JPH07214577A - Manufacture of electric equipment - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing electric equipment with excellent properties such as curability, crack resistance, thermal conductivity, ease of operation and breakdown strength. CONSTITUTION:A case storing the specified parts of electric equipment is filled with a filler with an average granular diameter of 300mum min. and a Fe2O3 content of 0.2wt.% max. Further, a thermocurable resin composition is injected at a degree of vacuum of 100Torr max to allow it to be cured.

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, cracking property, thermal conductivity, work rationalization, etc. can be improved, but there is a drawback that the withstand voltage characteristic is poor and it is difficult to apply 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, an average particle diameter is 300 μm in a case that accommodates predetermined parts of electric equipment.
After filling the above-mentioned filler having a Fe ₂ O ₃ content of 0.2 wt% or less, the thermosetting resin composition was added to 100 To
The present invention relates to a method for manufacturing an electric device, which is characterized by injecting at a vacuum degree of rr or less and curing.

The average particle size of the filler used in the present invention is 300 μm or more, preferably 600 to 1200 μm. The particle diameter 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 an unimpregnated part remains when the urethane resin composition or the epoxy resin composition is injected, and the thermal conductivity is lowered and the insulating property is also impaired. In addition, the filler is unevenly filled between the components, the coefficient of linear expansion of the entire device becomes non-uniform, peeling cracks occur around the coil and components during the heat cycle, and solder cracks occur at the solder joints of the board. . The content of Fe ₂ O ₃ in the filler used in the present invention is 0.2% by weight or less, preferably 0.1% by weight or less. Fe ₂ O ₃ is usually contained in the filler and it is difficult to completely remove it. However, in the present invention, a filler containing no Fe ₂ O ₃ can be used. When the Fe ₂ O ₃ content exceeds 0.2% by weight, the withstand voltage characteristic of the composition deteriorates and the insulating property of the device is impaired, so that it becomes difficult to apply it 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. Further, these fillers are preferably dried at 70 to 600 ° C. for the purpose of dehumidifying and dehydrating.
By subjecting the filler to a known iron removal treatment, the content of Fe ₂ O _{3 in} the filler can be reduced to 0.2% by weight or less. The use ratio of the filler is preferably in the range of 70 to 80% by weight based on the total amount of the filler and the thermosetting resin composition.

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 commercially available product, for example, trade name Poly bd R-45
HT, 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 reaction product of castor oil and a natural fat or oil having substantially no hydroxyl group.
IC Y-403, URIC H-31 (made by Ito Oil Co., Ltd.), etc. are mentioned. The urethane resin composition includes, for example, hexanediol, ethylene glycol, diethylene glycol, propylene glycol, octanediol,
It is also possible to use a low molecular weight polyol such as 2-ethylhexanediol, glycerin, pentaerythritol, or trimethylolpropane 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 addition product 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 fillers such as crystalline silica, fused silica, hydrated alumina, acid value alumina, talc, calcium carbonate, mica, glass beads, magnesium hydroxide and clay in order to improve the properties. May be used. 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, the electric device is filled with a filler in a case accommodating components such as an element, a substrate, a coil, and a lead wire, and the thermosetting resin composition is injected into the case at a vacuum degree of 100 Torr or less and cured. Obtained. When the degree of vacuum exceeds 100 Torr, the impregnating property of the resin composition into the filler decreases, the thermal conductivity decreases, and the insulating property deteriorates. As an electric device to which the present invention is applied, a plastic or metal case,
Transformers, solenoid coils, high-voltage transformers, electromagnetic clutches, ballasts, modules, igniters, controllers, regulators, which house electrical and electronic parts.
Examples thereof include electric devices such as airbag sensors, electric devices including a circuit board such as a ceramic substrate and a printed circuit board, and the like, and are particularly effective for application to high-voltage components.

[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 and kept at normal pressure and 80 ° C.
Cured 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.

