JPH065687B2 - Method for manufacturing resin-sealed semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a power transistor,
The present invention relates to a method for manufacturing a resin-sealed semiconductor device such as a diode.

[0002]

2. Description of the Related Art In a conventional general resin-sealed power transistor, a resin layer is not formed on the back surface of a heat dissipation support plate to which a transistor chip is fixed. Therefore, when the power transistor is attached to the external heat radiator, an insulator having relatively good thermal conductivity is provided between the back surface of the heat radiation support plate and the external heat radiator for electrical insulation between them. Since it was necessary to intervene a mica thin plate, etc., the work of mounting the power transistor became complicated.

In order to solve the above-mentioned drawbacks, for example, as disclosed in JP-A-57-147260, a thin sealing resin layer (several hundreds of μm thick) is formed on the back surface of the heat dissipation support plate. A structure has been proposed in which the mica sheet is formed and a mica thin plate or the like is unnecessary. 11 and 12 show a conventional transistor as described above and a manufacturing method thereof. In FIGS. 11 and 12, 1 is a heat dissipation support plate, 2 is leads, 3 is a power transistor chip, 4 is a chip protection resin, 5 is a sealing resin body, 6 is an upper mold, 7 is a lower mold,
Reference numeral 8 denotes an injection hole for press-fitting the sealing resin into a space 9 formed by clamping the upper mold 6 and the lower mold 7, and 10 denotes a mounting hole and 11 and 12 constitute a lead frame. It is a connecting part for. In addition, in FIG. 12, the connecting portions 11 and 12 are finally cut off.

[0004]

By the way, the resin coating portion 5a on one main surface side of the support plate 1 on which the chip 3 is mounted is necessarily formed thick in order to protect the chip 3 and the support plate 1 is formed. The resin coating portion 5b on the other main surface side is thinly formed in order to improve the heat radiation effect. For this reason, when the resin is injected from the injection hole 8 by, for example, the transfer molding method, the resin may not smoothly flow into the lower side of the support plate 1 and an unfilled portion or a portion having low dielectric strength may occur.
Although the power transistor has been described as an example, another semiconductor device such as a diode has a similar problem.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method of manufacturing a resin-sealed semiconductor device in which a thin resin coating portion can be favorably formed on the surface of the heat dissipation support plate opposite to the chip mounting surface. .

[0006]

The present invention for achieving the above object provides a metal supporting plate having a heat dissipation function, a semiconductor chip mounted on one main surface of the supporting plate, and the chip. Electrically connected leads, the support plate,
An insulating resin coating that covers a part of the chip and the leads, and a resin coating portion on one main surface side of the support plate is thicker than a resin coating portion on the other main surface side. In the method for manufacturing a resin-encapsulated semiconductor device in which the resin coating is formed, and the resin coating is also formed on the side surface of the support plate, the chip of the resin coating portion on the one main surface side is provided. A third coating portion thinner than the first and second coating portions is formed between the first coating portion to be coated and the second coating portion that covers one end side of the support plate. A resin encapsulation mold having a protrusion formed on the protrusion, the protrusion being continuous with a side surface of a molding cavity for obtaining the resin coating, and the chip and the resin sealing mold. The support plate with the lead is attached, and the support plate Note Injecting a fluid resin into the molding cavity through an injection hole provided in the resin sealing mold so as to correspond to one end side, while suppressing the flow of the resin at the protruding portion. The present invention relates to a method for manufacturing a resin-encapsulated semiconductor device, wherein a resin coating portion is formed on one and the other of the main surfaces of the support plate.

