JP2002343905A - Resin-molded circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that warp occurs in the conventional resin- molded circuit device due to the thermal expansion difference between the material of a molded part and the insulation board having one surface molded, thus cracking the insulation board to result in poor insulation. SOLUTION: The circuit device is structured such that the most portion of a circuit board is molded with an elastic resin except its one surface, and only molded portions enclosing fixed parts of terminal fixtures for fixing the board to a wiring conductor layer are molded with a rigid resin, thus making the elastic resin molded portions absorb a bending force due to the shrinkage difference between the board and the mold resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a resin mold for a circuit device having a circuit board, a circuit element and a circuit terminal fitting.

[0002]

2. Description of the Related Art FIG. 3 shows a cross-sectional view of a conventional circuit device.
A conventional structure will be described with reference to FIG. Four terminal fittings are fixed to the wiring conductor layer 2 of the circuit board 3 by soldering or brazing. The circuit element 5 is connected by the wiring conductor layer 2 to form an electronic circuit, and a portion of the terminal fitting 4 for connecting the circuit to the outside, which is fixed to the circuit board, is made of a highly rigid insulating material such as epoxy resin. Molded to be embedded in The insulating substrate is, for example, an alumina ceramics plate, and the wiring conductor layer 2 made of copper foil is fixed to form a circuit substrate 3. The terminal fitting 4 is formed of an L-shaped copper plate, the horizontal portion is fixed to the wiring conductor layer 2, and the vertical portion is provided with a lead wire for connection to the outside.
The circuit element 5 is connected to the wiring conductor layer 2 by soldering or bonding wire to form an electronic circuit such as an inverter, for example. Since power is taken out, the terminal fittings are required to have mechanical fixing strength. One side of the entire circuit device is molded with the same resin for the purpose of covering the fixing portion of the terminal fitting for the purpose of reinforcing the mechanical fixing and at the same time dustproofing and moistureproofing the entire circuit device. Since the insulating substrate has become larger due to the increase in the scale of the circuit device, the bending force caused by the difference in the thermal expansion coefficient between the mold resin and the ceramic substrate that are in close contact with each other causes cracks 23 to be generated in the insulating substrate, and moisture in the outside world is reduced. It may penetrate and cause insulation failure, causing a decrease in reliability.

[0003]

The bending force generated by the difference in the thermal expansion coefficient between the resin mold and the insulating substrate that are in close contact with each other prevents the insulating substrate from cracking.
An object of the present invention is to improve a resin mold.

[0004]

A circuit device having circuit elements and terminal fittings on a surface of a circuit board having a wiring conductor layer fixed to an insulating substrate, wherein the circuit element and terminal fittings are fixed to the wiring conductor layer. Then, an electronic circuit is formed by the circuit element and the wiring conductor layer, and the surface of each fixing portion between the terminal fitting and the wiring conductor layer and the end surface of the circuit board are connected and covered, so that the fixing force between the terminal fitting and the circuit board is formed. A circuit device molded by a rigid resin mold portion formed to reinforce the resin, and an elastic resin mold portion complementarily molded with a highly elastic resin so as to cover all the other surfaces of the circuit board portion I do. According to the second aspect, the rigid resin molded portion is a portion fixed to the wiring conductor layer, the surface of the horizontal portion of the terminal fitting, the strip-shaped peripheral portion extending to the horizontal portion between the terminal fittings on the extension, and the entire peripheral end surface of the circuit board. 3. The resin-molded circuit device according to claim 1, wherein the resin-molded circuit device is a rigid resin molded portion formed so as to be surrounded by a frame.

The rigid resin mold portion is mainly formed near the periphery of the insulating substrate. Most of the other resin mold parts are elastic and molded with a flexible resin such as polyurethane resin so as not to give a bending force due to contraction after thermal expansion to the insulating substrates that are in close contact with each other. The main purpose of the resin molded part is to prevent moisture and contaminants from adhering between the circuit element and the wiring conductor layer and the circuit board.

[0006] As described above, the circuit is divided into a rigid resin mold portion mainly intended to enhance the mechanical fixing force and another elastic resin mold portion having a large area, and the circuit is formed of materials having different mechanical properties. Since the entire surface of the substrate was complementarily molded, a resin mold was achieved that achieved the objectives of each part and eliminated the disadvantages of cracks caused by the conventional ceramic plate curvature.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. Reference numeral 1 denotes an insulating substrate to which a circuit conductor layer 2 is fixed to form a circuit board 3. Reference numeral 4 denotes a terminal fitting, which is fixed to the wiring conductor layer 2 by soldering or brazing. A circuit element 5 is connected to the wiring conductor layer 2 by soldering 6 and bonding wires 7 to form an electronic circuit, and a circuit terminal fitting 4 for connecting to each part of an electric component in a housing incorporating the electronic circuit. Is molded in such a manner that a portion fixed to the wiring conductor layer 2 is embedded in a highly rigid insulating material such as an epoxy resin, and this is referred to as a rigid molded portion 21. The insulating substrate 1 is, for example, an alumina ceramic plate having a thickness of about 0.6 mm, and a wiring conductor layer 2 made of a copper foil having a thickness of about 0.2 mm is fixed with an inorganic binder to form a circuit board.
The terminal fitting 4 is formed, for example, of an L-shaped copper plate having a thickness of about 0.8 mm and a width of 10 mm, a horizontal portion thereof is fixed to the wiring conductor layer 2 by brazing or the like, and a vertical connection portion has a lead wire for connection. Is attached with screws. Such a circuit device is, for example, an inverter or the like having a power control function. DC 48 V, 100 A is supplied to the DC input terminal, and constant voltage control is performed from the AC output terminal to AC 100 V plus and minus 1 V. AC power can be extracted. In this way, the terminal fitting 4 for flowing a large current is thick,
Since a somewhat hard external lead wire is connected, the fixing portion of the terminal fitting also requires mechanical fixing strength.

