JPS5835377B2 - Electronic device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an electronic device, such as a solid-state relay, which includes a heat generating semiconductor element such as a triac.

The heat generating semiconductor element is usually fixed to a heat sink in order to enhance the heat dissipation effect.

By the way, conventionally, in order to manufacture this type of electronic device, first, as shown in FIG. 4a, using molding molds 41 and 42,
After the heat dissipation plate 43 is attached to the case 44 by insert molding and the case 44 is extracted from the mold 41, 42, the heat generating semiconductor element 46 is attached via a metal adhesive 45 such as solder as shown in FIG. 4b. is fixed to the heat sink 43.

However, with the above manufacturing method, when fixing the element 46 to the heat sink 43 using the metal adhesive 45 as shown in FIG. 4b, heat is applied to melt the metal adhesive 45. This causes distortion and deformation in the molded resin constituting the case 44, resulting in a disadvantage that the commercial value is reduced and the airtightness between the case 44 and the heat sink 43 is impaired.

In other words, in order to properly dissipate heat, the heat dissipation plate 43
The heating element 46 must be set on the heat sink 43 with the fixed peripheral portion of the heating element 46 spaced apart from the bottom edge of the case 44 .

Moreover, in order to increase the effective heat radiation area of the heat sink 43,
External exposed area should be maximized.

In this way, when the number of externally exposed parts is increased, the holding area between the heat sink 43 and the case 44 becomes smaller, and the holding strength of the heat sink 43 becomes weaker.

When the heating element 46 is bonded to such a heat sink 43 with a weak holding strength with the metal adhesive 45, the heat sink 43 and the case 44 are bonded together.
The joint portion between the heat sink 43 and the case 44 is heated, and the heat sink 43 and the case 44 are separated, and the holding strength of the heat sink 43 is reduced, and the airtightness between the case 44 and the heat sink 43 is impaired.

As a method to solve this problem, it is possible to fix the element 46 to the heat sink 43 using a resin adhesive.

In other words, since the resin adhesive does not require heating, the case 44 will not be distorted or deformed.

However, resin adhesives have higher thermal resistance than metal adhesives, and the heat of the element 46 is not sufficiently transmitted to the heat sink 43.
Heat dissipation effect decreases.

In addition, resin adhesives tend to deteriorate due to heat, and the
6 is not suitable because the adhesive strength weakens over time.

This invention was made in view of the above-mentioned conventional drawbacks. First, a heat-generating semiconductor element is fixed to a heat sink by metal adhesion.
Then, by attaching this heat sink to the case by insert molding, the case will not be distorted or deformed, the heat dissipation efficiency will be improved, and the adhesive strength between the element and the heat sink can be ensured over the long term. The purpose is to provide a method for manufacturing electronic devices.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of a solid state relay obtained by the manufacturing method according to the present invention. A heat generating semiconductor element for large current switching such as a triac is fixed at 11, and a case 14 is made of transparent resin, and as shown in FIG. The peripheral portion 11a is exposed.

Reference numeral 15 denotes a printed wiring board, which is placed on a protrusion 16 formed integrally with the case 14, and on the surface of which is mounted electronic components 17 such as resistors and transistors that constitute a solid state relay circuit together with the element 12. .

18 is a cover fitted onto the case 14.

Next, the manufacturing process will be explained according to FIGS. 3a to 3d.

First, as shown in FIG. 3a, a flat heat sink 11 made of aluminum or the like is prepared, and as shown in FIG. The heat generating semiconductor element 12 is fixed by adhesion.

Among them, an electrical insulating plate (
(not shown) may be interposed.

Thereafter, as shown in FIG. 3c, the heat sink 11 to which the element 12 is fixed is placed on one of the molds 19, and a transparent resin is injected into the cavity 21 of the other mold 20 to form the bottom part 14a1. A case 14 is formed having a projection 16 and a step 22 for fitting with the cover (FIG. 1).

That is, the heat sink 11 is integrally attached to the case 14 by insert molding.

By the way, as shown in the figure, the bottom part 14a of the case 14
The mold 20 is placed so that the end portion 14b and the element 12 are separated
If insert molding is performed so that the element fixing peripheral portion 11a of the heat sink 11 is exposed from the case 14 when the case 14 is taken out from the mold 19. Heat is not directly transmitted to the element 12, and the element 12 is not adversely affected.

Among them, 23 is a recess provided in the mold 20 in order to position the element 12.

Thereafter, the molds 19 and 20 are opened to obtain a case 14 equipped with a heat sink 11 to which the heat generating semiconductor element 12 is fixed, as shown in FIG. 3d.

At this time, in order to dissipate heat well, the heat dissipation plate 11 separates the fixed peripheral part 11a of the heat generating element 12 from the end part 14b of the bottom part 14a of the case 14, so that the heat dissipation plate 11
must be set on the heat sink 11, and the heat sink 1 must be set on the heat sink 11.
In order to increase the effective heat dissipation area of 1, the external exposed area needs to be maximized.

In this way, if the number of externally exposed parts is increased, the holding area between the heat sink 11 and the case 14 becomes a little smaller, and the holding strength of the heat sink 11 becomes weaker. Since the joints are not heated,
The heat sink 11 and the case 14 do not separate, which prevents the holding strength of the heat sink 11 from decreasing, and also prevents the case 1 from peeling off.
4 and the heat sink 11 can be ensured.

Furthermore, as shown in FIG. 1, the printed wiring board 15 with the electronic components 1T mounted thereon is placed, and the cover 18 is fitted onto the case 14 to complete the solid state relay.

As described above, according to the method for manufacturing an electronic device according to the present invention, the heat-generating semiconductor element is fixed to the heat sink by metal adhesion, so that the heat radiation effect is improved and adhesive strength can be ensured over a long period of time.

Furthermore, since the above-mentioned fixing is performed in advance before forming the case, the heat required for metal bonding will not be transmitted to the case, and the case will not be distorted or deformed.

Furthermore, since the heat sink is attached to the case by insert molding, a high degree of airtightness between the case and the heat sink can be maintained.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of an electronic device using a fixed relay as an example, Figure 2
The figure is a sectional view taken along the line 2-2 in FIG. 1, FIGS. 3a to 3d are sectional views showing the manufacturing process, and FIGS. 4a to 4b are sectional views showing the conventional manufacturing process. 11... Heat sink, 11a... Element fixing peripheral part, 12
... exothermic semiconductor element, 13 ... metal adhesive material, 14
···Case.

Claims (1)

[Claims] 1. A method of manufacturing an electronic device, in which a heat-generating semiconductor element is fixed to a heat sink by metal adhesion, and then insert molding is performed so that the fixed periphery of the heat-generating semiconductor element attached to the heat sink is exposed from a case.