JPH08294924A - Manufacture of electric apparatus - Google Patents

Abstract

PURPOSE: To provide a method for manufacturing an electric apparatus in which the apparatus having excellent thermal conductivity and heat cycling properties can be efficiently manufactured. CONSTITUTION: The method for manufacturing an electric apparatus comprises the steps of filling filler having large particle size in a case of mold containing a component, smoothing the filling surface, then pressure-reducing and casting epoxy resin composition containing filler having small particle size, and curing the composition.

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 which is capable of efficiently manufacturing an electric device having excellent thermal conductivity and heat cycle property.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing electric equipment, parts are set in a case or a mold, and an acid anhydride and its curing accelerator or amine compound are mixed with a uniform mixture of an epoxy resin and an inorganic filler. A potting method is known in which an epoxy resin composition is injected and cured under normal pressure or vacuum. However, in this method, there is a limit to the amount of the inorganic filler to be mixed from the viewpoint of viscosity at the time of mixing and injection workability, and the epoxy resin composition undergoes volume shrinkage during curing, thus causing a crack in the cured product, There is a problem that the built-in coil, parts and case are easily peeled or cracked, and the thermal conductivity is low, so that the temperature of the electric device becomes high and the temperature to be used is limited. Furthermore, since the injection work is performed after the epoxy resin composition and the inorganic filler are mixed and defoamed under reduced pressure, it is necessary to use one having a long curing time of the epoxy resin composition and a long curing time after the injection. There is a limit to the rationalization of work processes and energy saving.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a method of manufacturing an electric device which can efficiently manufacture an electric device excellent in thermal conductivity and heat cycle property. To do.

[0004]

According to the present invention, a case or a mold in which parts are housed is filled with a filler having a large particle diameter, the filling surface is made smooth, and then a filler having a small particle diameter is contained. The present invention relates to a method for manufacturing an electric device, which comprises injecting an epoxy resin composition under reduced pressure to cure the composition.

Hereinafter, a method for manufacturing an electric device according to the present invention will be described. First, a large particle size filler (hereinafter referred to as filler (A)) is filled in a case or a mold in which parts are stored. The filler (A) preferably has an average particle diameter of 100 μm or more, and particularly 200 to 2000 μm.
It is preferred that The average particle diameter of the filler (A) is measured according to JIS-Z2602-1976. If the average particle size is too small, especially 10
If it is less than 0 μm, the voids between the particles are small, so that the unimpregnated portion is likely to remain when the epoxy resin composition is injected, and the filler (A) is unevenly filled between the parts, so that the entire electric device The coefficient of linear expansion tends to be uneven,
In addition, peeling and cracks tend to occur during heat cycle, and the thermal conductivity tends to decrease. Examples of parts housed in the case or the mold include diodes, resistors, capacitors, coils, and the like. The type of the filler (A) used in the present invention is not particularly limited and, for example, silica sand, silica, alumina, clay, mica, glass beads and the like are used. Commercially available products include Pearl Sand No. 4, Pearl Sand No. 6, Mikawa Sisand V-3 (trade name of Tochu Co., Ltd.), Morundum-A (trade name of Showa Denko KK), GB-
Examples thereof include AG, GB-AC, GB-B (trade name of Toshiba Ballotini Co., Ltd.). These may be used alone or in combination.

Next, after smoothing the filling surface of the filler (A) filled by vibrating the case or mold or smoothing it with a spatula, the epoxy resin composition is decompressed under this. Inject. Regarding the irregularities on the filling surface of the filler (A), the difference between the highest part and the lowest part is preferably within 5 mm from the viewpoint of the impregnating property of the epoxy resin composition. Further, the amount of the epoxy resin composition to be injected is preferably such that the entire filler (A) is sufficiently impregnated with the epoxy resin composition.

The epoxy resin composition used in the present invention has a small particle size filler (hereinafter referred to as filler (B)).
Are mixed. The average particle size of the filler (B) is 50 μm
It is preferably the following or less, and particularly preferably 5 to 20 μm or less. The average particle diameter of the filler (B) can be measured using a sedigraph (manufactured by MICROMERI-TICS, manufactured by Shimadzu Corporation). If the average particle size of the filler (B) is too large, the filler (B) precipitates quickly during storage of the epoxy resin composition, making it difficult to obtain the desired epoxy resin composition. In addition, when the epoxy resin composition is injected onto the filler (A), unimpregnated portions tend to remain, the thermal conductivity tends to decrease, and the insulating property tends to be impaired. In addition, filler (B) between the parts
Are non-uniformly filled, so that the linear expansion coefficient of the obtained electric device becomes non-uniform, and peeling and cracks tend to occur during the heat cycle. Examples of the filler (B) include crystalline silica, fused silica, hydrated alumina, alumina oxide, talc, calcium carbonate, mica, glass beads, magnesium hydroxide and clay. The commercially available products include CRT-AA, CRT-D,
RD-8 (Tatsumori brand name), C-303H, C-31
5H, C-308 (trade name of Sumitomo Chemical Co., Ltd.), SL
-700 (trade name of Takehara Chemical Industry Co., Ltd.) and the like. The filler (B) is used alone or in combination of two or more kinds.

