JPH0455483A - Heat-resistant and insulating varnish composition and formation of coating film using the same - Google Patents

Abstract

PURPOSE:To provide the subject composition composed of a main polymer liquid containing an organic polymer, a zirconium alkoxide, a silane coupling agent, etc., and useful for electrical and electronic parts or for imparting heat- resistance and electrical insulation to the parts. CONSTITUTION:The objective composition is composed of a main polymer liquid containing (A) an organic polymer such as polyamide imide or silicone resin, (B) a zirconium alkoxide, (C) a silane coupling agent such as gamma- glycidoxypropyl trimethoxysilane, (D) a catalyst for sol-gel process such as N,N-dimethylbenzylamine and (E) a solvent such as N,N-dimethylformamide.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a varnish composition that can impart heat resistance and electrical insulation to electrical or electronic equipment or their parts, and a coating using the same. The present invention relates to a method of forming.

(Prior art) Varnishes are widely used in electrical or electronic equipment to provide insulation or moisture-proofing properties or to form a protective film on the surface of the equipment or parts. and contributes to improved reliability. Organic varnishes are widely used because of their ease of operation and cost.

However, the polymer that is the main component of organic varnish is C-
Because it has a skeleton of C bonds or C-0-C bonds, it is easily oxidized or decomposed by heating, and its operating temperature limit is about 150°C. Therefore, in order to impart heat resistance to an organic varnish, it is necessary to add a flame retardant. Furthermore, as the temperature of organic varnish increases, its electrical insulation properties and high frequency characteristics become thicker (decreased).

In particular, organic varnishes have relatively low water repellency, making it difficult for absorbed moisture to be released (and the electrical properties are also significantly reduced. Furthermore, they are generally susceptible to organic solvents and chemicals, and are susceptible to deterioration by ultraviolet rays. .

As a varnish that compensates for such drawbacks of organic varnishes, there is a sulfur silicone varnish that has an inorganic part consisting of a siloxane bond (St-0-St) and an organic part consisting of a methyl group or a phenyl group. Although silicone varnishes have improved properties such as heat resistance, electrical properties, and water absorption compared to organic varnishes, their mechanical strength and chemical resistance are not sufficient. Furthermore, although silicone varnish is stable above 200"C, its stability at temperatures close to the melting point of solder, which is 26f)C, is insufficient. Silicone-based resins have a moisture resistance that is higher than that of epoxyphenol novolak. It is not preferable as a coating agent or sealant because it has a lower internal stress than other resins and a higher internal stress.

As the heat-resistant and insulating varnish, which is also currently preferred, there is a varnish containing polyimide resin as a main component. Polyimide resin has a glass transition temperature (Tg) of 240 to 25
Since the temperature is as high as 0°C, there is little deterioration in electrical properties at high temperatures, and the coefficient of thermal expansion is also small. Furthermore, it has high adhesion and hardness to conductors. However, it has drawbacks such as poor adhesion to copper foil, poor adhesion between layers made of the same type of resin, and high water absorption. Furthermore, since polyimide resin is very expensive, it poses a practical cost problem.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional drawbacks, and its purpose is to impart heat resistance and electrical insulation to electrical or electronic equipment or their parts. An object of the present invention is to provide a varnish composition capable of Still another object of the present invention is to provide a method for forming a film with excellent heat resistance and electrical insulation using the above-mentioned varnish composition.

(Means for Solving the Problems) The heat-resistant and insulating varnish composition of the present invention consists of a main polymer liquid containing an organic polymer zirconium alkoxide, a silane coupling agent, a sol-gel method catalyst, and a solvent. This achieves the above objective.

The heat-resistant and insulating varnish composition of the present invention may further contain a prepolymer liquid in addition to the main polymer liquid (the prepolymer liquid may contain zirconium alkoxide, a silane coupling agent, a titanium alkoxide, etc.). , a sol-gel process catalyst and a solvent.

The heat-resistant and insulating varnish composition of the present invention may be a mixture of the prepolymer liquid and the main polymer liquid.

