of an epoxy resin, b) 0.5 to 30% by weight, preferably 2 to 20% by weight of an anhydride, c) 0.1 to 5% by weight, preferably 0.5 to 3.5% by weight of a catalyst, and d) 50 to 98% by weight, preferably 60 to 95% by weight of a metal filler, A thermally conductive adhesive composition comprising: The catalyst has a core-shell structure in which the core is wrapped by the shell, the core of the catalyst contains an amine compound, and the shell of the catalyst is prepared by reacting at least two of an epoxy resin, an amine compound, and a polyisocyanate, and provides a thermally conductive adhesive composition.

[0013] The inventors of the present invention have found that by combining specific components in specific amounts, the thermally conductive adhesive composition of the present invention achieves excellent thermal conductivity with a small amount of conductive filler. Furthermore, the cured adhesive composition of the present invention exhibits good toughness that promotes stress relaxation.

[0014] <Component a) Epoxy resin> According to the present disclosure, the thermally conductive adhesive composition contains 0.5 to 30% by weight, preferably 2 to 20% by weight, more preferably 2 to 15% by weight of component a) epoxy resin based on the total weight of the thermally conductive adhesive composition.

[0015] The epoxy resin is curable due to the presence of reactive epoxy groups. Upon curing, the epoxy resin reacts with the anhydride of component b) to form a cross-linked thermosetting plastic having a three-dimensional network, imparting excellent adhesiveness and heat resistance to the adhesive composition.

[0016] When the content of component a) epoxy resin falls within the above range, the thermally conductive adhesive composition achieves an excellent balance among resin cohesiveness, thermal conductivity, and electrical conductivity.

[0017] In some examples of the present disclosure, per molecule of epoxy resin, the number of epoxy groups is more than 1, preferably about 2 or more.

[0018] The type of epoxy resin is not particularly limited, and any epoxy resin generally used in adhesive compositions can be used in the present disclosure. In some examples, the epoxy resin is selected from the group consisting of polyglycidyl ethers of polyphenols, polyglycidyl ethers of aliphatic polyols, polyglycidyl esters of aliphatic polycarboxylic acids, polyglycidyl esters of aromatic polycarboxylic acids, their derivatives, and any combination thereof. Preferably, the epoxy resin is selected from polyglycidyl ethers of polyphenols and their hydrogenated derivatives. More preferably, the epoxy resin is vinegar bisphenol A type epoxy resin, vinegar bisphenol F type epoxy resin, vinegar bisphenol S type epoxy resin, hydrogenated bis vinegar phenol A type epoxy resin, hydrogenated bis vinegar phenol F type epoxy resin, hydrogenated bis vinegar phenol S type epoxy resin, novolac type epoxy compounds, and any combination thereof.

[0019] Examples of commercially available epoxy resins include bisphenol A type epoxy resins such as jER828US, Epicote 828EL, and Epicote 1004 (all manufactured by Nippon Epoxy Resin Manufacturing Co., Ltd.); bisphenol F type epoxy resins such as Epicote 806 and Epicote 4004 (both manufactured by Nippon Epoxy Resin Manufacturing Co., Ltd.); bisphenol S type epoxy resins such as Epiclon EXA1514 (manufactured by Dainippon Ink and Chemicals, Inc.); and phenol novolac type epoxy resins such as Epiclon N-770 (manufactured by Dainippon Ink and Chemicals, Inc.). Examples of epoxy resins include, but are not limited to, those containing lipids; orthocresol novolac type epoxy resins such as Epiclon N-670-EXP-S (manufactured by Dainippon Ink and Chemicals, Inc.); dicyclopentadiene novolac type epoxy resins such as Epiclon HP7200 (manufactured by Dainippon Ink and Chemicals, Inc.) and XD-1000-L (manufactured by Nippon Kayaku Co., Ltd.); biphenyl novolac type epoxy resins such as NC-3000P (manufactured by Nippon Kayaku Co., Ltd.); and naphthalenephenol novolac type epoxy resins such as ESN-165S (manufactured by Toto Kasei Co., Ltd.).

