JPH11246771A - Silicone gel composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a silicone gel composition which can give a cured product having improved adhesion to a sealing resin by incorporating (A) a polyorganosiloxane with (B) a polyorganohydrogensiloxane, (C) a platinum catalyst and (D) an epoxy-containing polyorganosiloxane in a specified ratio so as to form a composition which can give a cured product having a specified penetration. SOLUTION: This composition comprises 100 pts.wt. component A represented by formula I (0.1-2.0 on the average per molecule; R<1> s are alkenyl groups; R<2> is a hydrocabon group; and n is an integer) and having a viscosity of 50-1,000,000 cSt; component B having two or more Si-bonded hydrogen atoms on the average, represented by average unit formula II (R<3> is a hydrocarbon group; a is 1.3-2.0, b is 0.02-1.05; and a+b=1.8-3.0), and used in such an amount that 0.3-2.0 Si- bonded hydrogen atoms are present per alkenyl of component A; a catalytic amount of component C being a platinum catalyst; and 0.01-10 pts.wt. component D represented by formula III (R<4> is an epoxy-containing by hydrocarbon group; R<5> is methyl or phenyl; R<6> is R<4> or R<5> , or hydrogen; an m is an integer). The penetration is 70-140.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyorganosiloxane composition which cures to form a silicone gel, and more particularly to an epoxy resin for encapsulation or potting in electronic equipment such as various sensors and power modules, and in particular for sealing semiconductors. The present invention relates to a polyorganosiloxane composition which forms a silicone gel having excellent adhesion to a resin.

[0002]

2. Description of the Related Art Various techniques have been disclosed for a polyorganosiloxane composition which can be cured by an addition reaction between an alkenyl group bonded to a silicon atom and a hydrosilyl group to form a gel-like material. Is widely used for potting and encapsulation of devices.

As such a polyorganosiloxane composition, JP-A-48-17847 discloses that the amount of hydrogen atoms bonded to silicon atoms of a polyorganohydrogensiloxane is determined in one molecule of the polyorganohydrogensiloxane. Japanese Patent Application Laid-Open No. 54-15 / 15 discloses that the average is 1.4 to 1.8 and the number of vinyl groups contained in the vinyl group-containing polyorganosiloxane is controlled to one or less per vinyl group.
957 and JP-A-54-48720 disclose that the amount of hydrogen atoms bonded to silicon atoms is
Disclosed are compositions present in relatively small amounts of 0.3 to 0.8 per individual. As the vinyl group-containing polyorganosiloxane, the above-mentioned JP-A-54-15
Japanese Patent Application Laid-Open No. 54-47720 discloses the use of polydimethylsiloxane having a molecular terminal blocked with a methylvinylphenylsiloxy group.
It has been proposed to use polyorganosiloxanes having at least two vinyl groups and at least one hydroxyl group both bonded to silicon atoms.

However, a silicone gel obtained by curing a polyorganosiloxane composition prepared by such a technique does not adhere to a base material due to its low tackiness, and is used for potting electronic parts and devices. When used for, the silicone gel has poor adhesion between the silicone gel and a part or device, or a sealing agent such as an epoxy resin used for sealing the same, so that a void is formed, from which moisture infiltration, corrosion and Insulation failure may be caused. In addition, when used for potting of high-voltage parts, the gap between the gel and the sealant becomes an air layer to generate a capacitor function and discharge, thereby impairing withstand voltage characteristics.

To solve these problems, Japanese Patent Application Laid-Open No.
JP-A-39658 discloses that a polyorganosiloxane containing a vinyl group-containing polyorganosiloxane has a vinyl group content of 0.1 to 2.0 per molecule, so that the silicone gel has an adhesive property with a sealant. It is disclosed to impart properties. However, by merely changing the molecular structure of such a vinyl-containing polyorganosiloxane, the adhesion between the silicone gel and the sealant cannot be sufficiently satisfied, and further improvement in adhesion is desired. Was.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide heat resistance and electrical insulation inherent to silicone,
In particular, it is an object of the present invention to provide a silicone gel composition capable of forming a silicone gel having extremely excellent adhesion to a sealing resin such as an epoxy resin.

[0007]

Means for Solving the Problems As a result of repeated studies to achieve the above object, the present inventor has found that a polyorganosiloxane composition which is cured by an addition reaction to form a gel-like material has a molecular terminal. It has been found that the object can be achieved by blending a linear polyorganosiloxane containing an epoxy group, and by setting the penetration after curing to a specific range, thereby completing the present invention. .

