JP2001151994A - Epoxy resin compositions and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high reliability semiconductor sealing epoxy resin compositions which excel in moldability with reduced voids on molding, deformation of gold wires, staining of the surface of a molded article and the like and, at the same time, excel in resistance to soldering properties. SOLUTION: The semiconductor sealing epoxy resin compositions comprise (A) an epoxy resin, (B) a phenolic resin, (C) a curing accelerator, (D) an inorganic filler, and (F) a polyorganosiloxane as the essential components, and the polyorganosiloxane being a mixture of (a) a polyorganosiloxane having a weight ratio of the siloxane to the organic subsistent in the polyorganosiloxane molecule of 10/90 to 35/65 and (b) a polyorganosiloxane having a weight ratio of the siloxane to the organic substituent in the polyorganosiloxane molecule of 40/60 to 60/40 at a weight ratio of polyorganosiloxane (a) to polyorganosiloxane (b) of 100/0 to 20/80.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent reliability such as moldability, soldering resistance after moisture absorption and temperature cycling resistance, and a semiconductor device using the same. is there.

[0002]

2. Description of the Related Art In recent years, in the market trend of miniaturization, weight reduction, and high performance of electronic devices, semiconductor integration is progressing year by year, and surface mounting of semiconductor devices is promoted. Demands for epoxy resin compositions as stopping materials have become increasingly severe. In particular, in the current situation where surface mounting of semiconductor devices is becoming common, a semiconductor device that has absorbed moisture is exposed to a high temperature during soldering, and cracks occur in the semiconductor device due to the explosive stress of vaporized water vapor. Due to the occurrence of peeling at the interface between the element or lead frame and the cured product of the epoxy resin composition,
Defects occur that greatly impair electrical reliability, and prevention of these defects, that is, improvement of solder resistance, has become a major issue. In order to improve the solder resistance, the epoxy resin composition contains a large amount of an inorganic filler to reduce the moisture absorption, lower the thermal expansion, and increase the strength of the semiconductor device. For this reason, low viscosity type epoxy resin,
Using a crystalline epoxy resin that is crystalline at room temperature but exhibits extremely low viscosity above the melting point, to prevent a decrease in fluidity during molding of the epoxy resin composition due to an increase in the amount of the inorganic filler. An approach has been proposed.

However, in an epoxy resin composition produced by heating and kneading each component, an epoxy resin composition containing a large amount of an inorganic filler is poorly dispersed in the resin component during the heating and kneading. It is difficult to obtain a uniform resin composition in the manufacturing process of the composition, and the uneven epoxy resin composition has poor affinity between the inorganic filler and the epoxy resin or phenol resin, and each component of the resin composition is uniform at the time of molding. Air does not form a large flow, entrainment of air increases, and a large amount of air bubbles in the molded product (hereinafter referred to as voids)
However, there are problems such as the remaining of the resin and the decrease in fluidity during molding. If voids are present in the molded product, external moisture easily enters the semiconductor device and moisture easily accumulates, so that the semiconductor element is easily corroded and reliability is reduced. Further, when the fluidity during molding of the epoxy resin composition is reduced, the semiconductor element is pushed up and exposed on the surface of the semiconductor device, so-called chip shift occurs, or the metal that connects the circuit of the semiconductor element and the lead frame is connected. A so-called gold wire deformation in which the wire is deformed or cut occurs, and further, a molding failure such as a so-called unfilled state in which the resin composition is not sufficiently filled in the mold.

[0004] As a method for improving the uniformity of the inorganic filler and the resin component, for reducing the voids and for improving the fluidity, many methods for adding a polyorganosiloxane have been proposed. However, although the addition of polyorganosiloxane is effective in reducing voids, on the other hand, it decreases the mechanical properties such as the bending strength of the cured product of the epoxy resin composition, or the polyorganosiloxane oozes out at the time of molding and gold. Since the surface of the mold or molded product is contaminated, the polyorganosiloxane is transferred to the interface between the semiconductor element present inside the semiconductor device and the lead frame on which the semiconductor element is mounted and the sealing resin, and the adhesion at these interfaces is significantly impaired. If the semiconductor device is soldered after absorbing moisture, various defects such as peeling at the interface and cracking of the semiconductor device due to the peeling will occur. For this reason, development of an epoxy resin composition which is excellent in compatibility between moldability such as voids during molding, mold contamination, fluidity, and the like and solder resistance has been desired.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an epoxy resin composition for semiconductor encapsulation which is excellent in fluidity during molding, has few voids, and is excellent in reliability such as soldering resistance of a molded semiconductor device. And a semiconductor device using the same.

