JPH10176035A - Epoxy resin composition for sealing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subjective composition excellent in fluidity and ordinary temperature preservablity and compatible with surface mounting by incorporating a specific crystalline epoxy resin compound, phenolic resin, curing accelerator and a specific proportion of inorganic filler as the essential components. SOLUTION: This composition comprises, as the essential components, (A) an crystalline epoxy compound having >=2 epoxy groups in one molecule and 50 to 150 deg.C melting point, preferably shown by formula I (OG is a group shown by formula II; R<1> is H, a 1-6C chain or cyclic alkyl, phenyl, etc.) etc., (B) a phenolic resin having >=2 phenolic hydroxyl groups in one molecule, (C) a salt from 1,8-diazabicyclo(5,4,0)undecene-7 and a polycarboxylic acid (preferably a ring-opened form of aromatic carboxylic acid and/or its anhydride), as a curing accelerator, and (D) inorganic filler accounting for 75 to 93wt.% of the whole composition. This composition dispenses with melt blending the curing accelerator with a part of the resin previously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-mountable epoxy resin composition for semiconductor encapsulation which is excellent in fluidity and room temperature storage characteristics.

[0002]

2. Description of the Related Art Epoxy resin compositions for semiconductor encapsulation (hereinafter referred to as "resin compositions") have been developed and produced to protect IC bodies from mechanical and chemical effects. Items required for this resin composition are changing depending on the type of IC chip, the structure of the package to be sealed, the environment in which it is used, and the like. At present, the biggest requirement is the improvement of cracks that occur when mounting the package, so-called solder cracks.As a result of various studies on this requirement, the resin composition containing a large amount of inorganic filler has been considerably improved. . Techniques for high filling of the inorganic filler include changing the particle size distribution and shape of the inorganic filler, reducing the viscosity of the epoxy resin and the phenol resin, and most of these techniques are used at the same time. However, the following problems have occurred due to the reduction in resin viscosity. Reduction of resin viscosity
The use of a curing accelerator, such as DBU or triphenylphosphine (hereinafter referred to as TPP), which already has a curing acceleration effect at the time of kneading the resin, because the molecular weight of the resin is made small and the molecules are easy to move. In addition, when the resin is kneaded, a part of the cross-linking reaction proceeds rapidly, and a predetermined fluidity is not exhibited. Further, for the same reason, there has been a disadvantage that the curing reaction gradually proceeds even at room temperature, and the room temperature storage characteristics of the resin composition deteriorate.

[0003] Therefore, investigations have been made on a curing accelerator which does not exhibit a curing accelerating action during resin kneading. For example, the sealing material is not particularly limited to a surface mountable sealing material.
No. 4399 describes that tetraphenylphosphonium tetraphenylborate (hereinafter referred to as TPP-K) is effective for improving room temperature storage characteristics and curability. However, this TPP-K does not show sufficient curability unless melt-mixed in advance with a part of the resin, and once melt-mixed, the room temperature storage characteristics of the resin composition are comparable to those of the case where DBU or TPP is used. Has proved to be insufficient. Further, as described above, the method of previously melting and mixing TPP-K with a part of the resin indicates that the number of production steps of the resin composition increases. Moreover, even if a DBU is used, TPP-K
Similarly to the above, it is common to use the resin by previously melting and mixing it with a part of the resin. This is because the DBU is liquid at room temperature. As described above, an increase in the number of production steps of the resin composition is unfavorable in terms of management.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of various studies in order to solve these problems, and it is not necessary to melt-mix a curing accelerator with a part of the resin in advance, and it is not necessary to melt and mix the curing accelerator. An object of the present invention is to provide a surface-mountable epoxy resin composition for semiconductor encapsulation, which is excellent in heat resistance and room temperature storage characteristics.

[0005]

Means for Solving the Problems The present invention provides: [1] (A) having two or more epoxy groups in one molecule,
(B) 1 crystalline epoxy compound having a melting point of 50 to 150 ° C.
A phenolic resin having two or more phenolic hydroxyl groups in the molecule; (C) a DBU as a curing accelerator;
A salt comprising a carboxylic acid having four carboxyl groups in one molecule and / or a partially ring-opened acid anhydride thereof, which forms an ion pair with DBU by giving at least one proton to U, and (D) inorganic An epoxy resin composition for encapsulating a semiconductor, comprising a filler as an essential component, and containing 75 to 93% by weight of an inorganic filler (D) in the entire resin composition. , Equation (1), Equation (2),
Or the epoxy resin composition for semiconductor encapsulation according to claim 1, which is represented by formula (3):

Embedded image (Wherein, R ₁ is a group or atom selected from hydrogen, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen, and they may be the same or different from each other. good.)

