Conductive epoxy resin composition for copper bonding

Abstract

The present invention discloses a conductive epoxy resin composition (especially a conductive epoxy resin composition for bonding a copper substrate), a cured product thereof and use thereof, and a semiconductor device comprising the cured product.

Description

Technical Field

[0001] The present invention relates to a conductive epoxy resin composition (particularly a conductive epoxy resin composition for bonding a copper substrate), a cured product thereof and use thereof, and a semiconductor device comprising the cured product. Background Art

[0002] Conductive epoxy adhesives are used for a variety of purposes in the manufacture and assembly of semiconductor packages, such as bonding integrated circuit chips to lead frames or other substrates. It is important that the cured adhesive exhibits high adhesion, high thermal conductivity, high moisture resistance, good temperature stability, and good reliability.

[0003] Traditional one-component conductive epoxy adhesives typically contain a conductive filler, an epoxy resin, and a curing agent. However, epoxy resins can be brittle, and other resins have been evaluated and used to impart flexibility, hydrophobicity, and other properties to die attach adhesives. In particular, conductive epoxy adhesives do not exhibit strong adhesion to copper substrates, especially at high temperatures, such as those above 260°C.

[0004] Therefore, there is still a need to develop a conductive epoxy resin adhesive that can bond to copper substrates with good adhesion at high temperatures, especially at high temperatures above 260°C. Summary of the Invention

[0005] After in-depth research, the inventors of the present invention found that the above problems can be solved by a conductive epoxy resin composition, which comprises:

[0006] (A) at least one epoxy resin system comprising: (A1) at least one epoxy resin having at least two glycidyloxy-containing aromatic groups bonded to each other via a divalent bridged cyclic hydrocarbon group or an aromatic group and optionally a C1-C6 alkylene group; and (A2) at least one resorcinol diglycidyl ether resin, wherein the resorcinol diglycidyl ether resin is present in an amount of 0.2 to 5.0 weight percent, based on the total weight of the composition;

[0007] (B) at least one anhydride curing agent;

[0008] (C) optionally at least one solvent;

[0009] (D) at least one electrically conductive filler; and

[0010] (E) optionally at least one catalyst.

[0011] In another aspect of the present invention, a cured product of the conductive epoxy resin composition according to the present invention is provided.

[0012] In still another aspect of the present invention, there is provided a semiconductor device comprising a cured product of the conductive adhesive according to the present invention.

[0013] In still another aspect of the present invention, there is provided use of a conductive epoxy resin composition and a cured product of the conductive epoxy resin composition for preparing a semiconductor package or a microelectronic device. DETAILED DESCRIPTION

[0014] It will be understood by those skilled in the art that the present invention is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the invention. Each aspect described in this manner may be combined with any one or more other aspects unless expressly indicated to the contrary. In particular, any feature indicated as preferred or advantageous may be combined with any one or more other features indicated as preferred or advantageous.

[0015] Unless otherwise specified, in the context of the present invention, the terms used should be interpreted according to the following definitions.

[0016] As used herein, the singular forms "a," "an," "the," and "the" include both singular and plural referents unless otherwise specified.

[0017] As used herein, the terms "comprising" and "including" are synonymous with "containing," "including," or "having" and are inclusive or open-ended and do not exclude additional, unrecited members, elements, or method steps.

[0018] Unless otherwise specified, the recitation of numerical endpoints includes all numbers and fractions subsumed within the corresponding range, as well as the recited endpoint.

[0019] All references cited in this specification are hereby incorporated by reference in their entirety.

[0020] Unless otherwise defined, all terms (including technical and scientific terms) used in the present invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0021] The present invention relates to a conductive epoxy resin composition, comprising:

[0022] (A) at least one epoxy resin system comprising: (A1) at least one epoxy resin having at least two glycidyloxy-containing aromatic groups bonded to each other via a divalent bridged cyclic hydrocarbon group or an aromatic group and optionally a C1-C6 alkylene group; and (A2) at least one resorcinol diglycidyl ether resin, wherein the resorcinol diglycidyl ether resin is present in an amount of 0.2 to 5.0 weight percent, based on the total weight of the composition;

[0023] (B) at least one anhydride curing agent;

[0024] (C) optionally at least one solvent;

[0025] (D) at least one electrically conductive filler; and

[0026] (E) optionally at least one catalyst.

[0027] (A) Epoxy resin system

[0028] According to the present invention, a significant feature is that the epoxy resin system (A) contained in the conductive epoxy resin composition comprises: (A1) at least one epoxy resin having at least two glycidyloxy-containing aromatic groups bonded to each other via a divalent bridged cyclic hydrocarbon group or an aromatic group and optionally a C1-C6 alkylene group; and (A2) at least one resorcinol diglycidyl ether resin, wherein the resorcinol diglycidyl ether resin is present in an amount of 0.2 to 5.0 wt % based on the total weight of the composition; this significantly improves adhesion to copper substrates at high temperatures.

