JPH1050908A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device capable of always obtaining a good electrical conduction state by screwing a heat sink and a heat radiation fin of a semiconductor package. A heat-dissipating plate is exposed on one surface of a semiconductor package sealed with a mold resin, and a screw hole portion for fixing the heat-dissipating plate to a heat-dissipating fin with screws by screws is provided on a mold resin portion. In the semiconductor device provided, a part of the lead frame communicating with the heat radiating plate is led out along the side surface of the screw hole 21, and the tip is disposed on the sealing resin surface around the screw hole 21. It is characterized by having a contact terminal 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a method of exposing a heat sink on which a semiconductor element is mounted on one surface of a semiconductor package sealed with a molded resin, and bringing the heat sink into close contact with a heat sink. And a structure of a semiconductor device in which a mold resin portion is fixed by screws.

[0002]

2. Description of the Related Art Video packs (product names) in which video output circuits such as TVs and HDTVs are integrated with discrete components.
Semiconductor device has been commercialized by the present applicant. 3 and 4 show an example of the semiconductor device. The lead frame is a frame 2 including a plurality of leads 1.
And a second member made of a heat radiating plate 3 having a thickness greater than that of the lead 1 are separately manufactured, and the second member made of the heat radiating plate 3 is attached to the first member at four mounting portions. It is integrated by caulking in 4. Since the tip of the lead 1 extends on the metal heat sink 3, a gap of about 0.5 mm is provided between the two to maintain electrical insulation.

A ceramic substrate 5 on which active and passive elements, circuit conductors for connecting these elements and external connection pads are formed in advance is fixed on a heat sink 3, and the pads and the leads 1 are connected by thin metal wires. After wire bonding and further performing wire bonding on the heat radiating plate to obtain a ground if necessary, the main part up to a position near the dashed line 7 in the drawing is thermosetting so that the surface of the heat radiating plate 3 is exposed. It is sealed with resin 8.

[0004] Such a semiconductor device is provided with screw holes for mounting to a mounting body such as a radiation fin at both ends thereof, and a screw is penetrated through the screw hole to form a screw hole provided in the mounting body. Screws are attached and the semiconductor device is tightly fixed on the mounting body. Depending on the application, such a semiconductor device may have to be completely electrically connected with a heat radiating plate in close contact with a heat radiating fin. In particular, in a power semiconductor device for high-frequency use, if a small resistance is generated between a radiating plate on which a chip such as an IC is mounted and a radiating fin to be adhered to, the characteristics of the IC and the like are impaired.
It is required that the heat radiating plate and the heat radiating fin be in an electrically complete conduction state when fixed to the heat radiating fin with screws.

However, in a semiconductor device having a structure in which a mold resin portion is fixed by screws, the structure of a screw hole is as follows. FIG. 6 shows a cross-sectional structure of the screw hole 21, and FIG.
Is shown. The lead frame 30 is connected and fixed by caulking to a heat sink on which a ceramic substrate on which a semiconductor chip is mounted is mounted at the caulking portion 31. Therefore,
Although the lead frame 30 is electrically connected to the heat radiating plate 3, there is no exposed portion of the lead frame 30 on the U-shaped wall surface of the screw hole 21 penetrating the screw 50 of the mold resin A. In the structure of the screw hole 21, it is impossible to establish electrical continuity between the radiator plate and the radiator fin through the screw 50.

Also, it is not always easy to secure an electrical conduction state by bringing the heat radiation plate and the heat radiation fin into close contact. As shown in FIG. 5, the heat radiating plate is surrounded by the mold resin. For example, if the mold resin has burrs or the like, a good contact state cannot be obtained. Further, the metal thick plate of the heat radiating plate is required to have complete flatness, but the heat radiating plate sealed with the mold resin is slightly curved when the mold resin cures and contracts, and is not completely flat. Even if the surface of the heat radiating plate can be formed flat, the surface of the heat radiating fin is not always flat.

[0007]

In order to solve the above problem, when the semiconductor device is screwed to the radiating fins, conductive grease is applied to a portion of the radiating plate on the back surface of the semiconductor device, so that the radiating plate and the radiating fin may be connected to each other. It is conceivable to improve the adhesion and keep the electrical conduction state good. However, the conductive grease is relatively expensive, and it is troublesome to apply the conductive grease to each of the heat radiation fins with screws when screwing the semiconductor package to the heat radiation fins.

