JPH01126317A - Ultraviolet ray curing type polyorganosiloxane composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition for semiconductor coating material, etc., preferably curable even in passing for long period until ultraviolet ray irradiation after coating and free from odor, by blending a specific polyorganosiloxane with a specific peroxyester and sensitizer at a specific ratio. CONSTITUTION:The aimed composition obtained by blending (A) 100pts.wt. polyorganosiloxane expressed by the formula [R<1> is monovalent hydrocarbon excluding vinyl group; 0.01<=a<=1; 0<=b<=3; 1<=a+b<=3] with (B) 0.1-10.0pts.wt. peroxyester expressed by the formula R<2>-O-O-C-O-R<3> (R<2> is 5-12C monovalent aliphatic hydrocarbon; R<3> is monovalent aromatic hydrocarbon) and (C) 0.01-5.0 pts.wt. sensitizer. Further more, preferably the component A has >=100cst viscosity at 20 deg.C and component B is tert.-hexylperoxy-benzoate and component C is ketones such as benzil.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a polyorganosiloxane composition that becomes gel-like, rubber-like, or resin-like when cured by ultraviolet irradiation.
More specifically, we use semiconductor coating materials to cover and protect the joints of semiconductors and encapsulate semiconductor devices with resin using methods such as potting, and assemblies that mount various electrical components on hybrid integrated circuits and printed wiring boards. The present invention relates to an ultraviolet curable polyorganosiloxane composition useful as a temporary fixing material for temporarily fixing parts in a process.

[Technical background of the invention and its problems]

Polyorganosiloxane has excellent properties such as electrical insulation, heat resistance, and moisture resistance, so it is widely used as coating materials and potting materials in fields such as electrical and electronic fields, optics, optoelectronics, and sensors. There is. Among them, polyorganosiloxane compositions that cure by UV irradiation do not require heating and can be cured in a short time.
Since it can be treated without worrying about the adverse effects of reaction by-products, its use is particularly widespread in this field.

2. Description of the Related Art There is a known technique for coating and protecting semiconductor joints and the like by curing a silicone rubber composition with ultraviolet rays. Such silicone rubber compositions include (1) U.S. Patent No. 3.7;
No. 26.710 proposes a composition that is made by adding various sensitizers to a vinyl group-containing polyorganosiloxane and is cured by high-intensity ultraviolet irradiation. However, this composition had the disadvantage that it only cured on the surface and did not harden uniformly to the inside. (2) Also, U.S. Patent Nos. 3 and 8
No. 16.282 presents an addition-crosslinking composition consisting of a mercapto group-containing polyorganosiloxane, polymethylvinylsiloxane and various organic peroxides. However, the disadvantages of this composition are that it has poor storage stability and gelation progresses even at room temperature, that synthesis of mercapto group-containing polyorganosiloxane requires a multi-step process, and that it does not produce the bad odor characteristic of mercapto groups. Release,
Another problem is that the heat resistance characteristic of silicone is lost, and although the adhesion to metal substrates is good, the metal is converted to sulfide by heating. (3) Also, special public service 1972-40
No. 334 discloses a composition in which a vinyl group-containing polyorganosiloxane and a polyorganohydrodiene siloxane are addition-crosslinked in the presence of a sensitizer, but this also cures only the surface and does not cure internally. Moreover, it has the disadvantage of causing a foaming phenomenon. (4
) Furthermore, JP-A-48-19682 proposes a composition comprising a polyorganosiloxane containing an acrylic unsaturated group and a sensitizer. However, although it has an excellent photosensitizing effect, it has the disadvantage that it is easily affected by oxygen and has large changes in photosensitivity over time and dark decay.In addition, it is difficult to synthesize polyorganosiloxanes containing acrylic unsaturated groups. There were also disadvantages in that it required several steps and the resulting silicone had poor heat resistance. (5) Also, JP-A-54-6
Publication No. 9197 proposes a composition comprising an azide group-containing polyorganosiloxane, a vinyl group-containing polyorganosiloxane, and an organic peroxide. This had the advantage of having excellent photosensitivity, being unaffected by oxygen, and having little change in photosensitivity over time, but had the disadvantage of yellowing. (6) Furthermore, JP-A-55-125123 discloses that a composition comprising a vinyl group-containing polyorganosiloxane or a vinyl group-containing polyorganosiloxane and an organic peroxide is irradiated with ultraviolet rays with a wavelength of 100 to 300 nm. We are proposing a method of hardening. However, this method was sensitive to oxygen, had a long curing time, and was incomplete. (7) Furthermore, JP-A-58-89650 discloses that low-molecular-weight polyvinylmethylsiloxane and tert-butylperoxybenzoate are added to polyorganohydrodienesiloxane which has a silicon-bonded vinyl group and a hydrogen group in the same molecule. We have proposed a method for uniformly curing the material from the inside to the surface and adhering it to various substrates. However, with this method, if the film coated on the substrate is left for a long time before being irradiated with ultraviolet rays,
Since t-butyl peroxybenzoate volatilizes, thin films are no longer cured, while thick films are not cured slowly and are insufficiently cured, resulting in poor physical properties of the cured product. Additionally, it has been pointed out that the odor of tert-butylperoxybenzoate or its decomposition products is extremely unpleasant to some people, which has become a major problem.

