JPH11222555A - Insulating protective coating agent for optical semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulating protective coating agent for optical semiconductors which has heat resistance and electric insulating properties and is excellent in light transmission properties and adhesion to a sealing resin. SOLUTION: This compsn. contains a polyorganosiloxane mixture contg., on average, 0.1-0.8 alkenyl group (based on the total molecules), a polyorganohydrogensiloxane, a platinum catalyst, and fumed silica and has a penetration (with a 1/4 cone) of 80-140.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective agent for insulating coatings of optical semiconductors, and more particularly, to an insulating agent for optical semiconductors which is excellent in electrical insulation and light transmittance and excellent in adhesion to a sealing resin. It relates to a coating protective agent.

[0002]

2. Description of the Related Art An optocoupler sends light generated by a light emitting element such as a light emitting diode to a light receiving element to constitute a switching circuit. Between the light emitting element and the light receiving element,
It is electrically insulated and optically coupled. Conventionally, transparent silicone has been used as an insulating coating protective agent between a light emitting unit and a light receiving unit. However, the silicone resin has a large difference in thermal expansion coefficient between the silicone resin and the epoxy resin used as a sealing material, and the interface between the two peels off to form an air layer therebetween, thereby producing a capacitor function in the air layer. The insulation withstand voltage cannot be increased.

[0003] Therefore, in order to prevent the formation of an air layer, the injection molding conditions of the sealing epoxy resin are controlled so that the interface between the epoxy resin and the silicone resin does not peel off.
Improvements have been made in the manufacturing process of optocouplers.
However, since the structure of the optocoupler is diversified, and a higher withstand voltage is eagerly desired, an optical semiconductor material having excellent adhesion with an epoxy resin so as not to require complicated control of the process. There has been a demand for an insulating coating protective agent.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide heat resistance and electrical insulation inherent to silicone, excellent light transmittance, and extremely excellent adhesion to a sealing resin such as an epoxy resin. Another object of the present invention is to provide an insulating protective agent for an optical semiconductor.

[0005]

Means for Solving the Problems As a result of repeated studies to achieve the above object, the present inventors have found that a coating protective agent containing a polyorganosiloxane that can be crosslinked by an addition reaction controls the crosslink density, It has been found that the object can be achieved by using a specific amount of fumed silica as a filler and setting the penetration of a gel obtained by curing to a specific range, thereby completing the present invention. Reached.

That is, the protective agent for an optical semiconductor insulating coating of the present invention comprises: (A) a general formula:

Embedded image (Wherein, R ¹ represents an alkenyl group; R ² represents a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond; a is an integer of 1 to 3; b is 0 Alkenyl group-containing polyorganosiloxane having a siloxane unit represented by the formula (1), wherein a + b is an integer of 1 to 3), and the remainder is a direct bond in which the organic group bonded to the silicon atom is R ^2. a linear or branched polyorganosiloxane, averaged R ¹ for all molecules of (a) 0.
Having a viscosity of 50 to 1,0 at 25 ° C.
100 parts by weight of a polyorganosiloxane mixture of 00000 cSt; (B) the general formula:

Embedded image (Wherein, R ³ represents a substituted or unsubstituted monovalent hydrocarbon group; c is an integer of 0 to 2; d is an integer of 1 to 3; provided that c + d is an integer of 1 to 3) A polyorganohydrogensiloxane having an average of more than two hydrogen atoms bonded to silicon atoms in the molecule, and an alkenyl group 1 in the component (A).
(B) an amount of 0.2 to 2.0 hydrogen atoms bonded to silicon atoms in component (B); (C) a catalytic amount of a catalyst selected from the group consisting of platinum and a platinum compound; And (D) a gel-like material containing 8 to 30 parts by weight of fumed silica which may optionally be surface-treated, and having a penetration of 80 to 140 with an ASTM D1403 1/4 cone, which is obtained by curing. There is a feature.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polyorganosiloxane mixture of the component (A) used in the present invention is a base polymer of the coating protective agent of the present invention, and contains a silicon compound in the siloxane unit represented by the above formula (I). Includes alkenyl group-containing polyorganosiloxanes having an alkenyl group R ¹ directly bonded to an atom. The siloxane skeleton of the alkenyl group-containing polyorganosiloxane may be linear, branched, cyclic or network. The remaining polyorganosiloxane in the component (A) has an organic group bonded to a silicon atom of R ^2.
Which has a linear or branched siloxane skeleton. The viscosity of component (A), which is a mixture, is 50 to 1,000,000 cSt at 25 ° C, and 100 to 50 cSt.
000 cSt is preferred. If it is less than 50 cSt, the gel obtained by curing is fragile and has a viscosity of 1,000,000 cSt.
If the ratio exceeds the above range, the flowability of the coating protective agent in an uncrosslinked state becomes poor, resulting in poor workability.

