JPS5841661B2 - Manufacturing method for resin-encapsulated semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a resin-sealed semiconductor device having a heat sink.

Generally, in a semiconductor device for high power use, a heat sink is bonded and fixed to a semiconductor element in order to dissipate heat generated during operation to a row section.

Then, a lead frame having lead pieces that are electrically connected to the semiconductor element is fixed to the heat sink, and this heat sink is placed on the bottom of the cavity of the mold, and then an insulating film is placed in the cavity. It is manufactured by injecting a synthetic resin and molding the semiconductor element and heat sink with the resin.

By the way, in order for the heat dissipation plate molded with the above-mentioned resin together with the semiconductor element to effectively exhibit its heat dissipation effect,
It is necessary to expose it from the surface of the resin molded part.

However, conventionally, as shown in FIG. 9, the heat dissipation plate 50 is set in a cantilevered state on the molding die 52,53 via the lead piece 51 for connecting the lead wire, and the insulating synthetic resin 54 is injected. Therefore, the adhesion between the heat dissipation plate 50 and the cavity bottom surface 55 of the molding die 52, 53 is poor, and the resin 54 tends to enter between the heat dissipation plate 50 and the cavity bottom surface 55. After molding, the heat dissipation plate 50, which should originally be exposed, is embedded in the molded portion 54, which may lead to a decrease in heat dissipation effect.

For this purpose, as shown in FIG. 10a, a lead piece 56 for pressurizing the heat dissipation plate is prepared which extends in the opposite direction to the lead piece 51 and is clamped by the molding die 52.53. The heat sink 50 installed on the bottom surface 54 is connected to the lead piece 5.
A method has been proposed in which the resin 54 is injected while the resin is held at a pressure of 1.56 mm.

However, with this method, after resin molding, the lead piece 56 for pressurizing the heat sink protrudes from the resin molded part 54 as an unnecessary part as shown in FIG. 10b.
This lead piece 56 must be cut off, which is troublesome, increases the number of steps, and has the drawback of poor productivity.

Therefore, the present invention arranges a heat sink pressing member in the molding die, and forms a through hole corresponding to the pressing member supported by the mold in the heat sink installed on the bottom surface of the mold cavity. After setting the heat dissipation plate in a state where it is elastically pressed against the bottom surface by the suppressing member, an insulating synthetic resin is injected into the space, so that the heat dissipation plate can be properly positioned without being buried in the resin. Resin molding can be performed, improving heat dissipation, and reducing the number of work steps.
An object of the present invention is to provide a method for manufacturing a resin-sealed semiconductor device that can improve productivity.

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

First, let's mourn the lead frame 1 as shown in FIG.

This lead frame 1 has a large number of lead pieces 2 (2□ to 2n) for connecting lead wires extending in one direction, which are integrally connected and held to a connecting piece 3 and a frame piece 4, making it a so-called single-in-line type. It is formed.

5 is a heat sink to which a semiconductor element 6 is fixed via a brazing material layer 7 (FIG. 2).

A coaxial through hole 17 is formed in this heat sink plate 5 in correspondence with a pressing member to be described later.

The lead piece 2 of the lead frame 1 is attached to the element setting surface of the heat sink 5 with an insulating layer 8 interposed therebetween as shown in FIG.

Next, the semiconductor element 6 and each lead piece 2 are connected by wire bonding.

After that, the heat dissipating plate 5 is placed in a molding die 9, as shown in FIG.
It is stored and installed in the empty space 11 of 10.

This mold 9 supports a heat dissipation plate pressing member 12 that can move forward and backward into the cavity 11, and furthermore, this pressing member 12 is biased by a spring 13 with a spring force toward the tip side.

With the heat dissipation plate 5 pressed against the bottom surface 14 of the cavity 11 with the tip of the pressing member 12, melted insulating synthetic resin 15 is injected into the cavity 11 as shown in FIG.
molded in resin.

After the resin 15 is solidified, the resin mold part 15 is taken out from the molds 9 and 10, and each lead piece 2 is separated from the connecting piece 3 and the frame piece 4, and as shown in FIG. A resin-sealed semiconductor device is obtained in which a portion 16 of the heat sink 5 is exposed.

Here, while the heat dissipation plate 5 housed in the cavity 11 of the molding molds 9 and 10 is elastically pressed against the cavity bottom surface 14 by the suppressing member 12, the insulating synthetic resin 15 is placed in the cavity 11. Since the heat sink 5 and the bottom surface 14 are injected, the adhesion between the heat sink 5 and the bottom surface 14 is improved, and the resin 15 can be prevented from entering between the two 5 and 14. Therefore, after resin molding, a part of the heat sink 5 is injected. 16 is reliably exposed and the heat dissipation effect can be effectively exhibited.

In addition, there is no need to remove the pressing member 12 after molding, resulting in good workability.

Furthermore, since the through holes 17 with a smaller diameter are formed in the heat dissipation plate 5 in correspondence with the suppressing members 12, the heat dissipation area becomes larger due to the through holes 17, and the heat dissipation effect becomes even more effective. The hole 17 and a through hole 18 (FIG. 5) formed in the resin molding 1 portion 15 corresponding to the pressing member 12 can be used as a screw hole for mounting a semiconductor device.