[Purpose of the invention]

The purpose of the present invention is to solve the above-mentioned problems, and in particular, to provide an ultraviolet ray that has good curing properties even after a long period of time has elapsed from application to irradiation with ultraviolet rays, and has an improved odor that is considered to be unpleasant. An object of the present invention is to provide a curable polyorganosiloxane composition.

[Structure of the invention]

In order to achieve these objectives, the present inventors conducted extensive research and found that polyvinylorganosiloxane containing a required amount of vinyl groups in the molecule, a peroxyester of an aliphatic alcohol having 5 or more carbon atoms, and a ketone. The present inventors have discovered that by adding a sensitizer such as the above, good curing properties can be maintained even after a long period of time has passed after application, and unpleasant odor can be improved, and the present invention has been completed.

That is, the present invention provides: (A) average composition formula % formula % (wherein R1 represents a substituted or unsubstituted monovalent hydrocarbon group excluding a vinyl group, a is 0.01≦a≦1, and b is 0≦
b<3, (a+b) is 1≦a+b≦3. 0.1 to 10.0 parts by weight of a peroxyester represented by an unsubstituted monovalent aliphatic hydrocarbon group, R3 represents a substituted or unsubstituted monovalent aromatic hydrocarbon group, and (C) The present invention relates to an ultraviolet curable polyorganosiloxane composition comprising 0.01 to 5.0 parts by weight of a sensitizer.

The polyorganosiloxane of component (A) in the present invention is represented by the above average compositional formula, where R' represents a substituted or unsubstituted monovalent hydrocarbon group other than a vinyl group; Alkyl groups such as methyl group, ethyl group, propyl group, butyl group, isobutyl group, amyl group, hexyl group, octadecyl group, allyl group, alkenyl group such as cyclohexenyl group, cycloalkyl group such as cyclopentyl group, cyclohexyl group , phenyl group, aryl group such as naphthyl group, aralkyl group such as benzyl group, β-phenylethyl group, alkaryl group such as tolyl group, xylyl group, mesityl group, or a part or all of the hydrogen atoms of these groups Groups substituted with halogen atoms, such as 3,3.3-trifluoropropyl L 3-chloropropyl group, chloromethyl group, chlorophenyl group,
Examples include dibromophenyl group.

In addition, in the present invention, all of the substituted or unsubstituted monovalent hydrocarbon groups (R') other than the vinyl group bonded to the silicon atom are methyl groups, or one consisting of a methyl group and a phenyl group. It is preferable that R1
When is composed of a methyl group and a phenyl group, the number of phenyl groups per silicon atom is in the range of 0.0001 to 0.1, preferably in the range of 0.0002 to 0.03.

By introducing phenyl groups, the photocuring time can be significantly shortened, especially when the siloxane coating is thin, but on the other hand, if the amount of phenyl groups is too large, the light transmittance of the siloxane will decrease. This is because it becomes difficult to obtain a relatively thick cured product.

