JPS6032977B2 - semiconductor envelope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a semiconductor envelope in which a semiconductor chip is supported on a heat dissipation deposit metal body through an electrically insulating and thermally conductive thin plate. The aim is to reduce costs by making it possible to use relatively inexpensive thin insulating plates.

In semiconductor devices, such as high-frequency transistors, it is advantageous to electrically insulate the electrodes that make up the bottom of the chip, such as the collector in a planar transistor, from the metal body for heat dissipation. minutes,
It is well known that this is because when the bottom electrode is a collector as described above, the output capacitance is not increased.

On the other hand, in a high-output transistor, it is necessary to dissipate heat generated within the chip from the bottom surface of the chip through an envelope heat sink. For these two reasons, conventional high-frequency, high-output transistors, including bipolar and unipolar types, have an envelope that has good thermal conductivity and a thin plate with good electrical insulation to connect the semiconductor chip to a metal body for heat dissipation. It is configured to support.

FIGS. 1 and 2 show a conventional envelope constructed in this manner, in which the heat dissipating metal body coupled and supported by the heat dissipating body consists of a stud 1 and a flat plate 11 with a hole for a set screw. These are electrically insulating and thermally conductive, such as a circular plate 2.
, 12 are glued on one side, and on the other side are glued the metal strips 3 and 13 that will serve as input terminals, the output terminals and metal strips 4 and 14, and the metal strips 5 and 5' that will serve as ground terminals (only in the case of Figure 1). has been done. The grounding terminal may be constructed of metal films 15, 15' formed on the disk 12, as shown in FIG. 2, and may be connected to the heat dissipating flat plate 11. As shown in FIG. 1, a semiconductor chip 7 having a transistor structure is bonded on one of the metal strips for input, output, or grounding, for example, an output metal strip 4, and other metal strips 3,
5, 5' and the electrodes in the chip are connected by thin wires 8, 9, 9'. In order to protect such a semiconductor chip 7 from the external atmosphere, for example, as shown in FIG. The inside of the cap containing the cap is isolated from the outside atmosphere or is molded and sealed with a synthetic resin material 16 as shown in FIG. Berylia, which is made of beryllium oxide ceramic, is usually used as the electrical insulator and thermal conductor mentioned above, but the powder of this substance is known as a skin poison, and it has the disadvantage of being disadvantageous and expensive in terms of manufacturing. be. A structure designed to reduce the amount of Beryllia used is shown in FIG. 3.

That is, the electrically insulating electrode support ring 27 is warmly attached around the upper surface of the heat dissipation stud 21, and the input metal band 23, the output metal band 24, and the ground metal bands 25, 25' are adhered to this upper surface. An electrically insulating and thermally conductive disk 22 is placed inside the ring 27 and adhered to the upper surface of the heat dissipation stud 21. It is necessary to form a metal film 28 on the upper surface of the disk 22 in order to adhere the semiconductor chip, and this metal film is connected to any metal band, such as the output metal band 24, by a pongee wire 29. . Electrodes in the semiconductor chip bonded onto the metal film 28 on the disk 22 are connected to appropriate metal bands using thin wires. The semiconductor chip can be isolated from the outside atmosphere by bonding, for example, a ceramic cap-like lid 26 to the metal band adhesive surface of the ring 27. Beryllia, which is an electrical insulator and a good thermal conductor, has a high thermal conductivity (~0.4 cal/cm).
s°C) and a not-excessive dielectric constant (~7), but as mentioned above, the powder is skin-like, so there is a problem with workability, and an envelope using beryllia has the disadvantage of being expensive. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a semiconductor envelope that uses a material with relatively low thermal conductivity, has good heat dissipation effects, is easy to construct, and is inexpensive.