Examples of R ¹ include vinyl, allyl, 1-butenyl, 1-hexenyl and the like, but a vinyl group is preferred because it is easy to synthesize and an appropriate curing speed can be obtained. R ² and other organic groups bonded to the silicon atom of the siloxane unit include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl and dodecyl; aryl groups such as phenyl; 2-phenylethyl, 2-phenylpropyl and the like And substituted hydrocarbon groups such as 3,3,3-trifluoropropyl, 3-methoxypropyl, 3-glycidoxypropyl, and 2- (3,4-epoxycyclohexyl). Of these, a methyl group is most preferred because it is easy to synthesize, has a degree of polymerization necessary for maintaining good physical properties after crosslinking, and maintains a low viscosity before crosslinking. In addition, when stability at a low temperature of −60 ° C. or less, which is often required for optical semiconductors, is required, it is preferable to introduce some phenyl groups as organic groups of R ² and other siloxane units. That is, 5 to 15 mol% based on all siloxane units of the component (A) when a phenyl group is introduced as a methylphenylsiloxane unit, and 2.5 to 1% when a phenyl group is introduced as a diphenylsiloxane unit.
It preferably contains 0 mol% of phenyl group-containing units.
Further, when particularly high light transmittance is required, a phenyl group may be used as a part of the organic group of R ² and other siloxane units in order to match the refractive index with that of the fumed silica compounded.

[0009] R ¹ is an average 0.1 to 0.8 pieces based on the total molecule of the component (A) is preferably present from 0.3 to 0.7 units. If the number is less than 0.1, sufficient crosslinking reaction is not performed, the shape is unstable, and sufficient mechanical strength cannot be obtained. On the other hand, if the number exceeds 0.8, the cured product becomes hard, and after curing, a coating protective agent having a hardness in an appropriate penetration range cannot be obtained.

The alkenyl group-containing siloxane unit represented by the formula (I) may be present at the terminal of the molecular chain of the component (A), at any point in the molecular chain, or at both of them. In order to obtain stability over time of physical properties after curing,
It is preferable that most of the alkenyl group-containing polyorganosiloxane in the component (A) be present at one end.
That is, as the component (A), a part thereof is polydimethylsiloxane having one end blocked with a dimethylvinylsiloxy group, or similarly, polymethylphenylsiloxane having one end blocked with a dimethylvinylsiloxy group,
It is particularly preferred to use both or both.

In the polyorganohydrogensiloxane of the component (B) used in the present invention, a hydrogen atom bonded to a silicon atom is present in the siloxane unit represented by the formula (II), (A) A component that acts as a crosslinking agent by an addition reaction with an alkenyl group in the component. 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). If the coating protective agent obtained by curing requires mechanical strength, it is three on average. It is preferable that it is above. Examples of the organic group of R ³ and other siloxane units are the same as those of R ^{2 in the} component (A), and the synthesis is easy.
From the viewpoint of compatibility with the component (A) and the properties of the resulting coating protective agent, a methyl group is most preferable, and a phenyl group may be introduced as a part of R ³ as necessary. The viscosity of the component (B) is preferably 10 to 10,000 cSt at 25 ° C., because it is easy to synthesize and handle, and does not volatilize during storage and during the crosslinking reaction.
0 cSt is more preferred.

The molecular structure of component (B) is not particularly limited as long as it has more than two hydrogen atoms directly bonded to silicon atoms on average per molecule as described above. Although it is possible to use those having a linear, branched or cyclic siloxane skeleton, straight-chain ones or polyorganohydrogensiloxanes comprising R ³ ₂ HSiO _1/2 units and SiO ₂ units for ease of synthesis Is preferred. Moreover, if the covering agent is particularly necessary mechanical properties, regardless of whether the siloxane backbone, at least some of the hydrogen atoms bonded directly to silicon atom, R ³ _2, such as dimethyl siloxane units HSiO _1/2
It is particularly preferred that it is present as a unit, that is, it is present at both ends when it is linear.

The amount of component (B) is such that the number of hydrogen atoms bonded to silicon atoms in component (B) is 0.2 to 2.0 per alkenyl group in component (A). It is such an amount. When the number of hydrogen atoms per one alkenyl group is less than 0.2, the crosslinking density is too low, so that crosslinking does not proceed sufficiently and fluidity remains even after crosslinking.
The desired physical properties cannot be obtained, which is not preferred. On the other hand, when the number of hydrogen atoms exceeds 2.0, the coating protective agent after curing becomes hard, and a material having an appropriate penetration cannot be obtained.