[0006]

Embedded image (In the formula, R ₂ is a group or atom selected from hydrogen, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen, and they may be the same or different from each other. good.)

[0007]

Embedded image (Wherein, R ₃ is a group or atom selected from hydrogen, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen, and they may be the same or different from each other. [3] The epoxy resin composition for semiconductor encapsulation according to claim 1 or 2, wherein the polycarboxylic acid is a partially ring-opened product of an aromatic carboxylic acid and / or an acid anhydride thereof. The epoxy resin composition for semiconductor encapsulation according to claim 3, wherein the partially ring-opened aromatic carboxylic acid and / or acid anhydride thereof is a partially ring-opened pyromellitic acid and / or acid anhydride thereof. 5) The epoxy resin composition for semiconductor encapsulation according to claim 1 or 2, wherein the polycarboxylic acid is a partially ring-opened product of a linear polymer carboxylic acid having a degree of polymerization of 4 or more and / or an acid anhydride thereof. [6] The linear high molecular carboxylic acid is polyacrylic acid Motomeko fifth semiconductor encapsulating epoxy resin composition according is.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A crystalline epoxy compound having two or more epoxy groups in one molecule and having a melting point of 50 to 150 ° C. used in the present invention is a planar epoxy compound having a stilbene skeleton such as phenyl, biphenyl, bisphenol, naphthalene or the like. Because it has a structural molecule in the main chain and is relatively small,
It shows crystallinity. The crystalline epoxy compound is a crystalline solid at room temperature, but once melted, has the property of becoming an extremely low-viscosity liquid. As the crystalline epoxy compound, a biphenyl type epoxy compound of the formula (1), a dihydroxydiphenylmethane type epoxy compound of the formula (2), and a stilbene type epoxy compound of the formula (3) are particularly preferable. R ₁ , R ₂ , R in the formulas (1) to (3)
₃ is a group or atom selected from hydrogen, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group and a halogen, which may be the same or different. These crystalline epoxy compounds may be used alone or as a mixture. The melting point of the crystalline epoxy compound is
50-150 ° C is preferred. When the temperature is 50 ° C. or higher, the material does not melt at room temperature, and thus the workability in the pre-kneading step and the like is excellent. 1
When the temperature is 50 ° C. or lower, the mixture can be easily melted in a kneading apparatus and uniformly kneaded.

The phenolic resin having two or more phenolic hydroxyl groups in one molecule used in the present invention is not particularly limited. Examples thereof include phenol novolak resin, cresol novolak resin, xylylene-modified phenol resin, terpene-modified phenol resin, And dicyclopentadiene-modified phenolic resins. There are no restrictions on the molecular weight, softening point, hydroxyl equivalent, etc. of these phenolic resins.
These phenolic resins may be used alone or as a mixture. In particular, when used as a resin compatible with surface mounting, a xylylene-modified phenol resin is more preferable.
Since the xylylene-modified phenol resin has a small amount of phenolic hydroxyl groups, the molded article has a low water absorption. In addition, due to the structure in which xylylene and phenol are bonded, the molecule has an appropriate flexibility, and there is little steric hindrance in the curing reaction,
Less inhibition of curability. Further, by reducing the average molecular weight, the viscosity can be reduced, and even if the average molecular weight is reduced, the curability is hardly reduced due to the chemical structure. The equivalent ratio of the epoxy group of the crystalline epoxy compound to the phenolic hydroxyl group of the phenol resin is 0.1.
5 to 2.0, more preferably 0.8 to 1.2. Outside of this range, the curability of the resin composition may decrease, or the glass transition temperature of the cured product may decrease.