[0020] <Component b) Anhydride> According to this disclosure, the thermally conductive adhesive composition contains 0.5 to 30% by weight, preferably 2 to 20% by weight, and more preferably 2 to 15% by weight of component b) anhydrous material, based on the total weight of the thermally conductive adhesive composition.

[0021] Component b) functions as a curing agent and reacts with component a) epoxy resin to form a crosslinked thermosetting plastic with a three-dimensional network, thereby imparting excellent adhesion and heat resistance to the adhesive composition.

[0022] When the content of component b) anhydrous material falls within the above range, the thermally conductive adhesive composition achieves an excellent balance between resin cohesiveness, thermal conductivity, and electrical conductivity.

[0023] To our surprise, the inventors have found that anhydrous curing agents impart significantly higher thermal conductivity to the entire adhesive composition compared to other types of epoxy resin curing agents, such as phenolic curing agents and amine curing agents (e.g., guanidine curing agents).

[0024] The type of anhydride is not particularly limited, and any anhydride commonly used in adhesive compositions may be used in this disclosure. In some examples, the anhydride is selected from the group consisting of monofunctional, difunctional, and polyfunctional anhydrides. The anhydride may be an aliphatic anhydride, an alicyclic anhydride, an aromatic anhydride, or any combination thereof. Preferably, the anhydride is nadic anhydride (NA), methylnadic anhydride (MNA), phthalic anhydride (PA), tetrahydrophthalic anhydride (THPA), methyltetrahydrophthalic anhydride (MTHPA), hexachloroendomethylenetetrahydrophthalic anhydride (chlorendic anhydride), endomethylenetetrahydrophthalic anhydride, hexahydrophthalic anhydride (HHPA), methylhexahydrophthalic anhydride (MHHPA), 5-norbo Ru Norbo such as nene-2,3-dicarboxylic acid anhydride Ru The following are selected from the group consisting of sene anhydrides, adipic anhydrides, trimellitic anhydrides, pyromellitic dianhydrides, maleic anhydrides (MA), succinic anhydrides (SA), nonenyl succinic anhydrides, dodecyl succinic anhydrides (DDSA), polyazelaic polyanhydrides, polysebacic polyanhydrides, and any combination thereof.

[0025] Examples of commercially available anhydrous compounds include HHPA, MTHPA, and DDSA from Anhydrides and Chemicals Inc. in Newark, New Jersey; MHHPA from BASF; and MA and MNA from Aldrich.

[0026] In some examples, the molar ratio of epoxy groups in component a) epoxy resin to anhydride groups in component b) anhydride is 0.2 to 3, preferably 0.7 to 1.3. This molar ratio ensures a sufficient crosslinking reaction between component a) epoxy resin and component b) anhydride.

[0027] <Component c) Catalyst> According to this disclosure, the thermally conductive adhesive composition contains 0.1 to 5% by weight, preferably 0.5 to 3.5% by weight, of component c) catalyst, based on the total weight of the thermally conductive adhesive composition.

[0028] Component c) the catalyst (hereinafter also referred to as the "core-shell catalyst") has a core-shell structure in which the shell encloses the core, and functions as a latent catalyst. The core-shell catalyst is stable during storage at a temperature of approximately -40°C. When heated to a temperature of 80°C or higher, the shell of the core-shell catalyst cracks, exposing the active amine-based compound inside the core, activating the catalyst and initiating the crosslinking reaction between a) epoxy resin and b) anhydride.

[0029] The catalyst core contains an amine compound, and the catalyst shell is prepared by reacting at least two of the following: epoxy resin, an amine compound, and polyisocyanate.

[0030] In some examples, the catalyst core may contain 0.001 to 3 parts by mass, preferably 0.01 to 2.5 parts by mass, more preferably 0.02 to 2 parts by mass, and even more preferably 0.03 to 1.5 parts by mass of an amine compound, based on 100 parts by mass of the catalyst core. When the content of the amine compound falls within the above range, a dense shell can be formed in a controllable manner during the shell formation reaction, ensuring high storage stability and solvent resistance of the core-shell catalyst.