In the above embodiment, at least the surface of each fixing portion between the terminal fitting 4 and the wiring conductor layer 2 and the end face 8 of the circuit board are connected and covered, so that the fixing force between the terminal fitting and the circuit board is enhanced. Rigid resin mold part 2 formed so that
1 is a complementary mold formed by an elastic resin mold portion 22 which reinforces the mechanical strength of the fixing portion and covers all other surfaces of the circuit board with a highly elastic resin for the purpose of dustproofing and waterproofing. In the complementary mold forming process, first, the terminal fitting 4 and the electronic component 5 are placed on the surface of the surface plate jig.
Is fixed to the wiring conductor layer 2 and the circuit board on which the electronic circuit is formed is pressed and placed, and the outer periphery of the peripheral end face 8 of the circuit board is surrounded by a female mold while maintaining a gap of, for example, 5 mm. While maintaining a gap of, for example, 5 mm in a shape surrounding the space 4, an insulating material, such as an epoxy resin, which becomes a rigid resin when cured, is injected into the gap, and after curing, the core alone is removed, and a polyurethane resin is filled and a complementary mold is filled. To form The female mold and the cured epoxy resin form a mold, and the filled elastic resin is molded.

According to the second aspect, as shown in FIG. 2, the rigid resin mold portion 21 is provided on the surface of the horizontal portion of the terminal fitting which is the portion fixed to the wiring conductor layer and on the horizontal portion between the terminal fittings on the extension thereof. It is formed so as to fill the entire belt-like peripheral portion 9 and the entire peripheral end surface 8 of the circuit board 3 and surround it in a frame shape. The rigid resin mold portion 21 mainly includes the insulating substrate 1.
Is molded in the vicinity of the periphery, and most of the other parts are molded with a resin having a high elasticity and a flexible material such as polyurethane resin so as not to apply a bending force due to shrinkage to the insulating substrates 1 which are in close contact with each other. The portion 22 of the elastic resin mold is mainly intended to prevent moisture and contaminants from adhering between the circuit element and the wiring conductor layer and the circuit board. As described above, the rigid resin mold portion 21 mainly intended to enhance the mechanical fixing force
And the elastic resin mold portion 22 of the other large area are divided to form a circuit device in which one side of the circuit board is formed by complementary molding with materials having different mechanical properties.

[0010]

A rigid resin mold portion for embedding and reinforcing the terminal fittings, and an elastic resin mold portion having high elasticity for dampproofing and dustproofing the circuit element and the wiring conductor layer, in place of the conventional molding using the same resin material. Since there is no need to perform rigid resin molding on the entire surface, no bending force is generated on the insulating substrate, and no crack is generated due to this. According to the present invention, it contributes to the improvement of the reliability of the resin-molded circuit device.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing another embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a structure of a conventional circuit device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating board 2 Wiring conductor layer 3 Circuit board 4 Terminal metal fittings 5 Circuit element 6 Soldering 7 Bonding wire 8 Circuit board end face 9 Strip-shaped peripheral part 21 Rigid resin molded part 22 Elastic resin molded part 23 Crack

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hidehisa Tachibana 3-1-156 Nishi-Awaji, Higashi-Yodogawa-ku, Osaka-shi, Osaka Inside Sansha Electric Works, Ltd. (72) Inventor Seiji Tanaka Nishi-Higashi-Yodogawa-ku, Osaka-shi, Osaka No. 3-56, Awaji F-term in Sansha Electric Manufacturing Co., Ltd. (reference) 4F206 AA39 AA42 AD03 AD19 AG03 AH33 AM32

Claims (2)

[Claims] 1. A circuit device comprising a circuit board, a circuit element, and a terminal fitting, wherein the circuit board has a wiring conductor layer fixed to a surface of an insulating substrate, and the circuit element and the terminal fitting are attached to the wiring conductor layer. A rigid resin mold forming portion that covers the circuit board end face and a fixed portion between each of the terminal fittings and the wiring conductor layer to form an electronic circuit by the circuit element and the wiring conductor layer; and a portion other than the rigid resin mold portion. And a resilient resin mold portion covering one side of the circuit board. 2. A rigid resin molded part includes a strip-shaped peripheral portion extending from a surface of a horizontal portion of a terminal fitting, which is a fixed portion to a wiring conductor layer, to a horizontal portion between terminal fittings on the extension, and an entire peripheral end surface of a circuit board. 2. The resin-molded circuit device according to claim 1, wherein the resin-molded circuit device is a rigid resin molded portion formed so as to surround the frame.