JPH0378779B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a heat dissipation support plate for power use in which a molded resin layer is provided not only on the side to which a semiconductor chip is fixed, but also on the opposite side. The present invention relates to a method of manufacturing a resin-sealed semiconductor device.

[Conventional technology]

A thin resin layer (several hundred μm thick) is also formed on the back side of the heat dissipation support plate to which the semiconductor chip is fixed, making it possible to create a resin seal that eliminates the need to use insulating plates such as mica thin plates when attaching to external heat dissipators, etc. A stop-type semiconductor device is disclosed in, for example, Japanese Patent Laid-Open No. 147260/1983.

In addition, it is the applicant's responsibility to use a mold as shown in FIG. 10 in order to form a thin resin layer on the back side of the heat dissipation support plate in this type of resin-sealed semiconductor device. This was proposed in Japanese Patent Application No. 114018/1983. In Fig. 10, 1 is a heat dissipation support plate, 2 is a lead, 3 is a power transistor chip, 4 is an internal lead, 5 is a protective resin, 6 is a molding resin, 7 is an upper mold, 8 is a lower mold, and 7a is a A partition-like protrusion that suppresses the flow of resin, 9 is a resin injection hole, and 10 is formed by clamping a mold. This is a blank space for molding. In this device,
When resin in a sticky state is injected into the heated molds 7 and 8 through the resin injection hole 9, the fat flows above and below the heat dissipation support plate 1. At this time, the flow of the resin on the upper side is suppressed by the protrusion 7a, and the flow of the resin on the lower side of the heat dissipation support plate 1 is relatively strengthened. As a result,
A thin resin layer can be favorably formed on the back surface of the heat dissipation support plate 1.

[Problem that the invention seeks to solve]

By the way, the flow of the molding resin 6 is roughly divided into a flow U above the support plate 1 and a flow L below the support plate 1, as illustrated by diagonal lines in FIG. Filling of the molding resin 6 into the void 10 is carried out through injection holes 9 at the top and bottom of the support plate 1.
Preferably, it starts from the side and ends at the lead 2 side end. The protrusion 7a is provided to achieve such filling.

However, it was found that there was a problem in the filling state of the relatively thick resin layer 6a above the chips 3 of the support plate 1. That is, as schematically shown in FIG.
The lower flow L of the resin is divided into a lower flow L 1 that advances toward the lead side end of the support plate 1, which is the basic flow direction of the resin, and a flow _L1 only on the lower side that advances toward the lead side end of the support plate 1 through the side surface of the support plate 1. It splits into flows L ₂ and L ₃ that wrap around above.
As a result of the resin flow L on the lower side being strengthened, at point A on the upper side of the support plate 1, the resin flow first increases.
A process occurs in which L ₂ and L ₃ collide, and then the resin flow U arrives. In such a resin-filled state, the air near point B causes resin flows U, L ₂ ,
By being surrounded by L ₃ , there is no way to escape, and eventually an unfilled portion is left in the resin layer 6 a near the top of the chip 3 .

Therefore, an object of the present invention is to satisfactorily fill resin on both the front side and the back side when manufacturing a semiconductor device having a thick resin layer on the front side of a support plate and a thin resin layer on the back side. Our goal is to provide a way to do so.

[Means for solving problems]

To achieve the above object, the present invention provides a support plate having a heat dissipation function and an electric conduction function and having a pair of mutually parallel side surfaces and a pair of end surfaces between the pair of side surfaces, and one of the support plates. a semiconductor chip fixed on the main surface of the support plate, an external lead for connecting the support plate connected to one side of the pair of end faces of the support plate, and at least one lead electrically connected to the semiconductor chip. comprising: an external lead for chip connection; a molded resin body that covers the support plate connection and a part of the chip connection external lead on the support plate side; the semiconductor chip; and a molded resin body that covers the support plate;
In the method for manufacturing a semiconductor device, the molded resin body is formed such that a resin layer on one main surface side of the support plate is thicker than a resin layer on the other main surface side, wherein the pair of support plates has a resin injection hole for injecting resin from the other side of the end face of
and a pair of lateral protrusions having protrusions for suppressing the flow of the resin injected from the resin injection hole, the protrusions being disposed along the pair of side surfaces of the support plate; a partition-like protrusion provided on at least a portion between the pair of lateral protrusions on the one main surface of the support plate to suppress the flow of resin from the other of the pair of end faces toward one side; preparing a resin sealing mold having a part, placing the support plate to which the semiconductor chip is fixed in a molding cavity of the resin sealing mold, and injecting resin from the resin injection hole. The present invention relates to a method of manufacturing a resin-sealed semiconductor device, characterized in that the molded resin body is formed by a method of manufacturing a resin-sealed semiconductor device.