[0031] In addition to the amine compound, the catalyst core may optionally contain an amine adduct. The amine adduct can be prepared by reacting the amine compound with an epoxy resin. In some examples, the molecular weight distribution of the amine adduct is greater than 1 and less than or equal to 7, preferably 1.01 to 6.5, more preferably 1.2 to 5, and even more preferably 1.5 to 4. When the molecular weight distribution of the amine adduct falls within the above range, the thermally conductive adhesive composition has high curability, high storage stability, and excellent adhesive strength.

[0032] In some cases, amine adducts can be obtained, for example, by reacting an epoxy resin and an amine compound in the presence of a solvent (if necessary) at a temperature of 50 to 250°C for 0.1 to 10 hours. The molar ratio of active hydrogen groups in the amine compound to epoxy groups in the epoxy resin is preferably 0.5 to 10:1, more preferably 0.8 to 5:1, and even more preferably 0.95 to 4:1 in order to economically obtain amine adducts having the desired molecular weight distribution.

[0033] The amine compound in the catalyst core is the same as or different from the amine compound in the catalyst shell, and preferably is the same.

[0034] The amine compound used to prepare the amine adduct in the catalyst core may be the same as or different from the amine compound used to prepare the amine compound in the catalyst core and / or the catalyst shell, and is preferably the same.

[0035] The amine compound in the catalyst core, the amine compound for preparing the amine adduct (if any), and the amine compound in the catalyst shell are independently selected from the group consisting of primary amines, secondary amines, imidazoles and their derivatives, imidazolines and their derivatives, and any combination thereof; preferably, selected from imidazoles and their derivatives.

[0036] The type of amine compound is not particularly limited, and those commonly used in adhesive compositions can be used in this disclosure.

[0037] In some examples, primary amines are selected from methylamine, ethylamine, propylamine, butylamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, ethanolamine, propanolamine, cyclohexylamine, isophoronediamine, aniline, toluidine, diaminodiphenylmethane, diaminodiphenylsulfone, and any combination thereof.

[0038] In some examples, the secondary amine is selected from dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, dimethanolamine, diethanolamine, dipropanolamine, dicyclohexylamine, piperidine, piperidone, diphenylamine, phenylmethylamine, phenylethylamine, and any combination thereof.

[0039] In some examples, imidazoles and their derivatives are selected from imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-aminoethyl-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-ethyl-4-methylimidazole, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazole, and 1-(2-hydroxy-3-butoxypropyl)-2-ethyl-4-methylimidazole, and any combination thereof.

[0040] In some examples, imidazolines and their derivatives include 1-(2-hydroxy-3-phenoxypropyl)-2-phenylimidazoline, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazoline, 2,4-dimethylimidazoline, 2-ethylimidazoline, 2-ethyl-4-methylimidazoline, 2-benzylimidazoline, 2-phenylimidazoline, 2-(o-tolyl)-imidazoline, tetramethylene-bisimidazoline, 1,3-trimethyl-1,4-tetramethylene-bisimidazoline, 1,3,3- Trimethyl-1,4-tetramethylene-bisimidazoline, 1,3-trimethyl-1,4-tetramethylene-bis-4-methylimidazoline, 1-hydroxy-3-phenoxypropyl-2-phenylimidazoline, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazoline, 1,2-phenylene-bis-imidazoline, 1,3-phenylene-bis-imidazoline, 1,4-phenylene-bisimidazoline, 1,4-phenylene-bis-4-methylimidazoline, and any combination thereof.

[0041] The epoxy resin used to prepare the amine adduct in the catalyst core may be the same as, or different from, the epoxy resin used to prepare the epoxy resin in component a) and / or the catalyst shell, and is preferably the same.

[0042] The epoxy resin in the catalyst shell is the same as, or different from, preferably the same as, the epoxy resin used to prepare the epoxy resin in component a) and / or the amine adduct in the core.

[0043] The definition, type, and preferred type of epoxy resin in component a) apply to the epoxy resin used to prepare the epoxy resin in the catalyst shell and / or the amine adduct in the core.

[0044] The type of polyisocyanate is not particularly limited, and those commonly used in adhesive compositions can be used in this disclosure.

[0045] In some examples, the polyisocyanate is a diisocyanate, a triisocyanate, or any combination thereof. In some examples, the polyisocyanate is preferably selected from the group consisting of aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, aliphatic triisocyanates, alicyclic triisocyanates, aromatic triisocyanates, and any combination thereof, and more preferably selected from aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, and any combination thereof.

