JP2755440B2 - Resin mold type semiconductor device and resin mold device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a resin-encapsulated semiconductor device such as a power transistor in which the entire body including a heat sink is molded with an exterior resin;
The present invention relates to a resin molding device used for the manufacture.

[Conventional technology]

2. Description of the Related Art Conventionally, a semiconductor device such as a power transistor which generates a large amount of heat has been resin-molded by exposing a heat radiating plate to a back surface. However, such a semiconductor device needs to be mounted on a chassis or the like with mica or a silicon rubber sheet interposed to insulate the heat sink, so that the mounting operation becomes complicated and the number of parts increases. Was.

Therefore, a resin-sealed power transistor having a structure in which the entire body including the heat sink is resin-molded as shown in FIGS. 6 and 8 has been developed.

The resin-sealed power transistor shown in FIG.
Semiconductor pellets 102 on a heat sink 101 having leads 100
Is mounted with solder 103, and the emitter electrode and the base electrode on the surface of the semiconductor pellet are wire-bonded to two leads (not shown) arranged on both sides of the leads of the heat sink with fine metal wires 104, respectively. Therefore, the whole is molded with the exterior resin 105, and the thickness of the exterior resin on the lower side of the heat sink 101 is 0.3 to 1.0 mm so that heat dissipation is not reduced.
Set to about.

In addition, a resin-sealed power transistor shown in FIG.
Except for the point 6 provided, it has the same configuration as the power transistor of FIG.

[Problems to be solved by the invention]

However, in the case of the resin-sealed power transistor shown in FIG. 6, in the resin molding step, the radiator plate 101 on which the semiconductor pellet 102 is mounted is mounted on the cavity between the upper and lower molds 107 and 108 of the resin molding apparatus as shown in FIG. 109
When the heat sink 101 is set to the position, the heat sink 101 is in a cantilever support state at the lead 100, and the heat sink 101 is
When the exterior resin is injected from the gate 110 and molded, the thickness of the exterior resin on the lower side of the radiator plate becomes thinner than the set value and the withstand voltage decreases. There was a problem that 101 was partially exposed.

On the other hand, the resin-sealed power transistor shown in FIG.
Since the heat radiating plate 101 can be set in parallel with the bottom surface of the cavity 109 with the 100 suspending pins 106 interposed between the upper and lower molds 107 and 108, the above problem does not occur. However, after removing the power transistor from the mold, it is necessary to cut the tip of the suspending pin 106 projecting from the side surface of the exterior resin 105, and the cut surface is exposed on the side surface of the exterior resin 105.
There is a problem that the creepage distance 1 when mounted is short, and the dielectric strength is inferior.

6 and 8, since the flow resistance of the exterior resin during resin molding is large below the heat radiating plate 101 and small above the heat sink, both of the resin-sealed power transistors shown in FIGS. As shown by the arrow A, the upper exterior resin turns downward and joins with the lower exterior resin. When the exterior resin on the upper side of the heat sink goes down to the lower side of the heat sink in this way, the lower air is trapped and degassing is insufficient, so pinholes and bubbles are likely to be generated at the joint of the exterior resin. There was a problem.

(Means for Solving the Problems) In order to solve the above problems, the resin-molded semiconductor device of the present invention has a heat sink provided with a tapered hole having a large diameter on the semiconductor pellet mounting surface side and a small diameter on the non-mounting surface side. Then, a part of the exterior resin is filled from the non-mount surface of the heat sink to the middle of the tapered hole, and a residual hole is formed in the exterior resin on the pellet mount surface side after the holding pin is extracted, and the pellet non-mount surface side The thickness of the resin is set to be thin to cover the entire surface of the heat sink.

In the resin molding apparatus according to the present invention, a heat sink holding pin is press-fitted from above into a tapered hole of a heat sink set in a cavity between the upper and lower molds, and a tip of the heat sink is locked in the middle of the tapered hole. A support pin for supporting the radiator plate from below when the radiator plate holding pin is press-fitted is provided immediately below the radiator plate holding pin and is provided in the lower mold so as to be freely retractable.

