Liquid compression molding material

Abstract

The purpose of the present invention is to provide a liquid epoxy resin composition that is suitable for use as a liquid compression molding material which has adequate rheological characteristics and does not leak from a mold if subjected to compression molding, while enabling easy and efficient sealing of a semiconductor element.　A liquid compression molding material according to the present invention comprises (A) an epoxy resin, (B) a curing agent and (C) a filler, while having a thixotropic index (TI) of from 0.8 to 4.0. Since this liquid compression molding material has adequate rheological characteristics, this liquid compression molding material does not leak from a mold if subjected to compression molding, and enables easy and efficient sealing of a semiconductor element.

Description

Technical Field

[0001] The present invention relates to a liquid compression molding material that can be suitably used in the manufacture of electronic components.

Background Art

[0002] Many semiconductor elements such as integrated circuits are encapsulated with an encapsulant. Although there are multiple molding methods for encapsulating semiconductor elements, in recent years, compression molding, which is relatively more suitable for manufacturing relatively large molded products, has been increasingly adopted for encapsulating semiconductor elements. This is due to the spread of wafer-level chip size packaging technology (which involves encapsulating the wafer that has not been diced into chips after circuit formation as it is).

[0003] Conventional curable resin compositions used for encapsulating semiconductor elements by compression molding were mainly solid resin compositions such as granular ones. However, recently, with the development of new compression molding technologies, liquid curable resin compositions are also often used. Hereinafter, such a liquid curable resin composition used for encapsulation by compression molding is referred to as a "liquid compression molding material". This "liquid compression molding material" may be abbreviated as an "LCM (Liquid Compression Molding) material".

[0004] As the liquid compression molding (LCM) material, a liquid epoxy resin composition is often used from the viewpoint of the balance of various properties such as electrical properties, moisture resistance, heat resistance, mechanical properties, and adhesiveness. As an example of the epoxy resin composition used as the LCM material, the liquid resin composition described in Patent Document 1 can be cited.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] However, it has been found that when a conventional LCM material is subjected to compression molding, there is a problem that it leaks from the mold joint and molding defects occur. This leakage reduces the molding efficiency and also causes loss of the LCM material, resulting in an increase in manufacturing cost.

[0007] In order to solve the above-described problems of the prior art, the present invention provides a liquid epoxy resin composition suitable for use as an LCM material, which has appropriate rheological properties, does not leak from a mold even when subjected to compression molding, and enables easy and efficient sealing of semiconductor elements.

MEANS FOR SOLVING THE PROBLEMS

[0008] As a result of intensive studies to solve the above problems, the present inventors have arrived at the present invention.

[0009] That is, the present invention includes, but is not limited to, the following inventions.

[0010] 1. A liquid compression mold material comprising the following components (A) to (C): (A) An epoxy resin; (B) A curing agent; and (C) A filler and having a thixotropic index (TI) of 0.8 to 4.0. A liquid compression mold material.

[0011] 2. The liquid compression mold material according to item 1 above, wherein component (C) contains particles having a particle size of 5 nm to 100 nm in an amount of 5 to 23% by weight based on the total weight of component (C).

[0012] 3. The liquid compression molding material according to item 2 above can be obtained by a method including a step of premixing at least a part of the particles having a particle size of 5 nm to 100 nm in component (C) with at least a part of component (A).

[0013] 4. The liquid compression molding material according to any one of items 1 to 3 above, wherein component (C) is surface-treated with a coupling agent.

[0014] 5. The liquid compression molding material according to any one of items 1 to 4 above, having a viscosity at 25 °C of 10 to 1000 Pa·s.

[0015] 6. The liquid compression molding material according to any one of items 1 to 5 above, wherein component (A) contains an aliphatic epoxy resin.

[0016] 7. The liquid compression molding material according to item 6 above, wherein the number average molecular weight of the aliphatic epoxy resin is 200 to 1000.

[0017] 8. The liquid compression molding material according to item 6 or 7 above, wherein the aliphatic epoxy resin contains a compound represented by the following general formula (I). [Chemical formula] [In the formula, n is an integer of 1 to 15.]

[0018] 9. The liquid compression molding material according to any one of items 1 to 8 above, wherein component (B) contains a phenol compound.

[0019] 10. The liquid compression molding material according to any one of items 1 to 9 above, wherein component (C) contains silica. [Advantages of the Invention]

[0020] Since the liquid compression molding material of the present invention has appropriate rheological properties, leakage from the mold does not occur even when subjected to compression molding, and the semiconductor element can be easily and efficiently sealed.

Brief Description of the Drawings

[0021]

Figure 1

Embodiments for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present invention will be described in detail. The present invention is a liquid compression molding material comprising the following components (A) to (C): (A) Epoxy resin; (B) Curing agent; and (C) Filler; and Relates to a liquid compression molding (LCM) material having a thixotropic index (TI) of 0.8 to 4.0. Regarding the above components (A) to (C) contained in the LCM material of the present invention, the following will be described.