[0046] In some examples, the aliphatic diisocyanate is selected from the group consisting of ethylene diisocyanate, propylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate, as well as any combination thereof.

[0047] In some examples, the alicyclic diisocyanates are selected from the group consisting of isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, norbornane diisocyanate, 1,4-isocyanatocyclohexane, 1,3-bis(isocyanatomethyl)-cyclohexane, 1,3-bis(2-isocyanatopropyl-2-yl)-cyclohexane, and any combination thereof.

[0048] In some examples, aromatic diisocyanates are selected from the group consisting of tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, and any combination thereof.

[0049] In some examples, aliphatic triisocyanates are selected from the group consisting of 1,6,11-undecane triisocyanate, 1,8-diisocyanate-4-isocyanatomethyloctane, 1,3,6-triisocyanatomethylhexane, 2,6-diisocyanatohexanoate-2-isocyanatoethyl ester, 2,6-diisocyanatohexanoate-1-methyl-2-isocyanatoethyl ester, and any combination thereof.

[0050] In some examples, the catalyst shell is prepared by reacting an epoxy resin, an amine compound, a polyisocyanate, and at least two optionally amine adducts. The amine adduct in the catalyst shell may be the same as, or different from, the amine adduct in the catalyst core, and is preferably the same. The definitions and preferred technical characteristics of the amine adduct in the catalyst core described above can also be applied to the amine adduct in the catalyst shell.

[0051] In some examples, the volume ratio of the core to the shell is approximately 100:1 to 100:50, preferably 100:1 to 100:20. When the volume ratio of the core to the shell falls within these ranges, the adhesive composition has good storage stability, good curing properties, and good dispersibility.

[0052] The ratio of epoxy resin, amine compound, polyisocyanate, and amine adduct (if present) in the catalyst shell is not particularly limited. Preferably, the polyisocyanate in the shell has a concentration of about 1 to 200 meq, preferably 10 to 100 meq, per kg of core. When the concentration of polyisocyanate falls within the above range, the core-shell catalyst has good resistance to mechanical shear force and imparts good curability to the entire adhesive composition.

[0053] The core-shell catalyst has a diameter of 0.5 μm to 10 μm, preferably 1 μm to 5 μm. 50 It may have particle size. In this specification, the core-shell catalyst "D 50"Particle size" refers to the median diameter in the volume-based particle size distribution curve obtained by measurement using a laser diffraction particle size analyzer.

[0054] In some examples, core-shell catalysts are formed by adjusting the dissolution conditions so that the core material is dissolved before, after, or simultaneously with the dissolution of the shell material in the dispersion medium, and then the shell is deposited onto or coated onto the core.

[0055] Examples of commercially available core-shell catalysts include, but are not limited to, the HXA series catalysts such as HXA 4982HP and HXA 3088F, which are available from Asahi Kasei Corporation.

[0056] <Component d) Metal filler> According to this disclosure, the thermally conductive adhesive composition contains 50 to 98% by weight, preferably 60 to 95% by weight, of a metal filler, based on the total weight of the thermally conductive adhesive composition.

[0057] Component d) imparts thermal and electrical conductivity to the entire adhesive composition.

[0058] When the metal filler content falls within these ranges, good thermal conductivity and good electrical conductivity can be achieved.

[0059] In some examples, the metallic filler is selected from the group consisting of silver, copper, gold, palladium, platinum, aluminum, bismuth, tin, their alloys, and glass coated with one or more of these metals and alloys. Preferably, the metallic filler is silver.

[0060] The shape of the metal filler is not particularly limited and can have various shapes such as spherical, granular, disc-shaped, cylindrical, cubic, rectangular, flake-shaped, needle-shaped, fibrous, and dendritic shapes, but a flake-shaped shape is preferred.

[0061] In some cases, the metal filler is silver flake, which has high thermal and electrical conductivity.