The catalyst selected from the platinum component (C) and the platinum compound used in the present invention promotes the addition reaction between the alkenyl group of the component (A) and the hydrosilyl group of the component (B). . As the component (C), chloroplatinic acid, a complex obtained from chloroplatinic acid and an alcohol, platinum-
An olefin complex, a platinum-vinylsiloxane complex, another platinum coordination compound, a simple substance of platinum (platinum black), or a substance in which a simple substance of platinum is supported on a carrier such as alumina or silica can be used. When the uncured coating protective agent of the present invention is stored in a single container, the coexistence of an alcohol-based or glycol-based solvent may impair the temporal stability 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 amount of the component (C) is an effective amount of the component (C) as a catalyst, and is preferably 1.0 to 30 ppm, more preferably 2.0 to 20 ppm, as a platinum atom relative to the component (A).
Is particularly preferred. If it is less than 1.0 ppm, it is susceptible to curing inhibition, and if it exceeds 30 ppm, it may be colored by heating.

The fumed silica of the component (D) used in the present invention improves the adhesion of the coating protective agent of the present invention to a sealant. The adhesion is due to the effect of silanol groups on the surface of the fumed silica, and the use of a small amount of fumed silica is more effective for improving the adhesion, the larger the specific surface area, the more effective it is. , B
Those having a specific surface area of 175 to 330 m ² / g by the ET method are preferred. In order to improve the affinity with the components (A) and (B) and the transparency and heat resistance of the coating protective agent after curing, trimethylchlorosilane, trimethylmethoxysilane, hexamethyldisilazane, hexamethylcyclotri Siloxanes, silanes such as octamethylcyclotetrasiloxane, silazanes and / or
Alternatively, it is preferable to use a surface treated with siloxanes.

The amount of the component (D) is 100%.
The amount is 8 to 30 parts by weight, preferably 10 to 25 parts by weight based on parts by weight. If the amount is less than 8 parts by weight, the adhesion to a sealing agent such as an epoxy resin is poor.
The fumed silica may aggregate to reduce the transparency and heat resistance of the cured coating protective agent.

The protective agent for an optical semiconductor insulating coating of the present invention comprises:
ASTM, which contains components (A) to (D)
It is prescribed so that the penetration measured by a 1/4 cone is in the range of 80 to 140, preferably 85 to 120, as defined in D1403. If the penetration is less than 80,
If the adhesion to the sealant is not sufficient, and if it exceeds 140, the cured coating protective agent layer is deformed when the sealant is injection-molded.

Various additives can be added to the coating protective agent of the present invention, if necessary, as long as the object of the present invention is not impaired. For example, for the purpose of providing adhesion (meta)
A silane compound or siloxane compound having a carbon functional group such as an acryloyl group or an epoxy group, or a cyclic siloxane having a side chain containing a trialkoxysilyl group and an ester bond and having a hydrogen atom bonded to a cyclic silicon atom And a cross-linking reaction retarder for increasing stability during storage at room temperature after the coating protective agent is prepared; and a flame retardant.

The components (A) to (D) are prepared by mixing uniformly using a mixing means such as a kneader in the presence or absence of a cross-linking reaction retarder. This type is preferable from the viewpoint of workability. Further, a mixture containing a part of the component (A) and the component (B) and a mixture containing a part of the component (A) and the component (C) are separately prepared and mixed immediately before use. It may be a coating protective agent. in this case,
The component (D) may be blended in one or both mixtures, but is usually distributed in both mixtures such that both mixtures maintain a proper fluidity.

The coating protective agent of the present invention is usually applied to the surface of a semiconductor chip by an extrusion, dropping, or pouring device, and causes a crosslinking reaction by heating to form a crosslinked product having a predetermined property. Regarding the heating conditions, for example, by heating at 60 ° C. for several minutes, a crosslinked body which does not flow and can maintain the shape can be obtained.

[0022]

The protective agent for an optical semiconductor insulating coating obtained by the present invention has excellent transparency, electrical insulation and heat resistance,
In addition, it has excellent adhesion to a sealant, and greatly contributes to improving the withstand voltage of a device using an optical semiconductor.
Therefore, the coating protective agent of the present invention is extremely useful as a coating protective agent for optical semiconductors such as optocouplers.

[0023]

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.

A-1: Average formula

Embedded image A: a polydimethylsiloxane mixture having a viscosity of 700 cP containing a vinyl group at the terminal of some polysiloxanes; A-2: average formula

Embedded image A-3: a polymethylphenylsiloxane mixture having a viscosity of 2,000 cP and containing a vinyl group at a terminal of some of the polysiloxanes;

Embedded image A-4: a polydimethylsiloxane having a viscosity of 650 cP containing a vinyl group at the terminal of some polysiloxanes;

Embedded image A-5: average formula having both ends vinyl group-containing polydimethylsiloxane having a viscosity of 650 cP.