That is, the silicone gel composition of the present invention comprises: (A) a general formula:

Embedded image (Wherein, R ¹ represents an alkenyl group or a monovalent hydrocarbon group containing no aliphatic unsaturated bond, and among R ¹ , (A)
R ² represents a monovalent hydrocarbon group containing no aliphatic unsaturated bond; and n is a positive integer). 100 parts by weight of a polyorganosiloxane having a viscosity at 25 ° C. of 50 to 1,000,000 cSt; (B) an average unit formula:

Embedded image (Wherein R ³ represents a substituted or unsubstituted monovalent hydrocarbon group; a is 1.3 to 2.0; b is 0.02 to 1.
05; wherein a + b is 1.8 to 3.0)
And a polyorganohydrogensiloxane having an average of more than two hydrogen atoms bonded to silicon atoms in the molecule, one alkenyl group in the component (A):
The hydrogen atom bonded to the silicon atom in the component (B) is 0.3
(C) a catalytic amount of a platinum-based catalyst; and (D) a general formula:

Embedded image (Wherein, R ⁴ represents a monovalent hydrocarbon group substituted with an epoxy group-containing group, R ⁵ represents a methyl group or a phenyl group; R ⁶ represents R ⁴ , R ⁵ or a hydrogen atom; Is R ⁶
Is 1 to 20 when R ⁴ is R ⁴ and an integer of 1 to 40 when R ⁶ is R ⁵ or a hydrogen atom). According to D1403, the penetration measured using a 1/4 cone is 70 to 140.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The polyorganosiloxane of the component (A) used in the present invention is a base polymer of the silicone gel composition of the present invention, and is a linear siloxane represented by the aforementioned general formula (I). It has a skeleton and has an alkenyl group directly bonded to a silicon atom as part or all of R ^{1 in} a terminal siloxane unit. The alkenyl group in R ¹ has an average of 0.1 to 2.0 in one molecule of the component (A),
Preferably, there are 0.4 to 1.4. This number is 0.1
If it is less than the number, the amount of the polyorganosiloxane that does not participate in the reaction increases, so that the adhesion to the substrate is reduced, and the shape is unstable, and sufficient mechanical strength cannot be obtained.

The viscosity of the component (A) is 50 to 25 ° C.
1,000,000 cSt, 300-5,000 cS
t is preferred. If it is less than 50 cSt, it is easy to flow in an uncrosslinked state, and the cured product is brittle. If it exceeds 1,000,000 cSt, the flowability of the coating protective agent in an uncrosslinked state becomes poor, resulting in poor workability.

The alkenyl group which is a part of R ¹ includes:
Examples thereof include vinyl, allyl, 1-butenyl, and 1-hexenyl, but a vinyl group is preferable because synthesis is easy and an appropriate curing speed can be obtained. Residual R ¹ and R
^2, the monovalent hydrocarbon group containing no aliphatic unsaturated bond, methyl, ethyl, propyl, butyl, hexyl, alkyl groups such as dodecyl, aryl groups such as phenyl; 2-phenylethyl, 2-phenylpropyl Aralkyl groups such as 1,3,3,3-trifluoropropyl,
Examples thereof include a substituted hydrocarbon group such as 3-methoxypropyl. Of these, a methyl group is most preferable because it is easy to synthesize and has a degree of polymerization necessary to maintain good physical properties after crosslinking, while maintaining a low viscosity before crosslinking and easy to handle. . When cold resistance is required, it is preferable to introduce some phenyl groups. That is, when the phenyl group is introduced as a methylphenylsiloxane unit, 5 to 15 mol%, and when it is introduced as a diphenylsiloxane unit, 2.5 to 10 mol% of the total amount of R ¹ and R ^2. It is preferable to include a content unit. When heat resistance is required, a phenyl group of up to 50 mol% based on the total amount of R ¹ and R ² can be used.

The polyorganohydrogensiloxane of the component (B) used in the present invention has, as shown by the average unit formula (II), a hydrogen atom bonded to a silicon atom, and its Si—H bond and (A) A component that acts as a crosslinking agent by an addition reaction with an alkenyl group in the component. In the average unit formula (II), a is 1.3 to 2.0;
b is 0.02 to 1.05, preferably 0.1 to 1.0, and a + b is 1.8 to 3.0. However, the number of hydrogen atoms bonded to silicon atoms is more than two on average in the molecule as a whole of the component (B), and if the silicone gel obtained by crosslinking has a mechanical strength, the average is three.
Preferably, the number is at least.