[0023] [Epoxy resin (component (A))] The LCM material of the present invention contains an epoxy resin. Hereinafter, this epoxy resin may be referred to as "component (A)". As component (A) in the LCM material of the present invention, an epoxy resin used as a sealing material can be used. The epoxy resin is preferably a polyfunctional epoxy resin having two or more functional groups. Examples of polyfunctional epoxy resins include monocyclic aromatic epoxy resins such as catechol diglycidyl ether, resorcinol diglycidyl ether, phthalic acid diglycidyl ester, 2,5-diisopropylhydroquinone diglycidyl ether, and hydroquinone diglycidyl ether; alicyclic epoxy resins such as 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, bis(3,4-epoxycyclohexyl) adipate, vinylcyclohexene monoepoxide, and diepoxylimonene; bisphenol type epoxy resins such as bisphenol A type, bisphenol F type, bisphenol AD type, and bisphenol S type; a mixture of oligomers obtained by partial polymerization of bisphenol type epoxy resins; bisphenol type epoxy resins with hydrogenated rings; tetramethylbis(4-hydroxyphenyl)methane diglycidyl ether; tetramethylbis(4-hydroxyphenyl)ether diglycidyl ether; biphenyl type or tetramethylbiphenyl type epoxy resins and resins with hydrogenated rings thereof; fluorene type epoxy resins such as bisphenol fluorene type epoxy resin and biscresol fluorene type epoxy resin; naphthalene type epoxy resins, etc. can be mentioned.

[0024] Furthermore, examples of the polyfunctional epoxy resin include polyfunctional glycidylamine type epoxy resins such as aminophenol type epoxy resins like triglycidyl-p-aminophenol, aniline type epoxy resins like diglycidylaniline, toluidine type epoxy resins like diglycidyl orthotoluidine, and diamino diphenylmethane type epoxy resins like tetraglycidyl diamino diphenylmethane; dicyclopentadiene type epoxy resins; polyfunctional glycidyl ethers such as trimethylolalkane type epoxy resins like trimethylolpropane triglycidyl ether, trimethylolmethane triglycidyl ether, and trimethylolethane triglycidyl ether.

[0025] In addition, other epoxy resins such as aliphatic epoxy resins, silylated epoxy resins, heterocyclic epoxy resins, diallyl bisphenol A type epoxy resins, and polyarylene ether diglycidyl ethers can also be used.

[0026] Among these epoxy resins, examples of the aliphatic epoxy resin include bifunctional aliphatic epoxy resins having two epoxy groups in the molecule such as alkylene glycol diglycidyl ether, poly(alkylene glycol) diglycidyl ether, and alkenylene glycol diglycidyl ether; polyfunctional aliphatic epoxy resins having three or more epoxy groups in the molecule such as polyglycidyl ethers of trifunctional or higher alcohols (trimethylolpropane, pentaerythritol, dipentaerythritol, etc.) [trimethylolpropane triglycidyl ether, pentaerythritol (tri- or tetra-) glycidyl ether, dipentaerythritol (tri-, tetra-, penta- or hexa-) glycidyl ether, etc.].

[0027] Among these aliphatic epoxy resins, bifunctional aliphatic epoxy resins are preferred. Examples of the bifunctional aliphatic epoxy resin include alkylene glycol diglycidyl ethers (alkanediol diglycidyl ethers) such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,3-propanediol diglycidyl ether, 2-methyl-1,3-propanediol diglycidyl ether, 2-butyl-2-ethyl-1,3-propanediol diglycidyl ether, 1,4-butanediol diglycidyl ether (tetramethylene glycol diglycidyl ether), neopentyl glycol diglycidyl ether, 3-methyl-2,4-pentanediol diglycidyl ether, 2,4-pentanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether (pentamethylene glycol diglycidyl ether), 3-methyl-1,5-pentanediol diglycidyl ether, 2-methyl-2,4-pentanediol diglycidyl ether, 2,4-diethyl-1,5-pentanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether (hexamethylene glycol diglycidyl ether), 1,7-heptanediol diglycidyl ether, 3,5-heptanediol diglycidyl ether, 1,8-octanediol diglycidyl ether, 2-methyl-1,8-octanediol diglycidyl ether, 1,9-nonanediol diglycidyl ether;Diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, tetraethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, poly(ethylene glycol / propylene glycol) diglycidyl ether, ditetramethylene glycol diglycidyl ether, tritetramethylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, dipentamethylene glycol diglycidyl ether, tripentamethylene glycol diglycidyl ether, polypentamethylene glycol diglycidyl ether, dihexamethylene glycol diglycidyl ether, trihexamethylene glycol diglycidyl ether, polyhexamethylene glycol diglycidyl ether and other polyalkylene glycol diglycidyl ethers (including oligoalkylene glycol diglycidyl ethers) may be mentioned.;

[0028] In one embodiment, the bifunctional aliphatic epoxy resin is a (poly)alkylene glycol diglycidyl ether, preferably a (poly)alkylene glycol diglycidyl ether having 1 to 20 alkylene glycol (alkyleneoxy) units, more preferably a (poly)alkylene glycol diglycidyl ether having 1 to 20 alkylene glycol units and 2 to 4 carbon atoms in the alkylene glycol unit. In another embodiment, the bifunctional aliphatic epoxy resin is a polyalkylene glycol diglycidyl ether having 2 to 20 alkylene glycol (alkyleneoxy) units, preferably a polyalkylene glycol diglycidyl ether having 2 to 20 alkylene glycol units and 2 to 4 carbon atoms in the alkylene glycol unit.