[Action]

As in the resin-encapsulated semiconductor device of the present invention, when the tapered hole is formed in the heat sink, when resin molding is performed using the resin molding device of the present invention, the tapered hole is pressed into the tapered hole of the heat sink from above. The heat sink can be held and set in parallel with the cavity bottom surface by the heat sink holding pins of the upper mold. When the exterior resin is injected into the cavity with the radiator plate holding pins pressed in from above as described above, the flow resistance of the outer resin on the radiator plate is increased by the radiator plate pins, and the outer package on the lower side of the radiator plate is increased. Since the difference from the flow resistance of the resin is reduced, the upper exterior resin is less likely to flow below the heat sink. Since the above-mentioned radiator plate holding pin is removed when the mold is removed, a residual hole is formed in the exterior resin on the upper side of the radiator plate so as to be continuous with the tapered hole of the radiator plate. , The dielectric breakdown voltage does not decrease.

Further, as in the resin molding device of the present invention, if the support pins for supporting the heat sink from below are located right below the heat sink holding pins and are provided so as to be freely retractable in the lower mold, the heat sink can be located at the bottom of the cavity. The heatsink holding pin can be sufficiently pressed into the tapered hole of the heatsink while being supported in parallel, so the heatsink is held even when the support pin is immersed and the heatsink support is released when the exterior resin is injected. It is held parallel to the cavity bottom without falling off the pin. If the exterior resin is injected with the support pins immersed as described above, the flow resistance of the exterior resin below the heat sink is not increased, and no residual holes are formed by the support pins.

〔Example〕

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a plan view showing one embodiment of a resin-sealed semiconductor device according to the present invention, and FIG. 2 is ABCDEF of FIG.
FIG. 2 is an enlarged cross-sectional view along a line, illustrating a power transistor.

1 and 2, reference numeral 1 denotes a heat radiating plate made of a relatively soft metal such as copper, and a lead 2 is integrally provided at one end of the heat radiating plate 1. A round hole 4 for forming a stopper insertion hole 3 is provided near the other end of the heat sink 1.
And two upwardly expanding tapered holes 5 for press-fitting the heat sink holding pins at the time of resin molding.

A semiconductor pellet 6 for a power transistor is mounted on the upper surface (pellet mount surface) of the heat sink 1 via solder 7, and the collector electrode on the lower surface of the pellet and the heat sink 1 are die-bonded. Then, the emitter electrode and the base electrode formed on the upper surface of the semiconductor pellet 6 and the two leads 8 and 9 provided on both sides of the lead 2 of the heat sink 1 are wire-bonded with the thin metal wires 10, respectively. The whole is molded with an exterior resin 11 such as an epoxy resin to constitute a resin-sealed power transistor.

The exterior resin 11 is composed of the semiconductor pellet 6 and the fine metal wire 10.
The sealing resin is molded into a stepped rectangular parallelepiped shape with a thicker wall, and the thickness of the exterior resin on the lower side of the heat sink 1 (the side on which the pellet is not mounted) is 0.3 to 0.3 mm so that good heat dissipation can be exhibited.
It is set to about 1.0mm. And this exterior resin 11
The stopper insertion hole 3 is formed concentrically with the round hole 4 of the radiator plate 1 in the thin lower part of the radiator plate. Further, above the taper hole 5 of the radiator plate 1, the radiator plate holding pin is removed. Are formed. In addition, a wedge-shaped projection 13 is formed below the tapered hole 5 by entering an exterior resin.

FIG. 3 is a partial sectional view showing one embodiment of the resin molding apparatus of the present invention. This resin molding apparatus is used for manufacturing a resin-sealed power transistor having the above-described configuration.

That is, in this resin molding apparatus, a stepped rectangular cavity 16 is formed between upper and lower molds 14 and 15, and a heat sink on which the semiconductor pellet 6 is mounted as described above is formed in the cavity 16. Set the above lead 2,
8 and 9 are sandwiched between upper and lower molds 14 and 15.
The leads 2, 8, and 9 are not cut and separated at the stage of the resin molding, and are still connected to each other by the tie bars of the lead frame.

The upper die 14 is provided with a circular pole 17 for forming the stopper insertion hole 3 protruding downward.
Two heat sink holding pins 18 press-fitted into the tapered hole 5 (only one heat sink holding pin is shown in FIG. 3).
Is provided right above the tapered hole 5 so as to be freely protruded and retracted. The heat radiating plate holder 18 is a pin made of a material harder than the heat radiating plate 1 and has a lower end portion 18a formed into a tapered shape. When the tapered lower end portion 18a is pressed into the tapered hole 5, the heat radiating plate 1 is temporarily attached. It is in a state and can be held without falling off.

