JPH0714952A - Semiconductor device - Google Patents

Abstract

PURPOSE:To mount semiconductor device packages with radiating fins automatically on a wiring board in the same process as semiconductor devices without a radiating fin, while being mixed with the semiconductor devices without a radiating fin by installing the radiating fins due to magnetic force between a sealed section and the radiating fins. CONSTITUTION:Ferromagnetic material 61, that is, the material including at least one of a ferromagnetic phase and a ferrimagnetic phase is added locally or dispersedly to mold resin 6 which constitutes a sealed section of a semiconductor device and radiating fins 7. The ferromagnetic material 61 which is included in at least one of the mold resin 6 and the radiating fins 7 is magnetized with magnetization axes being faced in one specified direction. Then, the mold resin 6 and the radiating fins 7 are fastened with magnetic force. Therefore, no special space is required for installation of the radiating fins 7. In the assembly of the semiconductor device, the radiating fins 7 can be installed after mounting the device on a substrate.

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 technique effective when applied to a semiconductor device having a radiation fin.

[0002]

2. Description of the Related Art With the increase in integration and speed of semiconductor devices,
The amount of heat generated by the semiconductor device is remarkably increased, and particularly in the case of a semiconductor device having an element with high power consumption, there is a problem that the amount of heat generated by power consumption is large and the semiconductor device does not operate accurately. One way to deal with this problem is to dissipate the generated heat into the surrounding air,
Conventionally, a semiconductor device to which a radiation fin is attached has been used.

In a conventional semiconductor device with a radiation fin, a method of attaching the radiation fin to a semiconductor package (hereinafter, the portion of the semiconductor device with the radiation fin excluding the radiation fin is referred to as a semiconductor package) is shown below (1) There are three methods from) to (3).

(1) Attach with an adhesive made of a thermosetting resin.

(2) Attach by brazing using a brazing agent.

(3) Mechanically (caulking, screwing) mounting.

When the adhesive of (1) is used, heating is necessary to harden the adhesive, and when the wax of (2) is used, the wax is melted, respectively.
In both cases (1) and (2), at least the area of the outer lead portion of the semiconductor device to be soldered for mounting on the printed wiring board has a melting point of the solder (melting point 180 ° C.) during this heating. Will be hotter than. Therefore,
When the radiation fin is attached after the semiconductor package is mounted on the wiring board, the solder on the portion already mounted on the wiring board is melted by the heating at the time of attaching the radiation fin, so that the wiring board mounting becomes incomplete.

Also in the case of adopting the mechanical mounting method of (3), if the heat radiation fins are mounted after the semiconductor package is mounted on the wiring board, the semiconductor package is mounted on the wiring board after mounting the wiring board. Since they are dense, it is difficult to attach the fins after mounting the wiring board.

For the reasons described above, conventionally, it has been necessary to attach the radiation fin to the semiconductor package before mounting the semiconductor package on the wiring board.

[0010]

However, as a result of examining the above-mentioned prior art, the present inventor has found the following problems.

In other words, in the conventional method, since the fins must be mounted before the substrate is mounted, both the semiconductor device with the heat radiation fin and the semiconductor device without the heat radiation fin are mixed and are automatically operated on the same line by an automatic machine. When the board is mounted, the semiconductor device with the heat radiation fin and the semiconductor device without the heat radiation fin are largely different in shape from each other, and therefore the automatic mounting is often impossible.

An object of the present invention is to provide a technique capable of automatically mounting a package of a semiconductor device with a radiation fin on a wiring board in the same process by mixing a package of the semiconductor device without the radiation fin.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0014]

Among the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

That is, in a semiconductor device with a heat dissipation fin, a material having a strong magnetic property (including at least a ferromagnetic phase or a ferrimagnetic phase) is added locally or dispersed to the sealing portion and the heat dissipation fin, and further, , Magnetizing the magnetization axis of the strong magnetic material included in at least one of the sealing portion and the radiation fin by aligning the magnetization axis in a predetermined direction, and fixing the sealing portion and the radiation fin by magnetic force. .

[0016]

According to the above-mentioned means, in the semiconductor device with the heat radiation fin, the heat radiation fin is attached by the magnetic force between the sealing portion and the heat radiation fin, so that special heating is required for attaching the heat radiation fin. In addition, since no special space is required, the semiconductor device can be assembled in the order in which the radiation fins are attached after the board is mounted. As a result, the package of the semiconductor device with the radiation fins can be mixed with the semiconductor device without the radiation fins and automatically mounted on the wiring board in the same step.

[0017]

Embodiments of the semiconductor device according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing a structure of a semiconductor device with a radiation fin according to an embodiment of the present invention in a mounted state on a substrate. 1 is a tab, 2 is a silicon chip, 3 is a pelletizing agent, and 4 is a bonding. Wires, 5 are leads, 6 is a mold resin that forms a sealing portion of the semiconductor device, 61 is magnet powder particles in the mold resin 6, 7 is a radiating fin, and 71 is a side of the radiating fin 7 that contacts the mold resin 6. A magnetized region forming an end portion, 72 a main heat dissipation portion of the heat dissipation fin 7 excluding the magnetized region 71, 8 a wiring board, 81 a wiring board 8
The parts to be attached to the wirings, and 9 are solders, respectively.

First, the manufacturing process of the semiconductor device shown in FIG. 1 will be described. The tab 1 is coated with a pelletizing agent 3 such as silver paste, and the silicon chip 2 is adhered to the coated surface. After that, the bonding wire 4 (using a gold wire) is sequentially thermocompression bonded to a predetermined position on the upper surface of the silicon chip 2 and the bonding lead 51 portion of the lead 5.