[0029] The molecular weight of the aliphatic epoxy resin (when the aliphatic epoxy resin is a polymer, the molecular weight is the number average molecular weight in terms of standard polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran as the elution solvent) is not particularly limited, but is preferably from 200 to 10,000, more preferably from 200 to 1,200, still more preferably from 200 to 1,000, and particularly preferably from 300 to 900.

[0030] More specific examples of the more preferred aliphatic epoxy resin include compounds represented by the following general formula (I), namely diglycidyl ethers of (poly)tetramethylene glycol. [Chemical formula] (In the formula, n is an integer from 1 to 15)

[0031] As the compound represented by the general formula (I), commercially available products such as the trade name "Epogose PT (general grade)" (Yokkaichi Gosei Co., Ltd., diglycidyl ether of polytetramethylene glycol, number average molecular weight 700 to 1000 ) may be used.

[0032] In the LCM material of the present invention, as the component (A), a single epoxy resin may be used, or two or more epoxy resins may be used in combination. In the present invention, it is particularly preferable that the component (A) contains an aliphatic epoxy resin, and it is more preferable that the aliphatic epoxy resin contains the compound represented by the general formula (I). Further, it is preferable that the number average molecular weight of the aliphatic epoxy resin is from 200 to 1,000.

[0033] [Curing agent (component (B))] The LCM material of the present invention contains a curing agent. This curing agent is not particularly limited as long as it can cure the above epoxy resin (component (A)). Hereinafter, this curing agent may sometimes be referred to as "component (B)".

[0034] Examples of the component (B) used in the LCM material of the present invention include imidazole compounds, amine compounds, phenol compounds, acid anhydrides, and the like. Among these, the imidazole compound may be latent or may be in the form of a microcapsule-type curing agent.

[0035] Examples of the imidazole compound include imidazole, 2-methylimidazole, 2-ethylimidazole, 1-isobutyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1,2-dimethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole and other 2-substituted imidazole compounds; trimellitic acid salts such as 1-cyanoethyl-2-undecylimidazolium trimellitate and 1-cyanoethyl-2-phenylimidazolium trimellitate; triazine ring-containing compounds such as 2,4-diamino-6-[(2-methyl-1-imidazolyl)ethyl]s-triazine, 2,4-diamino-6-[(2-undecyl-1-imidazolyl)ethyl]s-triazine, 2,4-diamino-6-[(2-ethyl-4-methyl-1-imidazolyl)ethyl]s-triazine; isocyanuric acid adducts of 2,4-diamino-6-[(2-methyl-1-imidazolyl)ethyl]s-triazine, isocyanuric acid adducts of 2-phenylimidazole, isocyanuric acid adducts of 2-methylimidazole, isocyanuric acid adducts of 2-phenyl-4,5-dihydroxymethylimidazole, and isocyanuric acid adducts of 2-phenyl-4-methyl-5-hydroxymethylimidazole. Among these imidazole compounds, 2-phenyl-4-methylimidazole, 2,4-diamino-6-[(2-methyl-1-imidazolyl)ethyl]s-triazine, 2-phenyl-4-methyl-5-hydroxymethylimidazole (including its isocyanuric acid adduct), etc. are preferable.

[0036] As the above microcapsule type curing agent, for example, a dispersion in which a powder of an amine compound is dispersed in a liquid epoxy resin can be used. This amine compound may be selected, for example, from aliphatic primary amines, alicyclic primary amines, aromatic primary amines, aliphatic secondary amines, alicyclic secondary amines, aromatic secondary amines, imidazole compounds and imidazoline compounds. This amine compound may be used in the form of a reaction product with a carboxylic acid, a sulfonic acid, an isocyanate, an epoxide, etc. These compounds may be used alone or in combination of two or more. For example, the above amine compound can be used in combination with a reaction product thereof with a carboxylic acid, a sulfonic acid, an isocyanate, or an epoxide. The volume average particle diameter of the powder of the above amine compound is preferably 30 μm or less, more preferably 5 μm or less. Further, it is preferable that the powder of the above amine compound has a melting point or a softening point of 60°C or higher from the viewpoint of suppressing thickening at 25°C.

[0037] As the phenolic compound, a novolak resin obtained by condensing a phenolic resin, particularly phenols or naphthols (for example, phenol, cresol, naphthol, alkylphenol, bisphenol, terpene phenol, etc.) with formaldehyde is preferably used. Examples of novolak resins include phenol novolak resin, o-cresol novolak resin, p-cresol novolak resin, α-naphthol novolak resin, β-naphthol novolak resin, t-butylphenol novolak resin, bisphenol A type novolak resin, xylylene-modified novolak resin, decalin-modified novolak resin, etc. Examples of other phenolic resins include dicyclopentadiene cresol resin, polyparavinylphenol, poly(di-o-hydroxyphenyl)methane, poly(di-m-hydroxyphenyl)methane, and poly(di-p-hydroxyphenyl)methane, etc.

[0038] Examples of the acid anhydride include phthalic anhydride; hexahydrophthalic anhydride; alkylhexahydrophthalic anhydrides such as methylhexahydrophthalic anhydride; tetrahydrophthalic anhydride; alkyltetrahydrophthalic anhydrides such as trialkyltetrahydrophthalic anhydride and 3-methyltetrahydrophthalic anhydride; hymic anhydride; succinic anhydride; trimellitic anhydride; pyromellitic anhydride, etc. Among these, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, etc. are preferable.

