JPH05109926A - Hybrid integrated circuit and microstrip substrate - Google Patents

Abstract

PURPOSE:To make a header operate as a compact and light heat dissipating material and to prevent a high output semiconductor element and a dielectric substrate from peeling off due to thermal stress by constituting the header of carbon fiber reinforced aluminum alloy and by joining a circuit substrate and the high output semiconductor element thereon. CONSTITUTION:A high output semiconductor element 1 is joined to a projecting part of a header 3 having a projecting part. A signal from a matching circuit and a driving circuit formed in an alumina substrate 2 is input and power amplification, etc., are performed. A value of linear expansion coefficient of carbon fiber reinforced aluminum alloy is close to that of linear expansion coefficient of the high output semiconductor element 1. That is, matching is possible in terms thermal expansion coefficient between the header 3 and the high output semiconductor 1. The high output semiconductor element 1 can be prevented from cracking and peeling due to thermal stress caused by heat generated in a matching process and heat generation during operation even if the high output semiconductor element 1 is directly joined to the header 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid integrated circuit and a microstrip substrate used for communication equipment and the like.

[0002]

2. Description of the Related Art FIG. 7 shows, for example, Hitachi Review Volume 72, No. 12, December 1990. FIG. 10 is a cross-sectional view showing a main part of a conventional high-power hybrid integrated circuit described in 104. In the figure, 1 is a high-power semiconductor element, 2 is an alumina substrate on which a matching circuit or the like is formed, 4 is a bonding material such as solder, 5 is a copper heat sink for heat dissipation, and 6 is a copper header on which the alumina substrate 2 is mounted. ..

Next, the operation will be described. The high-output hybrid integrated circuit is mounted on a communication device or the like and performs power amplification or the like by the high-output semiconductor element 1 to which signals from the matching circuit and the drive circuit formed on the alumina substrate 2 are input. At that time, the heat generated from the high-power semiconductor element 1 is transmitted to the copper header 6 through the copper heat sink 5 and further through the alumina substrate 2, and is released by the copper header 6.

FIG. 8 is a partial sectional view showing a conventional hybrid microwave integrated circuit. In the figure, 14a to 14
c is a metal plate joined to the inner bottom surface of the metal housing 41, 15
Reference numerals a and 15b are dielectric substrates such as microstrip substrates joined to the metal plates 14a and 14b, and 16 is a metal housing 4.
1 is a bonding material for bonding the inner bottom surface of the metal plate 14a to 14c and the metal plates 14a and 14b to the dielectric substrates 15a and 15b; and 17 is a semiconductor element mounted on the metal plate 14c (dielectric substrate 15a, 15 may be mounted on 15b), and 19 is a lid for isolating the inside of the metal housing 41 from the external environment.

In such a hybrid microwave integrated circuit, the material of the metal casing 41 is aluminum (density: density:
It is considered to be a light metal material such as 2.7 g / cm ³ ).

However, the linear expansion coefficient of aluminum is 2
4 ppm / ° C., but for the semiconductor element 17, for example, in the case of gallium arsenide, it is 6 ppm / ° C.
5a and 15b are 6 ppm / ° C. in the case of alumina. That is, the linear expansion coefficient of the metal casing 41 and those of the semiconductor element 17 and the dielectric substrates 15a and 15b are significantly different.

Therefore, a large thermal stress may occur on the semiconductor element 17 and the dielectric substrates 15a and 15b depending on the temperature change of the surrounding environment. As a result, the dielectric substrates 15a and 15b are broken, and the semiconductor element 17 and the dielectric substrates 15a and 15b are peeled off. In order to solve this problem, a low stress adhesive resin is used as the bonding material 16, or Kovar (coefficient of linear expansion:
The stress on the semiconductor element 17 and the dielectric substrates 15a and 15b is reduced by interposing the metal plate 4 (6.5 ppm / ° C.).