On the other hand, the lower mold 15 supports the heat sink 1 from below.
Three support pins 19 (only one support pin is shown in FIG. 3) are provided directly below the heat sink holding pins 18 so as to be freely protruded and retracted. At the time of injection into the cavity 16, the flat upper surface of the support pin 19 is lowered so as to be flush with the bottom surface of the cavity 16, and the support of the heat sink 1 is released.

When resin molding is performed by the resin molding apparatus configured as described above, first, with the upper mold 14 raised, the leads 2, 8, 9 are placed on the lower mold 15 and the semiconductor pellet 6 Is mounted in the cavity of the lower mold 15 and is supported from below by support pins 19, and the heat sink 1 is set in a state of being slightly floated in parallel with the bottom surface of the cavity. The leads 2, 8, and 9 are connected by the tie bars as described above and are still attached to the lead frame.

Then, the upper mold 14 is lowered, and the leads 2, 8, 9 are clamped and fixed between the upper and lower molds 14, 15 as shown in FIG. 3, and the circular pole 17 is inserted into the round hole 4 of the heat sink 1. I do. At the same time, the heat radiating plate holding pin 18 is lowered, and the tapered lower end portion 18a is pressed into the tapered hole 5 of the heat radiating plate 1 halfway, and then the support pin 19 is flush with the cavity bottom surface. And lower it. Thus, the heat sink 1 is supported by the support pins.
When the tapered lower end 18a of the radiator plate holding pin 18 is pressed into the tapered hole 5 from above by being supported by the lower portion 19, the tapered lower end 18a bites into the tapered hole 5 to be in a temporarily attached state. Is lowered to release the support of the radiator plate 1, the radiator plate 1 is held parallel to the cavity 16 while slightly floating from the bottom surface of the cavity 16.

When the holding of the heat radiating plate 1 is completed as described above, the exterior resin is injected into the cavity 16 from the gate 20, and the whole is molded. When the exterior resin is injected in this manner, the flow resistance of the exterior resin on the upper side of the heat sink 1 increases due to the presence of the heat sink holding pins 18, and the difference between the resin and the flow resistance of the exterior resin on the lower side of the heat sink 1 decreases. Therefore, since the upper exterior resin does not go under the heat sink 1, air escape is improved, and pinholes and bubbles are not generated at the joint portion of the exterior resin as in the related art. Further, since the heat sink 1 is held parallel to the bottom surface of the cavity 16, the thickness of the exterior resin on the lower side of the heat sink 1 is constant.

When the resin molding is completed, the heat sink support pins 18 are lifted up and removed, and the upper mold 14 is raised to take out the resin-sealed power transistor from the lower mold 15 and cut the tie bars to lead 2,8, Separate 9 from the lead frame.

The resin-encapsulated power transistor thus obtained has a residual hole 12 formed after extracting the heatsink holding pin 18 as described above.
8, the creepage distance when mounted on a chassis or the like is much longer than that of the conventional product shown in FIG. Therefore, the dielectric strength does not decrease unlike the conventional product.

In the case of resin molding, the heat sink 1 is provided with heat sink holding pins.
Since it is held at a predetermined interval in parallel with the bottom surface of the cavity 16 by the cavity 18, the thickness of the exterior resin on the lower side of the heat sink 1 is constant. Therefore, the problem that the heat sink is inclined as in the conventional product of FIG. 6 and the thickness of the lower exterior resin is reduced to lower the withstand voltage and that the heat sink is exposed is also solved.

Further, in the conventional products shown in FIGS. 6 and 8, there is a problem that the exterior resin on the lower side of the heat sink is easily peeled off. 5, the wedge-shaped protrusion 13 is formed, so that the intermediate portion of the thin resin covering the entire surface of the heat sink 1 on the non-pellet mounting side is locked in a state where the thin resin is prevented from coming off with respect to the heat sink 1. Since the wedge-shaped projections 13 are firmly held on the heat radiating plate 1, the exterior resin on the lower side of the heat radiating plate does not peel off.

