JP2020152740A - Resin composition for sealing sheet, sealing sheet, and semiconductor device - Google Patents

Abstract

To provide a sealing sheet which has good handleability and moldability even when a thickness is thin, holds flexibility for a long period of time, has an excellent adhesive force, and can efficiently and satisfactorily seal a semiconductor element by a compression molding method; a resin composition for sealing sheet formed into a formation material of the sealing sheet; and a resin sealing type semiconductor device which is sealed using the sealing sheet and had high quality and high reliability.SOLUTION: A resin composition for sealing sheet contains (A) a crystalline epoxy resin and/or liquid epoxy resin, (B) a phenol resin curing agent, (C) a curing accelerator, (D) an inorganic filler and (E) a ketimine group-containing silane compound.SELECTED DRAWING: None

Description

The present invention relates to a resin composition for a sealing sheet, a sealing sheet, and a semiconductor device.

As an electronic component used in an electronic device, there is a semiconductor package obtained by sealing a semiconductor element with a resin. Conventionally, this semiconductor package is generally manufactured by transfer molding using a solid epoxy resin encapsulant. On the other hand, in recent years, as electronic devices have become smaller and lighter, high-density mounting of electronic components on wiring boards has been required, and semiconductor packages are also being made smaller, thinner, and lighter. ..
Specifically, semiconductor packages such as LOC (Lead on Chip), QFP (Quad Flat Package), CSP (Chip Size Package), and BGA (Ball Grid Array) have been developed. More recently, so-called face-down package flip chips, wafer-level CSPs, etc., in which the circuit surface of a semiconductor element is mounted toward the wiring board side, have been developed.

As described above, with the progress of miniaturization and thinning of semiconductor packages, there have been cases where conventional transfer molding cannot be used. That is, when the semiconductor package becomes thin, the proportion of the inorganic filler to be blended in the encapsulant may be increased in consideration of the characteristics after curing. However, when the proportion of the inorganic filler increases, the melt viscosity of the encapsulant during transfer molding increases, and the filler of the encapsulant decreases. As a result, poor filling, residual voids in the molded product, wire flow (deformation / breakage of the bonding wire), increased stage shift, and the like occur, and the quality of the molded product deteriorates.

Therefore, as an alternative sealing method to transfer molding, the application of a compression molding method has been studied, and various sheet-shaped sealing materials used for this have been proposed. For example, Patent Document 1 describes a sealing resin sheet in which a plurality of resin sheets composed of an epoxy resin composition containing an epoxy resin, a curing agent, a curing catalyst or a curing accelerator, and an inorganic filler are laminated and heat-bonded. It is disclosed. Further, Patent Document 2 discloses a sheet-shaped sealing material having a thickness of 3.0 mm or less, which is made of a thermosetting resin composition that softens or melts at 70 to 150 ° C.

Japanese Unexamined Patent Publication No. 8-73621 Japanese Unexamined Patent Publication No. 2006-216899

However, the sealing resin sheet of Patent Document 1 has a problem that the molded product is warped as the size of the package or wafer becomes large. The problem can be improved by blending a large amount of an inorganic filler such as silica, but in this case, the melt viscosity increases, and the above-mentioned problems such as poor filling occur. On the other hand, the sheet-shaped encapsulant material of Patent Document 2 is sufficiently compatible with large-sized packages and the like, but if the sheet thickness is reduced to about 0.5 mm in order to make it thinner, it becomes fragile and gold. There is a problem in terms of handleability, such as difficulty in carrying it into the mold.

The present invention has been made to solve the above-mentioned problems of the prior art, and has good handleability and moldability even when the thickness is thin, retains flexibility for a long period of time, and has excellent adhesive strength. A sealing sheet capable of efficiently and satisfactorily sealing a semiconductor element by a compression molding method, a resin composition for a sealing sheet as a material for forming the sealing sheet, and a sealing sheet using the sealing sheet. An object of the present invention is to provide a resin-sealed semiconductor device having high quality and high reliability that has been stopped.

As a result of intensive research to achieve the above object, the present inventors have made it possible to handle and mold even if the thickness is reduced by using a ketimine compound in combination with a crystalline epoxy resin and / or a liquid epoxy resin. It has been found that a sealing sheet having good properties, flexibility is maintained for a long period of time, and has excellent adhesive strength can be obtained, and the present invention has been completed.

