JPH10154783A - Resin sealed semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the dielectric strength of an insulated semiconductor device. SOLUTION: A plurality of circular and polygonal projections 2 are provided on the semiconductor chip mount surface 4 side surface of a lead frame 1 mounted with a semiconductor chip 3 except the semiconductor chip mounted surface 4. After the lead frame 1 provided with the projections 2 is set in a resin molding tool 21 as shown in Fig. (c), the void 24 in the tool 21 is filled up with a resin by injecting the resin into the tool 21 through a resin injection port 22. The flowing velocity of the resin flowing on the semiconductor chip mounting surface 4 side (indicated by the arrow A) becomes slower due to the projections 2 and becomes equal to that of the resin flowing the rear surface 5 side of the lead frame 1 and moves toward external lead-out terminals 7. The bubbles in the void 24 are pushed by the resin and discharged to the out side through a deaerating port 23. Therefore, the bubbles existing in the void 24 are not mixed in the resin filling up the void 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating resin-sealed semiconductor device formed by transfer molding.

[0002]

2. Description of the Related Art A semiconductor chip is soldered to a lead frame, a bonding pad of the semiconductor chip is connected to an external lead terminal (outer lead) by a bonding wire, and a portion other than the external lead terminal is resin-sealed. In recent years, an insulated resin-encapsulated semiconductor device in which a semiconductor chip mounting surface and its back surface and side surfaces are also covered with a resin has become mainstream.

FIGS. 5A and 5B are main part configuration diagrams of a conventional insulating resin-sealed semiconductor device. FIGS. 5A and 5B are a plan view and a side view of a lead frame on which a semiconductor chip is mounted.
FIG. 1C is a cross-sectional view of a main part in a state where a lead frame on which a semiconductor chip is mounted is attached to a resin molding die. In FIG. 5, the semiconductor chip mounting surface 4 of the lead frame 1 is shown.
The surface on the side is flat, and the semiconductor chip mounting surface 4 is surrounded by a V groove 6 (FIG. 5A). The portion of the lead frame 1 excluding the external lead-out terminals 7 is resin-sealed including the back surface 5 of the lead frame 1 by transfer molding. In this case, the thickness of the resin on the back surface 5 side of the lead frame 1 needs to be reduced in order to maintain good heat dissipation. FIG.
(C) shows the resin molding die 21,
The resin flows from the resin molding die 21 to the lead frame 1 on which the semiconductor chip 3 is mounted, as indicated by arrows A and B, and fills the gap 24. After the gap 24 is filled with the resin, the resin molding die 21 is removed. The gap 24 between the resin molding die 21 and the back surface 5 of the lead frame 1 is extremely narrow because the thickness of the resin in this portion needs to be reduced.

[0004]

As described above, in the resin molding, on the back surface 5 side of the lead frame 1 where the gap 24 between the resin molding die 21 and the lead frame 1 is extremely narrow,
The resin has poor fluidity and is difficult to fill. Conversely, the gap between the resin molding die 21 and the lead frame 1 is easily filled widely on the semiconductor chip mounting surface 4 side. Therefore, the resin (arrow A) flowing through the gap on the semiconductor chip mounting surface 4 side flows into the opposite back surface 5 side of the lead frame 1, and at this time, bubbles are mixed into the resin, and resin filling failure occurs. This defective filling portion occurs in a thin portion of the resin of the molded semiconductor device (the surface opposite to the semiconductor chip mounting surface 4),
There is a problem that an electrical insulation failure is caused and the dielectric strength of the semiconductor device is reduced. In order to prevent this, if the gap on the back surface 4 side of the lead frame 1 is increased, the thickness of the resin in this portion is increased, the thermal resistance is increased, and the heat dissipation is deteriorated.

An object of the present invention is to solve the above-mentioned problems and to provide an insulating resin-sealed semiconductor device having an improved withstand voltage.

[0006]

In order to achieve the above object, in an insulating resin-sealed semiconductor device in which a lead frame on which a semiconductor chip is mounted is resin-sealed, a surface of the lead frame on which the semiconductor chip is mounted is provided. In addition, the projections are selectively provided on the surface other than the region where the semiconductor chip is mounted.

It is effective if the shape of the projection is circular or polygonal. Further, the shape of the projection may be stitched. . By providing the protrusion outside the area of the semiconductor chip mounting surface of the lead frame, the resin flow resistance on this surface side increases. Therefore, the flow of the resin on the semiconductor chip mounting surface side is delayed, and the flow of the resin on the back surface side of the lead frame becomes the same. Therefore, the resin flowing on the semiconductor chip mounting surface side joins with the resin flowing on the back surface side of the lead frame at the bubble vent hole of the resin molding die without going around the back surface side of the lead frame. As a result, air bubbles in the gap between the resin molding die and the lead frame are smoothly discharged from the air bubble removing hole, and the air bubbles can be prevented from being caught in the extremely narrow gap on the back surface side of the lead frame.