The details of the present invention will be explained below with reference to FIG. 4 showing one embodiment thereof. That is, a heat dissipating insulating plate 32 having a width sufficient for mounting a semiconductor chip and a relatively thin thickness is adhered onto the heat dissipating metal plate 31, and is thicker than this insulating plate 32 and has side surfaces sandwiching it. an insulator piece 36 in contact with
36' is glued onto the heat dissipation metal plate 31, and the input/output metal band 3
3 and 34 are glued to the top surface of the insulator piece. For grounding, for example, a metal film 35 formed by metallization on both ends of the heat dissipation insulating plate.
, 35'. The bonding point for the semiconductor chip is selected approximately at the center of the upper surface of the heat dissipation insulating plate 32, and either the input/output metal strip or the ground metal film is extended up to this point.
In the illustrated example, the output metal band 34 is extended. This extension portion and the heat dissipation insulating plate 32 must be bonded well thermally. The semiconductor chip is isolated from the outside atmosphere by using an insulating lid 38 having protrusions 39, 39' that engage both ends of a recess 37 formed by an insulating plate 32 and insulating pieces 36, 36'. Glue along the outer surface of the insulator piece. In another embodiment, as shown in FIG. 5, a stud 31 is used as the heat dissipating metal body, and grounding is performed using metal bands 35, 35'.

In the embodiments shown in FIGS. 4 and 5 constructed as described above, the heat dissipation insulating plate is in contact with the insulator piece on both sides, so the heat from the semiconductor chip is absorbed only from the bottom of the insulating plate. In addition, the heat is radiated supplementally from the sides, and the heat radiation effect is extremely large.

As an example, a sapphire plate made by the EFG method with a thickness of 0.2 willow is used as a heat dissipation insulating plate, and alumina ceramic pieces with a thickness of 1.5 are used as thick insulating pieces on both sides. The first using four beryllia ceramic plates.
It was found that the device exhibited almost the same thermal and high frequency performance as the conventional example with the configuration shown in the figure. As a modified example of the envelope of the present invention, as shown in FIG. You can shorten the length by connecting a pongee line to the part.

Further, as shown in FIG. 7, the heat dissipating insulating plate 32 can be made shorter than the insulating pieces 36, 36' on both sides thereof.

Furthermore, a grounding metal piece may be arranged in a bridge shape across the semiconductor chip, and a grounding pongee wire may be connected to this.
In order to facilitate the manufacture of the envelope, it is possible to roughen the heat dissipating metal body by forming, for example, a recess into which the above-mentioned insulating plate, insulator piece, and grounding metal piece fit together.

As is clear from the above, in the semiconductor envelope of the present invention,
The side surface of the thin heat dissipating insulating plate on which the semiconductor chip is mounted is in contact with a ceramic insulating piece made of alumina, etc., and heat is dissipated through this insulating piece as well, so the heat generated by the semiconductor chip can be rapidly dissipated. .

Therefore, a thin sapphire plate with relatively low thermal conductivity, such as a thin sapphire plate, can be used as a heat-dissipating insulating plate, which makes it possible to lower the price of the envelope due to its excellent workability and mass production. .

[Brief explanation of the drawing]

0 FIGS. 1 to 3 are perspective views of conventional semiconductor envelopes, and FIGS. 4 to 7 are perspective views of semiconductor envelopes of the present invention. 1, 11, 21, 31...metal body for heat radiation, 2, 12,
22, 32... Heat dissipation insulating plate, 3, 13, 23, 33
... Input metal band, 4, 14, 24, 34 ... Output metal band, 5, 5', 15, 15' 25, 25', 35, 3
5'...Grounding metal, 6, 26, 38...Lid, 16...Sealing mold, 7...Semiconductor chip, 8, 9, 9', 29...
- Thin wire for connection, 27... Insulator ring for electrode support, 36,
36'... Insulator piece for electrode support, 36A... Recess,
37... Concave portion, 39, 39'... Convex portion. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. A heat dissipating metal body, a heat dissipating insulating plate bonded to the heat dissipating insulating plate on which a semiconductor chip is placed, and an insulating electrode support piece that is thicker than the insulating plate and bonded to the metal body in contact with the side surface of the insulating plate. A semiconductor envelope comprising: a semiconductor chip support portion; and a lid member adhered to the support portion so as to isolate the semiconductor chip from the outside atmosphere.