JPH0210578B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for manufacturing a header, and more particularly to a method for manufacturing a header used for fixing a power transistor to be incorporated into a hybrid integrated circuit.

(B) Prior Art As shown in FIG. 1, a conventional hybrid integrated circuit includes an insulating substrate 1 made of ceramic or aluminum whose surface is anodized, a conductive path 2 provided in an arbitrary shape on the substrate 1, and a conductive path 2 provided in an arbitrary shape on the substrate 1. A heat sink 3 fixed on the conductive path 2 with solder, a power transistor 4 fixed on the heat sink 3, a sealing resin layer 5 covering and protecting the power transistor 4, and bonded to the peripheral edge of the substrate 1 with an adhesive sheet 6. and a lid body 7 that covers the entire body.

Hybrid integrated circuits with such a structure have been evaluated as having sufficient sealing for electronic equipment such as televisions, radios, stereos, etc. that have relatively favorable usage environments. However, it cannot be said that the sealing structure is sufficient for items such as electrical components of automobiles, which are used in extremely poor environments, and deterioration of power transistors, which consume electric power, has become a serious problem. That is, as a result of the heat cycle, cracks occur in the sealing resin layer 5, solder oxidation occurs due to oxygen entering through the cracks, and the thermal resistance between the power transistor 4 and the heat sink 3 increases, resulting in secondary destruction of the power transistor 4. It is.

In order to improve this drawback, as shown in Figure 2,
A groove 8 is provided around the heat sink 3, the power transistor 4 is fixed inside the groove 8 with solder, and a sealing resin layer 5 such as epoxy resin is applied to cover and protect the power transistor 4. At this time, the sealing resin layer 5 is filled in the groove 8 to prevent the sealing resin layer 5 from peeling off due to heat cycles. Furthermore, such conventional technology is disclosed in Japanese Patent Publication No. 55-41022 (HOIL23/28)
It is described in.

The heat sink 3 used in the improved hybrid integrated circuit described above is formed as shown in FIGS. 3A and 3B. First, as shown in Figure 3A, it is 13mm square and 3mm thick.
A copper piece of
A groove 8 of 300 μm is formed by pressing. In this process, the end of the groove 8 is deformed into a protrusion 9 of about 40 μm.
Can be done. Especially the protrusion 9 formed at the inner end of the groove 8
Since it becomes an obstacle to the fixation of the power transistor 4, it is necessary to remove it. Therefore, as shown in FIG. 3B, at least the inner protrusion 9 is flattened using a press die 10. However, since oil 11 is tightly interposed in the space between the press die 10 and the protrusion 9, the protrusion 9 cannot be eliminated by flat punching.

(c) Purpose of the Invention The present invention has been made in view of the above points, and an object thereof is to realize a heat sink manufacturing method that improves the conventional drawbacks.

(D) Structure of the Invention The present invention is configured such that after grooves are formed around the upper surface of a flat heat sink, the protrusions generated when forming the grooves are flattened with a mold having ventilation holes.

(E) Embodiment An embodiment of the heat sink manufacturing method according to the present invention will be described in detail with reference to FIGS. 4A and 4B. Common component parts are given common drawing numbers.

In FIG. 4A, a copper piece 13 mm square and 3 mm thick is used as the heat sink 3, and a loop-shaped groove 8 having a width of 500 μm and a depth of 300 μm is formed around the upper surface of the heat sink 3 by pressing. In this process, the ends of the grooves 8 are deformed to form protrusions 9 of about 40 μm. In particular, the protrusion 9 formed at the inner end of the groove 8 must be removed since it becomes an obstacle to the fixation of the power transistor 4.

In FIG. 4B, the protrusion 9 is removed by flat hammering. This step is the most characteristic feature of the present invention, and a vent hole 12 is provided in the press mold 10 for flat stamping. Then, the press die 10 and the protrusion 9
Even if oil 11 is present in the space formed by
Since there is an escape route to the outside from 2, flattening can be easily performed, and the protrusion 9 can be flattened to about 5 μm. The ventilation hole 12 penetrates from the center to the side of the press mold 10, but its shape is arbitrary, and it is sufficient that it can be connected to the outside air.

(F) Effects of the Invention According to the present invention, it is possible to easily realize a flat heat sink, and it is possible to mass-produce the heat sink 3 that is most suitable for the sealing structure of the power transistor 4.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view illustrating a conventional hybrid integrated circuit, Fig. 2 is a sectional view illustrating a hybrid integrated circuit using a grooved heat sink, and Fig. 3 A and B are manufacturing of a conventional grooved heat sink. 4A and 4B are cross-sectional views illustrating the method of manufacturing a heat sink according to the present invention. Explanation of main drawing numbers: 3 is the heat sink, 8 is the groove,
9 is a protrusion, 10 is a press mold, and 12 is a ventilation hole.

Claims (1)

[Claims] 1. A method for manufacturing a heat sink, which comprises forming grooves around the upper surface of a flat heat sink, and then flattening the protrusions generated during the formation of the grooves with a mold having ventilation holes.