[0006]

The present invention provides (A) an epoxy resin, (B) a phenolic resin, (C) a curing accelerator,
An epoxy resin composition comprising (D) an inorganic filler and (E) a polyorganosiloxane as an essential component, wherein the weight ratio of siloxane / organic substituent in the polyorganosiloxane molecule is from 10/90 to 35/65. The weight ratio of siloxane (a) to siloxane / organic substituent in the polyorganosiloxane molecule is 40/60 to 60/4.
Weight ratio of polyorganosiloxane (b) of 0 (a) /
(B) 100/0 to 20/80, and an epoxy resin composition for semiconductor encapsulation, and a semiconductor obtained by encapsulating a semiconductor element using this epoxy resin composition. Device.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin used in the present invention refers to all monomers, oligomers and polymers having two or more epoxy groups in one molecule, such as bisphenol A type epoxy resin and phenol novolak type epoxy resin. , Ortho-cresol novolak type epoxy resin, naphthol novolak type epoxy resin, triphenol methane type epoxy resin, dicyclopentadiene modified phenol type epoxy resin, phenol aralkyl type epoxy resin, terpene modified phenol type epoxy resin,
Examples include, but are not limited to, biphenyl-type epoxy resins, hydroquinone-type epoxy resins, stilbene-type epoxy resins, and bisphenol-F-type epoxy resins. These epoxy resins may be used alone or as a mixture. In order to improve the solder resistance of the semiconductor device, the amount of the inorganic filler in the resin composition is increased to reduce the moisture absorption, lower the thermal expansion, and increase the strength of the cured product of the obtained resin composition. In order to achieve this, it is particularly preferable to use 30% by weight or more of a crystalline epoxy resin which exhibits crystallinity at room temperature and becomes a liquid having an extremely low viscosity when the melting point is exceeded. As the crystalline epoxy resin, a resin having a characteristic of a melting point of 70 to 150 ° C. is preferable in terms of handling workability and workability at the time of kneading. The melting point of the crystalline epoxy resin in the present invention indicates the temperature at the top of the endothermic peak of crystal melting at a temperature rising from room temperature at 5 ° C./min using a differential scanning calorimeter.

The crystalline epoxy resin includes a resin having a structure represented by the general formula (1), the general formula (2) or the general formula (3).

Embedded image (In the formula, R ₁ represents an alkyl group having 1 to 6 carbon atoms, which may be the same or different from each other, and m is 0.
An integer from 4 to 4. )

[0009]

Embedded image (Wherein R ₂ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, which may be the same or different from each other. R ₃ represents an alkyl group having 1 to 1 carbon atom, M may be the same or different, and m is 0 to 4
Integer. )

[0010]

Embedded image (Wherein R ₄ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, which may be the same or different from each other. R ₅ represents an alkyl group having 1 to 6 carbon atoms, May be the same or different from each other.
An integer of 4. )

As specific examples, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxy-3,3 ', 5,
5'-tetramethylbiphenyl, 4,4'-methylenebis (2,6-dimethylphenol), 4,4 '-(1-
Glycidyl ether of methylethylidene) bis (2,6-dimethylphenol) or 4,4′-bis (2,3-hydroxypropyloxy) -2,2′-dimethyl-5,5′-ditert-butyldiphenyl sulfide Or 3-tert-butyl-2,4′-dihydroxy-3 ′, 5 ′, 6-trimethylstilbene;
3-tert-butyl-4,4'-dihydroxy-
3 ', 5', 6-trimethylstilbene, or 3-
Tert-butyl-4,4'-dihydroxy-3 ',
One or more kinds selected from three kinds of glycidyl etherified products of 5,5′-trimethylstilbene, and 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylstilbene;
4,4′-dihydroxy-3,3′-ditert-butyl-6,6′-dimethylstilbene, 2,2′-dihydroxy-3,3′-di-tert-butyl-6,6′-dimethylstilbene, 2, 4'-dihydroxy-3,3 '
-Ditertiarybutyl-6,6'-dimethylstilbene, 2,2'-dihydroxy-3,3 ', 5,5'-tetramethylstilbene, or 4,4'-dihydroxy-3,3'-ditertiarybutyl It is a mixture with at least one selected from six glycidyl etherified products of -5,5'-dimethylstilbene.

