JP2001035985A - Semiconductor device sealed with resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress increase in cost to a low level and reduce occurrence of resinous burrs on the soldering face of a heat radiation plate at molding. SOLUTION: A clamp region 6 to be clamped with a mold at molding and a soldering region 7 to be fixed by solder or conductive paste are formed on a face which is exposed without being sealed with resin, among a heat radiation plate 5 sides, and also a groove 8, is formed in the clamp region 6 molded in the heat radiation plate 5. Hereby, resinous burrs stay in the groove 8, which can prevent leakage of resin to the soldering region 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-sealed semiconductor device in which burrs are prevented from occurring during resin sealing of an IC.

[0002]

2. Description of the Related Art Conventionally, a heat generating chip such as a power MOS is die-bonded directly to a heat sink instead of an island of a lead frame, and the heat sink is exposed and protruded from a package surface to improve heat radiation. Many things have been proposed. (Japanese Patent Laid-Open No. 54-18280)
FIGS. 18 and 19)
FIG. 1 relates to a conventional resin-encapsulated semiconductor device.
8 is a sectional view taken along section II in FIG. 19, and FIG. 19 is a bottom view of the resin-sealed semiconductor device of FIG. 18 as viewed from the back.

[0003]

In the package structure, since the surface of the heat radiating plate is flat, the pressing at the time of molding is insufficient, and resin burrs 15 are generated on the heat radiating plate 5 exposed from the resin body 14. There was a problem. This resin burr has a problem that the appearance is poor in appearance, and when the heat sink 5 of the semiconductor device is soldered to a printed circuit board, the resin burr reduces the thermal contact area with the substrate. In order to solve this, a step of removing resin burrs is required, but there is a problem that the number of steps increases and the cost increases.

In order to suppress the occurrence of resin burrs on such a heat sink, Japanese Patent Application Laid-Open No. Sho 59-10242 discloses that a shallow concave portion is formed on the exposed lower surface of the heat sink to prevent the resin from being sealed. The contact area with the mold is reduced to increase the surface pressure to prevent the generation of resin burrs.

In Japanese Patent Application Laid-Open No. 4-199664, a convex portion is formed on the surface of a heat radiating plate, and a portion to be pressed by a mold at the time of sealing is made only a convex portion so that sufficient pressing can be performed. Has been reduced. However, there is a problem that the precision of the flatness of the surface of the heat sink that contacts the mold is required, and the manufacturing cost is increased.

Further, in Japanese Patent Application Laid-Open No. 4-199664, a polyimide tape or the like is applied to a convex portion on the surface of a heat sink to absorb variations in holding during sealing, but there is a problem that the number of parts increases and the cost increases. is there.

SUMMARY OF THE INVENTION It is an object of the present invention to suppress an increase in cost and reduce the occurrence of resin burrs on a soldering surface of a heat sink during molding.

[0008]

In order to solve the above-mentioned problems, the present invention employs the technical means of claims 1 and 2.

According to the first aspect of the present invention, the surface of the heat sink that is exposed without being resin-sealed is fixed to the clamp area to be clamped by the mold at the time of molding and the solder or the conductive paste. Since a groove is formed in the clamp region formed in the heat sink while forming the soldering region, resin burrs accumulate in the groove, thereby preventing resin leakage into the soldering region.

According to the second aspect of the present invention, since the air vent is formed between the edge of the clamp area formed on the heat sink and the groove, air in the resin near the side surface of the heat sink is further passed through the air vent. It can be discharged from the cavity to the outside, and voids in the resin body can be reduced.

[0011]

1 to 4 relate to a first embodiment of the present invention. FIG. 1 is a sectional view taken along a line II in FIG.
, FIG. 2 is a bottom view of the resin-sealed semiconductor device of FIG. 1 as viewed from the back, and FIGS. 3 and 4 show the resin-sealed semiconductor device set in a mold before resin sealing. 3 is a sectional view taken along the line III-III in FIG. 4, and FIG. 4 is a sectional view taken along the line II-II in FIG.

