JPH01302729A - Manufacture of plastic sealed type semiconductor device - Google Patents

Abstract

PURPOSE:To avoid the ununiformity of the resin flow and the generation of resin unfilled portion by separating a protruded portion to control the resin flow on one principal face of a supporting plate from a portion to form an installation notch or hole. CONSTITUTION:By using a mold for plastic seal having a protruded portion 29b, a portion to coat a chip 23 on a resin coated portion 37a on one principal face and a portion more thinly coated than a portion to coat the place near an installation notch 28 or hole are arranged apart from the installation notch 28 or hole. And, the onward movement of the sealing resin injected from an injection hole 31 set up near one end of a supporting plate 21 is controlled. Then, the sealing resin is injected from the injection hole 31 to a molding space of the mold for plastic seal, to form a resin coating body.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing resin-sealed semiconductor devices such as power transistors and diodes.

Prior Art In conventional general resin-sealed power transistors, a resin layer is not formed on the back surface of the heat dissipation support plate to which the transistor chip is fixed. When attaching to an external heat radiator, a mica thin plate or the like, which is an insulator with relatively good thermal conductivity, is interposed between the back surface of the heat radiating support plate and the external heat radiating plate for electrical insulation between them. ) The installation of the lower transistor became complicated.

In order to solve the above-mentioned drawbacks, for example,
Japanese Patent No. 147260 discloses a structure in which a thin sealing resin layer (thickness of several hundred micrometers) is formed also on the back surface of the heat dissipation support plate, thereby eliminating the need for a mica thin plate or the like. FIGS. 11 and 12 show the conventional transistor and its manufacturing method as described above. 11 and 12, fi+ is a heat dissipation support plate, (2) is a lead, (3) is a power transistor chip, (4) is a chip protection resin, (5) is a sealing resin body, ( 6) is the upper mold, (7) is the lower mold, (8) is the upper mold and the lower mold (6) and the lower mold (the cavity (9) formed by force clamping is sealed with resin) α■ is a mounting hole, αD(1'IJ is a connecting part for configuring the lead frame.
2 will eventually be cut off.

The problem to be solved by the invention is that the support plate [11
The resin coating part (5a) on one main surface side of the chip (3)
The supporting plate (1) is necessarily formed thickly to protect the
The resin recessed portion (5b) on the curved main surface side is formed thin in order to improve the heat dissipation effect. For this reason, the injection hole (8)
For example, when resin is injected using transfer molding method, K
, the resin would not flow smoothly into the lower side of the support plate (1), and there was a risk that unfilled areas or areas with low dielectric strength would occur.

Although the explanation has been made using a 5-power transistor as an example, similar problems exist in other semiconductor devices such as diodes.

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

Means for Solving the Problems To achieve the above objects, the present invention provides a metal support plate formed to have a heat dissipation function and having a notch or hole near one end, and the support plate. , a semiconductor chip mounted on one main surface of the chip, leads electrically connected to the chip, and an insulating resin covering covering a portion of the support plate, the chip, and the leads. , and the resin coating is formed such that the resin coating on one main surface side of the support plate is thicker than the resin coating on the other main surface side, and the cutout portion is attached to the hole portion. In the method for manufacturing a resin-sealed semiconductor device, the resin coating is formed such that a notch or a hole is formed for the mounting, and a portion of the resin coating on the one main surface side that covers the chip and a portion for the mounting. Injecting through an injection hole that is arranged so as to separate from the mounting notch or hole and create a thinner covering part than the part that covers the vicinity of the notch or hole, and that is arranged near one end of the support plate. Using a resin-sealing mold having a protrusion formed to suppress the progress of the molded sealing resin, the sealing resin is injected into the molded hole of the resin-sealing mold through the injection hole. The present invention relates to a method for manufacturing a resin-sealed medium conductor device, characterized in that the resin coating is formed by

Function: The protruding portion for suppressing the flow of the blocking resin of the present invention is separated from the mounting notch or hole forming portion, so that
It is possible to prevent non-uniformity in the flow of resin or unfilled portions of resin due to the formation of the mounting notch or hole.

EXAMPLE Next, with reference to FIGS. 1 to 11, the present invention will be carried out 1]
A resin-sealed transistor and a method for manufacturing the same will be described.

1, 2, and 3 show the completed transistor, FIG. 4 shows the chip mounted on the lead frame, FIG. 5 shows the lead frame with resin sealing completed, and FIG. FIG. 6 shows a mold, and FIGS. 7 to 10 show the process of forming a resin coating by transfer molding 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, the heat dissipation support plates made of nickel-coated copper plates, (22a) (22b) (22
c) are external leads made of the same material, (22a) is the pace lead, (22b) is the collector lead, (22c)
is the emitter lead. Reference numeral 123) is a silicon power transistor chip, on the upper surface of which a pace electrode and emitter electrode are formed, and on the lower surface a collector electrode 1. This chip device is fixed to the heat dissipation support plate f2D at the lower surface by solder (not shown) K. (24a) (
24c) is an internal lead made of aluminum wire;
between the pace electrode of the chip and the pace lead (22a), and between the emitter electrode of the chip (23) and the emitter lead (
22c). (Two are made of silicone resin for chip protection called junction coating resin. K is formed with a U-shaped notch. In addition, this notch 128) is replaced by a heat dissipation support, plate 0
1) It is also common practice to form K holes. Although FIG. 4 shows one power transistor in a lead frame, a single lead frame actually contains multiple transistors.