[0029] (A1) Epoxy resin

[0030] According to the present invention, the epoxy resin (A1) has at least two glycidyloxy-containing aromatic groups bonded to each other via a divalent bridged cyclic hydrocarbon group or an aromatic group and an optionally present C1-C6 alkylene group.

[0031] The glycidyloxy-containing aromatic group can have various structures, including but not limited to a glycidyloxy-containing monofunctional phenol, a glycidyloxy-containing polyfunctional phenol, a glycidyloxy-containing monofunctional naphthyl, a glycidyloxy-containing polyfunctional naphthyl, and combinations thereof. Specific examples can be represented by the following structural formulas Ep1 to Ep9:

[0032]

[0033] In the present invention, the glycidyloxy-containing aromatic group is not limited to the above structural formulas Ep1 to Ep9. In other embodiments, the glycidyloxy-containing aromatic group can be a phenol or naphthyl group containing a triglycidyl group or a tetraglycidyl group.

[0034] In the above structures, when two or more linkages to other structural sites are located on the naphthyl group, these bonds may be located on the same nucleus or on different nuclei.

[0035] In the present invention, the epoxy resin (A1) has at least two glycidyloxy-containing aromatic groups bonded to each other via a divalent bridged cyclic hydrocarbon group or an aromatic group and an optionally present C1-C6 alkylene group. This connection can be any desired combination of connection forms.

[0036] In a preferred embodiment, the epoxy resin (A1) has at least two glycidyloxy-containing aromatic groups bonded to each other via a divalent bridged cyclic hydrocarbon group. Examples of the divalent bridged cyclic hydrocarbon group can be represented by the following structural formulas X1 to X3:

[0037]

[0038] wherein each ring may have more than one R, and each R independently represents a hydrogen atom or a methyl group; and * represents a bonding site to the glycidyloxy-containing aromatic group.

[0039] In some embodiments, the epoxy resin (A1) has at least two glycidyloxy-containing aromatic groups bonded to each other by an aryl group. The term "aryl" herein refers to a polyunsaturated aromatic substituent, which can be a monocyclic or polycyclic ring (preferably 1 to 3 rings) that are fused together or covalently linked. Examples of aryl groups include, but are not limited to, phenyl, tolyl, xylyl, and 4-biphenyl.

[0040] In a preferred embodiment, the epoxy resin (A1) has at least two glycidyloxy-containing aromatic groups bonded to each other through an aryl group and a C1-C6 alkylene group. Examples of C1-C6 alkylene include -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH(CH3)CH2-, -CH(C2H5)CH2-, -CH2CH2CH2CH2-, -C(CH3)2CH2-, -CH(CH3)CH2CH2-, -CH2CH(CH3)CH2-, -CH(CH3)CH(CH3 )-, -CH2CH2CH2CH2CH2-, -CH(CH3)CH2CH2CH2-, -CH2CH(CH3)CH2CH2-, -C(CH3)2CH2CH2-, -CH2C(CH3)2CH2-, -CH(C2H5)CH2CH2-, -CH2CH(C2H5)CH2-, -CH(CH3)CH(CH3)CH 2-, -CH2CH2CH2CH2CH2CH2-, -CH(CH3)CH2CH2CH2CH2-, -CH2CH(CH3)CH2CH2CH2-, -CH2CH2CH(CH3)CH2CH2-, -C(CH3)2CH2CH2CH2-, -CH2C(CH3)2CH2CH2-, -CH(CH3)CH(CH 3) CH2CH2-, -CH(CH3)CH2CH(CH3)CH2-, -CH(CH3)CH2CH2CH(CH3)-, -CH2CH(CH3)CH2CH(CH3)-, -CH2CH(CH3)CH(CH3)CH2-, -CH(C2H5)CH2CH2CH2-, and -CH2CH(C2H5)CH2CH2-.

[0041] Specific examples of the combination of aryl and C1 to C6 alkylene include, but are not limited to, phenylmethyl, 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl, 2-methylnaphthyl, 3-methylnaphthyl, and 4-methylnaphthyl, which are represented by the following structural formulas X4 to X9:

[0042]

[0043] wherein each R′ independently represents a C1 to C6 alkylene group, preferably a C1 to C3 alkylene group, more preferably a methylene group; and * represents a bonding site to the glycidyloxy-containing aromatic group.

[0044] Among them, structural formulas X1 and X7 are particularly preferred from the viewpoint of providing toughness to the cured product of the composition.

[0045] In some embodiments, the epoxy resin (A1) may be selected from a glycidyloxy-containing biphenyl type epoxy resin, a glycidyloxy-containing naphthalene type epoxy resin, a glycidyloxy-containing epoxy resin having a divalent bridged cyclic hydrocarbon group, and combinations thereof.