Furthermore, the present invention provides a method for forming a heat-resistant and insulating film using a varnish composition comprising the main polymer liquid, comprising: applying the varnish composition to the surface of a substrate; The substrate to which the material was applied was heated to 150 to 3
forming a film on the surface of the substrate by heat treatment at a temperature in the range of 50°C, thereby achieving the above object.

Furthermore, the method of forming a film having heat resistance and insulation properties of the present invention includes applying the prepolymer liquid to the surface of the base material,
a step of forming a prepolymer layer on the surface of the base material; a step of applying the main polymer liquid to the surface of the prepolymer layer and forming a main polymer layer on the surface of the prepolymer layer; and the prepolymer layer. forming a film on the surface of the substrate by heat treating the substrate having the layer and the main polymer layer at a temperature in the range of 150 to 350°C;
, thereby achieving the above objective.

The organic polymer used in the main polymer liquid in the present invention is preferably an organic polymer with excellent heat resistance, such as polyamide-imide or silicone resin. Particularly suitable are polyamideimides having the following repeating units: When polyamideimide is used, 300
The coating changes color to black at high temperatures of around ℃. If it is necessary to avoid this discoloration, it is also possible to use silicone resin (silicone varnish). When silicone varnish is used in combination, the coating becomes slightly softer at high temperatures than when polyamideimide is used.

The zirconium alkoxide used in the main polymer liquid in the present invention is represented by Zr(OR')4. R
1 is a lower alkyl group. Specifically, Zr(0-C
H3)n, Zr(0-C2[s)4, Zr(0-fso
-C3Hv)4, Zr(0-C4H9)4, etc. may be used. Two or more of these alkoxides may be used in combination. The amount used is 100% of the above organic polymer.
It ranges from 1 to 20 parts by weight, preferably about 5 parts by weight. When 20 parts by weight or more is used,
The brittleness of the main polymer formed increases, and the main polymer layer of the coating is likely to peel off. If the weight is less than 1 weight, the coating is likely to be thermally deformed at high temperatures.

As the silane coupling agent used in the main polymer liquid, known silane coupling agents can be used.

Particularly suitable is a silane coupling agent having an epoxy group. These include, for example, γ-glycidodipropyltrimethoxysilane, γ-glycidoxypropylmethyljethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Two or more types of such silane coupling agents may be used in combination. The amount of the silane coupling agent used is within the range of 1 to 100 parts by weight based on 100 parts by weight of the organic polymer. When polyamideimide is used alone as the organic polymer, it is preferably 1 to 50 parts by weight, particularly about 10 parts by weight. If 50 parts by weight or more is used, the main polymer will have increased rigidity and brittleness, and the insulation and processability of the coating will decrease.

As the sol-gel method catalyst used in the main polymer liquid, a tertiary amine that is substantially insoluble in water and soluble in organic solvents is used. These include, for example, N,N-dimethylbenzylamine, tripropylamine, tributylamine, tripentylamine, especially N,N-
Dimethylbenzylamine is preferred. The amount used is 0.01 parts by weight of the total amount of organic polymer zirconium alkoxide and silane coupling agent.
~0.5 parts by weight, preferably about 0.03 parts by weight.

The main polymer liquid contains boric acid as necessary. By adding boric acid, the heat resistance and hardness of the resulting coating are significantly improved, and the coating is less likely to discolor when exposed to high temperatures. The content of boric acid is 15 parts by weight or less, preferably 05 to 6 parts by weight, based on ioo parts by weight of the organic polymer.

The solvent used for the main polymer liquid is N, N-
Dimethylformamide is preferably used.

The amount of solvent used is usually 100% of the total amount of the above ingredients.
It is 20 to 50 parts by weight per part by weight.

The main polymer liquid is prepared by mixing the organic polymer zirconium alkoxide, a silane coupling agent, a sol-gel method catalyst, and a solvent.

As the zirconium alkoxide used in the prepolymer liquid in the present invention, the same zirconium alkoxide as can be used in the main polymer liquid can be used.