In this embodiment, the lead frame shown in FIG. 4 is provided with a resin coating 3η as shown in FIG.

The resin-sealed transistor shown in FIGS. 1 to 3 is completed by cutting off the connecting portion rut. As is clear from FIGS. 1 to 3, a relatively thick resin coating (37a) is provided on one main surface (upper surface) of the support plate CD, and a thin resin coating is provided on the other main surface (lower surface). A resin covering portion (37b) is provided. The upper resin coating part (37a) is formed between the thickest main coating part (41) that covers the chip (c), the protective layer C9, and the internal IJ-board (24a), and the cut part (42). A thin covering part (43
and has. As a result, a groove (3 seconds) is formed corresponding to the thin coating part (43) on the 2nd surface of the resin coating with 0 force. Note that the groove O0 is a straight line connecting the mounting hole C3gI and the chip (C). It is not installed on top.

The resin coating body C17 shown in FIGS. 1 to 3 and 5 is made by combining the upper mold device shown in FIG. 6 and the lower mold ■ as shown in FIGS. , Figures 9 and 10
It is formed by injecting resin as shown in the figure. 6th
In the figures to FIG. 10, Oυ is an injection hole for press-fitting the sealing resin into the cavity G2 formed by clamping the upper mold t2'O and the lower mold WG2. (29
a) is a cylindrical bottle that protrudes from the upper mold to form the mounting hole (3') shown in Figure 1, and is attached to the heat dissipation support plate C.
It passes through the notch C (to) of υ. (29b) is a partition-like protrusion protruding from the upper mold 129, and the first
This forms the groove Oa shown in the figure. Note that the partition-like protrusion (29b) has a groove in its center that allows the resin to flow. The lead frame shown in Fig. 4 is placed in a mold 2900.
1, as shown by the arrow (2) in FIG. 6, the upper mold device and the lower mold 130) are brought together and clamped. At this time, the groove (36a) connects the lead (22a) to the groove (36a).
b) and the lead (22b) in the groove (36c).
c) and hold them together. As a result, as shown in FIGS. 7 and 8, the support plate (31) is placed in a floating state in the cavity (2) formed by the mold (29) <30). In addition, in order to obtain the resin coating r3 force shown in FIGS.
) is arranged so that it becomes narrower. However, if the strength of the resin flow is suppressed near the entrance of the wide cavity (32a) above the chip device according to the present invention, the injected resin will relatively easily penetrate into the narrow lower cavity (32b). do.

In order to inject the resin into the cavity C32, thermosetting epoxy resin is softened in a pot and injected into the gold W (G9) G (11) based on a known transfer molding method. Liquid resin is injected from the injection hole C31) shown in FIG. 7, and the entire cavity 621 is filled with the resin. Mold C'! Ill 030) is heated to a temperature (approximately 1500 to 200°) that thermosets the resin, so the filled resin thermosets within a short time (several minutes).
The resin coating Gη shown in FIGS. 9 and 10 is obtained.

In order to completely heat cure the lead frame, after taking it out from the mold (291), heat treatment is performed for an even longer period of time.

Resin coating Gη by transfer molding method f as described above
6, 7 and 9, the arrow (4)
When liquid resin is injected under pressure with the direction shown in ■,
The resin tends to be easily filled into the relatively wide upper space (32a). However, in this embodiment, since the protrusions (29b) are provided so as to intersect with the injection direction of the resin shown by the arrow (41), the flow of the resin is suppressed, and as a result, the flow of the resin is suppressed.
The flow of resin in the narrow space (32b) below the support plate f21) is relatively strengthened. With this K, the balance of the sealing flow in the upper cavity (32a) and the lower cavity (32b) has become better, and the conventional unfilled state of the lower cavity (32b) is almost no longer observed. That is, the lower void (
The problem of poor insulation of the thin resin coating portion (37b) formed on portion 32b) could be solved.

The flow of the resin is effectively suppressed by arranging the protrusion (29b) of the upper mold 4 in the shape of a partition orthogonal to the main flow direction of the sealing resin (the direction of the arrow (4f)). However, the optimum height and position differ depending on the number of molds, the size of the package, etc.

Note that since the pin (29a) is located in the main flow direction of the sealing resin when viewed from the injection hole C311, the pin (29a) also acts to suppress the flow of the sealing resin. Therefore, it is on the extension of the line connecting the injection hole Oυ and the pin (29a), and the pin (
The region opposite to the injection hole C311 in 29a) may not be filled with the °C sealing resin. However, in this embodiment, as is most obvious from FIG. 6, the flow of the sealing resin divided by degrees by the pin (29a) is
The above pin (29a)
The sealing resin easily wraps around to the area opposite to the arrow (4 (J
The protrusion (2) is on the extension of the straight line connecting the
A groove 09 is provided to reduce the effect of the pin (29a), and this groove 09 works to offset the effect of suppressing the flow of the sealing resin by the pin (29a).
It is possible to reliably prevent the area on the opposite side from not being filled.