[0046] Specific examples of the glycidyloxy-containing biphenyl type epoxy resin used as the epoxy resin (A1) in the present invention can be represented by the following structural formulas P1 and P2:

[0047]

[0048] Where n can be an average value from 1 to 5,

[0049]

[0050] Here, n can be an average value of 1 to 5.

[0051] A specific example of the glycidyloxy group-containing epoxy resin having a divalent bridged cyclic hydrocarbon group used as the epoxy resin (A1) in the present invention can be represented by the following structural formula P3:

[0052]

[0053] wherein n may be an average value of 1 to 5. In this structure, the diglycidyl-containing phenol group may be bonded to any structural site on the octahydro-4,7-methano-indene.

[0054] Since the present invention has the above-mentioned characteristic chemical structure, the aromatic hydrocarbon structure or the bridged hydrocarbon structure makes it tough and rigid, and thus the resin can provide enhanced toughness while maintaining heat resistance.

[0055] In a preferred embodiment, the epoxy resin (A1) preferably has an epoxy equivalent weight of 180 to 500 g / eq, preferably 200 to 400 g / eq.

[0056] In some embodiments, the epoxy resin (A1) may be prepared by a production method known in the art by reacting a phenolic resin with epichlorohydrin.

[0057] Examples of commercially available epoxy resins (A1) include NC-3000 series (NC-3000 and NC-2000-L) and XD-1000 manufactured by Nippon Kayaku Co., Ltd.

[0058] Particularly preferably, the epoxy resin (A1) incorporated into the conductive epoxy resin composition is present in an amount of 1 to 15% by weight, preferably 3 to 10% by weight, based on the total weight of the composition.

[0059] (A2) Resorcinol diglycidyl ether resin

[0060] According to the present invention, adding a specific amount of resorcinol diglycidyl ether resin (A2) to the epoxy resin (A1) provided in the present invention, i.e., 0.2 to 5.0 wt%, preferably 0.5 to 3.0 wt%, more preferably 0.75 to 2.25 wt%, based on the total weight of the composition, can significantly improve adhesion to a copper substrate.

[0061] Resorcinol diglycidyl ether (RDGE) has good oxygen barrier properties, as well as good chemical resistance, flexibility, and adhesion to various substrates. Compared to other epoxy resins, RDGE-based resins can provide beneficial conformer packing, improved hydrogen bonding, and inter-chain / intra-chain interactions within the resin.

[0062] In some embodiments, when the resorcinol diglycidyl ether resin comprises monomers, resorcinol exhibits a relatively low viscosity (e.g., about 200 to about 500 cps at about 25° C.) and a relatively high reactivity with epoxy resins. The resorcinol diglycidyl ether resin may have an epoxy equivalent weight of about 100 g to about 130 g. The resorcinol diglycidyl ether epoxide may have the general formula (I) shown below:

[0063]

[0064] Examples of resorcinol diglycidyl ether resins are RDGE, which is a purified form of RDGE, is available from CVC Thermoset Specialties. The RDGE has a viscosity of about 300 to 500 cps at about 25°C and a maximum of 10 ppm of residual epichlorohydrin.

[0065] Particularly preferably, the resorcinol diglycidyl ether resin (A2) may be incorporated into the conductive epoxy resin composition in an amount of 0.2 to 5.0 wt%, preferably 0.5 to 3.0 wt%, more preferably 0.75 to 2.25 wt%, based on the total weight of the composition.

[0066] In a preferred embodiment, the weight ratio of resorcinol diglycidyl ether resin (A2) to epoxy resin (A1) is 1:4 to 1:20, preferably 1:5 to 1:15, more preferably 1:6 to 1:10.

[0067] (B) Acid anhydride curing agent

[0068] According to the present invention, the conductive epoxy resin composition includes at least one acid anhydride curing agent (B). The acid anhydride curing agent (B) is not particularly limited as long as it can cure component (A).

[0069] Specific examples of the acid anhydride curing agent include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, nadic methyl acid anhydride, nadic acid anhydride, glutaric anhydride, methylhexahydrophthalic anhydride and methyltetrahydrophthalic anhydride. These anhydrides can be used alone or in combination.

[0070] Phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and the like are preferably used.

[0071] The amount of the anhydride curing agent (B) to be used is not particularly limited, and generally, it is preferred that the amount of the anhydride curing agent (B) is about 0.5 to 1.5 eq., and more preferably about 0.8 to 1.2 eq., per equivalent of the epoxy resin system (A). When the amount of component (B) is less than 0.5 eq., curing of the epoxy resin composition may be incomplete, while when it exceeds 1.5 eq., the toughness of the cured product may be lower than that of the cured product of the present invention.

[0072] Particularly preferably, the anhydride curing agent (B) may be incorporated into the conductive epoxy resin composition in an amount of 3 to 15 wt %, preferably 3.5 to 10 wt %, based on the total weight of the composition.