That is, the present invention provides the following [1] to [4].
[1] Contains (A) crystalline epoxy resin and / or liquid epoxy resin, (B) phenol resin curing agent, (C) curing accelerator, (D) inorganic filler, and (E) ketimine group-containing silane compound. Resin composition for sealing sheet.
[2] The resin composition for a sealing sheet according to the above [1], wherein the inorganic filler (D) is silica powder and is contained in an amount of 70 to 95% by mass in the entire resin composition for a sealing sheet.
[3] A sealing sheet comprising the resin composition for a sealing sheet according to the above [1] or [2].
[4] A semiconductor device including an element sealed by the sealing sheet according to the above [3].

According to the present invention, the handleability and moldability are good even when the thickness is thin, the flexibility is maintained for a long period of time, the adhesive strength is excellent, and the semiconductor element is efficiently formed by the compression molding method. A sealing sheet that can be sealed well, a resin composition for a sealing sheet that is a material for forming the sealing sheet, and a high-quality, highly reliable semiconductor that is sealed using the sealing sheet. The device can be provided.

Hereinafter, the resin composition for a sealing sheet, the sealing sheet, and the semiconductor device according to the embodiment of the present invention will be described in detail.
[Resin composition for sealing sheet]
The resin composition for a sealing sheet of the present embodiment includes (A) a crystalline epoxy resin and / or a liquid epoxy resin, (B) a phenol resin curing agent, (C) a curing accelerator, (D) an inorganic filler, and (E) It is characterized by containing a ketimine group-containing silane compound.
First, each component of the resin composition for a sealing sheet of the present embodiment (hereinafter, also simply referred to as a resin composition) will be described.

The epoxy resin of the component (A) used in this embodiment is a crystalline epoxy resin and / or a liquid epoxy resin. The crystalline epoxy resin is an epoxy resin that is solid at room temperature (25 ° C.), exhibits a crystalline state, and has a property that its viscosity greatly decreases when melted. The melting point of the crystalline epoxy resin is preferably 80 to 150 ° C, more preferably 90 to 130 ° C. Further, the liquid epoxy resin refers to an epoxy resin in a liquid or semi-solid state at room temperature (25 ° C.), and examples thereof include an epoxy resin having fluidity at room temperature (25 ° C.). The viscosity of the liquid epoxy resin at 25 ° C. is preferably 10,000 mPa · s or less, more preferably 1,000 to 6,000 mPa · s.
The melting point of the crystalline epoxy resin can be measured by the endothermic peak of DSC. The viscosity of the liquid epoxy resin at 25 ° C. can be measured with a rotary viscometer.

The crystalline epoxy resin of the component (A) and the liquid epoxy resin (hereinafter, also simply referred to as the epoxy resin of the component (A)) can be used without being limited by the molecular structure, molecular weight, etc. Biphenyl type epoxy resin, bisphenol A type epoxy resin and bisphenol F type epoxy resin are preferable. One of these may be used, or two or more thereof may be mixed and used.
The biphenyl type epoxy resin is an epoxy resin having a biphenyl skeleton, but the biphenyl skeleton in the present embodiment also includes a biphenyl ring obtained by hydrogenating at least one aromatic ring.
Specific examples of the biphenyl type epoxy resin include 4,4'-bis (2,3-epoxypropoxy) biphenyl and 4,4'-bis (2,3-epoxypropoxy) -3,3', 5, Epoxy obtained by reacting 5'-tetramethylbiphenyl, epichlorohydrin with a biphenol compound such as 4,4'-biphenol, or 4,4'-(3,3', 5,5'-tetramethyl) biphenol. Examples include resin. Among these, 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5'-tetramethylbiphenyl, 4,4'-(3,3', 5,5'- Glycidyl ether of tetramethyl) biphenyl is preferred. One type of biphenyl type epoxy resin may be used, or two or more types may be mixed and used.

