JPH07246625A - Manufacture of electrical apparatus - Google Patents

Abstract

PURPOSE:To obtain an electrical apparatus, which is excellent in hardening properties, resistance to crack, thermal conductivity and insulating characteristics by a method wherein thermosetting resin composition is poured under reduced pressure in a case or mold, in which the predetermined part of an electrical apparatus is housed, after filler having the specified particle diameter is charged in the case or mold, and finally hardened. CONSTITUTION:After filler having the average particle diameter of 300-500mum is charged in a case or mold, in which the predetermined part of an electrical apparatus is housed, thermosetting resin composition is poured under the vacuum of 100Torr or less and hardend. As the filler, single such as silica sand, silica, alumina, hydrated alumina, clay, mica, glass beard or the like or mixture consisting of two or more of the singles just mentioned above are used. Further, the filler dried up to 70-600 deg.C is preferably used. The preferable thermosetting resin composition to be used is resin composition made of urethane, epoxy, unsaturated polyester, silicon or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electric device, and more particularly to a method for manufacturing an electric device having excellent curability, crack resistance, thermal conductivity, workability and withstand voltage characteristics.

[0002]

2. Description of the Related Art Conventionally, an electric device which has been subjected to an insulation treatment has parts such as coils and circuit parts set in a plastic case or a metal case, and a uniform mixture of a resin and an inorganic filler is injected into the case under atmospheric pressure or vacuum. It is manufactured by the potting method that cures and cures. However, in this method, there is a limit in the amount of the inorganic filler to be mixed from the viewpoint of workability, so that there is a drawback that the product price becomes high. Further, since volume contraction occurs when the resin composition is cured, cracks are generated in the cured product, and peeling or cracks are likely to occur in the built-in coil or other component. Further, since the thermal conductivity is poor, the temperature of the device becomes high, and there is a problem that the temperature to be used is limited. Furthermore, in order to perform the injection work after mixing the resin composition and the inorganic filler and defoaming under vacuum,
It is necessary to use a resin composition with a long curing time, the curing time after injection becomes long, and the work process is rationalized,
There is a limit to energy saving. Recently, as a method for solving the above-mentioned drawbacks, a method of filling a filler in advance and then injecting and curing the resin composition has been studied. According to this method, crack resistance, thermal conductivity, work rationalization, etc. can be improved, but it has a drawback that it is inferior in withstand voltage characteristics and is difficult to be applied to high voltage parts.

[0003]

SUMMARY OF THE INVENTION The present invention provides a method for manufacturing an electric device which is free from the above-mentioned drawbacks of the prior art and is excellent in curability, crack resistance, thermal conductivity and insulation characteristics.

[0004]

According to the present invention, a thermosetting resin composition is prepared by filling a case or a mold containing a predetermined part of an electric device with a filler having an average particle size of 300 μm or more and 500 μm or less. The present invention relates to a method for manufacturing an electric device, which is characterized by injecting at a vacuum degree of 100 Torr or less and curing.

The average particle size of the filler used in the present invention is 300 μm or more and 500 μm or less. The particle size is
It is measured according to JIS Z 2602-1976.
If the average particle size is less than 300 μm, the particles are fine and the gaps between the particles are small, so that the unimpregnated portion remains when the resin composition is injected, and the thermal conductivity decreases and the insulating property also deteriorates. Further, the filler is unevenly filled between the components, the coefficient of linear expansion of the entire device becomes non-uniform, cracks are generated around the coil and the components during the heat cycle, and solder cracks are generated in the solder joint portion of the substrate. When the average particle size is more than 500 μm, the crack resistance is poor because the ratio of the resin composition existing in the gaps of the filler is large, and the surface area of the filler is large and the withstand voltage characteristics are poor, and the insulating property of the device is poor. It becomes difficult to apply to high voltage parts. The type of filler is not particularly limited, and for example, silica sand, silica, alumina, hydrated alumina, clay, mica, glass beads, etc. may be used alone or in combination of two or more.
You may use these together. Examples of the filler having the above-mentioned average particle size used in the present invention include MINISPHE.
RES # 2500, MINISPHERES # 24
00 (both are manufactured by UNIMIN, USA) and the like. Further, these fillers are preferably dried at 70 to 600 ° C. for the purpose of dehumidifying and dehydrating.