In FIGS. 1 and 2, the semiconductor element 1 is fixed to a heat sink 5 by solder or conductive paste 4. A bonding pad provided on the semiconductor element 1 is connected to a plurality of leads 3 by a gold wire or an aluminum wire 2. The resin-encapsulated semiconductor devices are configured by sealing them in a resin body 14 with a resin such as an epoxy resin. At this time, the lower surface of the heat sink 5 is exposed from the resin body 14.

FIGS. 3 and 4 show a state before the resin molding. The heat radiating plate 5 is a rectangular plate made of a heat conductive metal such as copper and aluminum as shown in FIGS. In addition, connecting portions 16 projecting outward are formed integrally at the central portions of the pair of opposing sides, respectively. A caulking convex portion 16a is formed at the tip of the upper surface of the connecting portion. The lower surface of the semiconductor element 1 is bonded to the center of the upper surface of the heat sink 5.

The lead frame 17 is formed by pressing or etching a metal plate such as copper, copper alloy, and 42 alloy, and has a plurality of leads 3 between the left and right frame portions 17a. These leads 3 are arranged at equal pitches in the left-right direction, extend in the front-rear direction, and are connected to each other. At this time, the lead 3 located closest to the frame portion 17a is formed to extend longer than other leads.

The lead frame 17 further includes a frame 1
A suspension lead 18 connected to the heat radiating plate 5 is integrally provided so as to protrude into the inside of 7a. In this case, a hole 18 a is formed in the suspension lead 18, and the heat sink 5 is connected to the lead frame 17 by inserting the caulking convex portion 16 a at the end of the connecting portion 16 into the hole 18 a of the suspension lead 18 and caulking. It is supposed to be. Each lead 3
Is finally cut off from the frame portion 17a and a predetermined formation is performed.

Now, as shown in FIG. 1 and FIG.
On the bottom surface, there are formed a clamp area 6 which is pressed by a mold during molding and a solder area 7 which is soldered to a printed circuit board. The clamp area 6 is continuously formed over the entire circumference by a certain length from the edge of the heat sink 5. Further, the clamp area 6 is formed more concavely than the soldering area 7. Further, a groove 8 is formed on the entire periphery of the clamp region 6 at a fixed distance from the edge of the heat sink 5. The number of the grooves 8 is not limited to one, but may be any number as long as it can be formed in the range of the clamp area 6. The sectional shape may be a rectangle as shown in FIG. 1 or another shape such as a V-shape. The groove 8 is formed by pressing or etching.

Next, a manufacturing process flow of the present semiconductor device will be described. The heat radiating plate 5 is formed from a metal plate (for example, a reel-shaped material) by mechanical processing such as pressing. At this time, the clamp region 6 and the groove 8 may be formed at the same time, or may be formed after being divided into individual pieces. The formation of the groove may be an etching process.

Next, as shown in FIGS. 3 and 4, the heat radiating plate 5 having the clamp region 6 and the groove 8 and the lead frame 17 are formed.
As described above, the connection is made by caulking the connecting portion 16 to the suspension lead 18 to obtain the lead frame 17 with the heat sink 5.

Next, the semiconductor element 1 is bonded to the surface of the heat sink 5 opposite to the surface where the groove 8 is formed by soldering or conductive paste 4. When connecting with silver paste, it is effective to apply silver plating in advance to the mounting region of the heat sink 5 on which the semiconductor element 1 is mounted in order to improve the adhesiveness.

Next, a bonding pad provided on the semiconductor element 1 and a plurality of leads 3 are connected by wires 2. Then, the semiconductor element 1, the leads 3, and a part of the heat sink 5 connected as described above are sealed with a mold resin.