[0039] Examples of the amine compound include tetramethyldiaminodiphenylmethane, tetraethyldiaminodiphenylmethane, diethyldimethyldiaminodiphenylmethane, dimethyldiaminotoluene, diaminodibutyltoluene, diaminodipropyltoluene, diaminodiphenylsulfone, diaminoditolylsulfone, diethyldiaminotoluene, bis(4-amino-3-ethylphenyl)methane, polytetramethylene oxide-di-p-aminobenzoate, etc. Among these, bis(4-amino-3-ethylphenyl)methane, etc. are preferable. Further examples of the above amine compounds include 2,4,6-tris(dimethylaminomethyl)phenol, diethylamine, triethylamine, diethylenetetramine, triethylenetetramine, 4,4-dimethylaminopyridine, and the like. The amine compound may be an amine adduct.

[0040] In the LCM material of the present invention, as the component (B), a single curing agent may be used, or two or more curing agents may be used in combination. In the present invention, it is preferable that the component (B) contains an imidazole compound, and it is more preferable to contain both an imidazole compound and a phenol compound (preferably liquid).

[0041] The LCM material of the present invention preferably contains the component (B) in an amount of 1 to 20% by weight, more preferably 2 to 15% by weight, and particularly preferably 3 to 10% by weight based on 100 parts by weight of the component (A).

[0042] [Filler (Component (C))] The LCM material of the present invention contains a filler. Hereinafter, this filler may be referred to as "component (C)". Examples of the filler of the component (C) used in the present invention include, but are not limited to, silica, alumina, talc, calcium carbonate, titanium white, red iron oxide, silicon carbide, boron nitride (BN), glass beads, and the like. In the present invention, it is preferable that the component (C) contains silica. This is because silica also functions as a rheology modifier. The silica may be natural silica (such as silica stone, quartz, etc.) or synthetic silica. The synthetic silica can be synthesized by any method including dry method and wet method. Further, the component (C) may be surface-treated with a surface treatment agent, for example, a coupling agent such as a silane coupling agent (which may have substituents such as a phenyl group, a vinyl group, a methacryloyl group, etc.). In the present invention, it is preferable that at least a part of the component (C) is surface-treated.

[0043] In one embodiment, component (C) includes silica powder. The silica powder can be obtained as a commercial product. In the present invention, it is more preferable that component (C) includes powder of fused silica and / or silica powder produced by a deflagration method. The deflagration method is a method of producing silica powder composed of fine spherical silica particles by oxidizing powder of metallic silicon dispersed in an oxygen stream by ignition, melting or vaporizing the obtained oxide (optionally containing unreacted metallic silicon) by heating using the reaction heat of the oxidation, and then subjecting it to cooling to a temperature below the melting point of the oxide. On the other hand, examples of the powder of fused silica include those composed of spherical silica particles and those composed of crushed silica particles. From the viewpoint of the fluidity of the LCM material, it is more preferable that component (C) includes silica powder composed of spherical silica particles (particularly those with a high sphericity).

[0044] In the LCM material of the present invention, as component (C), a single filler may be used, or two or more fillers may be used in combination. When component (C) includes two or more fillers, those fillers may differ in the substances contained in the particles constituting them, or when the fillers are composed of particles containing the same substance, those fillers may differ in the production method or some other property (for example, the particle size distribution described later). In one embodiment, component (C) includes two or more fillers.

[0045] The properties of the particles constituting component (C), such as the particle size distribution, are not particularly limited. However, from the viewpoint of an appropriate thixotropic index of the LCM material (described later), in the present invention, it is preferable that component (C) contains particles having a particle size of 5 nm to 100 nm, more preferably particles having a particle size of 10 nm to 50 nm, in an amount of 5 to 23% by weight, more preferably 8 to 19% by weight, based on the total weight of component (C). In this case, the properties other than the content in component (C) of the particles other than the particles having a particle size of 5 nm to 100 nm in component (C) are not particularly limited. The particle size distribution of the particles constituting the component (C) can be obtained by analyzing a micrograph (e.g., an electron micrograph) taken of a sample of the component (C) using image processing software and digitizing and statistically processing the sizes of all or part of the particles in the micrograph. Here, when the component (C) contains two or more fillers, the particle size distribution of the particles constituting the component (C) is the particle size distribution of the particles constituting the component (C) as a mixture of all of those fillers. In addition, the particles having a particle size of 5 nm to 100 nm in the component (C) are preferably surface-treated.

[0046] The LCM material of the present invention preferably contains the component (C) in an amount of 65 to 90% by weight, more preferably 68 to 88% by weight, and particularly preferably 70 to 85% by weight based on the total weight of the LCM material.

[0047] The LCM material of the present invention has a thixotropic index (TI) of 0.8 to 4.0. The TI is preferably 0.8 to 2.0. In the present invention, the TI of the LCM material is represented by the following formula: TI = η1 / η 10 (wherein, η1 is the viscosity of the LCM material measured using a rotational viscometer under the conditions of a temperature of 25°C and a rotational speed of 1 rpm and η 10 is the viscosity of the LCM material measured under the same conditions as η1 except that the rotational speed is 10 rpm ). is represented by

[0048] As described above, when a conventional LCM material is subjected to a sealing treatment by compression molding, leakage may occur from the mold joint. This means that the rheological properties of the conventional LCM material are not suitable for such a sealing treatment. As a result of various studies, the present inventors have found that a specific epoxy resin composition having a TI of 0.8 to 4.0 exhibits rheological properties suitable for a sealing treatment by compression molding and is useful as an LCM material. If the TI of the LCM material is less than 0.8, the LCM material will leak from the mold during compression molding. On the other hand, if the TI of the LCM material exceeds 4.0, it will be difficult for the LCM material to be discharged from the application means.