The thermosetting resin composition used in the present invention is not particularly limited, but has excellent curability, high vapor pressure,
A urethane resin composition, an epoxy resin composition, an unsaturated polyester resin composition, a silicone resin composition, and the like, which have less volatile components under vacuum, are preferable. For the polyurethane resin composition, for example, a polyurethane resin obtained by reacting a polyhydroxy compound with a polyisocyanate is used. As the polyhydroxy compound, liquid polybutadiene-based polyol, polyester polyol, polyether polyol, acrylic polyol, castor oil or castor oil transesterification product, tall oil derivative and the like are used. The liquid polybutadiene-based polyol is preferably 1,4-polybutadiene-based polyol having a molecular weight of 700 to 8000, particularly 1000 to 3000.
As this commercial product, for example, the product name Poly bd R
-45HT, R-45M (made by Idemitsu Petrochemical Co., Ltd.), etc. are mentioned. Castor oil is a triglyceride containing ricinoleic acid (1,2-hydroxyoleic acid) as a main component and has a hydroxyl group of about 2.7 in the molecule. Examples of the commercially available product include URIC-H-28, CAO (made by Ito Oil Co., Ltd.) and the like. The castor oil transesterification product is a transesterification product of castor oil and a natural fat or oil having substantially no hydroxyl group, and as a commercially available product thereof, for example, trade names URIC Y-403 and URIC H-31 (manufactured by Ito Oil Co., Ltd.) Etc. The urethane resin composition includes
For example, a low molecular weight polyol such as hexanediol, ethylene glycol, diethylene glycol, propylene glycol, octanediol, 2-ethylhexanediol, glycerin, pentaerythritol, and trimethylolpropane can be used together as a diluent. Further, a plasticizer having no hydroxyl group, for example, phthalic acid ester such as dioctyl phthalate, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, phosphoric acid ester and the like can be used in combination.

Examples of polyisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, diphenyl sulfone diisocyanate, triphenylmethane diisocyanate, hexane methylene diisocyanate, 3-isocyanate methyl-3,
5,5-trimethylcyclohexyl isocyanate, 3
-Isocyanate ethyl-3,5,5-trimethylcyclohexyl isocyanate, 3-isocyanate ethyl-3,5,5-triethylcyclohexyl isocyanate, diphenylpropane diisocyanate, phenylene diisocyanate, cyclohexylylene diisocyanate, 3,3'-diisocyanate dipropyl ether,
Polyisocyanates such as triphenylmethane triisocyanate and diphenyl ether-4,4'-diisocyanate, or the above isocyanates are used as phenols, oximes, imides, mercaptans, alcohols,
Those blocked with ε-caprolactam, ethyleneimine, α-pyrrolidone, diethyl malonate, hydrogen sulfite, sodium, boric acid and the like are used. These may be used alone or in combination of two or more. Further, a polymer of diisocyanate, a modified product thereof, or the like can also be used. An example of these is the trade name MR-1.
00, MTL, etc.

The epoxy resin composition used in the present invention is an epoxy resin having at least one epoxy group in one molecule, for example, a bisphenol A type epoxy resin,
Bisphenol F type epoxy resin, Bisphenol AD
Type epoxy resin, polyglycidyl ester of polyhydric alcohol and the like. Although these resins are not particularly limited, those which are liquid at room temperature are preferable, and commercially available products include Epicoat 828 (trade name of Shell Chemical Co., Ltd.) and GY.
-260 (Ciba Geigy product name), DER-331
(Trade name of Dow Chemical Co.) and the like. These can also be used in combination. You may use diethylene glycol monoglycidyl ether, diethylene glycol diglycidyl ether, polypropylene glycol, etc. as a diluent. An acid anhydride and a curing accelerator or an amine compound are used as a curing agent for these epoxy resins.

