JPH01261413A - Epoxy resin composition for sealing semiconductor - Google Patents

Abstract

PURPOSE:To obtain the title compsn. having excellent crack resistance, moisture resistance and low stress characteristics and good moldability, by using an epoxy resin, a polyester elastomer-modified phenol resin, a curing accelerator and an inorg. filler as essential components. CONSTITUTION:This epoxy resin compsn. for sealing semiconductors is prepared film an epoxy resin (A) (pref. an epoxy resin having an epoxy equivalent of 200 or smaller from the viewpoint of improving the resistance to thermal shock), a polyester elastomer-modified phenol resin (B), a curing accelerator (C) (e.g., triphenylphosphine) and an inorg. filler (D) (e.g., a molten silica powder or a glass fiber) as essential components. By using the component B as the curing agent, as flexible molecular chains uniformly exist in a resin cured product and the toughness of the cured product can be improved by a reaction of ester groups with epoxy groups which is presumed to occur in the molecule, excellent crack resistance, moisture resistance and low stress characteristics can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Field of Application) The present invention relates to an epoxy resin composition for semiconductor encapsulation, particularly excellent in crack resistance, moisture resistance, and low stress properties.

(Prior art) In recent years, with the trend towards miniaturization of electronic components, enlargement of semiconductor devices, and increase in the degree of integration, scratch resistance, moisture resistance,
It is desired to develop a sealing resin with excellent low stress properties.

By the way, as a conventional sealing resin for electronic parts, an epoxy resin composition containing a phenol nopolar resin as a curing agent has been used. However, such epoxy resin compositions do not satisfy the above-mentioned characteristics required as a semiconductor encapsulating resin.

For this reason, in addition to the above ingredients, various organic rubbers,
Epoxy resin compositions containing silicone compounds have been developed. For example, epoxy resin compositions for semiconductor encapsulation containing polyester-polyether type polyester elastomers are known (Japanese Unexamined Patent Publication No. 58-184
No. 204, Japanese Unexamined Patent Publication No. 58-225120).

However, even with these epoxy resin compositions, mold stains,
Properties such as moisture resistance, low stress properties, and crack resistance were insufficient.

(Problems to be Solved by the Invention) The present invention has been made to solve the above problems, and has excellent crack resistance, moisture resistance, and low stress properties required as a semiconductor encapsulating resin, and also has moldability. It is an object of the present invention to provide an epoxy resin composition that has good processability without clouding or the like.

[Structure of the Invention] (Means and Effects for Solving the Problems) The epoxy resin composition for semiconductor encapsulation of the present invention comprises (A) an epoxy resin, (B) a polyester elastomer-modified phenolic resin, and (C) a curing accelerator. , and (D) an inorganic filler as an essential component.

Hereinafter, the constituent components of the epoxy resin composition according to the present invention will be explained in detail.

In the present invention, the epoxy resin as component (A) is as follows:
Any compound having two or more epoxy groups in one molecule may be used, such as epoxy compounds such as bisphenol A type, bisphenol F type, phenol novolak type, cresol novolak type, and tris(hydroxyphenyl)methane. It will be done. Among such epoxy resins, epoxy resins having an epoxy equivalent of 200 or less are preferred, particularly from the viewpoint of thermal shock resistance.

Specific examples of such epoxy resins include ESCN
-195XL (manufactured by Sumitomo Chemical Co., Ltd., orthocresol novolac epoxy resin, softening point 79°C, epoxy equivalent weight 19
7), EPPN-202 (manufactured by Nippon Kayaku ■, phenol novolac epoxy resin, softening point 77°C, epoxy equivalent 1
89), ESMN-220 (manufactured by Sumitomo Chemical Co., Ltd., metacresol novolak epoxy resin, softening point 70°C, epoxy weight), YL-932 (manufactured by Yuka Shell Epoxy ■, tris(hydroxyphenyl)methane) Epoxy resin, softening point 63℃, epoxy equivalent 166)
, EPPN-502N (manufactured by Nikki Kayaku ■, softening point: 7 picoC, epoxy equivalent: 167).

The core of the technical idea of the present invention is the use of component (B), that is, a phenolic resin modified with a polyester elastomer. The polyester elastomer-modified phenolic resin is a component that has the effect of imparting crack resistance, moisture resistance, and low stress properties to the cured epoxy resin product.

The reason why the polyester elastomer-modified phenol resin exhibits the above effects will be explained below. Here, when considering conventional rubber-modified epoxy resin compositions, conventionally it has been common to use rubber particles dispersed in the resin. Also in the above-mentioned JP-A-58-184204 and JP-A-58-225120, a polyester elastomer is simply dispersed in an epoxy resin.