Examples of commercially available products used as biphenyl type epoxy resins include YX-4000 (epoxy equivalent 185, melting point 105 ° C.) and YX-4000K (epoxy equivalent 185, melting point 105 ° C.) manufactured by Mitsubishi Chemical Corporation. Examples thereof include YX-4000H (epoxy equivalent 193, melting point 105 ° C.), YL-6121H (epoxy equivalent 175, melting point 125 ° C.) (all of which are trade names).
Specific examples of the bisphenol A type epoxy resin include EXA-850CRP (epoxy equivalent 173, 25 ° C. viscosity 4500 mPa · s) manufactured by DIC Corporation. Specific examples of the bisphenol F type epoxy resin include YDF-8170C (epoxy equivalent 160, 25 ° C. viscosity 1250 mPa · s) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.

In addition to the epoxy resin of the component (A), an epoxy resin used as a sealing material can be used in combination as long as the effect of the present invention is not impaired.
When an epoxy resin other than the above crystalline epoxy resin and liquid epoxy resin is used in combination, the blending amount thereof is preferably 30 parts by mass or less, preferably 20 parts by mass, based on 100 parts by mass of the epoxy resin of the component (A). It is more preferably 10 parts by mass or less, and further preferably 10 parts by mass or less.

The phenolic resin curing agent of the component (B) used in the present embodiment is particularly limited as long as it has two or more phenolic hydroxyl groups in the molecule capable of reacting with the epoxy group in the epoxy resin of the component (A). Can be used without being used. Specifically, a novolak-type phenol resin such as phenol novolac resin and cresol novolak resin obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde, and these novolak-type phenol resins are epoxidized or butylated. Examples thereof include modified novolac type phenol resin, dicyclopentadiene modified phenol resin, paraxylene modified phenol resin, phenol aralkyl resin, naphthol aralkyl resin, triphenol alkane type phenol resin, polyfunctional phenol resin and the like. Of these, novolak-type phenolic resins and triphenolalkane-type phenolic resins are preferably used. One of these may be used, or two or more thereof may be mixed and used.

The blending amount of the phenolic resin curing agent of the component (B) is the number of phenolic hydroxyl groups (b) of the phenolic resin curing agent of the component (B) with respect to the number of epoxy groups (a) of the epoxy resin of the component (A). The range in which the ratio [(b) / (a)] is 0.3 or more and 1.5 or less is preferable, and the range in which the ratio is 0.5 or more and 1.2 or less is more preferable. When the ratio [(b) / (a)] is 0.3 or more, the moisture resistance reliability of the cured product can be improved, and when it is 1.5 or less, the strength of the cured product can be increased.

The curing accelerator of the component (C) used in the present embodiment is a component that promotes the curing reaction between the epoxy resin of the component (A) and the phenol resin curing agent of the component (B). As the curing accelerator of the component (C), a known curing accelerator can be used without particular limitation as long as it exhibits the above action.
Specific examples of the curing accelerator for the component (C) include 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 1,2-dimethylimidazole, and 2,4-dimethyl. Imidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 4-methylimidazole, 4-ethylimidazole, 2-phenyl-4-hydroxymethylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2 -Methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2 -Imidazoles such as phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole; 1,8-Diazabicyclo [5.4.0] Undecene-7 (DBU), 1,5-Diazabicyclo [4.3.0] Nonen, 5,6-dibutylamino-1,8-Diazabicyclo [5.4. 0] Diazavicyclo compounds such as undecene-7 and salts thereof; tertiary amines such as triethylamine, triethylenediamine, benzyldimethylamine, α-methylbenzyldimethylamine, triethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl) phenol, etc. Kind: trimethylphosphine, triethylphosphine, tributylphosphine, diphenylphosphine, triphenylphosphine, tri (p-methylphenyl) phosphine, tri (nonylphenyl) phosphine, methyldiphenylphosphine, dibutylphenylphosphine, tricyclohexylphosphine, bis (diphenylphos Examples thereof include organic phosphine compounds such as fino) methane and 1,2-bis (diphenylphosphino) ethane. Among these, imidazoles are preferable, and 2-phenyl-4-methyl-5-hydroxymethylimidazole is more preferable, from the viewpoint of good fluidity and moldability. One of these may be used, or two or more thereof may be mixed and used.

