JPH0927570A - Hybrid semiconductor integrated circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hybrid semiconductor integrated circuit device which is used for a microwave communication or the like, whose high reliability is ensured and which is miniaturized by a method wherein a quantity of heat generated in an output transistor pellet is dissipated efficiently. SOLUTION: A ceramic by a low-temperature firing technique is adopted for a ceramic substrate. Nearly the whole face of the ceramic substrate 3 is covered with a metal 5. A quantity of heat generated in a transistor pellet 1 is diffused to nearly the whole face of the ceramic substrate 3. Through holes 4 for heat dissipation are arranged equally on nearly the whole face of the ceramic substrate 3. Thereby, a heat dissipating area is expanded equivalently up to nearly the whole face of the ceramic substrate 3. It is possible to obtain a hybrid semiconductor integrated circuit device whose high reliability is ensured and which is miniaturized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid type semiconductor integrated circuit device, and more particularly to a hybrid type semiconductor integrated circuit device used for a power amplifier for transmission of high frequency communication such as microwave communication.

[0002]

2. Description of the Related Art The most basic structure of a conventional power amplifier is illustrated in FIG. 3 (a) and CC for illustration in FIG. 3 (b).
It was shaped like a cross section. In this case, the output transistor pellet 1 is directly a heat sink (heat sink).
7 has a good heat dissipation effect, but the output transistor pellet 1 and its input / output matching circuit 2 need to be discretely attached to the heat sink 7 and wiring between them is required. This has led to a larger circuit and higher costs.

As a method for solving these problems, a method has been devised in which a printed wiring is provided on a ceramic substrate and then an output transistor pellet or an input / output matching circuit is mounted. This is a kind of hybrid (semiconductor) integrated circuit. As a result, the wiring distance was effectively shortened and the high frequency characteristics were greatly improved.

An example of this kind of high frequency power amplification hybrid type semiconductor integrated circuit is disclosed in Japanese Patent Laid-Open No. 61-51946.
Is disclosed in Japanese Patent Publication No. FIG. 4 (a) is a rewrite of this example in an easy-to-understand manner with emphasis on heat dissipation of the output transistor, and its BB cross section is shown in FIG. 4 (b).

In this case, the output transistor pellets 1 and the input / output matching circuit 2 are bonded to the mounting surface 6 of the ceramic substrate 3, and the amount of heat generated by the output transistor pellets 1 is the mounting surface of the hybrid semiconductor integrated circuit. Although the heat is radiated to the surface (rear surface) opposite to the mounting surface 6 of, the ceramic substrate 3 generally has poor heat conduction.
For this type of hybrid semiconductor integrated circuit, heat dissipation measures are an important issue.

In order to dissipate heat, it is necessary to form a hole in the ceramic substrate and attach a metal to the inner surface of the hole by a method such as electroless plating, vapor deposition, or sputtering (this is called a through hole). If so, it is generally performed to block heat with a metal material such as solder to conduct heat.

In the past, since a ceramic substrate was made by a high temperature firing technique, a hard and durable ceramic was obtained, but a laminated ceramic such as a sandwich of ceramic and metal could not be made, and a through hole portion was not formed. During high temperature firing, heat stress was applied and cracks were likely to occur. Therefore, as shown in FIG. 4B, one or several through holes 4 are provided only in the portion where the output transistor pellet 1 is attached. However, this was not a sufficient heat dissipation measure.

[0008]

Needless to say, the market demands for communication devices are low price, small size, and no failure. Therefore, demands for hybrid type semiconductor integrated circuits for power amplification are also small and low cost. There is a strong demand for higher reliability along with the trend toward higher reliability.

In the case of a power amplifier, it is unavoidable that a certain amount of heat is consumed, so the smaller the size, the more the amount of heat generated will concentrate. The concentration of the heat quantity promotes the rise of the junction temperature of the output transistor, and in the worst case, it may lead to the thermal runaway of the transistor. Therefore, the most important issue is how to efficiently dissipate the generated heat.

It is an object of the present invention to provide a hybrid type semiconductor integrated circuit device for power amplification, which has excellent heat dissipation characteristics and is highly reliable.

[0011]

According to the present invention, a ceramic substrate on which an amplifying transistor pellet is mounted,
A hybrid semiconductor integrated circuit device comprising: a metal layer deposited on the entire mounting surface of the amplification transistor pellet of the ceramic substrate; and a through hole for heat dissipation provided in the ceramic substrate. can get.

[0012]

[Function] Ceramics made by low-temperature firing technology are used for the ceramic substrate, and metal is deposited on the entire surface to radiate the heat generated by the transistor pellets not only from the mounting area of the transistor pellets, but from almost the entire area of the ceramic substrate. And further forming a through hole for heat dissipation over the entire surface, the heat dissipation effect is enhanced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A is a top view of a hybrid type semiconductor integrated circuit according to an embodiment of the present invention. For convenience of explanation, a cross section taken along the line AA is shown in FIG. 1B.

The transistor pellet 1 and the input / output matching circuit 2 are mounted on the ceramic substrate 3 to form a hybrid semiconductor integrated circuit. A metal layer 5 is deposited on the entire upper surface of the ceramic substrate 3, and the ceramic substrate 3 is a multi-layer ceramic made by a low temperature firing technique together with the metal layer 5.