In contrast, the present inventors have discovered that polyester elastomers are soluble in phenol monomers (Journal of the Japan Rubber Association; No. 51).
Vol., No. 10, p. 792, Table 27 (1878)), we attempted to dissolve polyester elastomer in phenolic resin. As a result, they found that at high temperatures (about 200° C. or higher), the polyester elastomer dissolves in the phenolic resin and becomes transparent.

For example, 130 g of polyester elastomer (P-408, Toyobo Co., Ltd., melting point 170°C) is mixed with phenol novolak resin (BRG-558, manufactured by Showa Kobunshi @, softening point 97).
'0) Dissolved in 870g by stirring at 220℃ for 1 hour,
The mixture becomes clear.

However, the same polyester elastomer (P-40
H) 130 g of ortho-cresol novolak epoxy resin (ESCN-19), which is commonly used for semiconductor encapsulation resin.
5XL, manufactured by Sumitomo Chemical Co., Ltd., softening point: 79℃) 870g 2. Even when I tried to dissolve it under the conditions of stirring at 230"C for 2.5 hours, which is more advantageous for dissolution than the above conditions, it did not dissolve, and the polyester elastomer was dispersed in spots. I only did so.

In addition, when polyester elastomer modified phenolic resin is used as a curing agent for epoxy resin, the literature (Bu
Letin of the Chemical 5o
society of Japan, Val, 52(5), 1
488-1492 (1979)), it is presumed that a reaction between an ester group and an epoxy group occurs within the molecule.

As mentioned above, when polyester elastomer-modified phenolic resin is used as a curing agent for epoxy resin, it is assumed that flexible molecular chains exist uniformly in the cured epoxy resin and occur within the molecule. The toughness of the cured product is increased by the reaction between the ester group and the epoxy group, which gives it crack resistance, moisture resistance, and low stress. It is thought that it will show good results in the test.

In the present invention, the polyester elastomers used to modify the phenolic resin include polyester polyester resins shown in Table 1 and polyester-based polyester type elastomers. is preferred.

Table 1 Journal of Japan Rubber Association, Volume 57, No. 11, P, 895,
Table 3 Copied from (1984) Specific examples of such polyester elastomers are shown below.For example, Toyobo Co., Ltd.
Examples of the polyester/polyether elastomer (Perprene P-type) manufactured by Co., Ltd. include those shown in Table 2.

Table 2 In addition, polyester-polyethers (Hytrel) manufactured by Du Pont include those shown in Table 3.

Table 3 In addition, those shown in Table 4 are listed as polyester elastomers (Pelprene S-type) manufactured by Toyobo Ja Koji.

In Table 4, the phenolic resin to be modified with the polyester elastomer may be any resin as long as it has two or more phenolic hydroxyl groups in one molecule, such as phenol novolak resin, cresol novolak resin, etc. , resorcinol novolak resin, dicyclopentadiene phenol novolak resin, phenol aralkyl resin, tris (hydroxyphenyl)
Examples include methane and its polymer resin.

Among these phenol resins, phenol novolak resins having a hydroxyl equivalent of 150 or less, tris(hydroxyphenyl)methane, and polymer resins thereof are desirable from the viewpoint of reactivity.

Specific examples of such phenolic resins include BRC
-557 (Showa Molecular Stock, Phenol Novolac Tree) Finger, Softening Point 86°C, OH Equivalent 105), BRG-558
(Showa Molecular Co., Ltd., phenol novolac resin 1 finger, softening point 97°C, OH equivalent 105), TO-2131 (Dainippon Ink Co., Ltd., phenol novolac resin, softening point 80°C,
(OH equivalent: 1105), YL-13085 (Yuka shell epoxy stock, tris(hydroxyphenyl)methane, softening point: 120°C, OH equivalent: 98).

Polyester elastomer modified phenolic resin is 20
Melt the phenol resin by heating at 0 to 250°C, add and dissolve a predetermined amount of polyester elastomer while stirring, mix thoroughly and uniformly, and after confirming that the mixture has become transparent, take it out from the reaction vessel and cool it. After that, it can be prepared by grinding.

In the present invention, the curing accelerator for component (C) may be any substance as long as it promotes the reaction between the epoxy group and the phenolic hydroxyl group, such as various amines, various imidazoles, Examples include diazabicycloalkenes and organic phosphines.

