JPH08151432A - Liquid epoxy resin composition for sealing and method of preparing same - Google Patents

Abstract

PURPOSE: To provide an epoxy resin composition for sealing excellent in heat resistance, humidity resistance and markability in the PCT test and the TC test. CONSTITUTION: This composition comprises an epoxy resin, an organopolysiloxane having a vinyl group and a phenyl group as a side chain, an organopolysiloxane having Si-bonded hydrogen atoms and a polyether- modified polyether organopolysiloxane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid epoxy resin composition for sealing and a method for producing the same.

[0002]

2. Description of the Related Art A so-called chip-on-board (COB) system, in which semiconductor chips are mounted directly on a printed circuit board, has rapidly increased. It is known that the low stress characteristics of the encapsulating material that protects the semiconductor chip have a great influence on the performance and life of the semiconductor chip, not limited to such a COB type mounting form. A liquid epoxy resin composition containing a considerable amount of an inorganic powder such as silica is widely used as a resin composition for encapsulation having a low stress, but for example, heat resistance and moisture resistance in a PCT test are lowered. There is also a limit to the content of inorganic powder. Moreover, not only is the size of the semiconductor chips increased and the number of semiconductor chips mounted is increased, but if the substrates on which these semiconductor chips are mounted are made of metal, ceramics, plastics, etc. The demand for lowering stress becomes even more stringent. As the epoxy resin composition for encapsulation with improved low stress, those in which rubber such as polybutadiene or acrylonitrile is added, those in which silicone oil is added or the epoxy resin is modified with silicone oil are known. A phenomenon such as a decrease in moisture resistance, occurrence of bleeding on the surface of a cured product encapsulating a semiconductor chip, or warpage of a substrate due to stress associated with curing of an encapsulating material occurs. Further, there are problems that cracks may occur in the cured product during soldering or heat cycle, or peeling may occur between the cured product and the semiconductor chip.

[0003]

SUMMARY OF THE INVENTION The object of the present invention has been made in view of the above facts. The PCT test, TC
A liquid epoxy resin composition for encapsulation excellent in heat resistance, moisture resistance, fluidity, and marking property in a test, and a method for producing the same.

[0004]

The liquid epoxy resin composition for sealing according to claim 1 of the present invention is (1) an epoxy resin,
(2) Phenol novolac, (3) Organopolysiloxane having vinyl group and phenyl group in side chain, (4) Organopolysiloxane containing hydrogen bonded to silicon atom, and (5) Polyether-modified polyether organo The liquid epoxy resin composition for encapsulation according to claim 2, wherein the phenol novolac is contained in the liquid epoxy resin composition for encapsulation according to the total weight of the curing agent. 15% or more, wherein the liquid epoxy resin composition for encapsulation according to claim 3 is the epoxy resin composition for encapsulation according to claim 1 or 2, wherein the phenyl group is a Si—O unit 50.
It is characterized by being at least one or more for each,
The liquid epoxy resin composition for encapsulation of claim 4 is the composition of claim 1.
Alternatively, in the encapsulating liquid epoxy resin composition according to claim 2, a part of the polyether-modified polyether organopolysiloxane is an epoxidized polyether organopolysiloxane, and the encapsulating liquid epoxy resin composition according to claim 5. A liquid epoxy resin composition according to any one of claims 1 to 4, wherein the liquid epoxy resin composition contains a sorbitan ester having the following structural formula:

[0005]

Embedded image

(R is an alkyl group.) The liquid epoxy resin composition for encapsulation according to claim 6 is as defined in claim 1.
The liquid epoxy resin composition for encapsulation according to claim 4, wherein allylated phenol is used as the phenol novolac, and the method for producing the liquid epoxy resin composition for encapsulation according to claim 6 is: 1) Epoxy resin,
(2) Phenol novolac, (3) Organopolysiloxane having vinyl group and phenyl group in side chain, (4) Organopolysiloxane containing hydrogen bonded to silicon atom, and (5) Polyether-modified polyether organo An epoxy resin composition containing a polysiloxane is heated and mixed to react.