[0049] In the sealing process by compression molding, after the LCM material is applied to the object to be sealed, it takes a certain amount of time until stress is applied to the LCM material. During this period, the applied LCM material naturally spreads on the object to be sealed to some extent. If the TI of the LCM material is less than 0.8, the LCM material spreads to a position close to the inner surface of the mold. Therefore, when the LCM material is stretched by the applied stress, the stretched LCM material reaches the inner surface of the mold in a very short time, and depending on the shape of the mold, the LCM material may overflow from the mold before the mold is completely closed.

[0050] On the other hand, when the TI of the LCM material is within the above range, during the period from when it is applied to the object to be sealed until stress is applied, the LCM material only naturally spreads on the object to be sealed to a position relatively far from the inner surface of the mold. Therefore, the time required for such an LCM material stretched by the applied stress to reach the inner surface of the mold is longer than that time for the LCM material with a TI less than 0.8. As a result, the stretched LCM material reaches the inner surface of the mold after the mold is completely closed, and leakage of the LCM material from the mold is avoided. The above has been first discovered by the present inventors.

[0051] According to the above definition of TI, when the TI of the LCM material is 1 or less, the viscosity of the LCM material under relatively high shear stress is the same as or higher than the viscosity of the LCM material under relatively low shear stress. However, since the viscosity of the LCM material varies depending on the measurement conditions, the behavior of the LCM material under actual compression molding conditions may not match the behavior predicted from the TI according to the above definition.

[0052] Examples of means for achieving such appropriate rheological properties of the LCM material, i.e., appropriate TI, include appropriately adjusting the particle size distribution of component (C). For example, as described above, a particle size distribution containing fine particles with a particle size of 5 nm to 100 nm (e.g., 5 to 23% by weight based on the total weight of component (C)) can be mentioned. This means is particularly useful when component (C) contains silica. This is due to the fact that silica also functions as a rheology modifier.

[0053] The epoxy resin composition prepared using a filler containing such fine particles as described above and used as a sealing agent for semiconductors is disclosed, for example, in Patent Document 2. However, this epoxy resin composition is intended to be used as an underfill agent, and the underfill agent needs to have higher fluidity (e.g., evaluated as the "viscosity at 120°C" described later) than the LCM material. For this reason, in this epoxy resin composition, it is not preferable to increase the content of fine particles in the filler to a certain extent or more (e.g., more than 20% by weight based on the total weight of the filler).

[0054] In the LCM material of the present invention, the viscosity at 25°C is preferably 10 to 1000 Pa·s, more preferably 30 to 900 Pa·s, and even more preferably 50 to 800 Pa·s. In the present invention, the viscosity of the LCM material at 25°C is measured in the same manner as the measurement of the above η 10 is measured.

[0055] Also, in the LCM material of the present invention, the viscosity at 120°C is preferably 0.3 to 6.0 Pa·s, more preferably 0.5 to 5.5 Pa·s, and even more preferably 0.8 to 5.1 Pa·s. In the present invention, the viscosity at 120°C means the viscosity (unit: Pa·s) measured at 120°C after applying a vibration with a frequency of 10 Hz for 1 minute at 120°C under the condition that the shear strain is controlled to be constant using a rheometer. On the other hand, in the case of an underfill agent, usually, the viscosity at 120°C is less than 0.3 Pa·s.

[0056] If desired, the LCM material of the present invention may contain optional components, for example, those described below, in addition to the above components (A) to (C) which are essential components, as necessary.

[0057] · Curing accelerator If desired, the LCM material of the present invention may contain a curing accelerator. The curing accelerator used in the present invention is not particularly limited as long as it is a compound capable of accelerating the curing of the epoxy resin (component (A)) by the curing agent (component (B)), and known ones can be used. Examples of the curing accelerator include basic compounds such as amine compounds, phosphorus compounds, and organometallic compounds. Examples of the above amine compounds include 2,4,6-tris(dimethylaminomethyl)phenol, diethylamine, triethylamine, diethylenetetramine, triethylenetetramine, and 4,4-dimethylaminopyridine. The amine compound may be an amine adduct.

[0058] Examples of the above phosphorus compounds include trialkylphosphine compounds such as tributylphosphine and triarylphosphine compounds such as triphenylphosphine.

[0059] Examples of the above organometallic compounds include zinc naphthenate, cobalt naphthenate, tin octylate, cobalt octylate, bis(acetylacetonato)cobalt(II), and tris(acetylacetonato)cobalt(III).

[0060] When the LCM material of the present invention contains a curing accelerator, the amount of the curing accelerator is preferably 1 to 100 parts by weight, more preferably 5 to 50 parts by weight, based on 100 parts by weight of the total amount of components (A) to (C).