As the epoxy resin contained in the epoxy resin composition, an epoxy resin having at least one epoxy group in one molecule, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin. A polyglycidyl ether of polyhydric alcohol is used. Although these resins are not particularly limited, those which are liquid at room temperature are preferable, and commercially available products are Epicoat 828 (trade name of Yuka Shell Epoxy Co., Ltd.), GY-260 (trade name of Ciba-Geigy Co., Ltd.), and DER. -331 (trade name of Dow Chemical Japan Co., Ltd.) and the like. These can be used in combination. The epoxy resin may contain a reactive diluent such as polypropylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether and butanediol diglycidyl ether.

Further, in the epoxy resin composition, a curing agent, specifically an acid anhydride and a curing accelerator thereof, or an amino compound is used together with the epoxy resin. The acid anhydride is not particularly limited, but is preferably liquid at room temperature, and examples thereof include methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylendomethylenephthalic anhydride, dodecenylphthalic anhydride. Examples of commercially available products include HN-2200 (trade name of Hitachi Chemical Co., Ltd.) and QH-200 (trade name of Nippon Zeon Co., Ltd.). These may be used alone or in combination of two or more. The amount of the acid anhydride compounded is preferably 50 to 150 parts by weight, more preferably 70 to 100 parts by weight, based on 100 parts by weight of the epoxy resin.
Examples of the acid anhydride curing accelerator include 2-ethyl-4.
-Imidazole and its derivatives such as -methylimidazole, 1-cyanoethyl-4-methylimidazole and 1-benzyl-2-ethylimidazole, and tertiary amines such as trisdimethylaminophenol and benzyldimethylamine are used. 2E4MZ as a commercial product
(Shikoku Chemical Industry Co., Ltd. product name), BDMA (Kao Co., Ltd. product name) and the like. The compounding amount of these curing accelerators is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 3 parts by weight, per 100 parts by weight of the acid anhydride.

Examples of the amine compound include aromatic polyamines and modified products thereof, and aliphatic polyamines and modified products thereof. For example, an adduct of diaminodiphenylmethane and an epoxy resin is used. EH-5 as a commercial product
20 (Asahi Denka Kogyo KK product name), EH-551 (Asahi Denka Kogyo KK product name), Ancamine 2007 (Anchor Chemical Co., Ltd. product name) and the like. These can be used alone or in combination of two or more. The blending amount of these amino compounds is preferably 5 to 70 parts by weight, and more preferably 5 to 50 parts by weight, based on 100 parts by weight of the epoxy resin. The epoxy resin composition, 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 and the like. A colorant, a silane coupling agent, an antifoaming agent such as a silicone agent, a diluent such as a monoglycidyl ether or a diglycidyl ether, and the like can be added.

Next, the epoxy resin composition containing the above-mentioned epoxy resin, curing agent, filler (B) and the like is preheated at preferably 60 to 80 ° C., and after defoaming under reduced pressure of preferably 1 Torr or less, the filler is already added. It is injected into a case or a mold filled with (A) under a reduced pressure of preferably 20 Torr or less, and then preferably 60 to 150 ° C.
The electric device of the present invention can be obtained by heating and curing at (particularly preferably 80 to 120 ° C.) for 1 to 8 hours, or, when a mold is used, removing from the mold after curing. The electric device obtained by the manufacturing method of the present invention includes, for example, a transformer or a flyback transformer, a neon transformer, an ignition coil, or a caseless type transformer in which parts are housed in a case or a mold made of plastic or metal. Is mentioned.

[0012]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited thereto. Further, the measurement of the average particle diameter of the fillers (A) and (B) and the evaluation of various performances were performed by the following methods. (1) Average particle diameter of filler (A): JIS-Z260
The particle size distribution was measured according to 2-1976 "Method for testing particle size distribution of foundry sand", and the particle size when the cumulative weight% reached 50% by weight was taken as the average particle size. (2) Average particle size of filler (B): sedigraph 50
00EP (trade name, manufactured by Shimadzu Corporation), sodium hexametaphosphate having a starting particle diameter of 50 μm.
Filler (B) was added to a 1% by weight aqueous solution at a concentration of about 8% by weight, predispersed and ultrasonically cleaned for 20 minutes, and the particle size distribution was measured. When the cumulative% by weight was 50% by weight. The particle size was defined as the average particle size.