In addition, since the covering part (421) near the mounting hole that covers the individual area at one end of the support plate +11 is formed thinner than the main covering part (41), the covering part (421) near the mounting hole marked C in the upper mold ( Since the gap between the portion where the four holes are provided and the support plate (1) is narrow, the flow of the resin is also suppressed here.Therefore, the resin is injected from the injection hole OD located near the groove of the support plate (1). The resin is suppressed by both the mold part for forming the thin mounting hole vicinity coating part (43) and the protruding part (29b), and the flow of resin from one main surface side to the other main surface side is suppressed. Balance can be adjusted well.

By the way, when mounting the transistor shown in FIGS. 1 to 3, the lower resin coating part (37b) is usually mounted on a mounting plate that has an external heat dissipation function, and screws, bolts, etc. are inserted into the mounting hole c31. By penetrating the mounting member and fixing it to the mounting plate, it will cause a crank. It is not possible to make the area near the mounting hole OI very thin. For this reason, in this embodiment, the covering portion (4Z) near the mounting hole 0!1 is formed to a thickness that does not hinder the mounting, and the thin covering portion (43) in the groove (to) according to the present invention is formed in the vicinity of the mounting hole C3. The covering portion near !l (is formed thinner than 42).

Modifications The present invention is not limited to the above-described embodiments, but can be modified in various ways. For example, as shown in FIG. 13, a relatively thick covering portion (4
'lI is provided in a cylindrical shape, and a thin covering part (43) may be provided at 5 to surround it.In this case, the main covering part (4υ) is of course formed thickly.Also, the mounting hole 01 is close to the chip. position, insert the injection hole Oυ and pin (2) in Figure 6.
A protrusion (29b) may be provided between it and 9a). Further, the attachment hole 01 may be a notch (groove or recess). It is also applicable to diodes.

Effects of the Invention As is clear from the above, according to the present invention, the protruding part for suppressing the flow of resin on one main surface side of the support plate is separated from the part where the mounting notch or hole is formed. Therefore, it is possible to prevent uneven resin flow or unfilled areas of resin due to suppression of resin flow by the mounting notch or hole formation part, and form a good resin coating. can.

[Brief explanation of the drawing]

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 in FIG. 1, FIG. 3 is a sectional view taken along the line ■-■ in FIG. FIG. 5 is a perspective view showing the lead frame shown in FIG. 4 with a resin coating provided thereon, FIG. 6 is a perspective view showing a mold, Figure 7 shows the state in which the lead frame is placed in the mold.
8 is a sectional view of a portion corresponding to the line VII, FIG. 8 is a sectional view of a portion corresponding to the vn+- plane line of FIG. 7 and 8 are cross-sectional views showing the molds filled with resin, respectively; FIG. 11 is a perspective view showing a conventional transistor;
FIG. 12 is a sectional view showing a state in which a lead frame is placed in a mold and filled with resin to form the transistor of FIG. 11, and FIG. 13 is a perspective view showing a modification of the present invention. Qυ... Heat dissipation support plate, (22a) (22b) (22C
)--Lead, C3... Transistor chip, (2
4a) (24b piece...Inner lead, (29...Protective layer, (2Q...Notch, C piece...Upper mold, (29
a)... Pin, (29b piece... protrusion, C3 (1...
・Lower mold, 01)...Injection hole, Zeng...all places, (3
2a)...all the soil parts, (32b)...all the lower parts, C
37)...Resin coating, (37a)...One tree 1
1w covering part, +37b)...other resin covering part, (to)...groove, 01...attachment hole, (4υ...main covering part, (421...covering part near attachment hole, (43...
thin covering part. Agent Nori Takano Figure 2 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Scope of Claims] A metal support plate formed to have a heat dissipation function and having a notch or hole near one end, and a semiconductor chip mounted on one main surface of the support plate. , consisting of a lead electrically connected to the chip, and an insulating resin coating covering a part of the support plate, the chip, and the lead, and a resin on one main surface side of the support plate. The resin coating is formed such that the coating portion is thicker than the resin coating portion on the other main surface side, and the resin coating is formed such that a mounting notch or hole is formed in the notch or hole. In the method for manufacturing a resin-sealed semiconductor device, the coating portion is thinner than the portion of the resin coating portion on the one main surface side that covers the chip and the portion that covers the vicinity of the mounting notch or hole. is arranged so as to be generated separately from the mounting notch or hole, and is formed so as to suppress the progress of the sealing resin injected from the injection hole arranged near one end of the support plate. The resin coating is formed by using a resin sealing mold having a protruding part, and injecting the sealing resin into the molding space of the resin sealing mold from the injection hole. A method for manufacturing a sealed semiconductor device.