[0061] · Pigment The LCM material of the present invention may contain a pigment if desired. By including a pigment, the chromaticity of the LCM material of the present invention can be adjusted. Also, considering the possibility that the wiring in the electronic component may be affected by light, the use of a pigment is important. The pigment is not particularly limited, and for example, carbon black, titanium black such as titanium nitride, black organic pigments, mixed-color organic pigments, and inorganic pigments can be used. Examples of black organic pigments include perylene black and aniline black. Examples of mixed-color organic pigments include those pseudo-blackened by mixing at least two or more pigments selected from red, blue, green, purple, yellow, magenta, cyan, etc. Examples of inorganic pigments include graphite, and fine particles of metals and their oxides (including composite oxides), sulfides, nitrides, etc. Examples of such metals include titanium, copper, iron, manganese, cobalt, chromium, nickel, zinc, calcium, silver, etc. In the LCM material of the present invention, the pigment may be used alone or in combination of two or more. Also, the pigment may be used in combination with other colorants such as dyes.

[0062] From the viewpoint of heat resistance, the pigment is preferably carbon black.

[0063] ·Stabilizer The LCM material of the present invention may contain a stabilizer if desired. The stabilizer may be included in the LCM material of the present invention to improve its storage stability and extend the pot life. Various stabilizers known as stabilizers for one-component adhesives based on epoxy resins can be used, but from the high effect of improving storage stability, at least one selected from the group consisting of liquid boric acid ester compounds, aluminum chelates, and organic acids is preferred.

[0064] Examples of the liquid borate compound include 2,2'-oxybis(5,5'-dimethyl-1,3,2-oxaborinane), trimethyl borate, triethyl borate, tri-n-propyl borate, triisopropyl borate, tri-n-butyl borate, tripentyl borate, triallyl borate, trihexyl borate, tricyclohexyl borate, trioctyl borate, trinonyl borate, tridecyl borate, tridodecyl borate, trihexadecyl borate, trioctadecyl borate, tris(2-ethylhexyl) borate, bis(1,4,7,10-tetraoxoundecyl)(1,4,7,10,13-pentaoxatetradecyl)(1,4,7-trioxoundecyl) borate, tribenzyl borate, triphenyl borate, tri-o-tolyl borate, tri-m-tolyl borate, triethanolamine borate, and the like. Since the liquid borate compound is liquid at room temperature (25°C), it is preferable because it can keep the viscosity of the LCM material low. As the aluminum chelate, for example, aluminum chelate A can be used. As the organic acid, for example, barbituric acid can be used.

[0065] When the LCM material of the present invention contains a stabilizer, the amount of the stabilizer is preferably 0.01 to 30 parts by weight, more preferably 0.05 to 25 parts by weight, and still more preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the component (A).

[0066] ·Silicone-based additive The LCM material of the present invention may contain a silicone-based additive if desired. Inclusion of a silicone-based additive is preferable from the viewpoint of improving the fluidity of the LCM material. The silicone-based additive is preferably a dialkylpolysiloxane (examples of the alkyl group bonded to Si include methyl, ethyl, etc.), particularly dimethylpolysiloxane. The silicone-based additive may also be a modified dialkylpolysiloxane, for example, epoxy-modified dimethylpolysiloxane. Specific examples of the silicone-based additive include KF69 (dimethyl silicone oil, manufactured by Shin-Etsu Silicone), SF8421 (epoxy-modified silicone oil, manufactured by Toray Dow Corning), and the like. The silicone-based additive may be used alone or in combination of two or more kinds.

[0067] When the LCM material of the present invention contains a silicone-based additive, the amount of the silicone-based additive is preferably 0.1 to 1.0 part by weight, more preferably 0.25 to 1 part by weight, based on 100 parts by weight of the component (A).

[0068] · Coupling agent The LCM material of the present invention may contain a coupling agent if desired. Inclusion of a coupling agent, particularly a silane coupling agent, is preferable from the viewpoint of improving the adhesion strength. As the coupling agent, various silane coupling agents such as epoxy-based, amino-based, vinyl-based, methacrylic-based, acrylic-based, and mercapto-based can be used. Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, vinyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, and the like. These silane coupling agents may be used alone or in combination of two or more.

[0069] When the LCM material of the present invention contains a coupling agent, the amount of the coupling agent is preferably 0.01 to 5 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the component (A).

[0070] · Migration inhibitor The LCM material of the present invention may contain a migration inhibitor if desired. Migration is a phenomenon in which the metal of the wiring pattern elutes due to an electrochemical reaction, resulting in a decrease in the resistance value. The inclusion of a migration inhibitor is preferable from the viewpoint of improving the reliability of electronic components. Specific examples of the migration inhibitor include xanthines such as caffeine, theophylline, theobromine, and paraxanthine; tocols such as 5,7,8-trimethyltocol (α-tocopherol), 5,8-dimethyltocol (β-tocopherol), 7,8-dimethyltocol (γ-tocopherol), and 8-methyltocol (δ-tocopherol); tocotrienols such as 5,7,8-trimethyltocotrienol (α-tocotrienol), 5,8-dimethyltocotrienol (β-tocotrienol), 7,8-dimethyltocotrienol (γ-tocotrienol), and 8-methyltocotrienol (δ-tocotrienol); benzotriazoles such as benzotriazole, 1H-benzotriazole-1-methanol, and alkylbenzotriazoles; triazines such as 2,4-diamino-6-vinyl-S-triazine, 2,4-diamino-6-[2'-ethyl-4-methylimidazole-(1)]-ethyl-S-triazine, and 2,4-diamino-6-methacryloyloxyethyl-S-triazine; and isocyanuric acid adducts of the above benzotriazoles or triazines. These migration inhibitors may be used alone or in combination of two or more.