The curing accelerator comprising a salt of DBU and a polycarboxylic acid for use in the present invention comprises a polycarboxylic acid containing DBU.
Any one may be used as long as it gives at least one proton to form an ion pair. Examples of the polycarboxylic acid include benzenetetracarboxylic acid, naphthalenetetracarboxylic acid, biphenyltetracarboxylic acid, 2,2-bis (3,4-dicarboxydiphenyl) propane, benzophenonetetracarboxylic acid, and bis (3,4 Aromatic dicarboxylic acids such as -dicarboxydiphenyl) ether and the like, and partially opened products of these acid anhydrides, ethylenetetracarboxylic acid, methylcyclohexenedicarboxylic acid and partially opened products of these acid anhydrides, 4,8- Dimethyl-1,2,3,
5,6,7-hexahydronaphthalene-1,2,5,6
-Tetracarboxylic acid, cyclopentane-1,2,3,4
-Aliphatic tetracarboxylic acids such as tetracarboxylic acid, isobutylene, ring-opened copolymers of various olefins such as styrene and maleic anhydride, and linear polymer carboxylic acids such as polyacrylic acid; It is not limited to these. In particular, pyromellitic acid or polyacrylic acid is preferably used in terms of raw material cost and availability. Further, all ring-opened products of the exemplified carboxylic acids, partially ring-opened products thereof, and mixtures thereof are also included. The curing accelerator is added in an amount of 0.1 to 100 parts by weight of the total amount of the crystalline epoxy compound and the phenol resin.
5-20 parts by weight are preferred. If the amount is less than 0.5 part by weight, the curability is reduced. On the other hand, if the amount is more than 20 parts by weight, the curing is too fast, causing problems such as defective filling during molding.

The inorganic filler used in the present invention is not particularly limited, and those generally used for a sealing material can be widely used. Examples thereof include alumina, fused silica powder, spherical silica powder, crystalline silica powder, and secondary silica. Agglomerated silica powder and the like can be mentioned. In particular, spherical silica powder is preferred from the viewpoint of improving the fluidity of the resin composition. As the shape of the spherical silica powder,
In order to improve the fluidity, it is preferable that the shape of the particles themselves is infinitely spherical and the particle size distribution is broad. The amount of the inorganic filler is preferably 75 to 93% by weight in the total resin composition from the viewpoint of improving solder crack resistance. If it is less than 75% by weight, the water absorption does not decrease, and the solder crack resistance becomes insufficient. On the other hand, if it exceeds 93% by weight, the viscosity becomes high, causing gold wire deformation inside the semiconductor package, which is not preferable.

The resin composition of the present invention comprises, if necessary, a coloring agent such as carbon black in addition to the components (A) to (D).
Brominated epoxy resins, flame retardants such as antimony trioxide and antimony tetroxide, coupling agents such as γ-glycidoxypropyltrimethoxysilane, silicone oil, low stress components such as rubber, mold release agents, antioxidants, Various additives such as a surfactant can be blended. The resin composition of the present invention is obtained by mixing the components (A) to (D) and other additives at room temperature using a mixer, kneading with a kneading machine such as an extruder or a roll, cooling, and pulverizing. Can be

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

First, the abbreviations of the salts of DBU and polycarboxylic acid used in the examples are shown below. DBU-PMA: acetone in a flask equipped with a condenser,
And pyromellitic acid and completely dissolved,
Salt obtained by slowly dropping DBU of the same mole as pyromellitic acid DBU-PA: methanol in a flask equipped with a cooling tube,
And polyacrylic acid (Toagosei Chemical Industry Co., Ltd., A
C-10P) was added and dissolved, and DBU was slowly added dropwise.
The mixture is heated to ℃, methanol is distilled off, the reaction product is concentrated, then transferred to a vat and dried in vacuo at 100 ° C. The above two types of salts are solid at room temperature.

Example 1 51.5 parts by weight of a biphenyl type epoxy compound of the formula (4) (melting point: 105 ° C.)

Embedded image

48.5 parts by weight of a phenolic resin of the formula (5) (softening point: 73 ° C.)

Embedded image DBU-PMA 6.1 parts by weight Spherical silica (average particle size 15 μm) 820 parts by weight Carbon black 2.0 parts by weight Brominated bisphenol F type epoxy resin 4.0 parts by weight Carnauba wax 2.0 parts by weight Mixer at room temperature The mixture was kneaded at 100 ° C. using a biaxial roll, cooled and pulverized to obtain a resin composition. Spiral flow of the obtained resin composition, Shore D
Hardness, room temperature storage characteristics, and solder crack resistance were evaluated by the following methods. Table 1 shows the results.