As the silane coupling agent used in the prepolymer liquid, the same silane coupling agent as can be used in the main polymer liquid can be used. The amount of silane coupling agent used is 110 in total of the above alkoxides.
It is within the range of 1 to 10 parts by weight relative to 0 parts by weight.

The titanium alkoxide used in the prepolymer solution is designated Ti(OR2)4. R2 is a lower alkyl group theal. Specific Niha, Ti (0-CH3)4, Ti
(0-C2H5)4, Ti(0-C3HT)a, Ti(
0-C4H9)a, etc. may be used. Two or more of these alkoxides may be used in combination. By using titanium alkoxide, the thermal conductivity of the resulting coating is lowered, and the heat resistance of the base material is significantly improved. The amount used is in the range of 1 to 20 parts by weight, preferably about 3 parts by weight, based on 100 parts by weight of the zirconium alkoxide. When 20 parts by weight or more is used, the brittleness of the prepolymer increases and the prepolymer is likely to peel off. When the amount is 1 part by weight or less, the composite polymer becomes easily thermally deformed at high temperatures.

As the sol-gel method catalyst used for the prepolymer solution, the same sol-gel method catalyst as can be used for the above-mentioned main polymer solution can be used.

The amount used is o, oos to 0 per 100 parts by weight of the total amount of the alkoxide and silane coupling agent.
．． 3 parts by weight, preferably about 0.008 parts by weight.

Ethyl alcohol, isopropyl alcohol, butyl alcohol, etc. can be used as a solvent for the prepolymer liquid. The amount of the solvent used is 3 to 100 parts by weight based on the total IHoo parts by weight of the above-mentioned components.

The prepolymer liquid of the varnish composition of the present invention is prepared by mixing the above-mentioned zirconium alkoxide, a silane coupling agent, if necessary, a titanium alkoxide, a sol-gel method catalyst, and a solvent.

The varnish composition of the present invention may be a mixture of the main polymer liquid and the prepolymer liquid, if necessary.

The varnish composition of the present invention is a varnish for protecting various printed circuit boards, transistors, ICs, etc.; a varnish for coil impregnation for coating a coil with an insulating film; a binder for glass laminates and mica; a varnish for glass cloth; a varnish for printed circuit boards Adhesive for mounting devices on devices; Used in varnish for sealing semiconductor devices, etc. Therefore, various printed circuit boards, transistors 9, ICs, coils, glass, mica, etc. can be used as substrates that can be coated with the varnish composition of the present invention.

According to the method of the present invention, the heat-resistant and insulating coating of the present invention is formed, for example, as follows. First, a main polymer liquid is prepared by mixing the organic polymer zirconium alkoxide, a silane coupling agent, a sol-gel method catalyst, and a solvent. Next, this main polymer solution is applied to the surface of the base material on which a film is to be formed, or by immersing the base material in the polymer solution.
Apply to the base material and dry. As a result, hydrolysis and polycondensation reactions of the organic polymer zirconium alkoxide and the silane coupling agent proceed, and a layer of the main polymer is formed on the surface of the substrate. Preferably, this operation is repeated several times to form multiple layers. By stacking layers in this manner, the heat resistance and insulation properties of the final film are increased, and the breakdown voltage of the film is significantly increased. The base material on which one or more main polymer layers are formed in this way is heated to a temperature in the range of 150°C to 350°C for 30 minutes.
By heating for 0 seconds to I (1 minute), a heat-resistant and insulating film is formed on the substrate surface.

In the method of the present invention, before applying the main polymer liquid, the prepolymer liquid may be applied to the surface of the substrate to form a prepolymer layer, if necessary. To do this, first, the zirconium alkoxide, silane coupling agent, titanium alkoxide, sol-gel method catalyst, and solvent are mixed to prepare a prepolymer liquid. Next, this prepolymer liquid is applied to the base material, or the base material is immersed in the prepolymer liquid and then dried to form a prepolymer layer on the surface of the base material.