[0071] When the LCM material of the present invention contains a migration inhibitor, the amount of the migration inhibitor is preferably 0.01 to 5 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the component (A).

[0072] · Other additives The LCM material of the present invention may contain other additives, such as ion trappers, leveling agents, antioxidants, defoaming agents, thixotropic agents, viscosity modifiers, flame retardants, solvents, etc., within a range that does not impair the gist of the present invention, if desired. The types and amounts of the respective additives are as per conventional methods.

[0073] The method for producing the liquid compression molding (LCM) material of the present invention is not particularly limited. For example, components (A) to (C) and, if desired, other additives are introduced into an appropriate mixer simultaneously or separately, and stirred and mixed while being melted by heating if necessary to obtain a uniform composition, thereby obtaining the LCM material of the present invention. This mixer is not particularly limited, but a Lycra machine equipped with a stirring device and a heating device, a Henschel mixer, a three-roll mill, a ball mill, a planetary mixer, a bead mill, etc. can be used. Further, these devices may be used in appropriate combination.

[0074] In the LCM material of the present invention, when component (C) contains particles having a particle size of 5 nm to 100 nm (for example, 5 to 23% by weight based on the total weight of component (C)), preferably, the LCM material of the present invention is obtained by a method including a step of premixing at least a part of the particles having a particle size of 5 nm to 100 nm in component (C) with at least a part of component (A). The LCM material of the present invention can preferably be obtained by the above method.

[0075] The liquid compression molding material thus obtained is thermosetting and preferably cures in 0.1 to 3 hours, more preferably in 0.25 to 2 hours, under the condition of a temperature of 100 to 170°C.

[0076] The liquid compression molding material of the present invention is suitable for the production of electronic components, particularly semiconductor elements involving encapsulation by compression molding. More specifically, the liquid compression molding material of the present invention is particularly useful for the encapsulation treatment of a wafer that has completed circuit formation and has not been diced into chips when manufacturing a semiconductor element with a reduced package size by a wafer-level chip size package.

[0077] In the present invention, a cured product obtained by curing the LCM material of the present invention is also provided. In the present invention, further, an electronic component including the cured product of the present invention is also provided.

Example

[0078] Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto. In the following description, "parts" and "%" indicate parts by weight and % by weight, respectively, unless otherwise specified.

[0079] Examples 1 to 17, Comparative Examples 1 to 5 According to the formulations shown in Table 1, a predetermined amount of each component was mixed using a three-roll mill to prepare a liquid compression mold (LCM) material. In Table 1, the amounts of each component are represented by weight (unit: g).

[0080] · Epoxy resin (Component (A)) In the examples and comparative examples, the compounds used as Component (A) are as follows. (A-1): Diglycidyl ether of polytetramethylene glycol (number average molecular weight 700 to 1000) (trade name: Epogose PT (general grade), manufactured by Yokkaichi Synthetic Co., Ltd.) (A-2): Aminophenol type epoxy resin (trade name: 630, manufactured by Mitsubishi Chemical Corporation)

[0081] · Curing agent (Component (B)) In the examples and comparative examples, the compounds used as Component (B) are as follows. (B-1): Imidazole compound (trade name: Curezol 2P4MZ, manufactured by Shikoku Chemicals Corporation) (B-2): Imidazole compound (trade name: Curezol 2MZ-A, manufactured by Shikoku Chemicals Corporation) (B-3): Imidazole compound (trade name: Curezol 2P4MHZ-PW, manufactured by Shikoku Chemicals Corporation) (B-4): Liquid phenol novolak resin (trade name: MEH-8005, manufactured by Meiwa Kasei Co., Ltd.) (B-5): Amine compound (trade name: Kayhard A-A, manufactured by Nippon Kayaku Co., Ltd.) (B-6): Acid anhydride (trade name: HN-5500, manufactured by Hitachi Chemical Co., Ltd.)

[0082] · Filler (Component (C)) In the examples and comparative examples, the compounds used as Component (C) are as follows. These compounds are shown by dividing them into two groups: those with an average particle size exceeding 0.1 μm (100 nm) and those with an average particle size of 0.1 μm (100 nm) or less.

[0083] <Filler with an average particle size exceeding 0.1 μm (100 nm)> (C-1): Silica filler (trade name: SO-E2, manufactured by Admatechs Co., Ltd., average particle size: 0.6 μm) (C-2): Silica filler (trade name: SO-E5, manufactured by Admatechs Co., Ltd., average particle size: 1.5 μm) (C-3): Silica filler (trade name: SO-E6, manufactured by Admatechs Co., Ltd., average particle size: 2 μm)

[0084] <Filler with an average particle size of 0.1 μm (100 nm) or less> (C-4): Silica filler (trade name: Aerosil (registered trademark) R805, manufactured by Toagosei Co., Ltd., average particle size: 7 nm, surface-treated with octylsilane) (C-5): Silica filler (trade name: YA010C, manufactured by Admatechs Co., Ltd., average particle size: 10 nm, surface-treated) (C-6): Silica filler (trade name: YA050C, manufactured by Admatechs Co., Ltd., average particle size: 50 nm, surface-treated) (C-7): Silica filler (trade name: YC100C, manufactured by Admatechs Co., Ltd., average particle size: 100 nm, surface-treated)

[0085] In the examples and comparative examples, the properties of the LCM material were measured as follows.