Evaluation method (1) Spiral flow: using a mold for measuring spiral flow in accordance with EMMI-I-66, using a mold temperature of 17
The measurement is performed at 5 ° C., an injection pressure of 70 kg / cm ² , and a curing time of 2 minutes. Spiral flow is a parameter of liquidity,
The higher the value, the better. Unit cm. (2) Curability: mold temperature 175 ° C, pressure 70kg / c
Molding was performed with m ² and a curing time of 2 minutes, and the value of Shore D hardness measured 10 seconds after opening the mold was defined as curability. (3) Room temperature storage characteristics: After storing the resin composition at 25 ° C. for one week, the spiral flow was measured and shown as a ratio to the initial spiral flow value. Larger values indicate better room temperature storage characteristics. unit%. (4) Solder crack resistance: mold temperature 175 ° C, pressure 7
Eight 80 pQFP (1.5 mm thick) were molded at 0 kg / cm ² and curing time of 2 minutes, post-cured at 175 ° C. for 8 hours, and treated at 85 ° C. and a relative humidity of 60% for 168 hours. The number of package cracks after 10 seconds of treatment by IR reflow was visually observed.

Examples 2 to 5 Compounded according to the formulation shown in Table 1, a resin composition was obtained in the same manner as in Example 1, and evaluated similarly. Table 1 shows the results. The epoxy compound of formula (6) used in Example 3 (melting point: 80 ° C.) and the epoxy compound of formula (7) used in Example 4 (melting point: 96 ° C.) are shown below.

Embedded image

[0019]

Embedded image

Comparative Examples 1 and 2 A resin composition was prepared according to the formulation shown in Table 2, and a resin composition was obtained in the same manner as in Example 1 and evaluated in the same manner. Table 2 shows the results. Here, the molten mixture of DBU refers to a mixture obtained by melting and mixing 10 parts by weight of DBU with 90 parts by weight of the phenol resin of the formula (5).

[Table 1]

[0021]

[Table 2]

[0022]

The epoxy resin composition of the present invention is excellent in fluidity and room temperature storage characteristics. Also, 1,8
-Solder crack resistance is at the same level as compared with a resin composition using diazabicyclo (5,4,0) undecene-7 or triphenylphosphine.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 23/29 H01L 23/30 R 23/31

Claims (6)

[Claims] (A) a crystalline epoxy compound having a melting point of 50 to 150 ° C. and having two or more epoxy groups in one molecule,
(B) a phenolic resin having two or more phenolic hydroxyl groups in one molecule, and (C) 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as D) as a curing accelerator.
BU) and a partially ring-opened carboxylic acid having four carboxyl groups in one molecule and / or a partially ring-opened acid anhydride thereof (hereinafter referred to as “multiplicity”), which forms at least one proton with the DBU to form an ion pair with the DBU. And a salt comprising (D) an inorganic filler as an essential component, and 75 to 93% by weight of the inorganic filler (D) in the total resin composition.
An epoxy resin composition for encapsulating a semiconductor, characterized by comprising: 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the crystalline epoxy compound is represented by Formula (1), Formula (2), or Formula (3). Embedded image (Wherein, R ₁ is a group or atom selected from hydrogen, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen, and they may be the same or different from each other. (Good.) (In the formula, R ₂ is a group or atom selected from hydrogen, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen, and they may be the same or different from each other. (Good.) (Wherein, R ₃ is a group or atom selected from hydrogen, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen, and they may be the same or different from each other. good.) 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the polyvalent carboxylic acid is a partially ring-opened aromatic carboxylic acid and / or an acid anhydride thereof. 4. The epoxy for semiconductor encapsulation according to claim 3, wherein the partially ring-opened aromatic carboxylic acid and / or acid anhydride thereof is a partially ring-opened pyromellitic acid and / or acid anhydride thereof. Resin composition. 5. The epoxy resin for semiconductor encapsulation according to claim 1, wherein the polycarboxylic acid is a partially ring-opened product of a linear polymer carboxylic acid having a degree of polymerization of 4 or more and / or an acid anhydride thereof. Composition. 6. The epoxy resin composition for semiconductor encapsulation according to claim 5, wherein the linear polymer carboxylic acid is polyacrylic acid.