[0008]

FIG. 1 shows a first embodiment of the present invention.
FIGS. 1A and 1B are a plan view and a side view of a lead frame on which a semiconductor chip is mounted, and FIG. 1C is a view showing a state where the lead frame on which the semiconductor chip is mounted is attached to a resin molding die. It is a fragmentary sectional view. In FIG. 1, a plurality of circular and polygonal (here, hexagonal) projections 2 are provided on a portion other than the semiconductor chip mounting surface 4 on the semiconductor chip mounting surface 4 side of the lead frame 1 on which the semiconductor chip 3 is mounted. . The lead frame 1 provided with the projections 2 is attached to a resin molding die 21 as shown in FIG. 1C, resin is injected from a resin injection port 22, and the gap 24 is filled with the resin. The resin (arrow A) flowing on the semiconductor chip mounting surface 4 side and the resin (arrow B) flowing on the back surface 5 side of the lead frame similarly flow toward the external lead-out terminal 7 to remove bubbles in the gaps 24. Sweep out of the hole. At this time, since the protrusions 2 are provided so that the flow of the resin indicated by the arrow A and the flow of the resin indicated by the arrow B are the same, air bubbles existing in the gap 24 do not remain in the gap 24 on the back surface 5 side of the lead frame 1. Air bubbles are not mixed into the resin that is discharged from the air hole 23 and filled. It should be noted that the number and size of the projections 2 are such that the flow of the resin indicated by the arrow A and the arrow B becomes the same, and the resin indicated by the arrow A and the arrow B are provided at the same time to reach the bubble vent hole.

FIG. 2 shows a second embodiment of the present invention. FIGS. 2A and 2B are a plan view and a side view of a lead frame on which a semiconductor chip is mounted. In FIG. 2, the protrusions 2 are provided in the lateral direction of the lead frame 1 (in the direction perpendicular to the direction of the external lead-out terminals 7) to increase the flow resistance of the resin. Arrow B
And the resin flows at the same time so as to reach the bubble release holes 23 at the same time.

FIG. 3 shows a third embodiment of the present invention. FIGS. 3A and 3B are a plan view and a side view of a lead frame on which a semiconductor chip is mounted. In FIG. 3, the shape of the projection 2 is rectangular, and the longitudinal direction of the projection 2 is formed at right angles to the direction of the external lead-out terminal 7. By doing so, the flow resistance of the resin can be increased even if the area of the protrusion 2 is reduced. By doing so, the flow of the resin indicated by arrows A and B in FIG.
Can reach the bubble vent hole 23 at the same time.

FIG. 4 shows a fourth embodiment of the present invention. FIGS. 4A and 4B are a plan view and a side view of a lead frame on which a semiconductor chip is mounted. In FIG. 4, by forming the protrusions 2 in a stitch shape to increase the flow resistance of the resin indicated by the arrow A, the flow of the resin indicated by the arrow A and the arrow B illustrated in FIG. The resin indicated by the arrow B can reach the air vent hole 23 at the same time.

[0012]

According to the present invention, by providing a projection on the surface of the lead frame on the semiconductor chip mounting surface side, the resin filling the gap between the resin molding die and the lead frame can be reduced. The flow resistance is increased so that the flow of the resin on the semiconductor chip mounting surface side and the flow of the resin on the lead frame rear surface side are the same, so that each resin can reach the bubble vent hole simultaneously. This prevents air bubbles from being mixed into the narrow gap on the back surface side of the lead frame. As a result, resin sealing can be performed without including air bubbles, and the electrical withstand voltage can be improved.

[Brief description of the drawings]

1A is a plan view of a lead frame on which a semiconductor chip is mounted, FIG. 1B is a side view of the lead frame, and FIG. 1C is a resin molding of the lead frame on which the semiconductor chip is mounted. Cross-sectional view of main parts attached to mold

2A is a plan view of a lead frame on which a semiconductor chip is mounted, and FIG. 2B is a side view thereof.

FIG. 3A is a plan view of a lead frame on which a semiconductor chip is mounted, and FIG.

4A is a plan view of a lead frame on which a semiconductor chip is mounted, and FIG. 4B is a side view thereof.

FIGS. 5A and 5B are main part configuration diagrams of a conventional insulating resin-sealed semiconductor device, wherein FIG. 5A is a plan view of a lead frame on which a semiconductor chip is mounted, FIG. 5B is a side view thereof, and FIG. Sectional view of main part with lead frame mounted with resin mounted on resin mold

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame 2 Projection 3 Semiconductor chip 4 Semiconductor chip mounting surface 5 Back surface 6 V groove 7 External lead-out terminal 8 Mounting hole 21 Resin molding die 22 Resin injection port 23 Bubble vent hole 24 Gap

Claims (3)

[Claims] 1. An insulated resin-sealed semiconductor device in which a lead frame on which a semiconductor chip is mounted is resin-sealed.
A resin-encapsulated semiconductor device, wherein protrusions are selectively provided on a surface of a lead frame on which a semiconductor chip is mounted and on a surface other than a region where the semiconductor chip is mounted. 2. The resin-sealed semiconductor device according to claim 1, wherein the shape of the projection is circular or polygonal. 3. The resin-encapsulated semiconductor device according to claim 1, wherein said projections are formed in a stitch shape.