On the other hand, as a countermeasure on the semiconductor package side, the radiator plate is extended outside the mold resin, a through hole of a screw hole is provided in the radiator plate, and the radiator plate portion outside the mold resin is directly screwed to the radiator fin. It can be fixed. However, in such a case, although the adhesion between the heat sink and the heat radiation fins is improved, the force of suppressing the heat radiation fins does not act on the mold resin portion. For this reason, cracks and the like are likely to occur in the mold resin, which lowers the reliability of the semiconductor device.

In order to solve the above-mentioned problem, the applicant of the present invention protrudes a part of the lead frame 30 to be joined to the heat radiating plate by swaging as shown in FIG. It has been proposed that the projecting portion 23 is provided, and the projecting portion 23 and the screw thread of the screw 50 are brought into contact with each other to conduct the heat radiating plate and the heat radiating fin. However, in this structure, when the semiconductor device is mounted on the heat radiation fin, the protrusion provided in the screw hole 21 bends in the traveling direction of the screw 50. There is a problem that the screw thread of the screw 50 and the screw 50 do not come into contact with each other and do not conduct.

Further, when the screw 50 is mounted, the size of the screw 50 varies depending on the user, and depending on the size of the screw 50, there may be a case where conduction is not performed and a case where the conduction is not performed, and there is a problem that workability on the mounting side is reduced. The present invention has been made in view of the above problems, and does not cause a decrease in the reliability of a semiconductor device such as breakage due to cracks in a mold resin, and also uses a conductive grease when screwed and fixed to a radiation fin. Attach to the radiation fin without the need for coating,
It is an object of the present invention to provide a semiconductor device capable of always maintaining good electrical conduction between a heat sink and a radiating fin even when it is repeatedly removed.

[0011]

The present invention has the following features to attain the object mentioned above. That is, in the semiconductor device of the present invention, a heat dissipation plate is exposed on one surface of a semiconductor package sealed with a molded resin, and a screw hole portion for tightly fixing the heat dissipation plate to the heat dissipation fin with a screw with a screw is molded. In the semiconductor device provided in the resin portion, a part of the lead frame communicating with the heat sink is led out along the side surface of the screw hole, and the tip is disposed on the sealing resin surface around the screw hole. A semiconductor device having a contact terminal 32.

Here, the tip of the contact terminal and the seat surface of the screw are conducted, and the radiator plate and the radiator fin are conducted. As described above, a part of the lead frame communicating with the heat radiating plate is led out along the side surface of the screw hole, and the tip end includes a contact terminal arranged on the sealing resin surface around the screw hole. As a result, when screwing semiconductor devices,
The tip portion of the metal contact terminal surely contacts the bearing surface of the screw. Therefore, since the metal contact terminals communicate with the heat radiating plate, the heat radiating plate is completely electrically connected to the heat radiating fins via the metal screws. Therefore, even if there is a burr of the mold resin, a slight curvature of the radiator plate, or a deformation of the radiator plate due to a rise in temperature, the tip of the metal contact terminal communicating with the radiator is always in contact with the seat surface of the screw. Since it is connected to the radiating fins, a good electrical conduction state can always be maintained.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. The present invention is characterized by the structure of the screw hole portion 21 of the mold resin portion of the semiconductor device, and each configuration of the semiconductor device is the same as the semiconductor device described in the related art. The following description will be focused on the screw hole portion 21 which is.

FIG. 1 is an exploded view in which the semiconductor device is mounted on a radiation fin, and FIG. 2 is a plan view showing a lead frame 30. The caulking portion 31 is provided on the lead frame 30, and the caulking portion 31 is caulked with the projection provided on the heat sink 3, and the heat sink and the lead frame 30 are connected and fixed as described in the conventional example. ing. The present invention is characterized in that a contact terminal 32 extending from a caulking portion and connected to a screw 50 for mounting a semiconductor device is derived (see FIG. 2).

As shown in FIG. 2, the contact terminal 32 is provided with a screw 50 hole 21 from a substantially central portion between the caulking portions.
Is derived to the region where Derived contact terminal 3
2 is caulked and fixed to a heat sink 3 on which a ceramic substrate on which a semiconductor element is mounted and a lead frame 30;
A predetermined wire bonding connection is performed, and further the coating and protection is performed with a mold resin. In a state where the semiconductor device is connected to the lead frame 30, the semiconductor device is bent and separated into individual semiconductor devices. The bending may be performed before the semiconductor device is separated and divided.