[0073] (C) Solvent

[0074] In a preferred embodiment, the conductive epoxy resin composition may include at least one solvent (C) to disperse the epoxy resin system (A) and the conductive filler (D) to reduce the viscosity of the conductive epoxy resin composition.

[0075] Most conductive fillers (such as silver fillers) are commercially provided with organic coatings to avoid agglomeration. The solvent plays a role in dissolving or replacing the organic material from the silver filler surface. The solvent must have a balanced polarity to effectively remove the coating and keep the conductive filler dispersed in the solvent until it is distributed and solidified. The typical organic materials used by silver filler manufacturers include stearic acid, isostearic acid (isosteric acid), lauric acid, capric acid, capric acid, oleic acid, palmitic acid, or fatty acids neutralized with amines such as imidazoles. And an effective solvent is a solvent that removes these lubricants and other such lubricants from the silver filler surface.

[0076] There is no limitation on the type of solvent as long as its flash point is higher than 70° C., preferably higher than 90° C. The solvent can be selected from 2-(2-ethoxy-ethoxy)-ethyl acetate, propylene glycol monoethyl ether, butyl ethoxyethyl acetate, propylene carbonate, cyclooctenone, cycloheptanone, cyclohexanone, linear or branched alkanes, tripropylene glycol methyl ether, dipropylene glycol monomethyl ether and mixtures thereof.

[0077] Commercially available products can be used in the present invention. Examples include diisobutyl adipate available from Sinopharm Chemical Reagent Co., Ltd., 2-(2-butoxyethoxy)ethyl acetate available from BASF, and diethylene glycol monoethyl ether available from SIGMA-ALDRICH.

[0078] Particularly preferably, the solvent (C) may be incorporated into the conductive epoxy resin composition in an amount of 0.5 to 20 wt %, preferably 1 to 10 wt %, based on the total weight of the composition.

[0079] (D) Conductive filler

[0080] The conductive epoxy resin composition according to the present invention includes at least one conductive filler selected from the group consisting of silver, copper, boron nitride, aluminum oxide, gold, nickel, silver-containing alloys, copper-containing alloys, nickel-containing alloys, and combinations thereof. From a cost perspective, silver, copper, boron nitride, or aluminum oxide is preferably used as the conductive filler in the present invention.

[0081] In a preferred embodiment, the conductive filler may be: D 50 A silver filler having a particle size of 0.5 to 6.0 μm, preferably 0.8 to 5.0 μm, more preferably 1.0 to 5.0 μm, more preferably 1.1 to 1.4 μm, and even more preferably 1.1 to 3.0 μm. When the particle size of the silver filler is within the above range, the filler is better dispersed in the resin composition, which can improve the storage stability of the resin composition and provide uniform adhesive strength. Herein, the "D 50 The “particle size” refers to the median diameter in a volume-based particle size distribution curve obtained by measurement with a laser diffraction particle size analyzer.

[0082] In a preferred embodiment, the silver particles used in the conductive epoxy resin composition include particles with a flaky shape. Fillers with this shape have a high contact area between the fillers, which can reduce voids in the cured product. The shape of the silver particles is the shape when observed and analyzed by a scanning electron microscope (SEM), and a Philips XL30 can be used as an observation device for the SEM. Examples of flaky particles include particles with shapes such as plates, discs, scales, and flakes. Compared to the case where granular silver particles are in contact with each other, when the flaky silver particles are in contact with each other, the contact area increases. Therefore, if the conductive epoxy resin composition containing flaky silver particles is heat-cured, the density of the silver particles between each other will increase; therefore, it is speculated that not only the thermal conductivity and electrical conductivity of the cured product of the conductive epoxy resin composition are improved, but also the bonding strength to the surface of the base metal is improved.

[0083] In a preferred embodiment, the conductive filler may have a thickness of 2 to 15 g / cm 3 , preferably 3 to 7.5 g / cm 3 The tap density of silver filler.

[0084] In a preferred embodiment, the silver filler used in the present invention can be prepared by a known method such as a reduction method, a grinding method, an electrolysis method, an atomization method or a heat treatment method.

[0085] In some embodiments, the surface of the silver filler may be coated with an organic substance.

[0086] Herein, the state in which the silver filler is "coated with an organic substance" includes a state in which the organic solvent is adhered to the surface of the silver filler by dispersing the silver filler in the organic solvent.

[0087] Examples of the organic substance coating the silver filler may include: hydrophilic organic compounds such as alkyl alcohols having 1 to 5 carbon atoms, alkanethiols having 1 to 5 carbon atoms, and alkane polyols having 1 to 5 carbon atoms, or lower fatty acids having 1 to 5 carbon atoms; and hydrophobic organic compounds such as higher fatty acids having 15 or more carbon atoms and derivatives thereof, middle fatty acids having 6 to 14 carbon atoms and derivatives thereof, alkyl alcohols having 6 or more carbon atoms, alkylamines having 16 or more carbon atoms, or alkanethiols having 6 or more carbon atoms.