The number a of vinyl groups per silicon atom in component (A) must be in the range of 0.01≦a≦1 as described above. a
If a is less than 0.01, the curability is insufficient, and if a is less than 1
Even if it exceeds 100%, not only will sufficient effects not be obtained, but it will also have an adverse effect on mechanical properties and heat resistance, making it undesirable. Further, the number of hydrocarbon groups other than vinyl groups is also within the range of 0≦b<3. In particular, the number of vinyl groups is preferably 50% or less of all organic groups, and the viscosity at 25°C is 10%.
It is preferable that the viscosity is 0 cSt or more, and a viscosity of less than 100 cSt is insufficient in terms of curability and properties of the cured product. In a region where the number of vinyl groups and the viscosity are not within the above range, the curing time becomes longer, the heat resistance deteriorates, and the cured product becomes brittle, as described above. In addition, from the viewpoint of ease of synthesis, heat resistance, flexibility, crosslinking efficiency, etc., the vinyl group is preferably 0.02 to 10% of the total organic groups, and the viscosity is preferably 500 cSt or more. .

(^) The structure of the main chain of the component may be linear, cyclic, or branched, and even a type of polyorganosiloxane may have two
It may be a mixture of more than one species.

The peroxyester of the component (B) in the present invention decomposes and generates radicals when irradiated with ultraviolet rays, resulting in the above (
A) It cures the component.

R2 in the formula imparts compatibility with the above polyorganosiloxane, is a substituted or unsubstituted monovalent aliphatic hydrocarbon group, and has a total number of carbon atoms in the range of 5 to 12. . There are no particular restrictions on the structure, but from the viewpoint of ease of synthesis and compatibility, the total number of carbon atoms is 5 to 8,
For example, tert-pentyl group, tert-hexyl group,
A tert-octyl group is preferred, but a tert-hexyl group is particularly preferred from the viewpoint of suppressing volatility and eliminating unpleasant odor.

Further, R3 in the formula is a substituted or unsubstituted monovalent aromatic hydrocarbon group, and is not particularly limited, but one having a benzene nucleus is preferable from the viewpoint of reaction efficiency.

The peroxyester of the present invention is compatible with the above-mentioned polyorganosiloxane and has no coloration, and includes tert-hexylperoxybenzoate, tert-hexylperoxybenzoate, and tert-hexylperoxybenzoate.
t-octylperoxybenzoate, tert-hexylperoxy-4-chlorobenzoate, tert-
hexylperoxy-2,4-dichlorobenzoate,
Examples include tert-hexylperoxy-4 nitruoate. Among these peroxyesters, tert-hexyl peroxybenzoate is particularly preferred because it is liquid, has excellent compatibility, is easy to synthesize, and has a low vapor pressure at room temperature.

The amount of peroxyester as component (B) is 0.1 to 10.0 parts by weight, preferably 0.1 to 5.0 parts by weight, per 100 parts by weight of component (A). If the amount is less than 0.1 part by weight, the curing speed will be slow and a sufficient crosslinked structure will not be obtained. Further, even if it is added in an amount exceeding 10.0 parts by weight, the expected effect cannot be obtained.

Component (C), the sensitizer, absorbs the energy of the irradiated ultraviolet rays and transfers it to the peroxyester, thereby helping to generate radicals in the peroxyester, effectively utilizing the light energy, and transmitting it to the peroxyester. It is added to efficiently cure. Particularly when curing thick films, it has the effect of improving the curing properties in the deep part of the film, and when used in combination with peroxyester, it is better to use peroxyester alone than alone.
It provides excellent results in terms of curing speed and properties of the cured product.

The sensitizer of the present invention includes hydrocarbons such as naphthalene and anthracene; nitrobenzene, p-nitrodiphenyl,
Amine, nitro, phenolic compounds such as p-nitroaniline, 2-chloro-4-nitroaniline, p-nitrophenol, 2,4.6-)linitrophenol;
benzaldehyde, acetophenone, benzophenone,
Examples include ketones such as benzinope p, p'-tetramethyldiaminobenzophenone; quinones such as benzoquinone, 1,2-naphthoquinone, and anthraquinone; and anthrones such as anthrone; carbonyl compounds are particularly preferred.