Here, as shown in FIG. 4, the molding dies used in the resin molding process are:
The upper mold 9 is relatively close to and separated from the lower mold 10, and a cavity 19 corresponding to the outer shape of the resin body 14 is formed between the upper mold 9 and the lower mold 10. ing. In the cavity 19 of the upper mold 9, the clamp region 6 of the heat sink 5 is pressed against the connecting portion 16 of the heat sink 5.
A pin 11 is provided for pressing the surface on which is formed on the bottom surface of the cavity of the lower mold 10. Here, the cross-sectional shape of the pin 11 to be pressed is rectangular, but other shapes such as rectangular, circular, etc. may be used. The soldering area 7 is provided on the bottom surface of the cavity of the lower mold 10.
Escape so that it does not hit the cavity 19 of the lower mold.
3 are formed. The upper mold 9 and the lower mold 10 are provided with air vents 20 for venting air during molding. Further, a through hole 21 for air release is formed in a portion of the lower mold 10 in contact with the clamp region 6, and a through hole 22 for air release at the time of mold clamping is formed in the relief 13.

In the resin molding process, the lead frame 1
7 is set at a predetermined position on the lower mold 10, and the mold is clamped. Thus, as shown in FIG. 4, the radiator plate 5, the semiconductor element 1, the leads 3, and the like are housed in the cavity 19. At this time, the pin 11 provided on the upper die 9 hits the upper surface of the connecting portion 16 and presses the heat sink 5 downward by the clamping force. Thereby, the clamp area 6 of the heat sink 5 is pressed against the cavity surface of the lower mold 10. In this state, the epoxy resin is injected into the cavity 19 and hardened. As a result, a resin body 14 in which the semiconductor element 1, the upper portion of the heat sink 5, the leads 3, the wires 2, and the like are resin-molded is formed.

Thereafter, the resin molded product is taken out of the cavity 19, and the frame portion 17a of the lead frame 17 is removed.
And the molding of the lead 3 is performed, thereby completing the resin-encapsulated semiconductor device. As shown in FIG. 1, in this resin-sealed semiconductor device, the soldering region 7 of the heat sink 5 has a resin body 14
And is mounted in a state of thermal contact with the heat radiating plate 5 by soldering the soldering surface 7 to the printed circuit board. At this time, the tips of the leads 3 are also soldered to the electrodes of the printed circuit board.

According to the present embodiment, by providing the groove 8 in the clamp area 6, the leaked resin burrs accumulate in the groove 8 and generate resin burrs inside the groove 8 (into the soldering area 7). Can be eliminated. As a result, a clean surface free of resin burrs can be secured in the soldering area 7 of the radiator plate 5, eliminating the step of removing resin burrs.
Cost can be reduced.

In addition, there is no need for high processing accuracy of the clamp area 6 which contacts the inner surface of the cavity 19 of the lower mold 10 or high dimensional accuracy for connecting the heat sink 5 to the lead frame 17.

In the present embodiment, the connecting portion 16 connected to the lead frame 17 is provided on the heat radiating plate 5 so that the pressing pin 11 hits the connecting portion 16 to receive the clamping force of the mold. Therefore, the pin 11 is located at a position out of the connection region of the heat radiation plate 5 by the wire 2, and there is an advantage that the restriction in the wire bonding step is eliminated.

Next, a second embodiment will be described with reference to FIGS.

FIGS. 5 to 9 relate to a second embodiment of the present invention. FIG. 5 is a cross-sectional view taken along a line II in FIG. 6, and FIG. 7, 8 and 9 show the state of the resin-encapsulated semiconductor device set in a mold before resin encapsulation, and FIG. 7 is a cross-section taken along the line III-III in FIG. 8 and FIG. 8 are cross-sectional views II-
9 is a sectional view, and FIG. 9 is a clamp area 6 of FIG. 8 (see FIG. 5).
The enlarged sectional views of FIG.

The second embodiment is different from the first embodiment in that an air vent 23 is provided in a clamp area 6a from the edge of the heat sink 5 to the groove 8 in the clamp area 6 of the heat sink 5. The point is that an air vent 24 is provided in a region corresponding to the portion 6a of the clamp region of the lower mold 10. Further, a through hole 21 is formed in the lower mold 10 to allow air passing through the air vent 24 to escape.