The blending amount of the curing accelerator for the component (C) is preferably in the range of 0.1 to 5% by mass, more preferably in the range of 0.2 to 1% by mass, based on the entire resin composition. When the blending amount of the component (C) is 0.1% by mass or more, the effect of promoting curability can be sufficiently obtained, and when it is 5% by mass or less, the moisture resistance reliability of the molded product can be improved.

The inorganic filler of the component (D) used in the present embodiment is a component that is filled in the resin composition to adjust the viscosity of the resin composition and enhance the handleability and moldability when it is used as a sealing sheet to be described later. Is. As the inorganic filler of the component (D), any known inorganic filler generally used in this type of resin composition can be used without particular limitation.
Specifically, the inorganic filler of the component (D) is, for example, an oxide powder such as molten silica, crystalline silica, crushed silica, synthetic silica, alumina, titanium oxide, magnesium oxide; aluminum hydroxide, magnesium hydroxide. Hydroxide powders such as, and nitride powders such as boron nitride, aluminum oxide, and silicon nitride. One type of these inorganic fillers may be used, or two or more types may be mixed and used.

As the inorganic filler of the component (D), silica powder is preferable, molten silica is more preferable, and spherical molten silica is particularly preferable, among the above-exemplified examples, from the viewpoint of improving the handleability and moldability of the sealing sheet. Further, fused silica and silica other than fused silica can be used in combination, and in that case, the proportion of silica other than fused silica is preferably less than 30% by mass of the entire silica powder.

The inorganic filler of the component (D) has an average particle size of preferably 0.5 to 40 μm, more preferably 1 to 30 μm, and even more preferably 5 to 30 μm. Further, it is more preferable that the maximum particle size of the inorganic filler of the component (D) is 105 μm or less.
When the average particle size is 0.5 μm or more, it is possible to suppress a decrease in the fluidity of the resin composition and improve the moldability. Further, when the average particle size is 40 μm or less, it is possible to suppress the warp of the molded product obtained by curing the resin composition and prevent the deterioration of the dimensional accuracy. Further, when the maximum particle size is 105 μm or less, the moldability of the resin composition can be improved.
In the present specification, the average particle size of the inorganic filler of the component (D) can be obtained by, for example, a laser diffraction type particle size distribution measuring device, and the average particle size is based on the particle size distribution measured by the device. It is a particle size (d50) at which the integrated volume becomes 50%.

The blending amount of the inorganic filler of the component (D) is preferably in the range of 70 to 95% by mass, more preferably in the range of 75 to 90% by mass, based on the entire resin composition. When the blending amount of the inorganic filler is 70% by mass or more, an increase in the coefficient of linear expansion of the resin composition can be suppressed, and the dimensional accuracy, moisture resistance, mechanical strength and the like of the molded product can be improved. When the blending amount of the inorganic filler is 95% by mass or less, it is possible to suppress an increase in the melt viscosity of the resin composition, suppress a decrease in fluidity, and improve moldability. In addition, the sealing sheet obtained by molding the resin composition can be made hard to crack.

The ketimine group-containing silane compound of the component (E) used in the present embodiment is a compound having a ketimine group and an alkoxy group in one molecule, and is cured by containing the component (E) in the resin composition. The adhesive strength of an object can be increased.
The ketimine group-containing silane compound of the component (E) is not particularly limited as long as it has a ketimine group and an alkoxy group in one molecule, but is represented by the following general formula (1) from the viewpoint of enhancing the adhesive strength of the cured product. It is preferably a compound to be used.

In the above general formula (1), R ^{1 to} R ⁴ independently represent alkyl groups having 1 to 5 carbon atoms, and specifically, methyl group, ethyl group, n-propyl group, isopropyl group, and n-butyl. Examples include groups, isobutyl groups, sec-butyl groups, tert-butyl groups, various pentyl groups and the like. Of these, a methyl group, an ethyl group, a propyl group and a butyl group are preferable from the viewpoint of availability in the market.
R ⁵ represents an alkylene group having 1 to 10 carbon atoms, preferably 1 to ⁵ carbon atoms. The alkylene group may be linear or branched, and examples thereof include a methylene group, an ethylene group, a propylene group, a trimethylene group, a butylene group, and a pentylene group. Of these, an ethylene group and a trimethylene group are preferable.

a represents an integer of 0 to 2, and is preferably 0.