Specific examples of these carbonyl compounds include acetophenone and propiophenone. , benzophenone, 4.
4'-dichlorobenzophenone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether/lz, benzoin isopropyl ether, benzoin-n-butyl ether, penzoin isobutyl ether/
to4'-isopropyl-2-hydroxy-2-methyl-
Propiophenone, 2-hydroxy-2-methyl-propiophenone, p-dimethylaminoacetophenone, p
-tert-butyltrichloroacetophenone, p-t
Examples include ert-butyldichloroacetophenone, 2,2°-jethoxyacetophenone, penzyldimethylketanope 0-benzoylbenzoate, and the like. Among these, acetophenone, propiophenone, benzophenone, benzoin methyl ether, benzoin ethyl ether/lz from the viewpoint of compatibility with polyorganosiloxane and ease of blending.

Penzoin isopropylethenope Benzoin isobutylethenohe 4'-isopropyl-2-hydroxy-2
-Methyl-propiophenone, 2-hydroxy-2-methyl-propiophenone and methyl 0-benzoylbenzoate are particularly preferred.

The blending amount of the sensitizer as component (C) is 0.01 to 5.0 parts by weight, and 0.05 to 2 parts by weight per 100 parts by weight of component (A).
．． 0 parts by weight is preferred. If the amount is less than 0.01 part by weight, sufficient photocuring cannot be promoted, the curing speed is slow, and a sufficient crosslinked structure cannot be obtained, especially in thick films. Also, 5.
Even if it is added in an amount exceeding 0 parts by weight, no particular effect will be obtained, and on the contrary, too much light energy will be absorbed, slowing down the curing speed or inhibiting curing. In addition, cloudiness and poor dispersion may occur due to compatibility with polyorganosiloxane.

Component (C), the sensitizer, may be added alone or in combination of two or more, and liquid ones may be added as is or dissolved in another solvent 1, and solid ones may be added in a solvent or other solvent. It is preferable to dissolve it in another sensitizer or peroxyester, or to warm it above its melting point, to disperse it well in a portion of the polyorganosiloxane, and then add it.

The composition of the present invention is composed of a vinyl group-containing polyorganosiloxane as described above, a peroxyester, and a sensitizer, and is cured by irradiation with ultraviolet rays. Although there are no particular restrictions on the light source used, a high-pressure mercury lamp is preferred in practice.

In addition, in order to further improve the mechanical strength of the cured product,
If necessary, there is no problem in adding fumed silica, precipitated silica, calcined silica, silica aerogel, etc. These silicas may be used alone or in combination of two or more types, and It may be used as it is, or the surface may be treated with an organosilicon compound such as polydimethylsiloxane, octamethylcyclotetrasiloxane, or hexamethyldisilazane.

:Effects of the invention] The composition of the invention can coat and protect the joints of semiconductors,
As a semiconductor coating agent for resin-sealing semiconductor devices by methods such as potting, or as a temporary fixing material for temporarily fixing components in the assembly process of mounting various electrical components on hybrid integrated circuits and printed wiring boards. suitable for use. Since it cures well even if it is left for a long time after application and before irradiation with ultraviolet rays, the workability is significantly improved, and the unpleasant odor that was present in the past is also significantly reduced.

:Example] The present invention will be described below with reference to Examples. “Part” in Examples
All numbers indicate parts by weight.

Example 1 4 parts of tert-hexylperoxybenzoate were added to 100 parts of polydimethylsiloxane, which has a viscosity of 7.000 cSt at 25°C and contains 8.0 mol% of methylvinylsiloxy units, with both terminal ends of the molecule being capped with trimethylsilyl groups. Sample 1 was prepared by adding 1 part of benzophenone melted at 50° C. and uniformly dispersing the mixture using a universal kneader. This was applied to a thickness of 0.2 mm and 2 mm on a Teflon-coated stainless steel substrate, and after being left at room temperature for a predetermined period of time,
When irradiated with a 60 W/cm ozone-generating high-pressure mercury lamp (UV-7000, manufactured by Ushio Inc.) from a distance of 1 Q cm for 20 seconds, all of the materials were well cured and became rubber-like.