The contact terminal 32 is bent along the side surface of the screw hole 21, and the tip of the contact terminal 32 is further bent so as to be in contact with the mold resin surface A. More specifically, the contact terminal 3
2 is disposed on the mold resin near the periphery of the screw hole 21, and the surface of the contact terminal 32 is disposed so as to slightly protrude from the mold resin surface A (see FIG. 1).

As is apparent from FIG. 2, the contact terminal 32 is connected to the caulking portion 31 and the caulking portion 3
1 is connected and fixed to the heat sink as described above. Therefore, the heat radiating plate is electrically connected to the contact terminal 32. As shown in FIG. 3, when the semiconductor device is fixed to the heat radiating fin by screwing, the seat surface of the metal screw 50 and the contact terminal 32 are connected. Contact or washer 51
If there is, contact terminal 3 via washer 51
2 and the radiating fins are in an electrically good conduction state.

As described above, a part of the lead frame 30 communicating with the heat radiating plate is led out along the side surface of the screw hole 21, and the tip is disposed on the sealing resin surface around the screw hole 21. The provision of the contact terminals 32 ensures that the tips of the metal contact terminals 32 securely contact the bearing surfaces of the screws 50 when the semiconductor device is screwed. Therefore, since the metal contact terminal 32 communicates with the heat radiating plate, the heat radiating plate is completely electrically connected to the heat radiating fin through the metal screw 50. Therefore, even if there is a burr of the mold resin, a slight curvature of the radiator plate, or a deformation of the radiator plate due to a rise in temperature, etc., the tip of the metal contact terminal 32 communicating with the radiator is always at the seat surface of the screw 50. And the fins are connected to the radiating fins, so that good electrical continuity can always be maintained.

[0019]

As described above, according to the present invention, a part of the lead frame communicating with the heat radiating plate is led out along the side surface of the screw hole, and the leading end is formed of a sealing resin around the screw hole. It has a contact terminal disposed on the surface. Therefore, when the semiconductor device is fixed to the radiating fins with screws, the tip of the metal contact terminal communicating with the radiating plate is connected and fixed to the radiating fins via the seat surface of the screw. Therefore, no matter how many times the semiconductor device is attached to and detached from the heat radiation fins, conduction between them can always be ensured. Therefore, even if burrs of the mold resin, bending of the metal plate of the heat sink, deformation due to thermal expansion due to a rise in the temperature of the heat sink, and the like occur, the electrical conduction state between the heat sink and the radiation fins can always be stably maintained.

Further, according to the semiconductor device, it is possible to solve the problem that the conductive grease must be applied when mounting the conventional semiconductor device to the heat radiation fins with screws. Since the screw holes are fixed by screws, there is no problem that the reliability of the semiconductor device is impaired.

[Brief description of the drawings]

FIG. 1 is an exploded view in which a semiconductor device of the present invention is mounted on a radiation fin.

FIG. 2 is a plan view showing a lead frame used in the semiconductor device of the present invention.

FIG. 3 illustrates a conventional semiconductor device.

FIG. 4 illustrates a conventional semiconductor device.

FIG. 5 illustrates a conventional semiconductor device.

FIG. 6 is a diagram illustrating screw holes of a conventional semiconductor device.

FIG. 7 illustrates a lead frame of a conventional semiconductor device.

FIG. 8 is a diagram illustrating screw holes of a conventional semiconductor device.

Claims (2)

[Claims] 1. A mold resin portion is provided with a screw hole for exposing a heat sink on one surface of a semiconductor package sealed with a mold resin, and fixing the heat sink to a heat radiation fin with screws by screws. In the semiconductor device, a part of a lead frame communicating with the heat radiating plate is led out along a side surface of the screw hole, and a tip end of the contact frame is disposed on a sealing resin surface around the screw hole. A semiconductor device comprising: 2. The semiconductor device according to claim 1, wherein the tip of said contact terminal and said bearing surface of said screw are electrically connected, and said heat radiating plate and said heat radiating fin are electrically connected.