Hereinafter, the present invention will be described in detail. The encapsulating epoxy resin composition of the present invention contains an epoxy resin which is a matrix resin as an essential component and a phenol novolac as a curing agent. As this epoxy resin, various epoxy resins such as cresol novolac epoxy resin, alicyclic epoxy resin, bisphenol A type novolac epoxy resin, and phenol epoxy resin can be used alone or in combination. If such an epoxy resin contains an ionic substance such as chlorine ion, it not only damages the lead wire but also increases the insulating property of a cured product for sealing, which is not preferable. Phenol novolac, cresol novolac, bisphenol A novolac, and xylenol novolac can be applied to the above-mentioned curing agent of the epoxy resin. The content of these phenol novolacs in the curing agent is preferably 15% or more. The reason is that if it is less than 15%, it is not possible to improve the decrease in moisture resistance of the cured product when another curing agent such as an acid anhydride is used in combination. Examples of the curing agent used in combination with phenol novolac include amines such as dicyandiamide, imidazoles, and acid anhydrides such as methylhexahydrophthalic anhydride.

The liquid epoxy resin composition for encapsulation of the present invention comprises, in addition to the above matrix resin, an organopolysiloxane having a vinyl group and a phenyl group in the side chain, and an organopolysiloxane containing hydrogen bonded to a silicon atom. Contains siloxane. When an example of the organopolysiloxane having a vinyl group and a phenyl group on the side chain is shown by a structural formula,
As shown in the following (Chemical Formula 3), a compound having a vinyl group bonded to the terminal and a compound having a vinyl group bonded to the side chain are used.

[0009]

Embedded image

(In the formula, R represents an alkyl group, m of the repeating unit showing the skeleton structure is 49 or less, and n is 1 to 200.) Here, the phenyl group introduced into the side chain is an epoxy resin. It is desirable that the compatibility be improved, and the frequency thereof is preferably at least 1 per 50 Si-O units. In addition, an example of an organopolysiloxane containing hydrogen bonded to a silicon atom is represented by the structural formula:
As shown in, a polysiloxane in which hydrogen is bonded to silicon in the repeating unit is used.

[0011]

[Chemical 4]

In the formula, R represents an alkyl group, m of the repeating unit showing a skeletal structure is 2 to 40, and n is 49 or less. The blending ratio of the organopolysiloxane having a vinyl group and a phenyl group in the side chain and the organopolysiloxane containing hydrogen bonded to a silicon atom is 1: 1 by weight.
A ratio of 1 to 1:10 is suitable, but it is not intended to be limited. The total amount of these organopolysiloxanes is preferably 5 to 45% by weight with respect to the epoxy resin. That is, if it is less than 5%, the desired low stress property cannot be obtained, cracks may occur in the cured product during soldering or heat cycle, and peeling may occur between the cured product and the semiconductor chip. On the other hand, if it exceeds 45%, the fluidity is deteriorated, and it becomes difficult to discharge the semiconductor chip, and at the same time, the marking property is deteriorated.

When the organopolysiloxanes represented by (Chemical Formula 3) and (Chemical Formula 4) are used in combination, the cured product provided by the epoxy resin composition for encapsulation of the present invention effectively lowers the stress.

The epoxy resin composition for encapsulation of the present invention contains a polyether-modified polyether organopolysiloxane in addition to these essential components. This polyether-modified polyether organopolysiloxane is
For example, as shown in the structural formulas of (Chemical Formula 5) and (Chemical Formula 6), an organopolysiloxane having a polyalkylene oxide at both ends or side chains is used.

[0015]

Embedded image

[0016]

[Chemical 6]

(In the formula, R represents an alkyl group and POA represents a polyalkylene oxide.) This polyether organopolysiloxane is preferably 3 to 30% by weight based on the total amount of the above two kinds of organopolysiloxanes. Here, the reason why the polyether organopolysiloxane is used as a constituent substance is as follows. An organopolysiloxane having a vinyl group and a phenyl group in a side chain and an organopolysiloxane containing a hydrogen bonded to a silicon atom are compared with an epoxy resin. Since it is poor in compatibility and easily separated from the epoxy resin, it is used to eliminate this separation phenomenon. When the content of the polyether organopolysiloxane is less than 3% by weight, the phenomenon of separation from the epoxy resin cannot be prevented, and when it exceeds 30% by weight, a cured product produced by this epoxy resin composition for sealing. This is because bleeding that hinders the marking property occurs.

In order to prevent the marking property from deteriorating as a result of adding an organopolysiloxane effective for lowering the stress, the following (Chemical formula 7), (Chemical formula 7), ( As shown in Chemical formula 8), an epoxy-modified organopolysiloxane in which epoxy groups are introduced at both ends or side chains is effective, and is 3 to 30 relative to the total amount of the above two kinds of organopolysiloxanes.
Weight percent is preferred. It should be noted that the combined use with the organopolysiloxanes shown in (Chemical Formula 5) and (Chemical Formula 6) is not excluded.