[0088] Examples of higher fatty acids include: straight-chain saturated fatty acids such as pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, 12-hydroxyoctadecanoic acid, eicosanoic acid, behenic acid, tetracosanoic acid, hexacosanoic acid (cerotic acid), or octacosanoic acid; branched saturated fatty acids such as 2-pentylnonanoic acid, 2-hexyldecanoic acid, 2-heptyldodecanoic acid, or isostearic acid; and unsaturated fatty acids such as palmitoleic acid, oleic acid, vaccenic acid, elaidic acid, linoleic acid, linolenic acid, recinoleic acid, gadoleic acid, erucic acid, and shark oleic acid.

[0089] Examples of medium fatty acids include: straight-chain saturated fatty acids, such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, or tetradecanoic acid; branched saturated fatty acids, such as isohexanoic acid, isoheptanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, 2-propylheptanoic acid, isodecanoic acid, isoundecanoic acid, 2-butyloctanoic acid, isododecanoic acid, and isotridecanoic acid; and unsaturated fatty acids, such as 10-undecenoic acid.

[0090] Examples of methods for preparing a silver filler having a surface coated with an organic substance include, but are not particularly limited to, a method of preparing a silver filler by a reduction method in the presence of an organic solvent. Specifically, the silver filler can be obtained by mixing a silver carboxylate with a primary amine and depositing a conductive filler using a reducing agent in the presence of an organic solvent.

[0091] Commercially available silver fillers can be used as the conductive filler in the present invention. Examples thereof include FA-SAB-238 available from Dowa Hightech and EA0295 available from METALOR.

[0092] When the surface of the silver filler is coated with an organic substance, agglomeration of the silver filler in the adhesive composition can be better avoided or reduced.

[0093] In some embodiments, silver fillers can be used alone or in combination of two or more. Combinations of fillers of different shapes or sizes can reduce the porosity of the cured product. Examples of combinations include, but are not limited to, mixtures of flaky silver fillers and approximately spherical silver fillers whose central particle diameter is smaller than that of the flaky silver fillers.

[0094] Particularly preferably, the conductive filler (D) may be incorporated into the conductive epoxy resin composition in an amount of 65 to 95 wt %, preferably 70 to 95 wt %, based on the total weight of the composition.

[0095] (E) Catalyst

[0096] In some embodiments, a catalyst may be added to accelerate the curing process or to lower the temperature for thermal latent curing.

[0097] Various thermal curing catalysts known in the art can be used in the present invention, including phenylurea, boron trichloride amine complex, imidazole, aliphatic diurea, phenol, resorcinol, and combinations thereof. In a preferred embodiment, an effective catalyst for the composition is imidazole. Imidazole is a heterocyclic compound containing a nitrogen atom at the 1,3-position of the 5-membered ring. Specific examples of the imidazole catalyst include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-cyanoethyl-2-ethyl-4,5-methylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid addition product dehydrate.

[0098] Commercially available examples of imidazole catalysts are Curezol 2MA-OK or Curezol 2PHZ-S, which are available from Air Products. A commercially available example of a latent polyamine is available from Asahi KASEI as HXA3932HP.

[0099] Particularly preferably, the catalyst (E) may be incorporated into the conductive epoxy resin composition in an amount of 0.1 to 5 wt %, preferably 0.5 to 3 wt %, based on the total weight of the composition.

[0100] According to the present invention, a conductive epoxy resin composition is preferred, wherein based on the total weight of the composition, the conductive epoxy resin composition comprises:

[0101] 1 to 15% by weight, preferably 3 to 10% by weight, of at least one epoxy resin (A1) having at least two glycidyloxy-containing aromatic groups bonded to one another via a divalent bridged cyclic hydrocarbon group or an aromatic group and optionally a C1-C6 alkylene group,

[0102] 0.2 to 5.0% by weight, preferably 0.5 to 3% by weight, more preferably 0.75 to 2.25% by weight of at least one resorcinol diglycidyl ether resin (A2),

[0103] 3 to 15 wt. %, preferably 3.5 to 10 wt. % of at least one anhydride curing agent (B);

[0104] 0.5 to 20% by weight, preferably 1 to 10% by weight, of at least one solvent (C);

[0105] 65 to 95 wt. %, preferably 70 to 95 wt. % of at least one electrically conductive filler (D); and

[0106] 0.1 to 5% by weight, preferably 0.5 to 3% by weight, of at least one catalyst (E).

[0107] additive

[0108] Other commonly used additives may be further added to the conductive epoxy resin composition of the present invention, including toughening agents, fluxing agents, peroxides, flow additives, adhesion promoters, rheology modifiers, and mixtures thereof.