[0062] In some examples, the conductive filler is 0.5 to 20 μm, preferably 0.8 to 10 μm, more preferably 1 to 5 μm. 50 It may also be silver flakes having a particle size. Silver flakes D 50 When the particle size falls within these ranges, the silver flakes impart good thermal and electrical conductivity to the thermally conductive adhesive composition. In this specification, the "D" of the silver flakes 50 "Particle size" refers to the median diameter in the volume-based particle size distribution curve obtained by measurement using a laser diffraction particle size analyzer.

[0063] Examples of commercially available metal fillers include, but are not limited to, SA0201, available from Metalor Technologies.

[0064] <Thermally conductive adhesive composition> This invention, based on intensive research, is based on the total weight of the thermally conductive adhesive composition. a) 0.5 to 30% by weight, preferably 2 to 20% by weight of epoxy resin, b) 0.5 to 30% by weight, preferably 2 to 20% by weight of anhydrous material, c) 0.1 to 5% by weight, preferably 0.5 to 3.5% by weight of a catalyst, and d) 50-98% by weight, preferably 60-95% by weight of metal filler, A thermally conductive adhesive composition comprising, The present invention provides a thermally conductive composition in which the catalyst has a core-shell structure in which a shell encloses a core, the core of the catalyst contains an amine-based compound, and the shell of the catalyst is prepared by reacting at least two of the following: an epoxy resin, an amine-based compound, and a polyisocyanate.

[0065] Optionally, the thermally conductive adhesive composition further comprises additives different from components a) to d), which are preferably selected from adhesion promoters, curing accelerators, coupling agents, solvents, colorants, plasticizers, rheological additives, and any combination thereof.

[0066] As long as they do not adversely affect the effectiveness of the thermally conductive adhesive composition, there are no particular restrictions on the type and content of optional additives, if they are present.

[0067] In some cases, the solvent may be BCA (butyl carbitol acetate), which is available from Dow.

[0068] In some cases, the adhesion promoter may be A-186 or A-174, available from Momentive Performance Materials.

[0069] <Method for producing a thermally conductive adhesive composition> Thermally conductive adhesive compositions can be prepared by mixing all components together using common mixing methods such as mortars, propeller stirrers, kneaders, roller assemblies, and pot mills. The order in which each component is added and the mixing conditions are not particularly limited, as long as they do not adversely affect the effectiveness of the thermally conductive adhesive composition.

[0070] In some examples, the thermally conductive adhesive composition may have a Brookfield viscosity of 2,000 MPa·s to 100,000 MPa·s, preferably 5,000 MPa·s to 30,000 MPa·s, measured using a Brookfield RVT viscometer and a CP51 spindle at 25°C and 5 revolutions per minute (RPM).

[0071] <Use of thermally conductive adhesive compositions> The thermally conductive adhesive compositions of this disclosure can be used in electronic devices, preferably semiconductors and diodes, and more preferably for die attachment.

[0072] A thermally conductive adhesive composition can be applied to at least a portion of the surface of one or both adherends, the two adherends can be joined together, and the joined two adherends can be cured by exposing them to a heat of 80°C or higher.

[0073] For example, the adhesive compositions of the present disclosure can be printed or applied onto a substrate by any desired method, such as stencil printing, screen printing, gravure printing, or dispensing. The adhesive compositions of the present disclosure can be used in particular cases where an adhesive pattern is applied onto a substrate by fine-line stencil printing.

[0074] Therefore, the adhesive composition of this disclosure can be used to bond electronic components such as semiconductor devices, chip components, diodes, discrete components, or combinations thereof to electrodes on a circuit board, thereby forming an electronic circuit on the surface of the circuit board. [Examples]

[0075] This disclosure will be illustrated more specifically by the following embodiments. Please note that this disclosure is not limited by the following description.

[0076] (raw materials) epoxy resin XD-1000: An epoxy resin in which at least two glycidyloxy group-containing aromatic groups are bonded to each other by divalent intracyclic hydrocarbon groups; available from Japan. Epalloy® 5200: Cycloliphatic glycidyl ester, available from CVC Specialties. JER(registered trademark)828US: Liquid bisphenol A type epoxy resin, available from Mitsubishi Chemical Corporation.