Table 1 shows the measurement results of each curing property when the coating was left for a predetermined period of time before being irradiated with ultraviolet rays after coating.

Comparative Example 1 The same polydimethylsiloxane 10 used in Example 1
Sample 2 was obtained by adding 4 parts of tert-butyl peroxybenzoate and 1 part of benzophenone to 0 parts and uniformly dispersing them using a universal kneader. This was applied on a Teflon-coated stainless steel substrate to the same thickness of <0.2 mm and 2.0 mm, and after being left for a predetermined time, UV irradiation was performed in the same manner as in Example 1. The results are shown in Table 1. That's right.

Table 1 O: Good curability △: Poor deep curability ×: Tacked Poor curing Example 2 80 parts of polydimethylsiloxane with a viscosity of 3.000 cSt at 25°C, both ends of the molecular chain blocked with dimethylvinylsiloxy groups and fumed silica (Aerosil 200,
Three parts of a filler (manufactured by Nippon Aerosil Co., Ltd.) whose surface had been treated with hexamethyldisilazane were uniformly dispersed using a universal kneader. This contains 2, which has both molecular chain ends blocked with trimethylsiloxy groups and contains 10 mol% of methylvinylsiloxy units.
Sample 3 was prepared by adding 20 parts of polydimethylsiloxane having a viscosity of 12.000 cSt at 5°C, 4 parts of tert-hexylperoxybenzoate, and 1 part of acetophenone and uniformly dispersing them. This was placed on a printed wiring board made by coating a glass epoxy board with a copper wiring pattern and solder resist, with film thicknesses of Q, 4 mm, and 2.5 m, respectively.
m, and after being left at room temperature for 48 hours, ultraviolet ray irradiation was performed in the same manner as in Example 1. Both the 0.4 mm thick and 2.5 mm thick coated areas cured well and became rubber-like in exactly the same manner as immediately after coating. It was also confirmed that it adhered well to the glass epoxy substrate, copper plating parts, and solder resist coated parts.

Comparative Example 2 Sample 4 was prepared by replacing the peroxy ester with the same amount of tert-butyl peroxy ester in the composition of Sample 3 in Example 2. After being left at room temperature for 48 hours after coating, it was irradiated with ultraviolet rays under the same conditions as in Example 1, and the 0.4 mm thick thin film part did not harden at all and became sticky.

In addition, the surface of the 2.5 mm thick coated area was well cured and rubber-like without any tackiness, but the interface with the substrate was partially uncured or gel-like and did not cure sufficiently. This was confirmed.

Example 3 60 parts of polydimethylsiloxane, which has a viscosity of 6.000 cSt at 25°C and contains 3 mol% of methylphenylsiloxy units and whose molecular chain ends are capped with dimethylvinylsilyl groups, was coated with octamethylcyclotetrasiloxane on the surface. 9 parts of treated fumed silica were uniformly dispersed in a universal mixer. To this, 40 parts of polydimethylsiloxane with a viscosity of 7.000 cSt at 25°C containing 30 mol% of methylvinylsiloxy units and 5 parts of tert-hexylperoxybenzoate, 50 parts of tert-hexylperoxybenzoate, 0.8 part of benzophenone, 0.4 part of 2-hydroxy-2-methyl-propiophenone (Darocurel 173, manufactured by Merck) and 0.4 part of polyethylene glycol (UNIOX US-5, manufactured by NOF Corporation), melted at 0.01°C. Sample 5 was obtained by adding 2 parts and uniformly dispersing it. This is a paste-like composition with no fluidity. It is applied to a paper-phenol substrate to an average Q of 5 mm thickness, and after being left at room temperature for 72 hours, it is applied to a rectangular chip of a tantalum electrolytic capacitor or a dress ceramic. When a round chip of a capacitor was placed on it and irradiated with ultraviolet rays under the conditions of Example 1, it was well cured and the chip component was fixed. The cured product was rubber-like and adhered well to the substrate and chip components.