Further, as shown in FIG.
If it is formed on the bottom surface 14 of the cavity, the heat dissipation plate 5 can be resin-molded without fear of shifting from the predetermined position.

FIG. 7a shows another embodiment, in which a minute annular uneven portion 20 is formed on the heat dissipation plate 5 and comes into contact with the tip end surface of the suppressing member 12 around the axis of the pressing member 12, In this case, in addition to producing the same effects as in the above embodiment, deformation of the heat sink 5 and wear of the pressing member 12 can be suppressed.

That is, in order to increase the adhesion between the heat sink 5 and the cavity bottom surface 14, it is necessary to press the heat sink 5 with a pressure stronger than the pressure of the resin 15 injected into the cavity 11. In this case, the heat dissipation plate 5 may be distorted or warped, or the distal end surface of the suppressing member 12 may be easily worn out.
There is also a possibility that the tip surface may be damaged.

However, by forming the fine uneven portions 20 on the heat sink 5 as in this embodiment, even if the pressing force of the suppressing member 12 is relatively weak, the heat sink 5 can be pressed with a strong contact pressure through the uneven portions 20. Therefore, it is possible to suppress deformation of the heat sink 5 and wear of the front end surface of the suppressing member 12,
Furthermore, even if the tip end surface of the pressing member 12 is scratched, the uneven portion 20 is crushed by the pressure as shown in FIG. 7b and the wound is filled, so that no resin passage is formed in the tip end surface. The resin mold is made well.

FIG. 8 shows still another embodiment, in which the uneven portion 20 formed on the heat dissipation plate 5 extends to the part where it comes into contact with the resin 15 filled in the cavity 11. With this configuration, the heat dissipation The bonding relationship between the plate 5 and the resin 15 is strengthened, the uneven portion 20 can be used as a guide for positioning the semiconductor element 6, and the protrusion of the brazing material layer 7 for bonding the semiconductor element 6 can be prevented. can be prevented.

Incidentally, in each of the above embodiments, a single-in-line type lead frame is used, but it goes without saying that the same effects as described above can be obtained even if a true-in-line type lead frame is used.

As described above, according to the present invention, the heat dissipation plate pressing member, which can move forward and backward into the cavity of the molding die and is given elastic force, has a through hole corresponding to the suppression member and is attached to the bottom surface of the cavity. Since the resin is injected into the cavity while the installed heat sink is elastically pressed against the bottom surface, the resin is reliably prevented from entering between the heat sink and the bottom surface. , the heat sink can be properly embedded in the resin mold, and the heat dissipation area can be expanded by the through holes formed in the heat sink, thereby improving heat dissipation performance. It is possible to provide a method for manufacturing a resin-sealed semiconductor device that allows work to be carried out efficiently without requiring the effort of removing the pressing members one by one.

[Brief explanation of the drawing]

1 to 5 are explanatory diagrams showing an example of the manufacturing method of a resin-sealed semiconductor device according to the present invention in the order of steps, FIGS. 6 to 8 are explanatory diagrams of other embodiments, and FIGS. 10th
Figures a and 10b are explanatory diagrams of conventional examples. 1...Lead frame, 2...Lead piece, 5...
Heat sink, 6... Semiconductor element, 8... Insulating layer, 9, 1
0... Molding die, 11... Hollow space, 12... Heat sink pressing member, 13... Spring, 14... Hollow bottom surface, 15
... Insulating synthetic resin, 16 ... Exposed part of heat sink, 1
7... Through hole, 19... Positioning protrusion, 20... Uneven part.

Claims (1)

[Claims] 1. A lead frame having lead pieces for connecting lead wires is adhered to a heat sink to which a semiconductor element is bonded and fixed via an insulating layer, and the semiconductor element and the lead pieces are electrically connected. Then, the heat dissipation plate is installed on the bottom surface of the cavity of the mold, and a coaxial through-hole is provided corresponding to the heat dissipation plate suppressing member that is supported by the mold and is set to be movable into the mold cavity. is formed on the heat sink, the pressing member is given an elastic force toward the heat sink, the heat sink pressing member elastically presses the heat sink against the bottom of the cavity, and then the insulating synthetic resin is A method of manufacturing a resin-sealed semiconductor device, in which a heat sink is injected into a cavity and a heat sink is molded with the resin with a portion thereof exposed, together with the semiconductor element. 2. The method of manufacturing a resin-sealed semiconductor device according to claim 1, wherein a positioning protrusion that fits into a through hole formed in a heat sink is formed on the bottom surface of the cavity of the molding die. 3. The resin-sealed semiconductor according to claim 1 or 2, wherein the heat dissipation plate has a minute unevenness that is located around the axis of the suppressing member and comes into contact with the front end surface of the suppressing member. Method of manufacturing the device. 4. The method of manufacturing a resin-sealed semiconductor device according to claim 3, wherein the uneven portion formed on the heat sink extends to a contact area of the synthetic resin injected into the mold cavity.