Next, a main polymer layer is formed on the prepolymer layer in the same manner as above. Preferably, this operation may be repeated several times to alternately laminate prepolymer layers and main polymer layers. By heating the base material on which the prepolymer layer and the main polymer layer are formed in this way at a temperature in the range of 150°C to 350°C for 30 seconds to 10 minutes,
A film having heat resistance and insulation properties is formed on the surface of the substrate.

Furthermore, the prepolymer liquid and the main polymer liquid are mixed, and this mixed liquid is applied to the base material at a temperature of 150°C to 350°C.
A film having heat resistance and insulation properties can also be formed by heating at a temperature in the range of 30 seconds to 10 minutes.

(Function) In the method of the present invention, when a main polymer liquid containing an organic polymer zirconium alkoxide, a silane coupling agent, a sol-gel method catalyst, and a solvent is applied to the surface of a substrate, moisture in the air is easily absorbed. hardens.

This is because alkoxides in the treatment liquid are hydrolyzed by moisture in the air, and due to the action of the sol-gel catalyst,
This is because protons are taken away from the generated hydroxyl groups, and the dehydration polycondensation reaction between the hydrolysis products proceeds. At this time, the silane coupling agent is also hydrolyzed at the same time, and the alkoxy group becomes a hydroxyl group. Due to the action of the catalyst, ring opening of the epoxy group also occurs, producing a hydroxyl group. Then, a polycondensation reaction between the hydrolyzed silane coupling agent and the hydrolyzed alkoxide proceeds. Organic polymers also participate in polycondensation reactions. For example, when polyamide-imide is used as an organic polymer, the protons of the amide group are removed by the action of a sol-gel catalyst, and a polycondensation reaction with hydrolyzed zirconium alkoxide and a silane coupling agent proceeds. Zr-0-N bonds and 5i-0-N bonds are generated. When the main polymer liquid contains boric acid, the B3'' ion of B2O3 attracts the non-crosslinked oxygen atoms of the silane coupling agent and metal alkoxide to form a tetrahedral [B04]. As a result, S 1-0-B and Zr-0-B bonds are formed, and the breaks in the glassy network structure of the main polymer silane and zirconium are sealed with tetrahedral [BOa]. As a result, heat resistance and hardness increase, and a film with excellent water resistance and oxidation resistance is obtained.The above reaction proceeds even at room temperature, but heat treatment accelerates it and ensures completion of the reaction. A film having excellent heat resistance and electrical insulation properties is then formed.

The film thus formed consists of an inorganic part derived from the inorganic skeleton of the zirconium alkoxide and the silane coupling agent, and an organic part derived from the organic polymer such as polyamideimide and the organic group (epoxy group, etc.) of the silane coupling agent. The parts are chemically bonded. The main polymer is basically a porous polymer made of inorganic parts or a giant polymer in which these are bonded three-dimensionally,
Furthermore, a plurality of these polymers aggregate to form a porous three-dimensional matrix. The pores of this porous polymer are filled with the organic portion of the composite polymer and have a dense structure in which the pores are sealed with the organic material. Furthermore, since the organic part is chemically bonded to the inorganic part, the organic part is less prone to deterioration or volume reduction even at high temperatures, and has excellent moisture resistance, solvent resistance, and chemical resistance. And because the coating effectively isolates the substrate from oxygen and chemicals, irreversible thermal degradation due to oxidation or other chemical reactions does not occur, even at high temperatures.

When a prepolymer layer is formed below the main polymer layer, the reaction proceeds as follows. First, when a prepolymer liquid containing zirconium alkoxide, a silane coupling agent, and titanium alkoxide is applied to a substrate, it absorbs moisture in the air and hardens easily. This is because the alcocyte in the prepolymer liquid is hydrolyzed by moisture in the air, and the same dehydration polycondensation reaction as described above proceeds. At this time, the silane coupling agent is also hydrolyzed and condensed with the alcocyte in the same manner as above. As a result, Zr-0-TisZr-0-
Si, Zr-0-C, Ti-0-C, Tf-0-Sf
A prepolymer is formed having bonds such as. Furthermore, this prepolymer is also bonded to metal atoms and inorganic atoms within the base material via oxygen atoms, so that it firmly adheres to the surface of the base material.