Comparative Example 3 A composition was prepared as Sample 6 by replacing the peroxyester of Sample 5 of Example 3 with tert-butyl peroxybenzoate and excluding benzophenone and 2-hydroxy-2-methyl-propiophenone. This was coated on a paper phenol substrate with a thickness of 5mm.
When the chip component of Example 3 was placed on a product that had been left at room temperature for an hour and irradiated with ultraviolet rays under the conditions of Example 1, the chip component was not cured at all and only became sticky, unable to fix the chip component.

Example 4 50 parts of dimethylpolysiloxane having a viscosity of 1.000 cSt at 25°C and containing 5 mol% of methylphenylsiloxy units and having both terminal ends of the molecule blocked with dimethylvinylsilyl groups was treated with hexamethyldisilazane on its surface. Eight parts of fumed silica were uniformly dispersed using a universal mixer. In addition, the average composition is 2.7 mol% of trimethylsiloxy groups, 1.3 mol% of dimethylvinylsiloxy groups, 0.4 mol% of vinylmethylsiloxy groups, and 3.6 mol% of silicate groups (SiO□).
50 parts of a polyorganosiloxane consisting of 92 mole % of dimethylsiloxy groups were added uniformly. Furthermore, 4 parts of tert-octylperoxybenzoate, 1 part of benzophenone, and 0.15 part of the polyethylene glycol used in Example 3 were added to prepare Sample 7.

Coat this on a glass epoxy board to a thickness of 4 mm.
After 72 hours, ultraviolet rays were irradiated according to Example 1.
It cured well and became an elastomer. It also adhered well to glass epoxy substrates.

Comparative Example 4 The dialkyl peroxide 2,5-dimethyl-2,5-di(tert) was added to the base compound prepared in Example 4 in place of the peroxyester and benzophenone.
Sample 8 was prepared by adding 4 parts of (butylperoxy)hexyne-3 and uniformly dispersing the mixture. When this was coated on a glass epoxy substrate to a thickness of 0.4 mm and left for 48 hours, it was not cured by ultraviolet irradiation under the conditions of Example 1.

Reference example sample 1. 3. 5. 7 and 2. 4. The odor of Sample No. 6 was compared before and after UV irradiation. Table 2 shows the results of a survey conducted by 10 monitors, with unpleasant odors marked as C9, slightly unpleasant as B, and not so unpleasant as A. It was observed that unpleasant odor was improved in the examples according to the present invention.

Claims (1)

[Claims] 1 (A) Average composition formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R^1 is substituted or unsubstituted 1 excluding vinyl group)
represents a valent hydrocarbon group, a is 0.01≦a≦1, b is 0
100 parts by weight of a polyorganosiloxane represented by (B) the general formula R^2-O-O-C-O-R^3 (formula where R'' is a substituted or unsubstituted monovalent aliphatic hydrocarbon group having 5 to 12 carbon atoms, and R^3 is a substituted or unsubstituted monovalent aromatic hydrocarbon group. An ultraviolet curable polyorganosiloxane composition characterized by comprising 0.1 to 10.0 parts by weight of a peroxyester and (C) 0.01 to 5.0 parts by weight of a sensitizer. Claim 1: The polyorganosiloxane has a viscosity of 100 cSt or more at 25°C.
The polyorganosiloxane composition described in . 3. The polyorganosiloxane composition according to claim 1, wherein R^1 is a methyl group or a phenyl group. 4. The polyorganosiloxane composition according to claim 1, wherein R^2 is a tert-hexyl group or a tert-octyl group. 5. The polyorganosiloxane composition according to claim 1, wherein the peroxyester (B) is tert-hexyl peroxybenzoate or tert-octyl peroxybenzoate. 6. The polyorganosiloxane composition according to claim 1, wherein the sensitizer (C) is a ketone. 7. The polyorganosiloxane composition according to claim 1, wherein the sensitizer (C) is one or more selected from acetophenone, propiophenone, benzophenone, benzyl, benzoyl, and derivatives thereof.