Specific examples of such curing accelerators include amines such as N,N-dimethylcyclohexylamine, N-methyldicyclohexylamine, N,N',N"-tris(dimethylaminepropyl)hexahydro-s-triazine, Heptamethyldipropylenetriamine, triethylenediamine; As imidazoles, 2-ethylimidazole, 2-phenylimidazole, heptadecylimidazole; As diazabicycloalkenes, 1.
8-Diazabicyclo(5,4,0)undecene-7(D
BU), phenolic salts of DBU (e.g. U-CA
TSA Mol, San Abbott Co., Ltd.); Examples of organic phosphines include triphenylphosphine, tributylphosphine, tricyclohexylphosphine, and the like. Among these curing accelerators, from the point of view of electrical properties,
DBU, a phenol salt of DBU, triphenylphosphine, etc. are preferred.

In the present invention, the inorganic filler as component (D) includes various glass powders such as fused silica powder, crystalline silica powder, spherical silica powder, and spherical glass powder, talc, alumina powder, and calcium silicate powder. , calcium carbonate powder, various ceramic powders, glass fibers, low soda glass fibers, ceramic fibers, etc.

Among these, fused silica powder, spherical silica powder, high-purity glass TAM, and ceramic/cushion fiber are preferable, considering their electrical properties and special characteristics for semiconductor encapsulation. Well then, U.
An ultra-high purity filler containing almost no Th or the like is required, and in this case, fused silica powder or spherical silica powder in which U and Th are less than or equal to i PPb is preferred.

The components constituting the epoxy resin composition of the present invention include:
In addition to the above essential components, flame retardants such as brominated epoxy resins and antimony trioxide; such as natural waxes, synthetic waxes, straight chain fatty acids and their metal salts, acid amides, esters, and paraffins. Pigments such as carbon black and titanium dioxide; Surface treatment agents for fillers such as silane coupling agents; Various stress reducing agents such as silicone oil, silicone rubber, and ABS resin 1MB5 resin are added as appropriate. You can.

The blending ratio of each component mentioned above varies depending on the application, but the resin components, i.e. (A), (B), (C)
It is preferable that the total amount of filler occupies 20 to 30% by weight of the composition. Therefore, the inorganic filler (D) JA is added in an amount of about 70 to 80% by weight. This has a resin component of 20
If it is less than % by weight, the moldability of the composition, especially the fluidity, deteriorates,
On the other hand, if it exceeds 30% by weight, the thermal shock resistance of the cured product tends to deteriorate.

The blending ratio of (A) epoxy resin and (B) polyester elastomer-modified phenol resin in the composition is preferably such that the equivalent ratio of phenolic water group/epoxy group is 0.5 to 1.2. This is because the curability of the composition deteriorates if it deviates from this range.

(B) Modified polyester elastomer Regarding the modified amount of polyester elastomer in the phenol resin, the ratio to the entire epoxy resin composition for semiconductor encapsulation is 0.
The content is preferably 5 to 5% by weight, because if it is less than 0.5% by weight, the moisture resistance, low stress property, and crack resistance will not be sufficiently improved, while if it exceeds 5% by weight, mold fouling will occur. This is because they tend to deteriorate.

(C) Since the curing accelerator has different catalytic activity, the suitable range of blending cannot be determined unconditionally, but it is preferable that the curing accelerator does not exceed 1% by weight based on the total composition. This is because if it exceeds 1% by weight of the total composition, the temperature resistance tends to deteriorate.

The epoxy resin composition according to the present invention is prepared by thoroughly mixing the raw material components with a mixer such as a Henschel mixer, followed by melting treatment with hot rolls or melt mixing with a twin-screw extruder, followed by cooling and pulverization. It can be prepared by Then, the composition thus obtained is subjected to composite molding, transfer molding, injection molding, etc., either as a powder or in a tablet form, to seal a semiconductor device.

(Examples) Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited to these Examples as long as the technical idea of the present invention is not departed from.

Examples 1 to 6 and Comparative Examples 1 to 4 The ingredients shown below were blended in the proportions (wt%) shown in Table 5, mixed with a mixer, heated and kneaded with a twin-screw roll, cooled, and then pulverized. An epoxy resin composition was prepared.