[0077] anhydride DDSA: Dodecenyl succinic anhydride, available from Milliken Chemicals. DICY: Guanidine powder, available from A & C Catalysts. MEH-8000H: Phenolic resin, available from Meiwa Plastics Industry Co., Ltd. Jeffamine D 2000: Polyoxypropylenediamine, available from Huntsman.

[0078] catalyst HXA 4982HP: Core-shell catalyst, latent catalyst, D 50 Available from Asahi Kasei Corporation, with a particle size of 1 μm to less than 10 μm. HXA 3088F: Core-shell catalyst, latent catalyst, D 50 Particle size 1 μm to less than 10 μm, latent curing agent, available from Asahi Kasei Corporation. EMI-24CN: Ethylmethylimidazole, available from PCI Synthesis. Fujicure FXR1081: Modified aliphatic polyamine, available from T&K Toka. PN-H: Epoxy resin amine adduct, available from Ajinomoto Fine Techno Co., Ltd. 2MAOK: Imidazole catalyst, available from Air Products.

[0079] Metal filler SA0201: Silver flakes, available from Metalor Technologies.

[0080] solvent BCA: Butylcarbitol acetate, available from Dow.

[0081] Adhesion promoter A-186: Adhesion promoter, available from Momentive Performance Materials. A-174: Adhesion promoter, available from Momentive Performance Materials.

[0082] mixer For sample sizes of 500g or more, a loss mixer may be used. The loss mixer may have a mixer size of 1L to 20L, depending on the batch size of the sample.

[0083] For sample sizes of less than 500g, a speed mixer may be used as the mixer.

[0084] Preparation method In the following examples, the composition was prepared by the following steps:

[0085] Component a) and solvent BCA were weighed and mixed in a loss mixer at 30-60 revolutions per minute (RPM) for 1 hour at 80°C, then cooled to room temperature.

[0086] Components b) and d) were weighed and introduced into a Ross mixer, and mixed at room temperature at 30-60 RPM for 15 minutes (or mixed in a speed mixer at 2000 RPM for 2 minutes).

[0087] Next, component c) and the adhesion promoter were weighed and introduced into a Ross mixer, and mixed at room temperature at 30-60 RPM for 30 minutes (or at 1000 RPM for 2 minutes in a speed mixer).

[0088] The mixture was then degassed in a loss mixer for 15 minutes (or degassed in a speed mixer for 2 minutes).

[0089] Thermal conductivity A sample of the composition obtained above was placed in a Teflon mold measuring 3 cm in width and 0.5 to 2 mm in depth (thickness). The sample was cured in an oven. Next, the temperature of the composition was increased from 25°C to 175°C over 30 minutes, and then held at 175°C for 60 minutes to cure the composition, thereby forming a thermally diffusive pellet. The thermal conductivity of the pellet was measured by laser flash according to the test method specified in ASTM E 1461.

[0090] Unless otherwise specified, the raw materials in Tables 1 and 2 are expressed in parts by weight.

[0091] [Table 1]

[0092] [Table 2]

[0093] From Tables 1 and 2 above, it can be seen that in Examples 1, 18, 24, 29, and 30, the adhesive composition of this disclosure achieved excellent thermal conductivity with a small amount of conductive filler.

[0094] In Comparative Example 21, no catalyst was used. In Comparative Examples 2, 10, 19, 20, 36, and 37, a catalyst was used, but it was not a core-shell catalyst. In Comparative Examples 31, 32, and 35, a curing agent other than an amine was used. The thermal conductivity was undesirably low, or even unmeasurable.

[0095] Figure 1a is an SEM image of the cured thermal conductive adhesive composition of Example 1 of the present invention. Figure 1b schematically shows the SEM image of Figure 1a. Figure 2 is an optical microscope image of the uncured thermal conductive adhesive composition corresponding to Figure 1a. Figure 3 is an optical microscope image of the cured thermal conductive adhesive composition corresponding to Figure 1a.

[0096] In Figures 1a and 1b, substrate 200 and substrate 300 are joined with a thermally conductive adhesive composition 100. In the uncured adhesive composition 100 (shown in Figure 2), the metal filler and the rest of the adhesive composition (abbreviated as "resin") are uniformly dispersed. There are no metal-rich or resin-rich regions. The term "metal-rich region" refers to a region where metal is aggregated, and the metal content in this region is higher than the metal content in the surrounding region. The term "resin-rich region" refers to a region where resin is aggregated, and the resin content in this region is higher than the resin content in the surrounding region.