FIG. 9 is a sectional view showing a main part of a conventional microstrip substrate. In the figure, 23 is a dielectric substrate, 24a to 24c are wiring patterns formed on the dielectric substrate 23 by paste printing or vapor deposition, and 25 is a surface of the dielectric substrate 23 on which wiring patterns 24a to 24c are formed. On the opposite side of the wiring pattern 24a ~
It is a ground conductor formed by the same method as that of forming 24c.

Such a microstrip substrate is used by being mounted on, for example, a hybrid microwave integrated circuit.
As the dielectric substrate 23, an alumina substrate having a thickness of, for example, 0.635 mm is generally used from the viewpoint of ensuring strength.

Here, for example, when forming a 50 Ω microstrip line, the relative dielectric constant of alumina is 9.6.
Therefore, it is necessary to set the ratio of the width of the line of the wiring patterns 24a to 24c and the thickness of the dielectric to w / h = 1. That is, it is necessary to form a line having the same width as the dielectric thickness, and in this case, the line width is 0.635 mm. Further, in the microwave circuit, various functions such as a filter can be realized depending on the wiring pattern. However, as described above, since the width of the line is defined by the dielectric thickness and the dielectric constant, the size of the substrate is inevitably determined.

[0011]

Since the conventional hybrid integrated circuit and the microstrip substrate are configured as described above, the high output hybrid integrated circuit shown in FIG. 7 efficiently radiates heat. Structure is complicated,
There is a possibility that the high-power semiconductor element 1 may peel off due to the difference in linear expansion coefficient between the copper heat sink 5 and the high-power semiconductor element 1. Further, since the copper heat sink 5 and the copper header 6 are used, the weight becomes heavy and it is difficult to reduce the size and weight.

Further, in the hybrid microwave integrated circuit shown in FIG. 8, the metal plates 14a to 1b are provided between the dielectric substrates 15a and 15b and the semiconductor element 17 and the bottom surface of the metal housing 41.
Since 4c is interposed, there are problems such as an increase in the number of parts and an increase in man-hours during manufacturing.

In the microstrip substrate shown in FIG. 9, it is necessary to use a dielectric substrate 23 having a higher dielectric constant or to reduce the dielectric thickness in order to reduce the size. However, when the thickness of the dielectric is reduced, there is a problem that it is difficult to reduce the size in practice because the strength of the substrate is lowered and the handling becomes difficult when mounting in a metal housing.

The present invention has been made in order to solve the above-mentioned problems, and is a hybrid integrated circuit and a micro, which are reduced in size and weight, have improved reliability, and can reduce the number of steps in manufacturing. The purpose is to obtain a strip substrate.

[0015]

According to a first aspect of the present invention, there is provided a hybrid integrated circuit in which a header is made of a carbon fiber reinforced aluminum alloy, and a circuit board and a high power semiconductor element are bonded to the header. It is a thing.

In the hybrid integrated circuit according to the second aspect of the present invention, a carbon fiber reinforced aluminum alloy is used as the metal case, and the inner bottom surface of the metal case is subjected to an insulating film treatment to form a dielectric layer. Is.

The microstrip substrate according to the third aspect of the invention is a dielectric layer formed by subjecting the surface of a metal base made of a carbon fiber reinforced aluminum alloy to an insulating film treatment.

[0018]

The header according to the first aspect of the present invention has a relatively high thermal conductivity and has a density smaller than that of copper or the like, so that it functions as a small and lightweight heat dissipation material. And since the coefficient of linear expansion is close to that of gallium arsenide and alumina,
The high-power semiconductor element and the dielectric substrate are prevented from peeling due to thermal stress.

Further, since the metal housing of the second aspect of the present invention has a coefficient of linear expansion close to that of gallium arsenide, etc. or alumina, the weight of the conventional metal housing is maintained at the same level as that of the semiconductor. The element is prevented from peeling due to thermal stress. Further, the dielectric layer is formed integrally with the metal housing, and the step of adhering or joining the substrates can be omitted.