[0019]

[Chemical 7]

[0020]

Embedded image

(Wherein R is an alkyl group, POA is a polyalkylene oxide, m and n are 2 to 50, and p is 5 to 2).
00. ) To improve the compatibility with conventional epoxy resins, vinyl group-containing organopolysiloxanes, Si—H-containing organopolysiloxanes, and polyetherpolysiloxanes to form a uniform encapsulating epoxy resin composition. For this, the addition of sorbitan ester is effective, especially HLB.
(Hydrophile-Lipophile bal
Ance) is preferably 10 or more, and the addition amount is preferably 0.1 to 10 parts by weight with respect to the total amount of the epoxy resin, the above-mentioned two types of organopolysiloxane, and the polyether polysiloxane. . As the sorbitan ester, for example, a polyoxyethylene fatty acid ester having the structural formula shown in (Chemical Formula 9) is useful.

[0022]

[Chemical 9]

(R is an alkyl group.) When a semiconductor element mounted on a printed circuit board is encapsulated with the encapsulating epoxy resin composition described above, the viscosity that determines the level of fluidity is high. Is required as an important property, but in order to prepare a low viscosity, an allylated phenol having a repeating number of 2 to 6 is used together with an acid anhydride as a curing agent.
Alternatively, it is effective to add phenol novolac having a repeating number of 2 to 4. Addition of this type of phenol all imparts high adhesive strength and moisture resistance to the liquid encapsulating epoxy resin composition. Further, other inorganic powders such as silica, alumina and aluminum nitride may be added to control fluidity and low stress.

The reaction can be promoted by heating and mixing the resin composition containing the above components.

Examples and comparative examples will be given below.

[0026]

【Example】 [Comparative example]

Examples 1 to 5 and Comparative Examples 1 to 4 A bisphenol A type epoxy resin (epoxy equivalent: 175) was used as the epoxy resin, and Si- was used as the organopolysiloxane having a vinyl group and a phenyl group on the side chain.
Organopolysiloxane (m = 2) represented by (Chemical Formula 3) modified by phenyl at a ratio of 1 to 20 O units.
0, n = 20), the organopolysiloxane (m = 5, n = 20) shown in (Formula 4) is used as the organopolysiloxane containing hydrogen bonded to a silicon atom, and a phenyl group is attached to the side chain. Si as the introduced polysiloxane
A phenyl-modified polysiloxane at a ratio of 1 to 20 -O units is used, and a polyether-modified polyether polysiloxane having a side chain represented by the chemical formula 6 as a polyether-modified polyether polysiloxane (m =
50, n = 5), the side chain was modified with polyether, and both ends were epoxidized (Chemical Formula 7). The polyorganosiloxane (m = 5, n = 50) was used.

As a curing agent, methylhexahydrophthalic anhydride (MHHPA) (acid anhydride equivalent = 16
8), allylated phenol novolac (phenolic hydroxyl group equivalent = 280), phenol novolac (phenolic hydroxyl group equivalent = 120), DBU octylate (Product No. SA102 manufactured by San-Apro), epoxy resin, organopolysiloxane and polyether organo A fatty acid ester of polyoxyethylene sorbitan (HLB = 16) was used as a sorbitan ester added to improve compatibility with polysiloxane.

Each of the above components was blended in the proportions shown in (Table 1) and mixed with a disper to give 120 to 13
After reacting at 0 ° C for 1 hour while mixing, kneading with a twin-screw kneader for 15 minutes, further kneading twice with a triaxial roll, and 1 To
Defoaming was performed under rr to obtain a liquid epoxy resin composition for sealing.

In Table 1, a bisphenol A type epoxy resin is an epoxy resin, an organopolysiloxane having a vinyl group and a phenyl group on a side chain is a silicone A, and an organopolysiloxane containing hydrogen bonded to a silicon atom is shown. Silicone B, phenyl group-introduced polysiloxane silicone C, polyether-modified polyether polysiloxane silicone D, side chain polyether-modified polyorganosiloxane (without epoxy group) silicone E, side chain Polyorganosiloxane with polyether modified and both ends epoxidized is abbreviated as Silicone F, epoxy modified polyorganosiloxane (without polyether group) is abbreviated as Silicone G. It was abbreviated as rack.

The fluidity, bleeding property, marking property, PCT, TC, and warp test of the substrate of this composition were carried out under the following conditions, and the evaluation is shown in (Table 1).

Fluidity test: A liquid epoxy resin composition for encapsulation produced according to the composition and production conditions of Examples and Comparative Examples was used.
1g was dropped on a ceramic substrate heated to 0 ° C and the spread was measured.
~ 35 for ○, less than 25 diameter for △, 20 diameter
Those less than mm are indicated by x.