[0097] The inventors have surprisingly found that, during curing, the resin 12 aggregates in the adhesive composition of this disclosure, as shown in Figures 1a, 1b, and 3, causing the metal filler 11 to become denser. As a result, the metal fillers overlap each other over a larger area, significantly improving the thermal conductivity of the cured adhesive composition. Furthermore, the aggregation of the resin imparts good toughness to the cured adhesive composition, improving its stress relaxation.

[0098] Figure 4 is an optical microscope image of the cured thermally conductive adhesive composition of Comparative Example 2. In Figure 4, the metal filler and resin are uniformly dispersed. There are no metal-rich or resin-rich regions. The initial disclosures of this specification include at least the following aspects: [1] Based on the total weight of the thermally conductive adhesive composition, a) 0.5 to 30% by weight, preferably 2 to 20% by weight of epoxy resin, b) 0.5 to 30% by weight, preferably 2 to 20% by weight of anhydrous material, c) 0.1 to 5% by weight, preferably 0.5 to 3.5% by weight of a catalyst, and d) 50-98% by weight, preferably 60-95% by weight of metal filler, A thermally conductive adhesive composition comprising, The catalyst has a core-shell structure in which a shell encloses a core, the core of the catalyst comprises an amine compound, and the shell of the catalyst is prepared by reacting at least two of an epoxy resin, an amine compound, and a polyisocyanate, wherein the catalyst is a thermally conductive adhesive composition. [2] The epoxy resin in the shell of the catalyst is the same as or different from the epoxy resin in component a), preferably the same. The thermally conductive adhesive composition according to [1], wherein the epoxy resin in component a) and the epoxy resin in the shell of the catalyst are independently selected from the group consisting of polyglycidyl ethers of polyphenols, polyglycidyl ethers of aliphatic polyols, polyglycidyl esters of aliphatic polycarboxylic acids, polyglycidyl esters of aromatic polycarboxylic acids, derivatives thereof, and any combination thereof, preferably selected from polyglycidyl ethers of polyphenols and their hydrogenated derivatives; more preferably selected from the group consisting of bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, hydrogenated bisphenol A type epoxy resins, hydrogenated bisphenol F type epoxy resins, hydrogenated bisphenol S type epoxy resins, novolac type epoxy compounds, and any combination thereof. [3] The anhydride in component b) is selected from monofunctional, difunctional and polyfunctional anhydrides, preferably nadic anhydride (NA), methylnadic anhydride (MNA), phthalic anhydride (PA), tetrahydrophthalic anhydride (THPA), methyltetrahydrophthalic anhydride (MTHPA), hexachloroendomethylenetetrahydrophthalic anhydride (chlorendic anhydride) A thermally conductive adhesive composition according to [1] or [2], selected from the group consisting of anhydrides, endomethylenetetrahydrophthalic anhydride, hexahydrophthalic anhydride (HHPA), methylhexahydrophthalic anhydride (MHHPA), norbornene-based anhydrides such as 5-norbornene-2,3-dicarboxylic acid anhydride, adipic anhydride, trimellitic anhydride, pyromellitic dianhydride, maleic anhydride (MA), succinic anhydride (SA), nonenylucuccinate anhydride, dodecenyllucuccinate anhydride (DDSA), polyazelaic acid polyanhydride, polysebacic acid polyanhydride, and any combination thereof. [4] The thermally conductive adhesive composition according to any one of [1] to [3], wherein the molar ratio of epoxy groups in the epoxy resin of component a) to anhydride groups in the anhydride of component b) is 0.2 to 3, preferably 0.7 to 1.3. [5] The amine compound in the shell of the catalyst is the same as or different from the amine compound in the core of the catalyst, preferably the same. The amine compound in the core of the catalyst and the amine compound in the shell of the catalyst are independently selected from the group consisting of primary amines, secondary amines, imidazoles and their derivatives, imidazolines and their derivatives, and any combination thereof; preferably selected from imidazoles and their derivatives, according to any one of [1] to [4]. [6] The thermally conductive adhesive composition according to any one of [1] to [5], wherein the metal filler is selected from the group consisting of silver, copper, gold, palladium, platinum, aluminum, bismuth, tin, alloys thereof, and glass coated with one or more of these metals and alloys. [7] The thermally conductive adhesive composition according to any one of [1] to [6], wherein the polyisocyanate is a diisocyanate, a triisocyanate, or any combination thereof, and the polyisocyanate is preferably selected from the group consisting of aliphatic diisocyanate, alicyclic diisocyanate, aromatic diisocyanate, aliphatic triisocyanate, alicyclic triisocyanate, aromatic triisocyanate, and any combination thereof, and more preferably selected from aliphatic diisocyanate, alicyclic diisocyanate, aromatic diisocyanate, and any combination thereof. [8] A thermally conductive adhesive composition according to any one of [1] to [7], further comprising, optionally, additives different from components a) to d), preferably selected from adhesion promoters, curing accelerators, coupling agents, solvents, colorants, plasticizers, rheological additives, and any combination thereof. [9] A method for producing the thermally conductive adhesive composition described in any of [1] to [8] by mixing all the components together.