The ketimine group-containing silane compound of the component (E) is easily hydrolyzed under high temperature conditions during molding to produce a primary amine. Water adsorbed on the silica surface is sufficient as the water required for hydrolysis, but it may be mixed with pure water in advance. In addition, it may be used alone or in combination with other silane cuplinking agents.

Specific examples of the ketimine group-containing silane compound represented by the general formula (1) include N- (1-methylethylidene) -3- (triethoxysilyl) -1-propaneamine and N- (1,3-dimethyl). Butylidene) -3- (triethoxysilyl) -1-propaneamine, N- (1-methylpropylidene) -3- (triethoxysilyl) -1-propaneamine, N- (1-methylethylidene) -3 -(Methyldiethoxysilyl) -1-propaneamine, N- (1,3-dimethylbutylidene) -3- (methyldiethoxysilyl) -1-propaneamine, N- (1-methylpropylidene) -3 -(Methyldiethoxysilyl) -1-propaneamine, N- (1-methylethylidene) -3- (ethyldiethoxysilyl) -1-propaneamine, N- (1,3-dimethylbutylidene) -3- (Ethyldiethoxysilyl) -1-propaneamine, N- (1-methylpropanol) -3- (ethyldiethoxysilyl) -1-propaneamine, N- (1-methylethylidene) -3- (methyldimethoxy) Cyril) -1-propaneamine, N- (1,3-dimethylbutylidene) -3- (methyldimethoxysilyl) -1-propaneamine, N- (1-methylpropylidene) -3- (methyldimethoxysilyl) -1-Propanamine, N- (1-methylethylidene) -2- (triethoxysilyl) -1-ethaneamine, N- (1,3-dimethylbutylidene) -2- (triethoxysilyl) -1-ethaneamine , N- (1-methylpropanol) -2- (triethoxysilyl) -1-ethaneamine, N- (1-methylethylidene) -2- (methyldiethoxysilyl) -1-ethaneamine, N- (1, 3-Dimethylbutylidene) -2- (methyldiethoxysilyl) -1-ethaneamine, N- (1-methylpropylidene) -2- (methyldiethoxysilyl) -1-ethaneamine, N- (1-methylethylidene) ) -2- (Ethyldiethoxysilyl) -1-ethaneamine, N- (1,3-dimethylbutylidene) -2- (ethyldiethoxysilyl) -1-ethaneamine, N- (1-methylpropanol)- 2- (Ethyldiethoxysilyl) -1-ethaneamine, N- (1-methylethylidene) -2- (methyldimethoxysilyl) -1-ethaneamine, N- (1,3-dimethylbutylidene) -2- (methyl) Dimethoxysilyl) -1-ethaneamine, N- (1-methylpropyride) N) -2- (methyldimethoxysilyl) -1-ethaneamine and the like. Of these, N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propaneamine is preferable from the viewpoint of availability in the market.
One type of these ketimine group-containing silane compounds may be used, or two or more types may be used in combination.

The ketimine group-containing silane compound of the component (E) is easily hydrolyzed under high temperature conditions at the time of molding to produce a primary amine and a silanol group. The primary amine reacts with the epoxy resin of the component (A), and the silanol group causes a condensation reaction with the hydroxy group existing on the surface of the inorganic filler of the component (D) to cause the cured resin and the inorganic filler. The bond with is strengthened. As a result, when the resin composition of the present embodiment is used as a sealing material for a semiconductor device, the cured product has strong adhesiveness to a silicon chip or the like.

The content of the ketimine group-containing silane compound of the component (E) above with respect to the total amount of the resin composition is from the viewpoints of improving the adhesiveness of the cured product to silicon chips and the like, suppressing molding defects such as voids, and balancing economic efficiency. , It is preferably selected in the range of 0.5 to 2.0% by mass, more preferably 0.8 to 1.5% by mass.

Examples of commercially available products used as the ketimine group-containing silane compound of the component (E) are as follows, for example, N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propaneamine. Examples thereof include KBE-9103 manufactured by Silicone Co., Ltd., Silane Ace S340 manufactured by JNC Co., Ltd., and Z-6860 manufactured by Toray Dow Corning Co., Ltd.