The acid anhydride is not particularly limited, but those which are liquid at room temperature are preferable, for example, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylendomethylenephthalic anhydride, dodecenylphthalic anhydride and the like are used. To be Examples of commercially available products include HN-2000 (trade name of Hitachi Chemical Co., Ltd.) and QH-200 (trade name of Nippon Zeon Co., Ltd.). These can also be used in combination.
The compounding amount of the acid anhydride is preferably 50 to 150 parts by weight with respect to 100 parts by weight of the epoxy resin. Examples of acid anhydride curing accelerators include 2-ethyl-4-methylimidazole, 1-cyanoethyl-4-methylimidazole, and 1-cyanoethyl-4-methylimidazole.
Imidazole and its derivatives such as benzyl-2-ethylimidazole, and tertiary amines such as trisdimethylaminophenol and benzenmethylamine are used. Examples of commercially available products include 2E4MZ, 2E4MZ-CN (both are trade names manufactured by Shikoku Kasei Co., Ltd.), and BDMA (trade name manufactured by Kao Co.). The compounding amount of the curing accelerator is preferably 0.1 to 5.0 parts by weight per 100 parts by weight of the acid anhydride.
Examples of the amine compound include aromatic polyamines, modified products thereof, aliphatic polyamines, modified products thereof, bisspirocyclic diamine or derivatives thereof, and for example, an adduct of diaminodiphenylmethane and an epoxy resin is used. Examples of commercially available products include EH-520 (trade name of Asahi Denka Co., Ltd.), EH-551 (trade name of Adeka Co., Ltd.), Ancamine 2007 (manufactured by Anchor Chemical Co., Ltd.) and the like. These can also be used in combination. The blending amount of the amine compound is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the epoxy resin. As the unsaturated polyester resin composition,
For example, an unsaturated polybasic acid or anhydride thereof and an esterification product of a saturated polybasic acid or anhydride thereof and glycols, to which a crosslinking agent such as a vinyl monomer and a peroxide which is a curing agent are added are used. . As the cross-linking agent, those having a high vapor pressure with a small amount of volatile components under vacuum are preferable. As the silicone resin composition, for example, a silicone polymer having a siloxane bond, an alkoxide resin, an acrylic resin, an epoxy resin, a polyester resin,
A compound obtained by adding a curing agent such as peroxide and a curing initiator such as a platinum compound to a compound obtained by copolymerizing or mixing with a thermosetting resin such as urethane resin is used.

The thermosetting resin composition contains a filler such as crystalline silica, fused silica, hydrated alumina, alumina oxide, talc, calcium carbonate, mica, glass beads, magnesium hydroxide and clay in order to improve the properties. You may use. In addition, if necessary, red phosphorus, hexabromobenzene, dibromophenyl glycidyl ether, dibromocresyl glycidyl ether, flame retardants such as antimony trioxide, red iron oxide, ferric oxide, carbon, titanium white, etc. Various additives such as a foaming agent and a silane coupling agent can be blended. In the present invention, an electric device is filled with a filler in a case or a mold in which parts such as elements, substrates, coils, and lead wires are housed, and the thermosetting resin composition is placed in a vacuum degree of 100T.
It is obtained by injecting at or below orr and curing. Vacuum degree is 10
When it exceeds 0 Torr, the impregnating property of the resin composition into the filler is lowered, the thermal conductivity is lowered, and the insulating property is impaired. The electric equipment to which the present invention is applied includes a transformer or solenoid coil, a high-voltage transformer, an electromagnetic clutch, a ballast, a module, an igniter, a controller, a regulator, or an air, in which a plastic or metal case stores electrical parts and electronic parts. Store electrical and electronic components in electrical equipment such as back sensors, circuit boards such as ceramic boards and printed boards, and molds made of aluminum, etc., and remove them after curing under the above conditions. Examples of the mold-type electrical equipment such as the above transformers are also included. Of these, application to high-voltage parts is particularly effective.

[0011]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. The characteristics were evaluated by the methods shown below. (1) Model impregnation rate: A polyethylene beaker having a diameter of 50 mm was filled while vibrating the filler, and then weighed to obtain the weight (W ₀ g) of the filler. Next, the resin composition was injected, and the mixture was left under a reduced pressure of 10 Torr for 10 minutes,
Cured at 80 ° C. for 3 hours. Then, the cured product was taken out from the polyethylene beaker, the weight (W ₁ g) of the filler separated from the cured product without impregnating the lower resin composition was calculated, and the model impregnation rate was calculated from the following equation.

## EQU00001 ## Model impregnation rate (%) = [(W ₀ −W ₁ ) / W ₀ ] × 100 The model impregnation rate is to determine the rate of impregnation of the resin composition into the filler. When the amount of the filler is small, the model impregnation rate is high, indicating that the impregnation property is excellent.

(2) Impregnation into model equipment: A model equipment in which a primary coil, a secondary coil and parts are housed in a metal case is filled with 70% of filler dried at 600 ° C. for 2 hours.
The temperature was lowered to 0 ° C. and filling was performed while shaking. Next, after injecting the resin composition under a reduced pressure of 10 Torr, 10 Torr
The mixture was left standing at r for 3 minutes, returned to normal pressure and cured at 80 ° C. for 6 hours. Then, the obtained model device was cut, and the state of impregnation in the gap between the coil and the part and the state of impregnation of the resin composition in the filler were observed, and evaluated as follows. ◯: The gap between the coil and the component is impregnated, and the filler is impregnated with the resin composition. Δ: Some unimpregnated portion of the resin composition remains in the filler. X: A considerable amount of unfilled portion of the resin composition remains in the filler. (3) Crack resistance: 1 on a metal dish having a diameter of 60 mm
A 1 / 2-inch iron spring washer was set, and the resin composition was injected to the upper end of the washer and cured to obtain a test piece. After that, remove the metal petri dish and JIS C
A heat cycle test was performed in accordance with the heat cycle conditions of No. 2105, the crack generation state was observed, and the number of cycles in which cracks were generated was shown.