[Effect]

The partition-like protrusion in the present invention suppresses the flow of resin on one main surface of the support plate and strengthens the flow of resin under the other main surface of the support plate. When the flow of the resin on the other main surface side is strengthened, a flow of the resin wraps around onto the one main surface through the side surface of the support plate. However, this flow is blocked or suppressed by the lateral projections. As a result, the balance of the resin flowing on one main surface of the support plate and below the other main surface is improved, and the resin flow on one main surface of the support plate and the resin flowing from the other main surface side of the support plate to one side are improved. Collision with the resin flow that wraps around the main surface side is prevented or weakened, thereby preventing the occurrence of incomplete resin filling portions.

〔Example〕

Next, a method for manufacturing a resin-sealed power transistor according to an embodiment of the present invention will be described based on FIGS. 1 to 8.

First, a lead frame 11 shown in FIG. 1 is prepared. Although the figure shows one transistor, in reality, many transistors (for example, 10 transistors) are arranged in parallel. Reference numeral 12 denotes a support plate made of a Ni-coated Cu plate and having both a heat dissipation function and an electrical conduction function. Reference numeral 14 denotes an external lead for connecting the support plate connected to one end of the support plate 12, and functions as a collector lead.

13 and 15 are external leads for chip connection;
Each functions as a base lead and an emitter lead. Each external lead 13, 14, 15 is made of the same material as the support plate 12. 16 is a tie bar that bridges the external leads, and 17 is a strip that commonly connects the ends of the external leads. Support plate 1
On the side opposite to the external lead 2, there is a U-shaped notch 1.
8 and a thin wall portion 12b of the support plate 12 are formed. 12a is a thick portion of the support plate 12. Reference numeral 19 denotes a silicon power transistor chip, the lower surface of which serves as a collector electrode (not shown), and is fixed to one main surface of the support plate 12 with solder (not shown). A base electrode and an emitter electrode (not shown) are formed on the upper surface of the chip 19, and these electrodes and the outer leads 13 and 15 are connected by inner leads 20 and 21 made of Al wire. 22 is a chip protection resin made of silicone resin.

Further, in order to resin-seal the lead frame 11 to which the chip 19 shown in FIG. 1 is fixed, upper and lower molds 23 and 24 shown in FIGS. 2 to 4 are prepared. The upper and lower molds 23 and 24 are combined to form a molding cavity 25 as shown in FIGS. 3 and 4, and are a pair for holding the thin part 12b of the support plate. The truncated conical pin 23a, the cylindrical protrusion 23b for obtaining the mounting hole, the upper surface (one main surface side) to which the chip 19 of the support plate 12 is fixed. ) and a lateral protrusion 23d to prevent the resin from flowing from the lower surface (the other main surface side) of the support plate 12 to the upper surface side through the sides. and has. A groove 23e is provided in the center of the partition-like protrusion 24c, and the groove 23e becomes wider in the direction of the fat flow. This groove 23e has a function of compensating for the strength of the flow of resin in the central portion that is obstructed by the cylindrical projection 23b. Lower mold 2
4 has a pair of truncated conical pins 24a for holding the support plate 12, a lead arrangement groove 24b, and a resin injection hole 26.

Next, the lead frame 11 to which the chip 19 shown in FIG. 1 is fixed is placed in the molding cavity 25 of the molds 23 and 24 shown in FIG. 23 and 24 are clamped. From this, the leads 13 to 15 are attached to the upper and lower molds 23, 24.
The upper and lower pins 23a, 24a
The thin portion 12b of the support plate 12 is held between the two. The cylindrical projection 23b is located in the notch 18 of the support plate 12.
It contacts the lower mold 24 through. The partition-like protrusion 23c is located between the resin injection hole 26 and the chip 19. The lateral protrusion 23d is the partition-like protrusion 2
3c to approximately the center of the tip 19, and a slight gap is created between this tip and the support plate 12. Since the support plate 12 is housed in the molds 23 and 24 so that its position in the thickness direction is accurate, the spacing between the tip of the lateral protrusion 23d and the support plate 12 is highly accurate. Support plate 12
Compared to the upper cavity 25a formed above, the lower cavity 25b is extremely narrow, and the distance between the thick part 12a of the support plate and the lower mold 24 is about 0.5 mm.