As a result, resin burrs generated in the clamp area 6 of the heat sink 5 preferentially accumulate in the groove 8 through the air vents 23 and 24. In FIG. 8, the air vents 23, 24
Are arranged at substantially equal pitches at ten locations, but the number and arrangement pitch are not limited to this. According to this, the same operation and effect as in the first embodiment can be obtained, and in addition, the air in the resin near the side surface of the heat radiating plate 5 can be discharged from the cavity 19 through the air vents 23 and 24 to the outside. As a result, voids in the resin body 14 can be reduced. In FIG. 8, the air vents 23 and 24 are shown.
Although the case where both are formed has been described, the same operation and effect can be obtained by forming only the air vent 23 or forming only the air vent 24.

FIGS. 10 and 11 relate to the third embodiment and show a state in which the resin-sealed semiconductor device is set in a mold before resin sealing. FIG. 10 is a sectional view taken along the line III-III in FIG. FIG. 11 is a sectional view taken along the line II-II in FIG.

In the third embodiment, a caulking convex portion 16 a is formed at the base of the connecting portion 16 protruding outside from the heat sink 5, and the tip of the connecting portion 16 is pushed by the pin 11. I have. The suspension lead 18 is formed in a U-shape to avoid the pressing pin 11. Since the connecting portion 16 connected to the lead frame 17 is provided on the heat radiating plate 5 and the pressing pin 11 is brought into contact with the connecting portion 16 to receive the clamping force of the mold, the lead 3 is connected to the heat radiating plate. 5 can be approached, and the range in which wire bonding can be performed can be expanded. In addition, since the suspension leads 18 are taken out of the lead frame 17 at two locations, the strength of the heat radiating plate 5 with respect to the lead frame 17 is improved, and torsion and deformation in the assembly process can be reduced.

FIGS. 12 and 13 relate to the fourth embodiment and show a state in which the resin-sealed semiconductor device is set in a mold before resin sealing. FIG. 12 is a sectional view taken along the line III-III in FIG. FIG. 13 is a sectional view taken along the line II-II in FIG.

In the fourth embodiment, the heat radiating plate 5 has a rectangular shape and does not have a connecting portion projecting outward. The pressing pin 11 presses the center of the left and right sides of the heat sink 5, and the suspension lead 18 is connected to the pressing pin 11.
The parts are connected before and after the part pressed by. With such a configuration, substantially the same effects as in the first embodiment can be obtained.

FIGS. 14 and 15 relate to the fifth embodiment and show a state in which the resin-sealed semiconductor device is set in a mold before resin sealing. FIG. 14 is a sectional view taken along the line III-III in FIG. FIG. 15 is a sectional view taken along the line II-II in FIG.

In the fifth embodiment, the suspension leads 18 are connected at the center of the left and right sides of the heat radiating plate 5, and the pressing pins 11 are disposed in front of and behind the connection portions of the suspension leads 18. Each is pressed. According to this, in addition to substantially the same operation and effect as the first embodiment, 4
A stable pressing force can be received by the pressing pin 11 of the book.

FIGS. 16 and 17 relate to the sixth embodiment and show a state in which the resin-sealed semiconductor device is set in a mold before resin sealing. FIG. 16 is a sectional view taken along the line III-III in FIG. FIG. 17 is a sectional view taken along the line II-II in FIG.

In the sixth embodiment, steps 5a are formed on the front and rear sides of the heat sink 5, and the pressing pins 11 press the upper surface of the steps 5a. With such a configuration, the same operation and effect as those of the first embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 relates to a first embodiment of the present invention, and is a cross-sectional view taken along a line II in FIG. 2;

FIG. 2 relates to the first embodiment of the present invention, and is a bottom view of the resin-sealed semiconductor device of FIG. 1 as viewed from the back.

FIG. 3 relates to the first embodiment of the present invention, and is a cross-sectional view taken along section III-III in FIG.