As R ³ , those similar to R ^{2 in} component (A) are exemplified. From the viewpoint of ease of synthesis, compatibility with component (A), and physical properties of the resulting silicone gel, a methyl group is formed. Most preferably, a phenyl group may be introduced as a part of R ³ if necessary. The viscosity of such a polyorganohydrogensiloxane (B) component is as follows:
Due to the ease of synthesis and handling, and the lack of volatilization during storage and during the crosslinking reaction,
It is preferably from 0 to 10,000 cSt, more preferably from 15 to 500 cSt.

The molecular structure of component (B) is not particularly limited as long as it has an average of more than two hydrogen atoms in one molecule directly bonded to silicon atoms as described above. Shape, cyclic, those having a branched siloxane skeleton can be used, but from the ease of synthesis,
Linear, or R ³ ₂ HSiO _1/2 units and SiO ₂
Polyorganohydrogensiloxanes comprising units are preferred. Also, if the mechanical properties to the silicone gel is particularly necessary, regardless of whether the siloxane backbone, at least some of the hydrogen atoms bonded directly to silicon atom, R ³ ₂ HS such as dimethyl siloxane units
It is particularly preferred that it is present as an iO _1/2 unit, that is, if it is linear, it is present at both ends.

The amount of component (B) is such that the number of hydrogen atoms bonded to silicon atoms in component (B) is 0.3 to 2.0 per alkenyl group in component (A), Preferably, the amount is 0.35 to 1.5. When the number of hydrogen atoms per one alkenyl group is less than 0.3, crosslinking does not proceed sufficiently and not only the silicone gel becomes too soft, but also discoloration at high temperatures is remarkable. On the other hand, when the number of hydrogen atoms exceeds 2, the silicone gel after curing becomes hard, and it becomes harder with the lapse of time because it is not possible to obtain one having an appropriate penetration.

The platinum catalyst of the component (C) used in the present invention promotes an addition reaction between the alkenyl group of the component (A) and the hydrosilyl group of the component (B).
The component (C) includes chloroplatinic acid, a complex obtained from chloroplatinic acid and an alcohol, a platinum-olefin complex, and platinum-olefin.
Platinum compounds such as vinylsiloxane complexes, platinum-ketone complexes, and other platinum coordination compounds; palladium compounds such as tetrakis (triphenylphosphine) palladium; platinum or palladium alone (platinum black, palladium black), or alumina; A metal catalyst such as a carrier in which platinum or palladium alone is supported on a carrier such as silica; a mixture thereof and the like can be used. In addition,
When the uncured silicone gel composition of the present invention is stored in a single container, the coexistence of an alcohol-based or glycol-based solvent may impair the stability over time of the system. Therefore, in such a case, it is preferable to avoid using these solvents and dissolve them in ether solvents, hydrocarbon solvents, and the like.

The compounding amount of the component (C) is an effective amount of the component (C) as a catalyst, but is preferably 0.01 to 30 ppm as a catalyst metal atom for the component (A). 0.01pp
If it is less than m, the addition reaction does not proceed sufficiently, and if it exceeds 30 ppm, coloring may occur at high temperatures.

The epoxy group-containing polyorganosiloxane (D) used in the present invention improves the adhesion of the silicone gel of the present invention to a base material, an epoxy resin used as a sealant, and the like. .
The component (D) is a polyorganosiloxane represented by the general formula (III) and having an epoxy group-containing group bonded to a silicon atom at both terminals or one terminal. Examples of the epoxy group-containing group present as R ⁴ , and optionally as R ^6, include a 3-glycidoxypropyl group and a 2- (3,4-epoxycyclohexyl) ethyl group. Thus, a 3-glycidoxypropyl group is preferred. The terminal siloxane unit to which the epoxy group-containing group is not bonded may have a hydrogen atom bonded as R ^{6 in} addition to a methyl group and / or a phenyl group.

Other organic groups bonded to the silicon atom as R ⁵ and optionally R ⁶ are methyl or phenyl. A methyl group is preferred because of ease of synthesis and handling. m is 1 to 20 when an epoxy group-containing group exists at both ends, and 1 to 40 when an epoxy group-containing group exists at one end. If m is larger than the above value, the adhesion will be reduced. As the component (D), an oligomer having m of 1 to 3 is preferable because synthesis and purification are easy and a controlled effective amount of an epoxy group-containing group can be introduced into the system.