Next, as shown in FIGS. 5 and 6, based on the known transfer molding method, the epoxy resin, which has been heated and has become sticky, is poured into the injection hole 2.
6 into the cavity 25 under pressure. Molds 23, 24
Since the resin is heated to about 180° C., the epoxy resin filled in the cavity 25 is thermally hardened within a few minutes to form the molded resin body 27. At the time of resin injection to obtain this molded resin body 27, the partition-like protrusion 23 of the mold
c is the upper space 25 similar to the protrusion 7a in FIG.
By suppressing the flow of resin to a, the lower space 2 is relatively
Strengthen the flow of resin to 5b. Therefore, it is possible to prevent an unfilled portion of the resin from forming in the lower space 25b, and to form a thin resin layer 27b in a good manner. Further, the lateral protrusion 23d of the mold prevents the resin that has flowed through the lower cavity 25b from going around to the upper cavity 25a. That is, in FIG. 11, it acts to weaken the resin flows L ₂ and L ₃ . For this reason,
This prevents the occurrence of an unfilled portion of the resin near the top of the chip 19 in the upper space 25a, and allows a thick resin layer 27a to be formed satisfactorily. The flow of the resin at the center of the upper surface of the support plate 12 during resin injection is as follows:
Since the groove 23e is provided in the center of the partition-like protrusion 23c, it is relatively strong. That is, the cylindrical projection 2
3b is in front, the strength of the flow in the central part is prevented from being lower than on both sides of this central part. Further, since the groove 23e is formed to widen toward the end, the balance between the resin flowing on the upper surface of the support plate 12 and the resin coming around from the lower surface through the sides is improved.

Next, the molds 23 and 24 are unclamped, the lead frame 11 is taken out, and the molded resin body 27 is subjected to an even longer heat treatment in order to completely heat cure. Subsequently, the tie bars 16 and the strips 17 are cut and removed by press working to obtain the power transistor shown in FIGS. 7 and 8. Recesses 28, 29
are the truncated conical pins 23a and 24a of the mold, respectively.
It is formed in response to the Reference numeral 30 denotes a mounting hole through which a screw or the like is passed when attaching to an external heat sink, and is formed to correspond to the cylindrical pin 23b of the mold. The recesses 31 and 32 are formed corresponding to the protrusions 23c and 23d of the mold, respectively. The bottoms of the recesses 31 and 32 and the support plate 12
A thin resin layer is interposed between the two.

[Modified example]

The present invention is not limited to the embodiments described above, and the following modifications are possible, for example.

(A) The lateral protrusion 23d of the upper mold 23 may be slightly separated from the side wall of the mold 23 so that the recess 32 shown in the completed transistor shown in FIG. 9 is obtained. That is, the protruding portion 23d may be formed into a partition shape.

(B) In the completed transistor, the protrusion 23d may protrude from the side wall of the mold 23 parallel to the support plate 12 so that the opening inlet is provided only on the side surface of the molded resin body 27.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a lead frame according to an embodiment of the present invention, FIG. 2 is a perspective view showing a part of a mold according to an embodiment of the present invention, and FIG. FIG. 4 is a sectional view of the mold and lead frame corresponding to the portion along the lead 13 in FIG. 1, and FIGS. 5 and 6 are the molding A sectional view corresponding to FIGS. 3 and 4 showing a resin body formed therein;
Fig. 7 is a perspective view of the completed transistor, Fig. 8 is a plan view of the transistor shown in Fig. 7, Fig. 9 is a plan view showing a modified transistor, and Fig. 10 is a cross section showing the conventional mold and transistor. 11 is a perspective view showing the lead frame of the transistor shown in FIG. 10. 12... Support plate, 13, 14, 15... Lead, 19... Chip, 23... Upper mold, 23c
...Partition-like protrusion, 23d...Side protrusion, 2
4...Lower mold.

Claims (1)

[Claims] 1. A support plate having a heat dissipation function and an electrical conduction function and having a pair of mutually parallel side surfaces and a pair of end surfaces between the pair of side surfaces, and a semiconductor chip fixed on one main surface of the support plate. a support plate connection external lead connected to one side of the pair of end faces of the support plate; at least one chip connection external lead electrically connected to the semiconductor chip; and the support plate. A molded resin body that covers a part of the support plate side of the external lead for connection and the chip connection, the semiconductor chip, and the support plate, and a resin layer on one main surface side of the support plate. In the method of manufacturing a semiconductor device, in which the molded resin body is formed to be thicker than the resin layer on the other main surface side, the resin is injected from the other side of the pair of end surfaces of the support plate. a pair having an injection hole and a protrusion for suppressing the flow of resin injected from the resin injection hole, the protrusion being disposed along the pair of side surfaces of the support plate; At least a portion between the pair of side protrusions and the one main surface of the support plate to suppress the flow of resin from the other end face to the other side of the pair of end faces. preparing a resin sealing mold having a partition-like protrusion, disposing the support plate to which the semiconductor chip is fixed in a molding cavity of the resin sealing mold;
A method for manufacturing a resin-sealed semiconductor device, characterized in that the molded resin body is formed by injecting resin from the resin injection hole.