FIG. 4 relates to the first embodiment of the present invention, and is a cross-sectional view taken along the line II-II in FIG.

FIG. 5 relates to a second embodiment of the present invention, and is a cross-sectional view taken along a line II in FIG. 6;

6 relates to a second embodiment of the present invention, and is a bottom view of the resin-sealed semiconductor device of FIG. 5 as viewed from the back.

FIG. 7 relates to a second embodiment of the present invention, and shows a state in which the resin-encapsulated semiconductor device is set in a mold before resin encapsulation, and is a cross-sectional view taken along section III-III in FIG. .

8 relates to the second embodiment of the present invention, and shows a state in which the resin-encapsulated semiconductor device is set in a mold before resin encapsulation, and is a cross-sectional view taken along section II-II in FIG. 7; .

9 relates to a second embodiment of the present invention and shows a state where the semiconductor device is set in a mold before resin sealing of the resin-sealed semiconductor device, and is an enlarged view of a clamp region 6 (see FIG. 5) in FIG. It is sectional drawing.

10 is a cross-sectional view taken along section III-III in FIG. 11, showing a state in which the resin-sealed semiconductor device is set in a mold before resin sealing according to the third embodiment.

11 is a cross-sectional view taken along the line II-II in FIG. 10, showing a state in which the resin-sealed semiconductor device is set in a mold before resin sealing according to the third embodiment.

FIG. 12 is a cross-sectional view taken along the line III-III in FIG. 13, showing a state in which the semiconductor device of the resin-sealed semiconductor device is set in a mold before resin-sealing according to the fourth embodiment.

FIG. 13 is a cross-sectional view taken along section II-II in FIG. 12, showing a state in which the resin-sealed semiconductor device is set in a mold before resin sealing according to the fourth embodiment.

14 is a cross-sectional view taken along section III-III in FIG. 15, showing a state in which the resin-sealed semiconductor device is set in a mold before resin sealing according to the fifth embodiment.

15 is a cross-sectional view taken along the line II-II in FIG. 14, showing a state in which the resin-sealed semiconductor device is set in a mold before resin sealing according to the fifth embodiment.

16 is a cross-sectional view taken along section III-III in FIG. 17, showing a state in which the resin-sealed semiconductor device is set in a mold before resin sealing according to the sixth embodiment.

FIG. 17 is a cross-sectional view taken along section II-II in FIG. 16, showing a state in which the resin-sealed semiconductor device is set in a mold before resin sealing according to the sixth embodiment;

18 relates to a conventional resin-encapsulated semiconductor device and is a cross-sectional view taken along the line II in FIG.

19 relates to a conventional resin-encapsulated semiconductor device, and is a bottom view of the resin-encapsulated semiconductor device of FIG. 18 as viewed from the back.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor element 5 Heat sink 6 Clamp area 7 Soldering area 8 Groove 9, 10 Die 14 Resin body 23 Air vent

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/28 H01L 23/28 B // B29L 31:34 F term (Reference) 4F202 AA39 AD19 AH33 AM33 CA12 CB01 CB12 CK41 CK83 CP01 CQ01 CQ05 4F206 AA39 AD19 AH37 AM33 JA02 JB17 JF05 JQ81 4M109 AA01 BA01 CA21 DA07 DB03 FA04 GA05 5F061 AA01 BA01 CA21 DA06 DD12 EA02 EA03 5F067 AA09 AB02 BD05 CA03 EA04 DE03

Claims (2)

[Claims] In a resin-sealed semiconductor device in which a semiconductor element is fixed to a radiator plate and sealed in a resin body with a resin, a surface of the radiator plate that is exposed without being resin-sealed is provided with a mold. Resin sealing characterized by forming a clamp area to be clamped by a mold at the time of molding and a soldering area fixed by solder or conductive paste, and forming a groove in the clamp area formed on the heat sink. Semiconductor device. 2. The resin-encapsulated semiconductor device according to claim 1, wherein an air vent is formed between an edge of the clamp region formed on the heat sink and the groove.