[Equation 1] The model impregnation rate is obtained by determining the rate of impregnation of the resin composition into the filler, and the model impregnation rate is high and the impregnation rate is excellent when the filler in the unimpregnated portion is small.

(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, the resin composition was injected under a reduced pressure of 10 Torr, left at 10 Torr for 3 minutes, returned to normal pressure and cured at 80 ° C. for 6 hours. Then, the obtained model device was cut, and the impregnation state of the coil and the gap between the parts and the impregnation state of the resin composition with 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 / for a metal dish with a diameter of 60 mm
A 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 carry out JIS C 21
A heat cycle test was performed according to the heat cycle conditions of No. 05, the state of crack generation was observed, and the number of cycles in which cracks occurred 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, left under a reduced pressure of 10 Torr for 10 minutes, and cured at 80 ° C. under normal pressure for 3 hours to prepare a disc-shaped test piece having a diameter of 50 mm and a thickness of 10 mm, and conducting heat. The thermal conductivity (cal / cm · sec · ° C) was determined with a rate measuring device (manufactured by Dynatec). (5) Dielectric breakdown strength: 600 ° C in a mold adjusted to a thickness of 3 mm
The filler dried for 2 hours was cooled to 70 ° C. and filled with vibration. Next, the resin composition was injected under a reduced pressure of 10 Torr, left at 10 Torr for 3 minutes, returned to normal pressure and cured at 80 ° C. for 6 hours. Then, the ball-flat plate electrode was set on the obtained 3 mm-thick resin cured plate, and the breakdown voltage was measured in insulating oil for a short time. (6) Determination method of Fe ₂ O ₃ in the filler 30 g of the filler was put in a mortar and ground until it became fine powder of about 10 μm.
g is collected in a platinum crucible, 2 g of sodium carbonate is added thereto, and alkali melting is performed at a high temperature of 800 ° C. or higher. Then, the melt is dissolved in hydrochloric acid and then filtered, and Fe ions in the filtrate are measured by an atomic absorption method to calculate the amount of Fe ₂ O ₃ .

Examples 1 to 2 The filler ((B)) shown in Table 1 having an average particle size of 300 μm or more and a Fe ₂ O ₃ content of 0.2% by weight or less,
(C)) to produce a resin composition according to the formulation shown in Table 2,
The model impregnation rate of the resin composition, the impregnability into model equipment, the crack resistance, the thermal conductivity and the dielectric breakdown strength (withstand voltage characteristic) were examined according to the above-mentioned test method, and the results are shown in Table 2. From Table 2, it is shown that the resin composition is excellent in the model impregnation rate, the impregnation property in the model equipment, the crack resistance, the thermal conductivity, and the dielectric breakdown strength in each case.

Comparative Example 1 The characteristics were examined in the same manner as in Example 1 except that the filler (A) having a Fe ₂ O ₃ content of more than 0.2% by weight was used, and the results are shown in Table 2. However, the dielectric breakdown strength (withstand voltage characteristic) is reduced.

Comparative Example 2 The characteristics were examined in the same manner as in Example 1 except that the filler (D) having an average particle diameter of 200 μm was used, and the results are shown in Table 2. The impregnating ability of the equipment is significantly reduced.

Comparative Example 3 The characteristics of Example 1 were examined in the same manner as in Example 1 except that the filler was not used, and the results are shown in Table 2.
The crack resistance and thermal conductivity are extremely poor.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

According to the present invention, the filler in the case is uniformly and sufficiently impregnated with the thermosetting resin composition, and the cured product has no air bubbles and adheres well to parts, coils, etc. Similarly, it is possible to obtain an electric device exhibiting excellent impregnation property, adhesion property, and withstand voltage characteristic. 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.

Claims (1)

[Claims] 1. A thermosetting material after filling a filler containing a predetermined part of an electric device with a filler having an average particle diameter of 300 μm or more and an Fe ₂ O ₃ content of 0.2 wt% or less. Inject the resin composition at a vacuum degree of 100 Torr or less,
A method for manufacturing an electric device, which comprises curing.