[0086] (Viscosity of the LCM material at 25°C) Using a Brookfield HB rotational viscometer (with spindle SC4-14), the viscosity (unit: Pa·s) of the manufactured LCM material was measured at 25°C and 10 revolutions per minute. The results are shown in Table 1.

[0087] (Viscosity of LCM material at 120°C) Using a HAAKE MARS rheometer, for the manufactured LCM material, in the oscillation strain control mode, the viscosity (unit: Pa·s) after applying a vibration at a frequency of 10 Hz for 1 minute at 120°C was measured at 120°C. The results are shown in Table 1.

[0088] (Thixotropic index (TI) of LCM material) Except that the rotation speed was 1 revolution per minute, the viscosity (unit: Pa·s) of the manufactured LCM material was measured under the same conditions as the above "Viscosity of LCM material at 25°C". This viscosity to , excluding the above "Viscosity of LCM material at 25°C" at was used as the value to calculate the thixotropic index (TI) of the LCM material. The results are shown in Table 1.

[0089] (Evaluation of formability of LCM material) An amount of the manufactured LCM material corresponding to the volume of a disk with a diameter of 292 mm and a thickness of 400 μm was applied to a silicon wafer (a disk-shaped wafer with a diameter of 300 mm and a thickness of 780 μm). This silicon wafer was placed in a mold mounted on a compression molding device WCM300 (manufactured by Appic Yamada) and subjected to compression molding (sealing treatment) under the conditions of a temperature of 120°C and a pressure of 350 kN. The presence or absence of leakage of the LCM material from the mold during this compression molding was visually monitored. If leakage occurred, the formability of the LCM material was evaluated as ×, and if no leakage occurred, the formability of the LCM material was evaluated as 〇. If it was impossible to evaluate the formability by the above method, the formability of the LCM material was also evaluated as ×.

[0090] (Evaluation of fluidity of LCM material) 40 g of the manufactured LCM material was loaded into a dispenser ML-5000XII (manufactured by Musashi Engineering) equipped with a nozzle having an inner diameter of 10 mm, and discharged from the device at a discharge pressure of 0.2 MPa. When all of the loaded LCM material was discharged within 5 minutes, the fluidity of the LCM material was evaluated as ○, and when it took more than 5 minutes for all of the loaded LCM material to be discharged, the fluidity of the LCM material was evaluated as ×. Also, when it was impossible to evaluate the fluidity by the above method, the fluidity of the LCM material was evaluated as ×.

[0091]

Table 1-1

Table 1-2

Table 1-3

[0092] As is clear from Table 1, in any of Examples 1 to 17 in which the thixotropic index (TI) of the LCM material is 0.8 to 4.0, the LCM material exhibits appropriate fluidity to the extent that it can be easily discharged from the dispenser, has good moldability, and no leakage of the LCM material from the mold was observed when compression molding was performed together with a silicon wafer. On the other hand, in all of Comparative Examples 1, 3, and 5 in which the TI of the LCM material is less than 0.8, the moldability was insufficient, and when the LCM material was compression molded together with a silicon wafer, leakage of the LCM material from the mold was observed. Also, in both Comparative Examples 2 and 4, the LCM material was almost solid, and it was impossible to measure the viscosity and evaluate the moldability and fluidity.

Industrial Applicability

[0093] The LCM material of the present invention has appropriate rheological properties. Therefore, even when the LCM material of the present invention is subjected to compression molding, leakage from the mold does not occur, and the encapsulation of semiconductor elements by compression molding can be performed easily and efficiently. Thus, the LCM material of the present invention is useful in the manufacture of semiconductor elements involving encapsulation by compression molding, particularly in the manufacture of semiconductor elements with miniaturized packages by wafer-level chip scale packages.

Description of Reference Numerals

[0094] 1 Liquid compression mold (LCM) material 2 Silicon wafer 3 Upper mold 4 Lower mold

Claims

1. A liquid compression molding material comprising the following components (A) to (C): (A) epoxy resin; (B) a curing agent; and (C) Filler and having a thixotropic index (TI) of 0.8 to 4.0; Component (A) comprises an aliphatic epoxy resin, The liquid compression molding material, wherein the aliphatic epoxy resin has a number average molecular weight of 200 to 1,000.

2. The liquid compression molding material according to claim 1, wherein component (C) contains 5 to 23% by weight of particles having a particle size of 5 nm to 100 nm, based on the total weight of component (C).

3. 3. The liquid compression molding material according to claim 1, wherein component (C) is surface-treated with a coupling agent.

4. The liquid compression molding material according to any one of claims 1 to 3, having a viscosity of 10 to 1000 Pa·s at 25°C.

5. The liquid compression molding material according to any one of claims 1 to 4, wherein the aliphatic epoxy resin contains a compound represented by the following general formula (I): [C3] [In the formula, n is an integer from 1 to 15.]

6. The liquid compression molding material according to any one of claims 1 to 5, wherein component (B) contains a phenol compound.

7. The liquid compression molding material according to any one of claims 1 to 6, wherein component (C) comprises silica.

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