(4) Thermal conductivity: A polyethylene beaker having a diameter of 50 mm was filled with the filler while vibrating. Next, the resin composition was injected, and the mixture was left under a reduced pressure of 10 Torr for 10 minutes, and cured at 80 ° C. under normal pressure for 3 hours.
mm, 10 mm thick disc-shaped test piece was prepared, and the thermal conductivity (cal / c) was measured with a thermal conductivity measuring device (manufactured by Dynatec).
m · sec · ° C.) was calculated. (5) Withstand pressure life time: 120 for a die adjusted to a thickness of 3 mm
The filler dried at 12 ° C. for 12 hours was cooled to 70 ° C. and filled with vibration. Next, 10 Torr of resin composition
After injection under reduced pressure of r, leave at 10 Torr for 3 minutes,
The mixture was returned to normal pressure and cured at 80 ° C. for 6 hours. Then, the column-plate electrode was set on the 3 mm thick resin cured plate obtained,
The breaking time of the cured product was measured under the conditions of 80 ° C., 1 kHz and 18 kV.

Examples 1 to 3 Table 1 having an average particle size of 300 μm or more and 500 μm or less
The resin composition prepared by using the fillers ((D) and (E)) shown in Table 1 and having the composition shown in Table 2 was used, and the model impregnation rate of the resin composition and the impregnability into model equipment according to the test method were used.
The crack resistance, thermal conductivity, and withstand voltage life time (withstand voltage characteristics) were examined, and the results are shown in Table 2. From Table 2, it is shown that these characteristics are excellent in any of the examples.

Comparative Examples 1 to 3 In Example 1, resin compositions prepared by using the fillers ((A), (B) and (C)) having an average particle size of more than 500 μm and having the formulations shown in Table 2 are used. The characteristics were examined in the same manner as in Example 1 except for the fact that the results were shown in Table 2. However, the crack resistance and the withstand voltage life time (withstand voltage characteristics) were deteriorated.

Comparative Example 4 The characteristics were examined in the same manner as in Example 1 except that the filler (F) having an average particle diameter of 200 μm was used and the resin composition prepared according to the formulation shown in Table 2 was used. The results are shown in Table 2, and the model impregnation rate and the impregnability into the model equipment are significantly reduced.

Comparative Example 5 In Example 1, the characteristics were examined in the same manner as in Example 1 except that the filler was not used and the resin composition prepared by the formulation shown in Table 2 was used, and the results are shown in Table 2. However, the crack resistance and the thermal conductivity are remarkably inferior.

[0018]

[Table 1]

[0019]

[Table 2] * 1 Ep-828: Bisphenol A type epoxy resin:
Yuka Shell Co., Ltd. * 2 HN-2000: Methyltetrahydrophthalic anhydride: Hitachi Chemical Co., Ltd. * 3 C2E4MZCN: 1-Cyanomethyl 2-ethyl 4
Methylimidazole: Shikoku Kasei Co., Ltd. * 4 KBM-403: γ-glycidoxypropyltrimethoxysilane: Shin-Etsu Silicone Co., Ltd. * 5 C-308: Aluminum hydroxide: Sumitomo Chemical Co., Ltd.

[0020]

According to the present invention, the thermosetting resin composition is uniformly and sufficiently impregnated into the filler in the case or the mold,
There are no bubbles in the cured product, and parts, coils, etc. adhere well, and it is possible to obtain an electric device exhibiting excellent impregnation and adhesion as in the conventional potting method. In addition, in the conventional potting method, a filler of 1.0
The use ratio of the resin composition with respect to was limited to 0.4 by weight ratio, but according to the present invention, the amount of the filler can be made larger than this, so that the total cost can be reduced, and at the time of curing. Curing shrinkage and thermal expansion are small, and crack resistance, thermal conductivity of the cured product, and heat cycle property are improved.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B29L 31:34

Claims (1)

[Claims] 1. An average particle diameter of 300 μm or more and 500 μm in a case or a mold containing a predetermined part of an electric device.
A method of manufacturing an electric device, comprising filling a thermosetting resin composition with a degree of vacuum of 100 Torr or less and curing it after filling m or less filler.