(3) Impregnating property with filler (A): diameter 6
Fill a 0 mm polyethylene beaker with shaking the filler (A). Next, the epoxy resin composition containing the filler (B) was heated to 60 ° C., defoamed at 0.5 Torr for 5 minutes, and then injected under a reduced pressure of 10 Torr.
After curing at 30 ° C. for 3 hours, it is cut in half perpendicular to the circumferential direction, and the impregnation state of the epoxy resin composition with respect to the filler (A) in the cross section is observed and evaluated according to the following criteria. did. ◯: The epoxy resin composition is impregnated between the particles of the filler (A). X: An unimpregnated part is recognized. (4) Heat transfer coefficient: Molded according to (3) above in a disk-shaped mold having a diameter of 50 mm and a thickness of 10 mm. The obtained disk was taken out and measured using a thermal conductivity measuring device (Cimatech manufactured by Dynatec Co., Ltd.). (5) Crack resistance: Tested according to the crack resistance test of JIS-C2105 "Test method for solvent-free liquid resin for electrical insulation". The number of crack test pieces was set to 5, a predetermined cooling / heating cycle was performed, and the presence or absence of cracks was confirmed for each cycle, and the number of cycles in which cracks first occurred was described. (6) Coefficient of linear expansion: 5 mm using a test piece for measuring thermal conductivity
A 5 mm × 5 mm test piece was cut out, and the linear expansion coefficient (° C. -1) was determined using a TMA thermophysical tester (manufactured by Rigaku Corporation).

Further, the materials used in Examples and Comparative Examples are as follows. (1) Filler (A) -Pearl Sand No. 4 (TOCHU CO., LTD. Trade name, silica sand: average particle size 417 μm) -GB-AC (Toshiba Ballotini Co., Ltd. product name, glass beads: average particle size 200 μm) EC-40 (trade name of Tokai Mineral Co., Ltd., crystalline silica:
Average particle diameter 40 μm) (2) Filler (B) -CW-308 (Sumitomo Chemical Co., Ltd. trade name, hydrated alumina: average particle diameter 8 μm) -EC-15 (Tokai Mineral Co., Ltd. trade name, crystals Silica: average particle diameter 15 μm) -EC-H (Tokai Mineral Co., Ltd. trade name, crystalline silica: average particle diameter 150 μm) (3) Epoxy resin: DER-331 (Dow Chemical Japan Co., Ltd. trade name) (4) Reactive diluent: polypropylene glycol diglycidyl ether manufactured by Asahi Denka Co., Ltd., trade name ED-506 (5) acid anhydride: HN-2200 (trade name of Hitachi Chemical Co., Ltd.) (6) curing accelerator: 2E4MZ-CN (Shikoku Chemicals
(Trade name)

Examples 1 to 4 Using the epoxy resin composition and the filler (A) in the formulations shown in Table 1 (the units of these formulations are "parts by weight"), the epoxy resin was prepared according to the test method of (3) above. Each property of the test piece obtained by impregnating with the resin composition and curing was examined. However, the thermal conductivity was measured as in (5) above, and the linear expansion coefficient was measured as in (6) above. The results are shown in Table 1. In all cases, the impregnating property of the filler (A) was good, the thermal conductivity was high, the linear expansion coefficient was small, and the crack resistance was also good.

Comparative Example 1 A test piece was prepared in the same manner as in Example 1 except that the filler (A) was not used, and the respective characteristics were examined. The results are shown in Table 2. The coefficient was low, the coefficient of linear expansion was small, and the crack resistance was poor. Comparative Example 2 The filler (A) filled in the case in Example 1
A test piece was prepared in the same manner as in Example 1 except that the filling surface was not flattened, and the respective properties were examined. The results are shown in Table 2. The impregnability of the epoxy resin composition with the filler (A) is shown in Table 2. Remarkably decreased.

Comparative Example 3 A test piece was prepared in the same manner as in Example 1 except that crystalline silica having an average particle size of 150 μm was used as the filler (B). Table 2
However, the impregnation property into the filler (A) was poor, the coefficient of linear expansion was large, and the crack resistance was also poor. Comparative Example 4 A test piece was prepared in the same manner as in Example 1 except that crystalline silica having an average particle size of 40 μm was used as the filler (A), and the respective properties were examined. The results are shown in Table 2. As shown, the impregnation property into the filler (A) was poor, the coefficient of linear expansion was large, and the crack resistance was also poor.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

According to the present invention, it is possible to efficiently manufacture an electric device having high thermal conductivity and excellent crack resistance.

Claims (1)

[Claims] 1. A case or mold in which parts are housed is filled with a filler having a large particle diameter, the filling surface is made smooth, and then an epoxy resin composition containing a filler having a small particle diameter is injected under reduced pressure. A method of manufacturing an electric device, which comprises curing by curing.