[0109] In some embodiments, the conductive epoxy resin composition may include a toughening agent to enhance the toughness of the epoxy resin, such as liquid butadiene rubber. The liquid butadiene rubber may include: a homopolymer or copolymer containing repeating units derived from butadiene or isobutadiene; or a copolymer of butadiene or isobutadiene with acrylate and / or acrylonitrile, such as liquid butadiene acrylonitrile rubber.

[0110] In some embodiments, the liquid butadiene rubber used as the toughening agent of the present invention may contain reactive end groups, such as amino-terminated liquid nitrile rubber (ATBN) or carboxylate-terminated liquid acrylonitrile rubber (CTBN) or liquid rubber containing free epoxy or methacrylate end groups.

[0111] The addition of liquid butadiene rubber used as a toughening agent in the present invention is believed to improve the mechanical strength of the cured adhesive composition at elevated temperatures, particularly temperatures above 90°C, preferably above 180°C, or even more preferably above 250°C.

[0112] Liquid butadiene rubber is commercially available, for example, from NOVEON under the trade name get.

[0113] According to the present invention, the additive may be present in an amount of 0.1 to 13 wt %, preferably 0.5 to 3 wt %, based on the total weight of the composition.

[0114] Preparation method of conductive epoxy resin composition

[0115] The conductive epoxy resin composition according to the present invention can be prepared by mixing the following at room temperature: (A1) at least one epoxy resin having at least two glycidyloxy-containing aromatic groups bonded to each other via a divalent bridged hydrocarbon group or aromatic group and optionally a C1-C6 alkylene group; (A2) at least one resorcinol diglycidyl ether resin, wherein the resorcinol diglycidyl ether resin is present in an amount of 0.2 to 5.0% by weight based on the total weight of the composition; (B) at least one acid anhydride curing agent; (C) optionally at least one solvent; (D) at least one conductive filler; (E) optionally at least one catalyst; and other additives, if present. The method for preparing the conductive epoxy resin composition is not particularly limited, as long as a composition in which the above components are uniformly mixed can be obtained.

[0116] Cured product and semiconductor device

[0117] In another aspect of the present invention, a cured product of the conductive epoxy resin composition according to the present invention is provided.

[0118] In a preferred embodiment, the curing temperature of the conductive epoxy resin composition is 120°C to 200°C, preferably 150°C to 180°C.

[0119] The conductive epoxy resin composition of the present invention can be used for bonding to circuits of electronic components, for example, as a die attacher for bonding a semiconductor component to another semiconductor component and / or as a die attacher for bonding a semiconductor component to a support member for mounting the semiconductor component.

[0120] In a preferred embodiment, the cured product of the conductive epoxy resin composition has an adhesive strength greater than 10 MPa at room temperature and greater than 1.3 MPa at 260° C., wherein the test materials are a bare silicon chip and a copper lead frame.

[0121] In another aspect of the present invention, there is provided a semiconductor device including a cured product of the conductive epoxy resin composition according to the present invention.

[0122] A semiconductor device including a cured product of the conductive epoxy resin composition according to the present invention is excellent in adhesive strength at a high temperature of 260°C.

[0123] In still another aspect of the present invention, there is provided use of the conductive epoxy resin composition and a cured product of the conductive epoxy resin composition according to the present invention in preparing a semiconductor package or a microelectronic device.

[0124] Example

[0125] The following examples are intended to help those skilled in the art better understand and implement the present invention. The scope of the present invention is not limited by the examples, but is defined by the appended claims. Unless otherwise indicated, all parts and percentages are based on weight.

[0126] Raw materials:

[0127] DDSA is a liquid mixture of several isomeric alkenyl succinic anhydrides available from Milliken Chemicals.

[0128] XD-1000 is an epoxy resin having at least two glycidyloxy-containing aromatic groups bonded to each other via a divalent bridged cyclic hydrocarbon group, and is available from Nippon.

[0129] ERISYS RDGE is a resorcinol diglycidyl ether resin available from CVC Specialties.

[0130] Jb TM 828US is a bisphenol A liquid epoxy resin available from Mitsubishi Chemical.

[0131] ZX1059 is a bisphenol F type epoxy resin available from TOHTO Chemical Industry Co., Ltd.

[0132] Ras-1 is an epoxy resin containing greater than 50% by weight of 2,6-diglycidylphenyl glycidyl ether, available from Henkel.

[0133] N-730 is a multifunctional phenol novolac-based epoxy resin available from DIC Corporation.

[0134] EX-191P is a low-chloride, monofunctional aromatic epoxy compound based on glycidyl benzoate, available from Nagase ChemteX.

[0135] MY 0510 is a triglycidylated p-aminophenol available from Huntsman.

[0136] ERISYS TM GA 240 is a tetrafunctional epoxy resin based on meta-xylenediamine available from CVC Specialties.