Bleedability test: The liquid epoxy resin composition for encapsulation produced under the compounding and production conditions of Examples and Comparative Examples was cured at 150 ° C. for 3 hours, and the cured product was cured at 260 ° C.
After being dipped in the solder bath for 30 seconds, the presence or absence of the bleeding phenomenon on the surface of the cured product was visually observed.

Marking test: A liquid epoxy resin composition for encapsulation produced under the composition and production conditions of Examples and Comparative Examples was cured at 150 ° C. for 3 hours, and the surface of the cured product was manufactured by Baba Inbo. After marking with Bonmark Ink B (trademark) and drying at 125 ° C. for 2 hours, peeling with cellophane tape was observed, and those not peeled were indicated by ◯, and those peeled were indicated by x.

PCT test: A liquid epoxy resin composition for encapsulation produced under the composition and production conditions of Examples and Comparative Examples was applied to an aluminum pattern element at 10 mmφ and a thickness of 1.5 mm (MA.
X) and cured at 150 ° C. for 3 hours, and then left under conditions of 2 atm, 121 ° C. and 100% relative humidity for 100 hours, 200 hours, and 300 hours, and the presence or absence of cracks was observed. ⊚ indicates that there was no crack even after standing for 300 hours, ∘ indicates that cracks occurred within 100 to 200 hours, and x indicates that cracks occurred within 100 hours. TC test: The same test piece as the PCT test was tested at 65 ° C (30
Min) -room temperature (5 min) -125 [deg.] C. (30 min) / thermal shock was repeatedly applied and the presence or absence of cracks was observed.
○, 50 when there is no crack at the time of 200 cycles
Those in which cracks occurred by the cycle are shown by x.

Substrate warpage test: 5 × 50 mm, thickness 0.
After coating the epoxy resin composition for encapsulation produced in the composition and production conditions of the example and comparative example to a thickness of 0.8 mm on the entire surface of a 635 mm alumina substrate and heating and curing at 150 ° C. for 3 hours, The amount of warp of the substrate was measured along a diagonal line with a roughness measuring instrument, and those having a diameter of less than 200 μm were indicated by ◯ and those having a diameter of 200 μm or more were indicated by X.

[0036]

[Table 1]

[0037]

When the liquid epoxy resin compositions for sealing of Examples 1 to 5 and Comparative Examples 1 to 4 are compared, an epoxy resin, a phenol novolac, an organopolysiloxane having a vinyl group and a phenyl group on the side chain (silicone). A),
An encapsulating epoxy resin composition comprising an organopolysiloxane containing hydrogen bonded to a silicon atom (silicone B) and a polyether-modified polyether organopolysiloxane (silicone D, silicone E) as a component , Marking property due to bleeding property, PC
It can be confirmed that the heat resistance and moisture resistance supported by the T test and the TC test are improved.

[0038]

According to the liquid epoxy resin composition for encapsulation according to any one of claims 1 to 6 of the present invention, and the method for producing the same, P
It has excellent heat resistance, moisture resistance, fluidity, and marking properties in CT and TC tests.

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Claims (6)

[Claims] 1. An epoxy resin, (2) phenol novolac, (3) an organopolysiloxane having a vinyl group and a phenyl group in a side chain, (4) an organopolysiloxane containing hydrogen bonded to a silicon atom, And (5) a polyether-modified polyether organopolysiloxane, which is a liquid epoxy resin composition for encapsulation. 2. The encapsulating liquid epoxy resin composition according to claim 1, wherein the phenol novolac content is 15% or more based on the total weight of the curing agent. 3. The Si—O unit 50 wherein the phenyl group is
The liquid epoxy resin composition for encapsulation according to claim 1 or 2, which is at least one per one. 4. The liquid epoxy resin composition for sealing according to claim 1, wherein a part of the polyether-modified polyether organopolysiloxane is an epoxidized polyether organopolysiloxane. 5. The encapsulating liquid epoxy resin composition according to claim 1, which contains a sorbitan ester having the following structural formula. Embedded image (R is an alkyl group.) 6. (1) Epoxy resin, (2) Phenol novolac, (3) Organopolysiloxane having vinyl group and phenyl group in side chain, (4) Organopolysiloxane containing hydrogen bonded to silicon atom, And (5) a method for producing a liquid epoxy resin composition for encapsulation, which comprises mixing and reacting an epoxy resin composition containing a polyether-modified polyether organopolysiloxane with heating.