Therefore, the heat transmitted from the semiconductor pellet 6 to the heat sink 1 is efficiently transmitted to the resin on the non-mounting surface side of the pellet, and good heat radiation is possible.

FIG. 4 is a plan view showing another embodiment of the resin-encapsulated semiconductor device of the present invention, and shows a resin-encapsulated power transistor using a heat-dissipating plate 1 'having a forked tip as a heat-dissipating plate. ing. Other configurations are the same as those of the resin-sealed power transistors of FIGS. 1 and 2, and therefore, in FIG. 4, the same members are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 5 (a) is a partial side view showing another example of the heat radiation holding pin of the resin molding apparatus of the present invention, and FIG. 5 (b) is a sectional view taken along line GG of FIG. Heat sink plate
18 'are provided around the tapered lower end 18a'.
The cutting edge 18b 'is formed. When such a bite blade 18b 'is formed, the tapered lower end 1
8a 'is pressed into the tapered hole 5 of the heat sink 1,
18b 'penetrates around the tapered hole 5 and has an advantage that the heat sink 1 can be held more reliably.

As described above, the present invention has been described by taking the resin-sealed power transistor and the resin molding device for the power transistor as examples. However, the present invention is not limited to only these examples. Various changes can be tolerated, such as changing the number of 12 to one or three or more, and fixing the heatsink holding pin 18 to the upper mold, and also allows heatsinks other than the power transistor. It can be applied to various semiconductor devices having the following.

〔The invention's effect〕

As is clear from the above description, the resin-encapsulated semiconductor device of the present invention does not generate pinholes or bubbles in the exterior resin on the lower side of the heat sink during resin molding, and can keep the thickness constant. It is hard to peel off the exterior resin on the lower side of the radiator plate, and the creepage distance to the taper hole of the radiator plate when mounted on a chassis etc. is long. Semiconductor device.

In addition, the resin molding device of the present invention requires only providing the heat sink holding pins and the support pins on the upper and lower molds of the conventional resin molding device, so that the improvement is simple and does not cause a significant cost increase. Resin molding can be performed with an operation index almost the same as that of the resin molding apparatus, and the effect of reducing the occurrence rate of defective products is exhibited.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of a resin-sealed semiconductor device of the present invention, FIG. 2 is an enlarged sectional view taken along the line ABCDEF of FIG. 3 is a partial sectional view showing one embodiment of the resin molding apparatus of the present invention, FIG. 4 is a plan view showing another embodiment of the resin-sealed semiconductor device of the present invention, and FIG. Partial side view showing another example of the heat sink holding pin of the resin molding apparatus of the present invention. FIG.
It is a G line sectional view. FIG. 6 is a sectional view of a conventional resin-coated semiconductor device, and FIG.
FIG. 8 is a cross-sectional view of a resin molding device used for manufacturing the semiconductor device, FIG. 8 is a cross-sectional view of another conventional resin-coated semiconductor device, and FIG. 9 is a cross-sectional view of a resin molding device used for manufacturing the semiconductor device. It is. 1, 1 ': heat sink, 2, 8, 9: lead, 5: tapered hole, 6: semiconductor pellet, 10: thin metal wire, 11: exterior resin, 12: residual hole, 14: upper mold, 15: lower Mold, 16… cavity, 18,1
8 ': Heatsink holding pin, 19: Support pin.

Claims (2)

(57) [Claims] 1. A semiconductor pellet mounted on a heat sink and a lead disposed in the vicinity of the semiconductor pellet are wire-bonded. In a resin-molded semiconductor device which is set sufficiently thinner than the resin thickness and covers the entire surface of a heat sink, a tapered hole for press-fitting a heat sink holding pin from above at the time of resin molding is formed in the heat sink. A part of the exterior resin is filled from the non-mount surface of the heat sink to the middle of the tapered hole, and a residual hole is formed in the exterior resin on the pellet mounting surface side after the holding pin is extracted. Resin-molded semiconductor device. 2. A heat sink holding pin, which is press-fitted from above into a tapered hole of a heat sink set in a cavity between upper and lower molds and whose leading end is locked in the middle of the tapered hole, is provided on the upper mold. A resin molding apparatus, wherein a support pin for supporting the heat sink from below when the holding pin is press-fitted is located directly below the heat sink holding pin and is provided so as to be able to protrude and retract from the lower mold.