[0137] Epalloy TM5200 is a cycloaliphatic glycidyl ester available from CVC Specialties.

[0138] ERISYS TM GE 22 is epoxidized cyclohexanedimethanol available from CVC Specialties.

[0139] 5000 is a diepoxide of a cycloaliphatic alcohol (hydrogenated bisphenol A) available from CVC Specialties.

[0140] ERISYS TM GE 60 is an aliphatic multifunctional epoxy resin available from CVC Specialties.

[0141] ERISYS TM GE 40 is epoxidized pentaerythritol available from CVC Specialties.

[0142] ERISYS TM GE 30 is a low viscosity grade of trimethylolpropane triglycidyl ether. It is a highly epoxy-functional resin available from CVC Specialties.

[0143] CELLOXIDE 2021P is a cycloaliphatic epoxide available from DAICEL CORPORATION.

[0144] CELLOXIDE 2081 is a cycloaliphatic epoxide available from DAICEL CORPORATION.

[0145] OXBP is biphenylbisoxetane, which is available from UBE INDUSTRIES, LTD.

[0146] 2-(2-Butoxyethoxy)ethyl acetate is available from SIGMA-ALDRICH.

[0147] CTBN 1300X8 is a carboxyl terminated butadiene-acrylonitrile copolymer used as a toughening agent, available from NOVEON.

[0148] 2MAOK is an imidazole catalyst available from Air Products.

[0149] EA0295 is a silver filler available from METALOR.

[0150] A-186 is an adhesion promoter from GE Silicones.

[0151] YH307 is a modified anhydride available from Milliken Chemicals.

[0152] Epiclon B-570-H is 3-methyl-tetrahydro-phthalic anhydride available from DIC Europe GmbH.

[0153] RIKACID MH700 is 4-methylhexahydrophthalic anhydride, which is available from New Japan Chemical Co., Ltd.

[0154] NC-3000-L is a glycidyloxy-containing biphenyl type epoxy resin available from Nippon.

[0155] NC-3500 is a glycidyloxy-containing biphenyl type epoxy resin available from Nippon.

[0156] HXA 3932HP is a latent hardener available from Asahi KASEI.

[0157] Preparation method:

[0158] In the following examples, the compositions were prepared by the following steps:

[0159] 1. Epoxy resin (A1) and RDGE (A2) (or other epoxy resins replacing RDGE in comparative examples), solvent (C) (if present) and tackifier (if present) were first mixed at 60° C. for 1 hour, and then they were further mixed at room temperature by using a speed mixer at 2000 r / min for 2 minutes;

[0160] 2. Then add the catalyst (E) and mix with a high-speed mixer at 2000 r / min for 2 minutes;

[0161] 3. Add toughening agent (if present) and mix by using a high-speed mixer at 2000r / min for 2 minutes;

[0162] 4. Add anhydride (B) and mix using a high-speed mixer at 2000 r / min for 2 minutes; and

[0163] 5. Add conductive filler (D) and mix using a high-speed mixer at 1000 r / min for 2 minutes, followed by degassing.

[0164] Test method:

[0165] Die shear strength

[0166] Room temperature die shear strength (RTDSS) was measured at 25°C using a DAGE 4000. The composition was applied to a 2 x 2 mm 2 The samples were heated to 175°C at 5°C / min in an N2 atmosphere and cured for 1 hour. No pressure was used. Each sample was tested eight times under the same conditions and the average die shear strength was calculated and recorded by simple averaging to eliminate errors. The average RTDSS target was greater than or equal to 10 kg / mm 2 .

[0167] High temperature die shear strength (HTDSS) was measured at 260°C using a DAGE 4000 with a heater adapter plate capable of reaching 260°C. The composition was applied to a 2x2 mm 2 The samples were heated to 175°C at 5°C / min in an N2 atmosphere and cured for 1 hour. No pressure was used. Each sample was tested eight times under the same conditions and the average die shear strength was calculated and recorded by simple averaging to eliminate errors. The average HTDSS target was greater than or equal to 1.3 kg / mm 2 .

[0168] Inventive Example 1 and Comparative Examples 1 to 16

[0169] In this set of examples, one conductive epoxy resin composition containing RDGE according to the present invention (Ex. 1) and 16 compositions (Com. Ex. 1 to Com. Ex. 16) in which RDGE was replaced with other epoxy resins were prepared based on the weight percentages specified in the table below. The samples were tested for RTDSS and HTDSS.

[0170]

[0171]

[0172]

[0173] Table 1 shows that the compositions containing RDGE have higher average die shear strength on copper leadframes at both room temperature and elevated temperature than any of the compositions containing other epoxy resins.

[0174] Inventive Examples 2 to 4 and Comparative Examples 17 and 18

[0175] In this set of examples, conductive epoxy compositions were prepared having the epoxy resin (A1) of the present invention (Ex. 2 to Ex. 4) and other epoxy resins (Com. Ex. 17 to 18) based on the weight percentages specified in the table below. The samples were tested for RTDSS and HTDSS.