Preferred examples of the component (D) include the following compounds. One type may be used alone, or two or more types may be used in combination.

[0021]

Embedded image

The component (D) can be used, for example, by adding an allyl glycidyl ether, 1- to a hydrosilyl group of a polyorganohydrogensiloxane having a hydrogen atom bonded to a silicon atom at a molecular terminal in the presence of a platinum-based catalyst.
It can be synthesized by an addition reaction of an epoxy group-containing compound such as vinyl-3,4-epoxycyclohexane. As the platinum-based catalyst, the same catalysts as those exemplified as the component (C) can be used.

The amount of component (D) is 100
0.01 to 10 parts by weight to 0.5 parts by weight
6 parts by weight are preferred. If the amount is less than 0.01 part by weight, the effect of imparting adhesion to the silicone gel is not sufficient, and if it exceeds 10 parts by weight, the inherent heat resistance and physical properties of the silicone are significantly reduced.

The silicone gel composition of the present invention comprises (A)
~ (D) component, the hardness after curing is ASTM D1
It is prescribed so that the penetration measured by 1/4 cone is in the range of 70-140, preferably 80-120. If the penetration is less than 70, sufficient adhesion to the substrate and the sealant cannot be obtained, and if it exceeds 140, the cured silicone gel is deformed when the sealant is injection-molded.

As long as the object of the present invention is not impaired, the silicone gel composition of the present invention may contain, if necessary, a fumed silica which has been subjected to a surface treatment with a silylating agent such as fumed silica or hexamethyldisilazane; Inorganic fillers such as precipitated silica, silica aerogel, diatomaceous earth, crushed quartz, titanium oxide, calcium carbonate; toluene, xylene, n-
A solvent such as hexane; and a crosslinking reaction retarder such as acetylene alcohol and a reaction product thereof with polysiloxane; and an additive such as a flame retardant can be incorporated.

The silicone gel composition of the present invention comprises (A)
The components (D) to (D) can be prepared by uniformly mixing using a mixing means such as a kneader in the presence or absence of a crosslinking reaction retarder, and can be stored in a single container at room temperature or low temperature. This type is preferred from the viewpoint of workability. Further, a mixture containing a part of the component (A), the component (B) and the component (D), and a mixture containing a part of the component (A) and the component (C) are separately prepared and used immediately before use. And then cured to obtain a silicone gel. The mineral filler may be incorporated in one or both mixtures, if necessary, but is usually distributed in both mixtures so that both mixtures each have a reasonable flow.

The silicone gel composition of the present invention usually comprises
The surface of a substrate such as a semiconductor chip is treated by a casting, impregnating, dropping, coating or injecting device, and a cross-linking reaction is caused by heating to form a silicone gel having a predetermined property and adhered to the surface of the substrate. The heating condition is, for example, 18
By heating at 0 ° C. for several minutes, a cured product that does not flow and can maintain its shape is obtained.

[0028]

The cured product of the silicone gel composition obtained by the present invention is excellent in electrical insulation and heat resistance, and excellent in adhesion to a substrate and a sealant covering the outside thereof. This greatly contributes to improving the withstand voltage of a device using a semiconductor. Therefore, the silicone gel composition of the present invention is extremely useful for potting high voltage components such as power modules and photocouplers.

[0029]

The present invention will be described more specifically with reference to the following examples. The present invention is not limited to these examples. In the examples and comparative examples, all parts mean parts by weight, and the viscosity indicates a viscosity at 25 ° C. The following symbols are used for the hydrocarbon group. Me: methyl group, Vi: vinyl group, Ph: phenyl group.

In Examples and Comparative Examples, (A)
The following materials were used as the component (D). The following molecular formulas are all average formulas, and those containing a plurality of intermediate siloxane units and / or a plurality of terminal siloxane units simply indicate the number of siloxane units and do not mean a block copolymer, All copolymers are random copolymers. D-4 and D-5 are the epoxy group-containing alkoxysilane and ester bond-containing cyclic polysiloxane used for comparison, respectively.