Next, when a main polymer layer is formed on the base material on which this prepolymer layer is formed in the same manner as described above, the main polymer also undergoes a dehydration polycondensation reaction with the alco-cows remaining in the prepolymer layer. The polymer layer and prepolymer layer are strongly bonded.

The film thus formed is made of a composite polymer in which a prepolymer and a main polymer are chemically bonded to each other. The prepolymer is -0-Sj-0-1-0-T
Since it contains an i-0- bond, there is almost no change in shape or dimension due to heat, and because it contains a Zr component, it has appropriate toughness. Furthermore, since the prepolymer liquid contains titanium alkoxide, the prepolymer has 0
-Ti-0 bond.

The 0-Ti-0 bond has good thermal conductivity, but prevents heat from being transferred to the base material when exposed to high temperatures, and provides the base material with good heat resistance.

As described above, the film of the present invention has both the heat resistance and insulation properties of the inorganic part and the flexibility of the organic polymer, so it has excellent heat resistance and electrical insulation properties, and is highly processable. . Furthermore, because it has low thermal conductivity and a dense bridge structure, it effectively blocks external high temperatures and chemical substances such as oxygen from the base material, giving the base material excellent heat resistance.

For example, when the heat-resistant and insulating film of the present invention is formed on a base material such as polyethylene terephthalate,
Even after being left in a silicone oil bath for 20 seconds, the base material showed no changes such as deformation, discoloration, or deterioration. Furthermore, even if left at 150°C for 30 minutes, there was no shrinkage or distortion.
．． 0.05% or less. As for the insulation properties of the film, the resistance is 109Ω and the dielectric breakdown voltage is 8000V or more.

In the varnish composition of the present invention, by changing the ratio of the organic part to the inorganic part, it is possible to obtain a film with characteristics depending on the intended use of the base material. For example, coatings for electrical parts are
In addition to heat resistance and electrical insulation, resistance to corona discharge and arc discharge is required. In order to obtain such a coating, it is preferable to increase the proportion of the inorganic part in the varnish composition.

Binder for Mica When used as an insulating coating for glass cloth, flexibility is required, so it is preferable to increase the proportion of the organic portion. As described above, the varnish composition of the present invention allows the properties of the coating to be easily adjusted depending on the use of the substrate, and can be used for a wide range of purposes.

(Example) The invention will be explained below with reference to examples.

EXAMPLE 1 In this example, the varnish composition of the present invention was used as a varnish for coil impregnation. First, the components shown below were mixed with stirring to prepare a prepolymer liquid.

0 titanium tetraisotubs
0.5i 1 Pro 8° Nord
46,5 Sotokel Process Catalyst A small amount of the above prepolymer solution was applied to a coil and dried to form a prepolymer layer.

Next, the following components were mixed with stirring to prepare a main polymer liquid.

Main polymer liquid component weight % Hon.
2.97 ethyl silica)
12.2
7 Zirconium Tetraphyte (Zr02)
10%) 1.89 toluene
18
．． 00 methyl booklum Tmid
19.28 Sotocale process catalyst
Continuous use of more than a trace amount was possible. When the electrical characteristics of the coating formed on the coil were evaluated, the results shown in Table 1 were obtained.

Table 1 This main polymer solution was applied to the surface of the coil on which the prepolymer was formed above. Further, the prepolymer liquid and the main polymer liquid were repeatedly applied several times, and the coil was heat-treated at a temperature of 120 to 170°C to obtain a coil coated with an insulating film.

Both of the above two types of polymer liquids had low viscosity and sufficiently penetrated into the inside of the coil, and a film was also formed on the surface of the conductive wire inside the coil. The obtained coil had good heat resistance and was heated at 250° C. to 300° C. for 20,000 hours. In this example, the varnish composition of the present invention was used as a varnish for mica. Varnishes for mica are required to be highly flexible and have excellent heat resistance.