[10] Use of any of the thermally conductive adhesive compositions described in [1] to [8] for electronic devices, preferably semiconductors and diodes, more preferably for die attachment.

Claims

1. Based on the total weight of the thermally conductive adhesive composition, a) 0.5 to 30% by weight of epoxy resin, b) 0.5 to 30% by weight of anhydrous material, c) 0.1 to 5% by weight of catalyst, and d) 50-98% by weight of metal filler, A thermally conductive adhesive composition comprising, The catalyst has a core-shell structure in which a shell encloses a core, the core of the catalyst contains an amine compound, and the shell of the catalyst is prepared by reacting at least two of an epoxy resin, an amine compound, and a polyisocyanate, wherein the catalyst is a thermally conductive adhesive composition.

2. The shell of the catalyst is composed of the same or different epoxy resin as the epoxy resin in component a), The thermally conductive adhesive composition according to claim 1, wherein the epoxy resin in component a) and the epoxy resin in the shell of the catalyst are independently selected from the group consisting of polyglycidyl ethers of polyphenols, polyglycidyl ethers of aliphatic polyols, polyglycidyl esters of aliphatic polycarboxylic acids, polyglycidyl esters of aromatic polycarboxylic acids, derivatives thereof, and any combination thereof.

3. The thermally conductive adhesive composition according to claim 1 or 2, wherein the anhydride in component b) is selected from monofunctional, difunctional, and polyfunctional anhydrides.

4. A thermally conductive adhesive composition according to any one of claims 1 to 3, wherein the molar ratio of epoxy groups in the epoxy resin of component a) to anhydride groups in the anhydride of component b) is 0.2 to 3.

5. The shell of the catalyst is composed of the same or a different amine compound as the amine compound in the core of the catalyst. The thermally conductive adhesive composition according to any one of claims 1 to 4, wherein the amine compound in the core of the catalyst and the amine compound in the shell of the catalyst are independently selected from the group consisting of primary amines, secondary amines, imidazoles and their derivatives, imidazolines and their derivatives, and any combination thereof.

6. The thermally conductive adhesive composition according to any one of claims 1 to 5, wherein the metal filler is selected from the group consisting of silver, copper, gold, palladium, platinum, aluminum, bismuth, tin, alloys thereof, and glass coated with one or more of these metals and alloys.

7. The thermally conductive adhesive composition according to any one of claims 1 to 6, wherein the shell of the catalyst is composed of a polyisocyanate, and the polyisocyanate is selected from the group consisting of diisocyanate, triisocyanate, and any combination thereof.

8. The thermally conductive adhesive composition according to any one of claims 1 to 7, further comprising an adhesion promoter, a curing accelerator, a coupling agent, a solvent, a colorant, a plasticizer, a rheological additive, and any combination thereof, which are different from components a) to d).

9. A method for producing the thermally conductive adhesive composition according to any one of claims 1 to 8, by mixing all the components together.

10. Use of the thermally conductive adhesive composition according to any one of claims 1 to 8 for use in electronic devices.

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