In addition to the above-mentioned components, the resin composition of the present embodiment includes components generally blended in this type of resin composition as long as the effects of the present embodiment are not impaired, for example, a coupling agent; synthetic wax, and the like. Release agents such as natural waxes, higher fatty acids, metal salts of higher fatty acids; colorants such as carbon black and cobalt blue; low stress imparting agents such as silicone oil and silicone rubber; hydrotalcites; ion trapping agents, etc. can do.

Examples of the coupling agent include epoxysilane-based, aminosilane-based, ureidosilane-based, vinylsilane-based, alkylsilane-based, organic titanate-based, and aluminum alcoholate-based coupling agents. These may be used alone or in admixture of two or more.
As the coupling agent, an aminosilane-based coupling agent is preferable from the viewpoint of moldability, flame retardancy, curability and the like, and in particular, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-amino. Propylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, (N-phenyl-γ-aminopropyl) trimethoxysilane and the like are preferable.

When a coupling agent is used, the blending amount thereof is preferably in the range of 0.01% by mass or more and 3.0% by mass or less of the entire resin composition, and more preferably in the range of 0.1% by mass or more and 1% by mass or less. preferable. If the blending amount of the coupling agent is 0.01% by mass or more, the moldability can be improved, and if it is 3.0% by mass or less, the generation of foaming is suppressed during molding, and voids and surface swelling are formed in the molded product. Etc. can be suppressed.

The resin composition of the present embodiment contains (A) a crystalline epoxy resin and / or a liquid epoxy resin, (B) a phenol resin curing agent, (C) a curing accelerator, (D) an inorganic filler, and (E) a ketimine group. After sufficiently mixing (dry blending) the contained silane compound and the various components to be blended as necessary with a mixer or the like, melt-kneading with a kneading device such as a hot roll or kneader, cooling, and then an appropriate size Crush into. The crushing method is not particularly limited, and a general crusher, for example, a speed mill, a cutting mill, a ball mill, a cyclone mill, a hammer mill, a vibration mill, a cutter mill, a grinder mill or the like can be used. Of these, a speed mill is preferably used. The pulverized product can then be adjusted into a particle aggregate having a predetermined particle size distribution by sieving classification, air classification, or the like.

[Encapsulation sheet]
Next, the sealing sheet of the present embodiment will be described.
The sealing sheet of the present embodiment is a sheet-shaped molded product obtained by using the above-mentioned resin composition for a sealing sheet as a material and molding the resin composition into a sheet shape. The sealing sheet is obtained, for example, by heating and melting the resin composition of the present embodiment between the pressure members, compressing it, and molding it into a sheet. More specifically, the resin composition is supplied onto a heat-resistant release film such as a polyester film so as to have a substantially uniform thickness to form a resin layer, and then the resin layer is rolled while being heated and softened. And roll by hot press. At that time, a heat-resistant film such as a polyester film is also arranged on the resin layer. After rolling the resin layer to a desired thickness in this way, it is cooled and solidified, the heat-resistant film is peeled off, and further cut into a desired size and shape if necessary. As a result, a sealing sheet of any size can be obtained.
The heating temperature for softening the resin layer is usually about 80 to 150 ° C. If the heating temperature is less than 80 ° C., the melt mixing becomes insufficient, and if it exceeds 150 ° C., the curing reaction proceeds too much and the moldability may decrease during heat curing.

It sealing sheet of the present embodiment, the temperature 175 ° C. by a Koka type flow tester, the melt viscosity measured under a load of 10 kg (shear stress 1.23 × ¹⁰ 5 Pa), a 2~50Pa · s Is preferable, and 3 to 20 Pa · s is more preferable. When the melt viscosity is 2 Pa · s or more, the occurrence of burrs can be suppressed, and when it is 50 Pa · s or less, the filling property is improved and the generation of voids and unfilled portions can be suppressed.

The sealing sheet of the present embodiment is suitable for sealing parts such as semiconductor elements, and the size of the sealing sheet is appropriately adjusted according to the size of the parts to be sealed. The size of the sealing sheet can be arbitrarily prepared, but for example, 200 × 200 mm to 600 × 600 mm is preferable. Further, the thickness of this sealing sheet is preferably 0.1 to 2.0 mm. If the thickness is 0.1 mm or more, there is no risk of cracking, the handling is excellent, and the product can be easily carried into the compression molding die without any trouble. Further, if the thickness is 2.0 mm or less, the melting of the sealing sheet in the mold is not delayed at the time of semiconductor sealing, and the molding does not become defective.

