JPS62193269A - Circuit device for microwave or milliwave - Google Patents

Abstract

PURPOSE:To assure the strict contact by a simple method wherein a metallic thin sheet is inserted between a semiconductor device and a metallic base to tighten the semiconductor device to the base using a tightening means such as screws etc. CONSTITUTION:A metallic foil 7 is inserted into a power FET 1 and a base 3 while the power FET 1 is tightened to the base 3 by small fixing screws 4. The metallic foil 7, being very mild, can be well deformed into the irregularities between the case of power FET 1 and the base 3 filling the gap 3 between them by the tightening force of small fixing screws 4 so that the power FET 1 and the base 3 may be brought into enough electrical and thermal contact with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a microwave or millimeter wave circuit device that can be used in an amplifier having a semiconductor device in a metal case in satellite communications, microwave lines, and the like.

Conventional technology In recent years, due to the construction of digital communication networks using communication satellites and the expansion of microwave lines as the amount of communication information increases, the number and quality of millimeter wave circuit devices including microwaves and sub-millimeter waves has been increasing. . In addition, semiconductors are essential for miniaturization, low power consumption, and high reliability, and power amplifier devices usually use metal case type microwave power gallium arsenide (GaAs) FET (hereinafter referred to as PA1).
7-FIT) is used.

FIG. 3 is a perspective view illustrating the attachment of a conventional power FIT to a microwave or millimeter wave circuit device. In the figure, 1
is a power FET and has a metal case type. 2 is a printed circuit board, which is a glass fiber-based fluororesin (trade name: Teflon, DuPont) impregnated substrate, an alumina substrate, or the like.

3 is the base, and a metal plate such as aluminum or copper is used. 4 is a machine screw for mounting, and 5 is a washer for mounting.0 FIG. 4 is a sectional view of the power FKT1 mounted on the base 3. Here, 6 is a contact surface between the power FRT1 and the base 3, and the case of the power FIICT1 is electrically connected to the base 3 via this contact. It is very important to make this contact closely in microwave or millimeter wave circuit devices.

Firstly, even if contact cannot be maintained over the entire surface of the contact surface 6 and there is slight lifting or unevenness, there will be a distribution constant between the case of the power FKT1 and the base 3 at ultra-high frequencies of lG1-17 or higher. This generates capacitive and inductive components, making the potential of the power FIET 1 unstable, which not only causes deterioration of characteristics but also induces oscillation. Especially K
It is very noticeable in microwaves and millimeter waves of U-band (transmission frequency 14 to 14.5 GH2) or higher.

The second problem is heat radiation. For example, in the microwave circuit device that we prototyped, the power consumed by one stone is P. is 12W. On the other hand, the thermal resistance between the power FET semiconductor chip junction and the power FET mounting base is ideally 6°C/W, but
If the contact between the power FET and the base is partially lifted, the thermal resistance will easily increase by 6~b Considering the temperature difference ΔTj, ΔTj=12W x ((6~7)℃/W-5℃/Vl
N=12-24°C. It has already been confirmed that when the temperature of the junction increases by 24 degrees Celsius, the average life of the power FIT decreases by about 40%, so it can be seen that multiple contacts are important from the standpoint of reliability.

Conventionally, in order to maintain this contact, maintaining a high degree of smoothness through machining such as grinding the contact surface 6 of the base 3, and mounting the base 3 relied solely on tightening the small and medium screws 4.

Note that silicone grease for heat dissipation, which is often used in low frequency circuit devices, helps solve the problem in terms of heat dissipation, but since it is an electrical insulator, it obstructs electrical connections and cannot be used at all, especially at high frequencies. Of course you can't.

Problems to be Solved by the Invention With such conventional contact methods, not only the cost of machining the base is high, but also the accuracy thereof is limited.

Additionally, the Power FIT case itself has warps and unevenness.

Furthermore, strict contact could not be guaranteed due to factors such as variations in tightening during installation.

The present invention has been made in view of these points, and it is an object of the present invention to enable precise contact with a simple method.

Means for Solving the Problems The present invention solves the above problems by inserting a soft thin metal plate between the case of a microwave or millimeter wave semiconductor device such as a power FIET and the base for mounting the device.
It presses the device and case together.

Operation The present invention can ensure strict electrical and thermal contact between the case and the base of the semiconductor device due to the above-described configuration.

Embodiment FIG. 1 is a perspective view illustrating an embodiment of the microwave or millimeter wave circuit device of the present invention. In Figure 1, 1
2 is a power FIT, 2 is a printed circuit board, 3 is a base, 4 is a machine screw for mounting, and 6 is a washer for mounting, and the above are the same as those described in the conventional technology. 7 is a metal foil, and its material is preferably a relatively soft metal such as aluminum or annealed copper. A thickness of about 0.04 to 0.21 seconds is suitable.

FIG. 2 is a sectional view showing an embodiment of the microwave or S IJ wave circuit device of the present invention, in which all the terms 7 are the power FK
It is shown that the power FiET 1 is inserted between the T1 and the base 3, and the power FiET 1 is attached to the base 3 by tightening with machine screws 4. The metal foil 7 is soft, so use the machine screws 4 for installation.
Tightening is done by power F] ET1 case and base 3
Since the uneven portion between the power FKT 1 and the base 3 is sufficiently deformed to fill the gap, sufficient electrical and thermal contact between the power FKT 1 and the base 3 can be maintained.

Actually, KU band (transmission frequency 14-14.5 GHz)
) In the microwave circuit device, the base area is approximately 16.5
9.7- G & M S Power FIT (installation using M2 machine screws)
When installing the aluminum base (the surface finish is W specified in JIS-B 0031 to reduce processing costs), the aluminum ((JIS-H4160 Good results were obtained when mounting through AlN30H-0 (thickness: 02 m) specified in .

In this example, metal foil cut into an H shape was used;
If the case of the power FET has sufficient rigidity, it may be rectangular, and even if there is some burr on the cut surface, it will be crushed, so the cutting process may be simple.

Further, in the above explanation, aluminum was used as the material for the metal foil, but the same effect can be obtained with other materials such as phosphor deoxidized steel or copper foil such as tough pitch copper.

Effects of the Invention As described above, according to the present invention, it is possible to maintain close electrical and thermal contact with an extremely simple configuration, and it is extremely useful in practice.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating the attachment of a power FAT to a base according to an embodiment of the present invention, FIG. 2 is a sectional view of the same, and FIG.
The figure is a perspective view illustrating the attachment of a conventional power FET to a base, and FIG. 4 is a sectional view thereof. 1...Power FET, 3...Base, 6...
...Contact surface, 7...Metal foil. Name of agent: Patent attorney Toshio Nakao and 1 other person/-
--Power FET 3---Base 1st Figure 7---All, 1:t<Figure 2!

Claims (1)

[Claims] The semiconductor device includes a semiconductor device whose case is made of metal and a metal base for mounting the semiconductor device, a thin metal plate is inserted between the semiconductor device and the metal base, and the semiconductor device is fastened using screws or other tightening means. A microwave or millimeter wave circuit device which is fastened to the metal base.