According to the present invention, the flow of the sealing resin injected from the injection hole arranged near one end of the support plate is suppressed by the protrusion. The flow of the resin injected into the molding space near the side wall of the molding space covers the semiconductor chip well. If the molding die does not have the protrusion according to the present invention, the molding plate adjacent to the side surface of the support plate is not separated by the support plate from above and below, and the resin flows freely. Therefore, the balance of resin injection between the upper side (one main surface side) and the lower side (other main surface side) of the support plate cannot be adjusted. On the other hand, when the protrusion is provided so as to be continuous with the side wall of the molding cavity according to the present invention, the resin flow in the side surface region of the support plate is adjusted, and the resin flow is well balanced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A resin-sealed transistor according to an embodiment of the present invention and a method of manufacturing the same will now be described with reference to FIGS.

FIGS. 1, 2 and 3 show a completed transistor, FIG. 4 shows a state in which a chip is mounted on a lead frame, FIG. 5 shows a lead frame completed with resin sealing, and FIG. 6 shows. A mold is shown, and FIGS. 7 to 10 show steps of forming a resin coating by a transfer molding method using the mold.

When forming the transistors shown in FIGS. 1 to 3, first, a semiconductor device assembly called a lead frame shown in FIG. 4 is prepared. In FIG. 4, 21 is a heat dissipation support plate made of a nickel-coated copper plate, and 22a, 22b, 22c.
Is an external lead made of the same material, 22a is a base lead, 22b is a collector lead, and 22c is an emitter lead. 23 is a silicon power transistor chip,
A base electrode and an emitter electrode are formed on the upper surface, and a collector electrode is formed on the lower surface. The chip 23 is fixed on the lower surface to the heat dissipation support plate 21 by solder (not shown). Reference numerals 24a and 24c are internal leads made of aluminum wire, and are arranged between the base electrode of the chip 23 and the base lead 22a and between the emitter electrode of the chip 23 and the emitter lead 22c. 25
Is a protective layer made of silicon resin for chip protection called a junction coating resin. Reference numeral 26 is a connecting portion between leads called a tie bar. Reference numeral 27 is a connecting portion that connects the lead ends in common. Heat dissipation support plate 21
A U-shaped notch 28 is formed at one end 21 a of the. Incidentally, it is often practiced to form a hole in the heat dissipation support plate 21 instead of the cutout portion 28. Although FIG. 4 shows one power transistor in the leadframe, a single leadframe actually contains multiple transistors.

In this embodiment, the lead frame shown in FIG. 4 is provided with a resin coating 37 as shown in FIG.
The resin-sealed transistor of FIGS. 1 to 3 is completed by cutting off the connecting portions 26 and 27. As is apparent from FIGS. 1 to 3, a relatively thick resin coating portion 37a is provided on one main surface (upper surface) side of the support plate 21, and a thin resin coating portion 37b is provided on the other main surface (lower surface) side. Is provided. The upper resin coating portion 37a includes the chip 23 and the protective layer 2.
5, the thickest first covering portion 41 for covering the inner leads 24a, 24c, a portion 42 for covering the one end 21a side of the support plate 21, the first covering portion 41 and the second covering portion 42 And a third covering portion 43 formed thinner than these. As a result, the groove 38 is formed on the surface of the resin coating 37 so as to correspond to the thin coating portion 43. The groove 38 is not provided on the straight line connecting the mounting hole 39 and the chip 23.