The phenolic resin used in the present invention refers to all monomers, oligomers and polymers having two or more phenolic hydroxyl groups in one molecule.
Phenol novolak resin, cresol novolak resin, phenol aralkyl resin, terpene-modified phenol resin, dicyclopentadiene-modified phenol resin, naphthol aralkyl resin, triphenolmethane-type resin, bisphenol compound, and the like, but are not limited thereto. . Further, these phenol resins may be used alone or in combination.

The curing accelerator used in the present invention includes:
A substance that can serve as a catalyst for a cross-linking reaction between the epoxy resin and the phenol resin. Specific examples include amine compounds such as tributylamine and 1,8-diazabicyclo (5,4,0) undecene-7, and triphenylphosphine. ,
Examples include organic phosphorus compounds such as tetraphenylphosphonium / tetraphenylborate salts, and imidazole compounds such as 2-methylimidazole, but are not limited thereto. These curing accelerators may be used alone or as a mixture. Examples of the inorganic filler used in the present invention include fused silica, crystalline silica, alumina, silicon nitride, and aluminum nitride. When increasing the amount of the inorganic filler, fused silica is generally used. Fused silica can be used in either a crushed or spherical form. However, in order to increase the blending amount of the fused silica and to suppress an increase in the melt viscosity of the molding material, it is preferable to mainly use a spherical form. In order to further increase the blending amount of the spherical silica, it is desirable to adjust the particle size distribution of the spherical silica to be wider.

The polyorganosiloxane used in the present invention refers to a polysiloxane having a skeleton of dimethylpolysiloxane, diphenylpolysiloxane, or methylphenylpolysiloxane, and generally gives an affinity to an epoxy resin or a phenol resin. For this reason, an organic substituent having a C, O, N, S atom or the like in addition to the organic substituent of the methyl group or the phenyl group may be present in the main chain or the side chain. Specifically, vinyl group, phenethyl group, hydroxy group, carboxy group, acrylic group, alkoxy group, epoxy group, polyether group, caprolactone group, amino group,
Examples include, but are not limited to, ureido groups, isocyanate groups, and mercapto groups. When the polyorganosiloxane used in the present invention is used alone, the weight ratio of siloxane / organic substituent in the polyorganosiloxane molecule is preferably 10/90 to 35/65, more preferably 15/85 to 30/70. It is. In the present invention, the weight ratio of siloxane / organic substituent in the polyorganosiloxane molecule is defined as the total weight of Si and O atoms derived from the siloxane bond present in the molecule and the total weight of atoms derived from the organic substituent. Weight ratio. If the weight ratio of the siloxane is less than 10% by weight, the hydrophilicity becomes too strong, and the effect as a plasticizer uniformly dissolved in the cured product of the epoxy resin composition becomes too strong, so that the glass transition temperature of the cured product is lowered. In addition, mechanical characteristics such as bending strength are reduced. In addition, due to the strength of the hydrophilicity, the moisture absorption of the cured product of the epoxy resin composition is significantly increased, and peeling of the interface of the base material and cracking of the semiconductor device due to the solder reflow treatment after moisture absorption easily occur. On the other hand, if the weight ratio exceeds 35% by weight, the hydrophobicity becomes too strong, so that the affinity for the resin component in the epoxy resin composition is low, and the epoxy resin composition is agglomerated and dispersed in the epoxy resin composition after the heat kneading step. During the molding, the compatibility with the resin composition is further reduced by heating,
There is a strong tendency to seep and contaminate the mold surface and molded product surface,
In addition, it oozes out at the interface between the semiconductor element and the base material such as a lead frame existing inside the semiconductor device, and after curing, reduces the adhesiveness at the interface between the base material and the cured product of the epoxy resin composition. The effect of reducing soldering is also low, and water tends to accumulate in the voids, causing peeling and cracking in the solder reflow treatment, which is not preferable.