A varnish composition was prepared by mixing the components shown below with stirring.

Ingredient weight% Main lyamide-imide compound xysolan carblinking agent (SH6040)
Ethyl silicate 31, 76 2, 10 6, 30 Table 2 Toluene methyl sulfur amide salt process catalyst 24, G.

24,04 Apply a small amount of the above varnish composition to mica and heat at 170 to 230°C.
was heated for 3 minutes. Table 2 shows the electrical properties of the obtained film.

(Left below) This example shows an example in which the varnish composition of the present invention was used for semiconductor coating. Semiconductor encapsulation varnishes must cure at relatively low temperatures, have high heat resistance, water resistance, and solvent resistance, have a small coefficient of thermal expansion, have good adhesion to semiconductor chips and lead frames, and have excellent dielectric properties. It is required that the ratio be low.

First, a varnish composition was prepared by mixing the components shown below with stirring.

(hereinafter "7-/i-li-Table 3
31.76 units Kinsilane fJ linking agent (SH6040) 1.90 Ethyl silicate
12.28 Silconium tetraphyte phenol solution (ZnO2to%)
1.89 toluene
26.83 dimethyl lumamide
27.00 Soluble process catalyst
A semiconductor element was sealed by a conventional method using a small amount of the above varnish composition. The obtained semiconductor device had excellent solvent resistance, and no problems such as softening of the film occurred even when heated to 80°C to 100°C. The electrical properties of the coating are shown in Table 3.

1) After being left at 85°C and 85% RH for 4 days.

A coil coated with an insulating film was obtained in the same manner as in Example 1, except that a prepolymer solution containing the components shown below was used as the prepolymer solution for the outermost layer of the clay.

(Left below) This Riamidoimidene xysilane cuff linking agent (SH6040
) 8.55 ethyl silicate
1.71 boric acid 4,27 dimethyl lumamide 2
7.00-inch Rouker process catalyst
It is possible to easily adjust characteristics such as trace amount.

Therefore, the varnish composition of the present invention can be suitably used for various types of electrical or electronic equipment.

that's all

Claims (1)

[Scope of Claims] 1. A heat-resistant and insulating varnish composition comprising a main polymer liquid containing an organic polymer, zirconium alkoxide, a silane coupling agent, a sol-gel method catalyst, and a solvent. 2. In addition to the main polymer liquid, it further contains a prepolymer liquid, and the prepolymer liquid contains a zirconium alkoxide, a silane coupling agent, a titanium alkoxide, a sol-gel method catalyst, and a solvent. The varnish composition described in . 3. The varnish composition according to claim 2, wherein the varnish composition is a mixture of the prepolymer liquid and the main polymer liquid. 4. The varnish composition according to claim 1 or 2, wherein the organic polymer is polyamideimide. 5. The varnish composition according to claim 1 or 2, wherein the main polymer liquid further contains boric acid. 6. The varnish composition according to claim 1 or 2, wherein the sol-gel catalyst is a tertiary amine that is substantially insoluble in water and soluble in organic solvents. 7. The varnish composition according to claim 6, wherein the sol-gel method catalyst is N,N-dimethylbenzylamine. 8. A method of forming a heat-resistant and insulating film using the varnish composition according to claim 1, comprising: applying the varnish composition to the surface of a substrate; A method for forming a heat-resistant and insulating film, the method comprising: forming a film on the surface of the base material by heat-treating the base material at a temperature in the range of 150 to 350°C. 9. A method of forming a heat-resistant and insulating film using the varnish composition according to claim 2, comprising applying the prepolymer liquid to the surface of the substrate, and applying the prepolymer layer to the surface of the substrate. a step of applying the main polymer liquid to the surface of the prepolymer layer to form a main polymer layer on the surface of the prepolymer layer; and having the prepolymer layer and the main polymer layer. A method for forming a heat-resistant and insulating film, comprising: forming a film on the surface of a base material by heat-treating the base material at a temperature in the range of 150 to 350°C.