A-1: Average formula

Embedded image A-2: average formula having a viscosity of 2,000 cP and having a terminal vinyl group-containing polymethylphenylsiloxane represented by the following formula:

Embedded image B-1: average formula having a viscosity of 700 cP and having a terminal vinyl group-containing polydimethylsiloxane;

Embedded image A polymethylhydrogensiloxane having a viscosity of 50 cP; C-1: a platinum-tetramethyltetravinylcyclotetrasiloxane complex containing 2.0% by weight in terms of platinum atom;

[0032]

Embedded image

Examples 1 to 5 and Comparative Examples 1 and 2 With the compositions shown in Table 1, each of the above-mentioned materials was mixed at room temperature until uniform using a kneader to prepare silicone gel compositions. The penetration and adhesion after curing of these compositions were evaluated as follows.

Penetration 40 ml of the uncured coating material was placed in a 50 ml Pyrex beaker, and cured by heating in a hot air drier at 180 ° C. for 1 hour. After cooling to room temperature, ASTM D1403
The penetration was measured using a 1/4 cone to obtain the initial penetration. This was further left in a hot air drier at 180 ° C. for a predetermined period of time and then returned to room temperature. The penetration was measured in the same manner, and the penetration after heating was used as a measure of heat resistance.

Adhesion 2 g of the uncured coating agent was placed in an aluminum Petri dish and heated at 180 ° C.
For 30 minutes to cure. After cooling to room temperature,
Pour 0.5 g of uncured epoxy resin on top
The composition was cured by heating on a hot plate at 80 ° C. for 5 minutes. It was cooled to room temperature, taken out of the petri dish, and peeled off between the cured coating agent and the epoxy resin, and the adhesion was qualitatively evaluated. The epoxy resin is KE-6
00 (Toshiba Chemical Corporation, Resin 1) and XN1184
SP / XN1185SP (Ciba Geigy Co., Ltd., Resin 2) was used.

The results are shown in Table 1. The silicone gel using an epoxy group-containing alkoxysilane or an ester bond-containing cyclic polysiloxane as an adhesion improver did not show adhesion. The silicone gel obtained from the composition of the present invention showed excellent adhesion.

[0037]

[Table 1]

Example 6, Comparative Examples 3 to 5 Using A-1, B-1, C-1 and D-1 in the compositions shown in Table 2, silicone gel compositions were prepared.
Comparative Example 3 and Comparative Example 4 are different from Example 6 in that the amount of B-1
Comparative Example 5 shows that a large amount of D-
1 is used. The obtained silicone gel composition was cured by heating at 180 ° C. in the same manner as in Example 1, and the penetration and adhesion were evaluated.

The results are as shown in Table 2. When the penetration is 65, the adhesion is poor, and the penetration is 15
In the case of No. 0, the fluidity was large even after curing, and the adhesion could not be measured. In addition, the silicone gel obtained from Comparative Example 5 using a large amount of the epoxy group-containing polyorganosiloxane showed a large change in penetration due to heating.

[0040]

[Table 2]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 83:05 83:06) (C08L 83/07 83:05 63:00)

Claims (2)

[Claims] (A) A general formula: (Wherein, R ¹ represents an alkenyl group or a monovalent hydrocarbon group containing no aliphatic unsaturated bond, and among R ¹ , (A)
R ² represents a monovalent hydrocarbon group containing no aliphatic unsaturated bond; and n is a positive integer). 100 parts by weight of a polyorganosiloxane having a viscosity at 25 ° C. of 50 to 1,000,000 cSt; (B) an average unit formula: (Wherein R ³ represents a substituted or unsubstituted monovalent hydrocarbon group; a is 1.3 to 2.0; b is 0.02 to 1.
05; wherein a + b is 1.8 to 3.0)
And a polyorganohydrogensiloxane having an average of more than two hydrogen atoms bonded to silicon atoms in the molecule, one alkenyl group in the component (A):
The hydrogen atom bonded to the silicon atom in the component (B) is 0.3
(C) a catalytic amount of a platinum-based catalyst; and (D) a general formula: (Wherein, R ⁴ represents a monovalent hydrocarbon group substituted with an epoxy group-containing group, R ⁵ represents a methyl group or a phenyl group; R ⁶ represents R ⁴ , R ⁵ or a hydrogen atom; Is R ⁶
Is 1 to 20 when R ⁴ is R ⁴ and an integer of 1 to 40 when R ⁶ is R ⁵ or a hydrogen atom). The silicone gel composition according to D1403, wherein the penetration measured using a 1/4 cone is 70 to 140. 2. The silicone gel composition according to claim 1, wherein R ⁴ is a 3-glycidoxypropyl group.