Next, sealing is carried out by a transfer molding method. The mold resin 6 used as a sealing material is suitable with a filler (silica or the like) mixed for adjusting strength and expansion coefficient. Powder-sized magnets having a size (hereinafter, referred to as magnet powder particles) are dispersed and mixed in the mold resin 6. At this time, the magnet powder particles are magnetized by aligning the magnet powder particles in the same axial direction so that the magnetization axis of the magnet powder particles coincides with the desired magnetization direction. The magnet powder particles are formed of a material having strong magnetism. By the above steps, the sealing is completed and the semiconductor package is completed.

After the sealing is completed, the outer leads 52 of the semiconductor package are arranged on the mounting portion 81, and a heat source such as infrared rays is sprayed on the solder 9 to which the mounting portion 81 is adhered,
The solder 9 is melted and the semiconductor package is mounted on the wiring board 8.

Since the magnet powder particles in the mold resin 6 of the semiconductor package are uniformly magnetized in a fixed direction, the mold resin 6 itself has a property as a magnet, and the magnetizing region of the heat radiation fin 7 is further provided. Since 71 is made of a highly magnetic material and has the property of sticking to a magnet, the heat radiation fin 7 can be attached to the semiconductor package by the magnetic force acting between the mold resin 6 and the magnetized region 71. This completes the manufacturing process.

As can be seen from the above description, according to the semiconductor device with the radiation fin of this embodiment, the following effects can be obtained.

That is, since the heat radiation fin 7 is attached by the magnetic force between the mold resin 6 and the magnetized region 71 of the heat radiation fin 7, it is not necessary to specially heat the heat radiation fin 7 for attachment. Therefore, the solder 9 does not melt when the radiation fin 7 is attached. Furthermore, no special space is required when attaching the radiation fin 7. Therefore, after mounting the semiconductor package on the wiring / wiring board 8, the semiconductor device can be assembled in the order of attaching the heat radiation fins 7 to the semiconductor package. As a result, the package of the semiconductor device with the radiation fins can be mixed with the semiconductor device without the radiation fins and automatically mounted on the wiring board 8 in the same step.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Nor.

For example, in the present embodiment, magnets made of a material having a strong magnetic property are made into powder particles and dispersed and mixed in the mold resin 6, but the present invention is not limited to this. It may be mixed locally in the mold resin 6.

Further, in the present embodiment, the magnetized regions 71 of the heat radiation fins 7 are concentrated and mixed in one region of the heat radiation fins 7. However, the present invention is not limited to this, and the magnetized regions 71 are formed. The heat radiation fins 7 may be dispersed and mixed in the whole.

Further, in this embodiment, the mold resin 6 itself has the property of a magnet and the heat radiation fin 7 has the property of attaching to the magnet in the mold resin 6, but the present invention is not limited to this. Alternatively, the properties of the mold resin 6 and the heat radiation fin 7 may be reversed, that is, the heat radiation fin 7 itself may have the property of a magnet, and the mold resin 6 may have the property of attaching to the magnet of the heat radiation fin 7. Of course, both the mold resin 6 and the heat radiation fin 7 may have a magnet property. However, in this case, it is necessary to adjust the magnetization directions of the mold resin 6 and the radiation fin 7 so that the regions on the side where the mold resin 6 and the radiation fin 7 contact each other have different polarities of the magnets.

[0029]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

Since the radiation fins can be attached after the semiconductor package is mounted on the wiring board, when mounting the semiconductor package of the semiconductor device with the radiation fins on the substrate, the same mounter as the semiconductor device without the radiation fins can be used. In particular, in the case of automatic mounting, the package of the semiconductor device with the heat radiation fin can be mixed with the semiconductor device without the heat radiation fin and automatically mounted on the wiring board in the same process without any capital investment. The mounting accuracy on the wiring board can be performed with high accuracy as in the case of the semiconductor device having no heat radiation fin.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a semiconductor device with a radiation fin according to an embodiment of the present invention, which is surface-mounted on a wiring board.

[Explanation of symbols]

1 ... tab, 2 ... silicon chip, 3 ... pelletizing agent,
4 ... Bonding wire (Au wire), 5 ... Lead, 51
... bonding leads, 52 ... outer leads, 6 ... molded resin, 61 ... magnet powder particles (material with strong magnetism), 7
... Radiating fins, 71 ... Magnetized regions of the radiation fins 7 (Fe, Ni or alloys thereof having a strong magnetic property), 72 ... Main radiation portions (Al, Cu, etc.) of the radiation fins 7, 8 ... Wiring board, 8
1 ... Mounting part (copper foil), 9 ... Solder.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Gen Murakami, 5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Inside the Semiconductor Division, Hitachi, Ltd. (72) Kazuo Shimizu, 5 Kamimizumoto-cho, Kodaira, Tokyo Hitachi Co., Ltd. Semiconductor Division, 20-1-1 (72) Inventor Shigeru Ishii 5-2-1 Kamisuihonmachi, Kodaira-shi, Tokyo Inside Semiconductor Division, Hitachi Ltd.

Claims (1)

[Claims] 1. In a semiconductor device with a heat dissipation fin, a strong magnetic material is locally or entirely dispersed and added to the sealing part and the heat dissipation fin, and further, both of the sealing part and the heat dissipation fin are added. A semiconductor device with a heat dissipation fin, wherein at least one of the strongly magnetic materials has a magnetization axis aligned in a predetermined direction and magnetized to fix the sealing portion and the heat dissipation fin by magnetic force.