[0176] Table 2

[0177]

[0178]

[0179] The results in Table 2 show that the combination of RDGE according to the present invention and epoxy resin (A1) can improve RTDSS and HTDSS, while adding RDGE to epoxy resins other than A1 is ineffective in improving RTDSS or HTDSS.

[0180] Inventive Examples 5 to 8

[0181] In this set of examples, conductive epoxy compositions (Ex. 5 to Ex. 8) of the present invention were prepared with varying amounts of RDGE based on the weight percentages specified in the table below. The samples were tested for RTDSS and HTDSS.

[0182] Table 3

[0183]

[0184]

[0185] The results in Table 3 show that inclusion of a specific amount of RDGE according to the present invention can improve RTDSS and HTDSS.

[0186] Inventive Examples 9 to 12

[0187] In this set of examples, conductive epoxy resin compositions (Ex. 9 to Ex. 12) of the present invention having different anhydride curing agents were prepared based on the weight percentages specified in the table below. The samples were tested for RTDSS and HTDSS.

[0188] Table 4

[0189]

[0190]

[0191] The above results in Table 4 show that there is no limitation on the type of the acid anhydride curing agent according to the present invention.

[0192] While some preferred embodiments have been described, many modifications and variations are possible in light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described without departing from the scope of the appended claims.

Claims

1. A conductive epoxy resin composition comprising: (A) at least one epoxy resin system comprising: (A1) at least one epoxy resin selected from those represented by the following structural formulas P1, P2 and P3, and combinations thereof: Where n is the average value from 1 to 5, Where n is the average value from 1 to 5, where n is an average value from 1 to 5; and (A2) at least one resorcinol diglycidyl ether resin, wherein the resorcinol diglycidyl ether resin is present in an amount of 0.2 to 5.0 weight percent based on the total weight of the composition; (B) at least one anhydride curing agent; (C) optionally at least one solvent; (D) at least one electrically conductive filler; and (E) optionally at least one catalyst.

2. The composition according to claim 1, wherein The resorcinol diglycidyl ether resin (A2) is present in an amount of 0.5 to 3.0 wt % based on the total weight of the composition.

3. The composition according to claim 2, wherein The resorcinol diglycidyl ether resin (A2) is present in an amount of 0.75 to 2.25 wt %, based on the total weight of the composition.

4. The composition according to any one of claims 1 to 3, wherein the anhydride curing agent (B) is selected from phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyl nadic anhydride, nadic anhydride, glutaric anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and combinations thereof.

5. The composition according to any one of claims 1 to 3, wherein the conductive filler (D) is selected from the group consisting of silver, copper, gold, nickel, alloys containing silver, alloys containing copper, alloys containing nickel, and combinations thereof. The composition according to claim 5 , wherein the conductive filler (D) is silver or copper.

7. The composition according to any one of claims 1 to 3, wherein the catalyst (E) is selected from phenylurea, boron trichloride amine complex, imidazole, aliphatic diurea, phenol, and combinations thereof.

8. The composition according to claim 7, wherein the catalyst (E) is resorcinol.

9. The composition of any one of claims 1 to 3, wherein the composition further comprises an additive selected from the group consisting of toughening agents, fluxing agents, peroxides, flow additives, adhesion promoters, rheology modifiers, and combinations thereof.

10. The composition according to any one of claims 1 to 3, wherein Component (A1) is present in an amount of 1 to 15 wt %, based on the total weight of the composition.

11. The composition according to claim 10, wherein Component (A1) is present in an amount of 3 to 10 wt %, based on the total weight of the composition.

12. The composition according to any one of claims 1 to 3, wherein Component (B) is present in an amount of 3 to 15 wt %, based on the total weight of the composition.

13. The composition according to claim 12, wherein Component (B) is present in an amount of 3.5 to 10 wt %, based on the total weight of the composition.

14. The composition according to any one of claims 1 to 3, wherein Component (C) is present in an amount of 0.5 to 20 wt %, based on the total weight of the composition.

15. The composition according to claim 14, wherein Component (C) is present in an amount of 1 to 10 wt %, based on the total weight of the composition.

16. The composition according to any one of claims 1 to 3, wherein Component (D) is present in an amount of 65 to 95 wt %, based on the total weight of the composition.

17. The composition according to claim 16, wherein Component (D) is present in an amount of 70 to 95 wt %, based on the total weight of the composition. 18 . A cured product of the conductive epoxy resin composition according to claim 1 . 19 . A semiconductor device comprising a cured product of the conductive epoxy resin composition according to claim 18 .

20. Use of the conductive epoxy resin composition according to any one of claims 1 to 17 or a cured product of the conductive epoxy resin composition according to claim 18 in preparing semiconductor packages or microelectronic devices.

Images