Since the input / output matching circuit 2 is basically a passive circuit, the amount of heat generated is concentrated in the transistor pellet 1, but since the metal layer 5 is directly bonded to this, the metal has good heat conduction, The heat quickly diffuses on the surface of the ceramic substrate 3.

In the case of a multilayer ceramic produced by the low temperature firing technique, since the thermal stress on the ceramic material during the firing process is small (since firing is low temperature), there is almost no need to worry about cracks in the through holes. Therefore, as many through holes as necessary can be provided. In the case of the embodiment shown in FIG. 1B, the through holes 4 are provided substantially evenly over the entire surface of the ceramic substrate.

The heat spread over the entire surface of the ceramic substrate 3 through the metal layer 5 is efficiently dissipated to the outside by the through holes arranged substantially evenly.

The thermal resistance of heat radiation in this case is calculated. FIG.
As shown in, the actual heat dissipation area of the ceramic substrate 3 is W ×
Let L and thickness be t. Further, when the effective thermal conductivity including the through hole of the ceramic substrate is k, the thickness of the metal layer is d, and the proportional coefficient is C, the thermal resistance Rth is given by the following equation.

When W ≠ L, Rth = [Ct / k · 2d · (L−W)] ln [WL + 2
Lt] / [WL + 2Wt], and when W = L, Rth = Ct ² / k · d · L · (L + 2t).

Therefore, in order to improve heat dissipation (to reduce the thermal resistance of the ceramic substrate), the thickness t of the ceramic layer is made small, the thermal conductivity k is made large (through holes are increased), and the thickness d of the metal layer is made. It is necessary to increase the size and increase the equivalent heat dissipation area.

Although reducing the thickness t of the ceramic layer or increasing the number of through holes lowers the strength of the substrate, by sandwiching the ceramic layer above the metal layer except the portion where the output transistor pellet is attached, Can be reinforced.

In the example of FIG. 1, the input / output matching circuit 2 is
This is also formed on the upper surface or inside the ceramic substrate formed by the low temperature firing technique, and has a three-layer (multilayer) structure of the ceramic substrate 3, the metal layer 5, and the ceramic substrate on which the input / output matching circuit 2 is formed. As a result, the strength is increased.

[0024]

According to the present invention, in the case of a hybrid semiconductor integrated circuit for power amplification, the ceramic substrate has a multi-layer ceramic structure formed by a low temperature firing technique.
By covering the entire surface of the ceramic transistor pellet mounting surface with metal, the heat radiation area of the heat generated by an equivalent transistor pellet is expanded to almost the entire ceramic board, and through holes for heat radiation are also provided almost evenly on the entire ceramic board to radiate heat. It has the effect of greatly improving efficiency.

This not only improves the reliability of the hybrid type semiconductor integrated circuit, but also covers the surface of the metal portion (a portion substantially corresponding to the input / output matching circuit mounting portion) except the transistor pellet mounting portion with ceramic ( Since heat is not generated in this portion), the ceramic substrate is reinforced, or the ceramic portion of the ceramic substrate is further multi-layered so that the transmission line (signal wiring) layer is arranged in the inner layer, so that there is an effect that the overall size can be reduced.

[Brief description of drawings]

FIG. 1 is an external view of an embodiment of the present invention.

FIG. 2 is a diagram for calculating heat dissipation of a ceramic substrate.

FIG. 3 is an external view of an example of a conventional power hybrid type semiconductor integrated circuit device.

FIG. 4 is an external view of another example of a conventional power hybrid semiconductor integrated circuit device.

[Explanation of symbols]

 1 Transistor Pellet 2 Input / Output Matching Circuit 3 Ceramic Substrate 4 Through Hole 5 Metal (Layer) 6 (Component) Mounting Surface L Horizontal Width of Equivalent Radiation Area of Ceramic Substrate W Vertical Width of Equivalent Radiation Area of Ceramic Substrate t Thickness of Ceramic Substrate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunihiko Sugawa 3-18-21 Shibaura, Minato-ku, Tokyo NEC Engineering Co., Ltd.

Claims (5)

[Claims] 1. A ceramic substrate on which amplification transistor pellets are mounted, a metal layer deposited on the entire mounting surface of the amplification transistor pellets of the ceramic substrate, and a heat dissipation layer provided on the ceramic substrate. A hybrid semiconductor integrated circuit device comprising a through hole. 2. The hybrid semiconductor integrated circuit device according to claim 1, wherein the ceramic substrate is a ceramic substrate formed by a low temperature firing technique. 3. The hybrid semiconductor integrated circuit device according to claim 1, wherein the through holes for heat dissipation are evenly provided under the metal layer. 4. The hybrid semiconductor integrated circuit device according to claim 1, further comprising a second ceramic substrate provided on a surface of the metal layer excluding a portion where the transistor pellets are mounted. . 5. The hybrid semiconductor integrated circuit device according to claim 4, wherein a signal wiring layer is provided inside or on the upper surface of the second ceramic substrate.