Epoxy resin A: ESCN-195XL (Sumitomo Chemical ■, softening point 79°C, epoxy equivalent weight 197, orthocresol novolac epoxy resin) Epoxy resin B: YL-932H (oiled shell epoxy ■1 softening point 63°C, epoxy equivalent weight 116fi,
Tris(hydroxyphenyl)methane epoxy resin) Polyester elastomer modified phenolic resin ABRG
-558 (Showa Kobunshi ■, softening point 97℃, OH equivalent 10
5. P-15 P-15
0)+ (Toyobo Co., Ltd., polyester/polyether elastomer) (100 g) was added and stirred until the mixture became transparent, taken out after 30 minutes, cooled, and pulverized to prepare.

Polyester elastomer modified phenolic resin BP-1
It was prepared in the same manner as in A above, using 5-fool (Toyobo ■, polyester/polyester elastomer) instead of 50M.

Polyester elastomer modified phenolic resin CBRG
It was prepared in the same manner as in A above using 880 g of -558 and 200 g of S-1001.

Polyester elastomer modified phenolic resin DBRG
It was prepared in the same manner as in case A above using 620 g of -558 and 400 g of S-1001.

Polyester elastomer modified phenolic resin EYL-
6085 (oiled shell epoxy ■, OH equivalent 98, softening point 120°C, tris(hydroxyphenyl)methane)
500g and 150g of XL-225L (Mitsui Toatsu Chemical Co., Ltd., OH 1198, softening point 92℃, phenol aralkyl resin) were put into a universal mixer, heated to 250℃ and melted, and S-13001 ( 200 g of Toyobo (Polyester ψ polyester elastomer) was added thereto and mixed until the mixture became transparent. After 1 hour, the mixture was taken out, cooled, and pulverized.

Phenol resin: ERG-558 (Showa Molecular Co., Ltd., softening point 97°C, OH equivalent 105. Phenol novolak resin) Curing accelerator A Nitriphenylphosphine curing accelerator B
: 1,8-diazabicyclo(5,4,0) undecene-7 Polyester elastomer A: P-150M (Toyobo ■, polyester/polyether elastomer Polyester elastomer B: S-1001 (Toyobo ■, polyester/polyester elastomer inorganic Filler A: GR-807 (Toshiba Ceramics Co., Ltd., 11 average particle size 22.8JLm) Inorganic filler B: 5GA (Toshiba Ceramics ■, average particle size 5.25JLm) Flame-retardant epoxy resin: BREN-S (Japanese) Lignifying agent ■, softening point 84℃, epoxy equivalent 278, Br content! 35.7
%) Flame retardant aid: Antimony trioxide Mold release agent: Caruna wax Pigment: Carpon black Surface treatment agent: Epoxysilane coupling agent Examples 1 to 6 and Comparative Examples 1 to 4 obtained as above A test piece was prepared by transfer molding at 175°C for 13 minutes using the epoxy resin composition of
The bending modulus, glass transition temperature, and coefficient of thermal expansion were measured. In addition, the piezo element was sealed, and the principal stress at the chip center was measured and used as residual stress. In addition, mold stains were visually observed after 200 shots.

In addition, using each epoxy resin composition, a semiconductor element (6.7 x 8.7 mm) for thermal shock resistance test was prepared under the above molding conditions.
2) was sealed and after cured at 175°C for 4 hours,
The obtained resin molded element was heated to -65℃ (30 minutes) → 25℃
A thermal cycle test (TCT) was conducted in which one cycle was 150°C (5 minutes) → 150°C (30 minutes) → 25°C (5 minutes) to investigate the occurrence of defects.

Furthermore, using each epoxy resin composition, a moisture resistance evaluation element (8.7 x 8.7 tmm2) was sealed under the above molding conditions, and after cured at 175°C x 4 hours, 135°C x 8
Placed in a high temperature and high humidity atmosphere of 5% RH for 48 hours, then VPS (paper phase reflow) at 215°C for 2 minutes.
The process was carried out and a test device was produced.

At this point, we checked the crack occurrence rate of the package. Thereafter, a PC:T (pressure hooker test) at 127°C x 2.5 atm was performed to check for occurrence of defects.

The results are shown in Table 6.

[Effects of the Invention yA] As detailed below, the epoxy resin composition of the present invention has the following properties:
Compared to conventional epoxy resin compositions, rack resistance, r
M has excellent moisture properties, low stress properties, and good moldability, and can guarantee high reliability especially when used for encapsulating semiconductor devices, so it has extremely great industrial value.

Applicant's agent: Patent attorney Takehiko Suzue

Claims (1)

[Scope of Claims] An epoxy for semiconductor encapsulation characterized by having (A) an epoxy resin, (B) a polyester elastomer-modified phenol resin, (C) a curing accelerator, and (D) an inorganic filler as essential components. Resin composition.