Embedded image B-1: average formula having a viscosity of 2,000 cP and having both ends vinyl group-containing polymethylphenylsiloxane.

Embedded image A polymethylhydrogensiloxane having a viscosity of 50 cP; B-2: average formula

Embedded image A polymethylhydrogensiloxane having a viscosity of 100 cP; B-3: average formula

Embedded image A polymethylhydrogensiloxane having a viscosity of 50 cP; C-1: a platinum-vinylsiloxane complex dissolved in polydimethylsiloxane having both ends blocked with vinyldimethylsiloxy units, in terms of platinum atom, 0.5 wt. D-1: fumed silica having an average particle size of 12 nm, a specific surface area of 200 m ² / g and a surface treated with hexamethyldisilazane; and D-2: an average particle size. Is 7 nm and the specific surface area is 300 m ² / g.

Examples 1 to 6 and Comparative Examples 1 to 3 With the compositions shown in Table 1, the above-mentioned materials were mixed at room temperature until uniform using a kneader to prepare uncured coating protective agents. Penetration after curing of these coating protective agents, light transmittance, and adhesion with epoxy resin,
The evaluation was performed as follows.

Penetration Uncured coating agent is placed in a Pyrex beaker, and
It was cured by heating in a hot air drier at 30 ° C. for 30 minutes. Remove from beaker at room temperature, ASTM D1403
The penetration was measured using a 1/4 cone to obtain the initial penetration. This is further placed in a hot air dryer at 180 ° C for 3
After standing for 0 days, the temperature was returned to room temperature, and the penetration was measured again as the value after the heat resistance test.

Light transmittance The uncured coating material is cured by heating at 180 ° C. for 30 minutes in the same manner as described above, and then placed in a 1 mm-thick quartz cell to measure the transmittance of light having a wavelength of 600 nm. It was measured.

Adhesion with Epoxy Resin 1 g of the uncured coating agent was placed in an aluminum dish and kept at 180 ° C.
For 30 minutes to cure. Then, 1 g of an uncured epoxy resin was poured thereon, and was cured by heating on a hot plate at 180 ° C. for 10 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. As epoxy resin, XN1184SP / XN1185SP
(Trade name of Nagase Chiba Co., Ltd.) and MR150SGC (trade name of Nitto Electric Industry Co., Ltd.).

The results are shown in Table 1.

[0031]

[Table 1]

The insulating coating protective agents of Examples 1 to 6 are excellent in light transmittance and adhesion to epoxy resin, and also excellent in heat resistance. On the other hand, the protective agents of Comparative Examples 1 and 3 using polydimethylsiloxane having vinyl groups at both ends have poor adhesion and heat resistance. The protective agent of Comparative Example 2 was improved in adhesiveness by adding a large amount of fumed silica, but was inferior in light transmittance and extremely low in heat resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 33/00 H01L 31/00 A

Claims (4)

[Claims] (A) A general formula: (Wherein, R ¹ represents an alkenyl group; R ² represents a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond; a is an integer of 1 to 3; b is 0 Alkenyl group-containing polyorganosiloxane having a siloxane unit represented by the formula (1), wherein a + b is an integer of 1 to 3), and the remainder is a direct bond in which the organic group bonded to the silicon atom is R ^2. a linear or branched polyorganosiloxane, averaged R ¹ for all molecules of (a) 0.
Having a viscosity of 50 to 1,0 at 25 ° C.
100 parts by weight of a polyorganosiloxane mixture of 000 cSt; (B) the general formula: (Wherein, R ³ represents a substituted or unsubstituted monovalent hydrocarbon group; c is an integer of 0 to 2; d is an integer of 1 to 3; provided that c + d is an integer of 1 to 3) A polyorganohydrogensiloxane having an average of more than two hydrogen atoms bonded to silicon atoms in the molecule, and an alkenyl group 1 in the component (A).
(B) an amount of 0.2 to 2.0 hydrogen atoms bonded to silicon atoms in component (B); (C) a catalytic amount of a catalyst selected from the group consisting of platinum and a platinum compound; And (D) a gel-like material containing 8 to 30 parts by weight of fumed silica which may optionally be surface-treated, and having a penetration of 80 to 140 with an ASTM D1403 1/4 cone, which is obtained by curing. An optical semiconductor insulating coating protective agent, characterized in that: 2. The coating protective agent according to claim 1, wherein part of (A) is polydimethylsiloxane and / or polymethylphenylsiloxane having one end blocked with dimethylvinylsiloxy unit. 3. The coating protective agent according to claim 1, wherein (B) is a polymethyl hydrogen siloxane having a dimethyl hydrogen siloxane unit. 4. The coating protective agent according to claim 1, which is a coating protective agent for an optocoupler.