A resin coating 37 shown in FIGS. 1 to 3 and 5.
Is formed by combining the upper die 29 and the lower die 30 shown in FIG. 6 as shown in FIGS. 7 and 8, and injecting the resin therein as shown in FIGS. 9 and 10. 6 to 10, reference numeral 31 is an injection hole for press-fitting the sealing resin into the molding space 32 formed by clamping the upper mold 29 and the lower mold 30. Reference numeral 29a denotes a columnar pin protruding from the upper mold 29 to form the mounting hole 39 shown in FIG. 1, and penetrates the notch 28 of the heat radiation support plate 21. Reference numeral 29b is a partition-shaped protruding portion that protrudes from the upper mold 29, and forms the groove 38 of FIG. The partition-shaped protruding portion 29b is formed so as to be continuous with both side walls of the molding cavity 32, and has a groove 35 in the center thereof for allowing the resin to flow. When inserting the lead frame shown in FIG. 4 into the molds 29, 30, the arrow 33,
As shown by 34, the upper die 29 and the lower die 30 are aligned and clamped. At this time, the lead 22a is held by the groove 36a, the lead 22b is held by the groove 36b, and the lead 22c is held by the groove 36c. As a result, as shown in FIGS. 7 and 8, the support plate 21 is placed in the molding cavity 32 formed by the molds 29 and 30.
Are placed in a floating state. Further, in order to obtain the resin coating body 37 shown in FIGS. 1 to 3, the upper void 32a is widened and the lower void 32b is narrowed. However, according to the present invention, since the protrusion 29b for suppressing the strength of the resin flow is provided in the vicinity of the entrance of the wide space 32a above the chip 23, the resin injected from the injection hole 31 has a narrow lower space. It also relatively well penetrates into the place 32b.
Further, since the protruding portion 29b is continuous with the side wall of the molding space 32, the resin flow near the side surface of the support plate 21 is suppressed.

The resin is injected into the molding space 32 by softening the thermosetting epoxy resin in the pot based on a known transfer molding method and pressurizing the resin into the molds 29 and 30. As a result, the liquid resin is injected from the injection hole 31 shown in FIG. 7, and the entire molding cavity 32 is filled with the resin. The molds 29 and 30 have a temperature (1
Since it is heated to about 50 to 200 ° C., the filled resin is heat-cured within a short time (several minutes), and FIG.
The resin coating 37 shown in FIG. It should be noted that, in order to completely heat cure, after taking out the lead frame from the molds 29 and 30, heat treatment is further performed for a long time.

In the formation of the resin coating 37 by the transfer molding method as described above, when a liquid resin having a directionality shown by an arrow 40 in FIG. 6, FIG. 7 and FIG. The void 32a tends to be easily filled with the resin. However, in this embodiment, since the protrusion 29b is provided so as to intersect with the resin injection direction indicated by the arrow 40, the flow of the resin near the upper side of the support plate 21 and the side surface of the support plate 21 is suppressed, As a result, the resin flow in the narrow space 32b below the support plate 21 is relatively strengthened. As a result, the upper void 32a and the lower void 32b are
The balance of the flow of the sealing in the above was improved, and the unfilled state of the lower cavity 32b, which was conventionally present, was hardly seen.
That is, the thin resin coating portion 37 formed in the lower space 32b
We were able to solve the problem of poor insulation in b.

By disposing the protruding portion 29b of the upper mold 29 in a partition shape orthogonal to the main flow direction of the sealing resin (direction of arrow 40), the resin flow is effectively suppressed. The optimum values of the height and the position are different depending on the number of molds to be taken and the size of the package.

Since the pin 29a exists in the main flow direction of the sealing resin when viewed from the injection hole 31, the pin 29a also works to suppress the flow of the sealing resin. Therefore, the injection hole 31
And the pin 29a is an extension of the line connecting the pin 29a and the pin 29a.
Unfilling of the sealing resin may occur in a region of the side a opposite to the injection hole 31. However, in this embodiment, as shown in FIG.
As is most apparent from the above, since the flow of the sealing resin divided by the pin 29a is again suppressed by the protruding portion 29b, the sealing resin easily wraps around to the region opposite to the pin 29a, and the unfilling is surely performed. To be prevented. Further, in this embodiment, the groove 35 for reducing the action of the protruding portion 29b is provided on the extension line of the straight line connecting the arrow 40 and the pin 29a, and this groove 35 has the action of suppressing the flow of the sealing resin by the pin 29a. Since it works to cancel the
It is possible to reliably prevent the non-filling of the area on the opposite side of.