[Semiconductor device]
The semiconductor device of this embodiment includes an element sealed by the above-mentioned sealing sheet. The semiconductor device can be manufactured by sealing a semiconductor element fixed on a substrate by compression molding using the sealing sheet. An example of the method will be described below.
First, a substrate on which a semiconductor element is mounted is covered with a sealing sheet so as to be sandwiched between the two sealing sheets, and the semiconductor element is placed at a predetermined position in a cavity of a compression molding die. Compression molding is performed at the temperature and pressure of. The molding conditions are preferably a temperature of 100 to 190 ° C. and a pressure of 4 to 12 MPa. After molding, it is post-cured at a temperature of 130 to 190 ° C. for about 2 to 8 hours. By this heat curing, the sealing sheet is cured in close contact with the semiconductor element, and a resin-sealed semiconductor device in which the semiconductor element is sealed so as not to come into contact with the external atmosphere can be manufactured.

Since the semiconductor device thus obtained is sealed by compression molding using a sealing sheet that is easy to handle even if it is thin and has excellent moldability, it has high quality and high reliability even if it is thin. can do.
The semiconductor element sealed in the semiconductor device of the present embodiment may be a known semiconductor element and is not particularly limited. For example, an IC (Integrated Circuit), an LSI (Large Scale Integration), and the like. Diodes, thyristors, transistors and the like can be exemplified. In particular, in the case of a semiconductor element having a thickness of 0.1 to 1.5 mm after sealing, which is difficult to seal with a conventional sealing material, a semiconductor device using the sealing sheet can be used. The manufacturing method is particularly useful.

Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these examples. The materials used in the following examples and comparative examples are as shown in Table 1.

(Examples 1 to 6, Comparative Examples 1 to 3)
Each raw material was mixed at room temperature (25 ° C.) so as to have the composition shown in Table 2, and then heated and kneaded at 80 to 130 ° C. using a hot roll. After cooling, it was pulverized using a speed mill to prepare a resin composition for a sealing sheet.
The obtained resin composition for a sealing sheet is sandwiched between a release film made of polyester, placed between hot plates at 80 ° C., heated and pressurized at a pressure of 10 MPa for 1 minute, and sealed with a thickness of 0.5 mm. A sheet was prepared.
Further, the semiconductor chip was sealed using the obtained sealing sheet. That is, first, a 150 mm × 30 mm sheet was cut out from the obtained sealing sheet. This cut-out sealing sheet is placed in a compression molding die, a substrate on which a semiconductor chip is mounted is placed on top of the cut-out sealing sheet, and the above-mentioned sealing sheet is further placed on top of the substrate. Compression molding was performed under the condition of minutes. Then, after curing at 175 ° C. for 4 hours, a semiconductor device was manufactured.

Various characteristics of the resin composition for a sealing sheet, the sealing sheet, and the semiconductor device (product) obtained in each of the above Examples and Comparative Examples were evaluated by the methods shown below. The results are also shown in Table 2. In Table 2, blanks indicate no compounding.

* 1: Classification was performed using a sieve with an opening of 75 μm.

<Resin composition>
(1) Spiral flow Using a mold conforming to the EMMI standard, transfer molding was performed at a temperature of 175 ° C. and a pressure of 9.8 MPa, and measurement was performed.

(2) Gel time According to the gelation time A method specified in 7.5.1 of JIS C 2161, about 1 g of the resin composition for a sealing sheet is applied on a hot plate at 175 ° C. and put on a stirring rod. It was stirred and the time until it became a gel and could not be stirred was measured.

(3) Koka type flow viscosity flow characteristics evaluation apparatus (manufactured by Shimadzu Corporation, product name: Flow Tester CFT-500 type), the temperature 175 ° C., load 10 kg (shear stress 1.23 × ¹⁰ 5 Pa environment The melt viscosity in (below) was measured.