Further, the weight ratio of siloxane / organic substituent in the hydrophilic poorganosiloxane molecule is 10/10.
90-35 / 65 polyorganosiloxane (a);
Siloxane / organic substituent weight ratio of 40 / 60-60
The epoxy resin composition in which the weight ratio of (a) / (b) to the hydrophobic polyorganosiloxane (b) is in the range of 100/0 to 20/80 with the hydrophobic polyorganosiloxane (b) has a hydrophobic polyorganosiloxane core. Since a hydrophilic polyorganosiloxane is coordinated as a compatibilizing agent with the resin component to form a stable micro-domain structure around the periphery thereof, a polyorganosiloxane is used more easily than when a hydrophilic polyorganosiloxane is used alone. Reduces decrease in moldability and interfacial adhesion due to bleeding out of the siloxane component during molding, and prevents a decrease in glass transition temperature and a decrease in mechanical properties due to the dissolution of the polyorganopolysiloxane component into the cured crosslinked structure of the resin component. be able to. If the weight ratio of the hydrophobic polyorganosiloxane (b) exceeds 80% by weight, the characteristics of the hydrophobic polyorganosiloxane become strong, and the above-mentioned disadvantages may occur, which is not preferable.

The epoxy resin composition of the present invention comprises (A)
The component (E) is an essential component, but if necessary, a brominated epoxy resin, a flame retardant such as antimony trioxide, a silane coupling agent, a coloring agent such as carbon black, a natural wax and a synthetic wax, etc. , A low-stress additive such as silicone rubber and synthetic rubber. The epoxy resin composition of the present invention comprises (A)
After mixing the component (E) and other additives, the mixture is heated and kneaded using a heating kneader or a hot roll, and then cooled and pulverized. In order to manufacture a semiconductor device by encapsulating an electronic component such as a semiconductor element using the resin composition of the present invention, it is sufficient to cure and mold by a molding method such as a transfer mold, a compression mold, and an injection mold.

[0017]

The present invention will be specifically described below with reference to examples.
The unit of the compounding amount is part by weight. Example 1 Epoxy resin containing 3,3 ', 5,5'-tetramethylbiphenol diglycidyl ether as a main component (YX4000H, Yuka Shell Epoxy Co., Ltd., melting point 105 ° C, epoxy equivalent 195. 7.9 parts by weight Phenol aralkyl resin (XL225 manufactured by Mitsui Chemicals, Inc., softening point 75 ° C., hydroxyl equivalent 175) 7.1 parts by weight Spherical fused silica 84.0 parts by weight 1,8- 0.2 parts by weight of diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 0.3 parts by weight of polyorganosiloxane of formula (4) (weight ratio of siloxane / organic substituents = 16% by weight)

Embedded image After mixing 0.2 parts by weight of carnauba wax and 0.3 parts by weight of carbon black using a mixer, the surface temperature was 90 ° C. and 2 parts.
The mixture was kneaded using a biaxial roll at 5 ° C., and the obtained kneaded material sheet was cooled and pulverized to obtain an epoxy resin composition. The properties of the obtained epoxy resin composition were evaluated by the following methods. Table 1 shows the results.