Further, since the second coating portion 42 which covers the one end side region of the support plate 21 is formed thinner than the first coating portion 41, the second coating portion of the upper mold 29 is formed. The gap between the portion where 42 is provided and the support plate 21 is narrowed, and the flow of resin is suppressed also here. Therefore, the resin injected from the injection hole 31 arranged in the vicinity of one end of the support plate 21 is suppressed by both the mold portion for forming the thin second coating portion 42 and the protruding portion 29b, and one main The balance of the resin flow between the surface side and the other main surface side can be adjusted well.

By the way, the transistor shown in FIGS. 1 to 3 is usually mounted by placing the lower resin coating portion 37b on an external mounting plate having a heat radiating action, and mounting members such as screws or bolts in the mounting holes 39. Through, and thereby fixed to the mounting plate. When the head or nut such as a screw or a bolt or the like strongly presses the vicinity of the mounting hole 39 during such mounting, a crack is generated, so that the vicinity of the mounting hole 39 cannot be made too thin. Therefore, in this embodiment, the covering portion 42 near the mounting hole 39 is formed to have a thickness that does not hinder the mounting, and the groove 38 according to the present invention is formed.
The thin third covering portion 43 in is formed thinner than the second covering portion 42 near the mounting hole 39.

[0019]

[Modification] The present invention is not limited to the above-described embodiment, but various modifications can be made. For example, mounting hole 3
9 may be a notch (groove or recess). It can also be applied to a diode.

[0020]

As is apparent from the above, according to the present invention, a molding die having a continuous projection on the side wall of the molding cavity is used, and the projection is used to support one main surface side of the support plate and the support. Since the flow of the resin near the side surface of the plate is suppressed, the flow of the resin on one and the other of the main surfaces of the support plate is well balanced, and a good resin coating can be formed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a transistor according to an embodiment of the present invention.

FIG. 2 is a plan view of the transistor of FIG.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a perspective view showing a lead frame for forming the transistor of FIG.

5 is a perspective view showing a state in which a resin coating is provided on the lead frame of FIG.

FIG. 6 is a perspective view showing a mold.

FIG. 7 is a view showing a state in which a lead frame is put in a mold.
4 is a cross-sectional view of a portion corresponding to line BB in FIG.

FIG. 8 is a view showing a state in which a lead frame is put in a mold.
4 is a cross-sectional view of a portion corresponding to line AA in FIG.

9 is a cross-sectional view showing a state in which the mold of FIG. 7 is filled with resin.

10 is a cross-sectional view showing a state where the mold of FIG. 8 is filled with resin.

FIG. 11 is a perspective view showing a conventional transistor.

12 is a cross-sectional view showing a state where the transistor of FIG. 11 is formed by a mold.

[Explanation of symbols]

 21 Support Plate 23 Chip 29 Upper Mold 29b Projection 30 Lower Mold 31 Injection Hole 32 Molding Space 41 First Covering Part 42 Second Covering Part 43 Third Covering Part

Claims (1)

[Claims] 1. A metal support plate having a heat dissipation function, and a semiconductor chip mounted on one main surface of the support plate,
A resin coating portion that is composed of a lead electrically connected to the chip, an insulating resin coating that covers the support plate, the chip, and a part of the lead, and that is on one main surface side of the support plate. A method for manufacturing a resin-encapsulated semiconductor device in which the resin coating is formed so as to be thicker than the resin coating on the other main surface side, and the resin coating is also formed on the side surface of the support plate. In the first main surface side, between the first coating portion that covers the chip of the resin coating portion on the one main surface side and the second coating portion that covers one end side of the support plate, Third thinner than the covering part of second
A resin-sealing die is provided which has a protrusion formed so as to produce a covered portion, and the protrusion is continuous to the side surface of the molding cavity for obtaining the resin-coated body. The supporting plate with the chip and the leads is attached to a fixing mold, and the molding space is formed from an injection hole provided in the resin sealing mold so as to correspond to the one end side of the supporting plate. A resin-sealed mold characterized by injecting a fluid resin into a place and forming a resin coating portion on one and the other of the main surfaces of the supporting plate while suppressing the flow of the resin at the projecting portion. Manufacturing method of semiconductor device.