<Sealing sheet>
(1) Flexibility Cut out a sealing sheet with a width of 10 mm, a length of 50 mm, and a thickness of 0.5 mm, clamp the part 15 mm from one end, set it on the gantry at a height of 18 mm, and one end of the sheet is self-weight. The time until contact with the upper surface of the gantry was measured (initial).
Separately, a sealing sheet having a width of 10 mm, a length of 50 mm, and a thickness of 0.5 mm was cut out, left at 25 ° C. for 168 hours, and then similarly clamped at a portion 15 mm from one end and placed on a gantry. The height was set to 18 mm, and the time until one end of the sheet came into contact with the upper surface of the gantry was measured by its own weight.

<Cured product>
(1) Glass transition point (Tg)
A stick-shaped sample was prepared from the cured product obtained by heating and curing at 175 ° C. for 3 minutes, and the temperature was raised by a thermal analyzer (TMA) (manufactured by Seiko Instruments Inc., product name: TMA SS-150). The temperature was raised at a speed of 10 ° C./min, and the TMA chart was measured and obtained from the intersection of the two tangents.

(2) Flexural strength and flexural modulus The sample prepared in the same manner as in (1) above was measured at a temperature of 25 ° C. in accordance with JIS K 6911.

(3) A disc-shaped cured product having a diameter of 50 mm and a thickness of 3 mm was obtained by compression molding at 175 ° C. for 2 minutes under a pressure of 12 MPa and then curing at 175 ° C. for 8 hours. It was. This cured product was allowed to stand in saturated steam at 127 ° C. and 0.25 MPa for 24 hours, and the increased mass before and after the treatment was calculated and calculated from the following formula.
Water absorption (%) = increased mass (g) / initial mass of cured product (g)

(4) Adhesive Strength with Silicon Chip A sealing sheet was transferred onto the silicon chip into a square shape having a side of 2 mm at a molding temperature of 150 ° C. and a molding pressure of 100 kg / cm ² for 10 minutes. A shearing force was applied to the obtained molded product, and the shearing force at the time of breaking was used as the adhesive force.

<Product (semiconductor device)>
(1) Reflow resistance (MSL test)
The semiconductor device was subjected to a moisture absorption treatment at 85 ° C. and 85% RH for 72 hours, and then heated in an infrared reflow furnace at 240 ° C. for 90 seconds (MSL test: Level 3) to detect defects (peeling and cracking). The incidence was examined (number of samples = 20).

(2) Moisture resistance reliability (pressure cooker test: PCT)
The semiconductor device was allowed to absorb water in a pressure cooker under the conditions of 127 ° C. and 0.25 MPa for 72 hours, and then vapor reflow was performed at 240 ° C. for 90 seconds to examine the occurrence rate of defects (open defects) (sample). Number = 20).

(3) High temperature standing reliability (highly accelerated life test: HAST)
The semiconductor device was left in a constant temperature bath at 180 ° C. for 1000 hours, and the incidence of defects (open defects) was examined (number of samples = 20).

As is clear from Table 2, the sealing sheet of the present embodiment has flexibility even when left at room temperature for a long time, has good handleability, and has good adhesion to a silicon chip. Met.
Further, the semiconductor device manufactured by using the sealing sheet has obtained good results in all of the MSL test, the pressure cooker test, and the highly accelerated life test, which is high as a resin-sealed semiconductor device. It was confirmed that it has reliability.

The sealing sheet of the present invention is excellent in handleability and moldability even when the thickness is reduced. Therefore, it is useful as a sealing material for compression molding of a thin semiconductor element, and a high-quality and highly reliable resin-sealed semiconductor device can be manufactured.
In addition to semiconductor elements, it can also be used as a sealing sheet for sealing parts and the like so as not to be exposed to the external environment.

Claims (4)

Encapsulation containing (A) crystalline epoxy resin and / or liquid epoxy resin, (B) phenolic resin curing agent, (C) curing accelerator, (D) inorganic filler, and (E) ketimine group-containing silane compound Resin composition for sheets. The resin composition for a sealing sheet according to claim 1, wherein the inorganic filler (D) is silica powder and is contained in an amount of 70 to 95% by mass in the entire resin composition for a sealing sheet. A sealing sheet comprising the resin composition for a sealing sheet according to claim 1 or 2. A semiconductor device including an element sealed by the sealing sheet according to claim 3.