Evaluation method Spiral flow: Using a mold for measuring spiral flow according to EMMI-1-66, a mold temperature of 175 ° C.
It was measured at an injection pressure of 70 kgf / cm ² and a curing time of 2 minutes. Bending strength under heat: JIS K6
It was measured according to 911. The unit is kgf / mm ² . Glass transition temperature (Tg): A test piece formed by transfer molding at 175 ° C. and a curing time of 2 minutes was further cured at 175 ° C. for 8 hours, and then subjected to thermomechanical analyzer (TM, manufactured by Seiko Electronics Co., Ltd.)
(A-120, heating rate 5 ° C./min). Unit ℃. Gold wire deformation: 144pQFP package (package size 20 × 20 × 1.4mm, chip size 9 × 9m
m, gold wire: 25 μm diameter, lead frame: copper) at a mold temperature of 175 ° C., a molding pressure of 75 kgf / cm ² , and a curing time of 2
Molded in minutes. The obtained package was observed with a soft X-ray fluoroscope, and the deformation rate of the gold wire was represented by (flow amount) / (gold wire length) (unit%). Solder resistance: The 144pQFP package whose gold wire deformation was measured was post-cured at 175 ° C. for 8 hours. The obtained semiconductor package is placed in an environment at 85 ° C. and a relative humidity of 85% for 1 hour.
After standing for 68 hours, the difference in weight before and after moisture absorption was divided by the weight before moisture absorption to determine the moisture absorption rate, which was expressed as%. Thereafter, the semiconductor package was immersed in a solder bath at 240 ° C. for 10 seconds. Observe external cracks with a microscope and calculate the number of cracks [(number of packages where cracks occur) / (number of all packages) × 100] by%.
Displayed with. Also, this package was observed using an ultrasonic flaw detector, and the number of peelings at the interface between the chip (SiN-coated product) and the cured product of the epoxy resin composition [(number of packages where peeling occurred) / (number of total packages) ) × 100] in%. Void: The number of voids having a diameter of 0.1 mm or more observed in a package was observed as an average per package in an ultrasonic flaw detector observation of 144 pQFP evaluated for the number of peelings by soldering resistance. Releasability: A package of 144 pQFP whose gold wire deformation was measured was molded 10 times in a row. In these 10 moldings, the number of times of adhesion to the mold at the time of release from the mold and the occurrence of cracks / chips in the molded product was 5 or more times, Δ was 1 to 4 times, and 発 生 was not generated. Molded product stain: The surface of the molded product after 10th continuous molding was visually observed in the evaluation of releasability, and a cloudy one was evaluated as x and a glossy one was evaluated as good.

Examples 2 to 5 and Comparative Examples 1 to 3 The same procedures as in Example 1 were carried out except that the composition was the same as in Example 1 except that the type and addition amount of the polyorganosiloxane were changed. To obtain an epoxy resin composition.
The evaluation was performed in the same manner as described above. The structural formulas of other polyorganosiloxanes used in Examples and Comparative Examples are shown below. Table 1 shows the formulation and results. Weight% of siloxane in Table 1
Represents the weight ratio of siloxane / organic substituent.

Embedded image

[0020]

Embedded image

[0021]

Embedded image

[0022]

Embedded image

[0023]

[Table 1]

[0024]

Industrial Applicability The epoxy resin composition of the present invention has uniform flow characteristics, and has very few voids, gold wire deformation, and surface contamination of molded products, and a semiconductor device sealed with this has excellent solder resistance. I have.

Continued on the front page F term (reference) 4J002 CC03X CC05X CC07X CD04W CD05W CD06W CD11W CP033 CP093 CP103 DE147 DF017 DJ007 DJ017 EN026 EU116 EW016 EW176 EY016 FD017 FD020 FD090 FD130 FD160 GQ00 4M109 AA01 EB03 EB02 EB02 EB02 EB02 EB02 EB02 EB02 EB02 EB02 EC03 EC05 EC20

Claims (4)

[Claims] 1. An epoxy resin composition comprising (A) an epoxy resin, (B) a phenolic resin, (C) a curing accelerator, (D) an inorganic filler, and (E) a polyorganosiloxane as essential components. When the weight ratio of siloxane / organic substituent in the organosiloxane molecule is 10 / 90-3.
5/65 polyorganosiloxane (a) and polyorganosiloxane (b) having a weight ratio of siloxane / organic substituents in the polyorganosiloxane molecule of 40/60 to 60/40 by weight (a) / (b) ) Is 100 / 0-20
/ 80, which is an epoxy resin composition for semiconductor encapsulation. 2. An epoxy resin having a melting point of 70 to 15 (A).
2. The epoxy resin composition for semiconductor encapsulation according to claim 1, which contains a crystalline epoxy resin at 0 ° C. in an amount of 30% by weight or more. 3. A crystalline epoxy resin represented by the general formula (1):
The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the epoxy resin composition is at least one selected from general formulas (2) and (3). Embedded image (In the formula, R ₁ represents an alkyl group having 1 to 6 carbon atoms, which may be the same or different from each other, and m is 0.
An integer from 4 to 4. ) (Wherein R ₂ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, which may be the same or different from each other. R ₃ represents an alkyl group having 1 to 6 carbon atoms, May be the same or different from each other.
An integer of 4. ) (Wherein R ₄ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, which may be the same or different from each other. R ₅ represents an alkyl group having 1 to 6 carbon atoms, May be the same or different from each other.
An integer of 4. ) 4. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition for semiconductor encapsulation according to claim 1, 2 or 3.