The dielectric layer according to the third aspect of the invention may be thin because it is formed on the metal substrate. As a result, the line width of the wiring pattern can be reduced, and the substrate can be miniaturized.

[0021]

EXAMPLES Example 1. FIG. 1 is a sectional view showing a main part of a high power hybrid integrated circuit according to a first embodiment of the present invention. In the figure, 3 is a header made of carbon fiber reinforced aluminum alloy, and other parts are the same as those shown in FIG. 7 with the same reference numerals.

FIG. 2 is a patent application filed on October 9, 1990 by the same applicant as the applicant of the present application (Japanese Patent Application No.
3 is a characteristic diagram showing characteristics of the carbon fiber reinforced aluminum alloy shown in No. 272666). In the figure, A ₁ ~
A ₄ are carbon fiber volume contents of 0.15, 0.
The case of 3, 0.4, and 0.55 is shown.

In the high power hybrid integrated circuit shown in FIG.
The high-power semiconductor element 1 is joined to the convex portion of the header 3 having the convex portion. Then, a signal from a matching circuit or a driving circuit formed on the alumina substrate 2 is input to perform power amplification or the like.

The linear expansion coefficient of the carbon fiber reinforced aluminum alloy can be selected in the range of 3 to 16 ppm / ° C. (see FIG. 2), and the linear expansion coefficient of copper is about 17 ppm / ° C. It is a value close to the linear expansion coefficient. That is,
It is possible to match the thermal expansion coefficient between the header 3 and the high-power semiconductor element 1.

Therefore, even if the high-power semiconductor element 1 is directly bonded to the header 3, the high-power semiconductor element 1 is prevented from cracking or peeling due to thermal stress due to heat generated in the bonding process or heat generated during operation. To be done. That is, reliability is secured. Further, since the thermal conductivity of the carbon fiber reinforced aluminum alloy is relatively good at 127 w / m · K, the heat generated during the operation is sufficiently radiated from the header 3.

Further, the density of the carbon fiber reinforced aluminum alloy is, for example, about 2.5 g / cm ³ (point A ₂ in FIG. 2), and this high-power hybrid integrated circuit has a conventional structure using a copper header and a copper heat sink. Compared to ones, the weight is about 1 /
It is 3.

Example 2. FIG. 3 is a partial sectional view showing a hybrid microwave integrated circuit according to a second embodiment of the present invention. In the figure, 11 is a metal housing made of carbon fiber reinforced aluminum alloy, 12 is an insulating oxide film formed by subjecting the inner bottom surface of the metal housing 11 to alumite treatment, and 13a and 13b are formed on the insulating film 12. It is a wiring pattern. The other parts have the same reference numerals and are shown in FIG.
It is the same as that shown in.

In the hybrid microwave integrated circuit having such a structure, the metal housing 11 is formed by molding a carbon fiber reinforced aluminum alloy, and as described above, the linear expansion coefficient of the carbon fiber reinforced aluminum alloy is 3 to. 16ppm / ℃
The range can be selected.

Therefore, for example, when the semiconductor element 17 is made of gallium arsenide, the linear expansion coefficient is 6 ppm /
A carbon fiber reinforced aluminum alloy in which carbon fibers are mixed so that the temperature becomes ℃ may be used. In that case, the linear expansion coefficient is matched between the metal housing 11 and the semiconductor element 17.
Therefore, cracking or peeling of the semiconductor element 17 due to thermal stress is prevented.

Insulating oxide film 12 which is a dielectric layer
Is alumina formed by alumite treatment, but since it is formed integrally with the metal casing 11, it contributes to reduction of man-hours at the time of manufacturing the integrated circuit. Further, being integrally molded with the metal casing 11, the insulating oxide film 12 has sufficient strength.
As a result, the insulating oxide film 12, which is the dielectric layer, may be thin. Therefore, for example, when forming a microstrip line with the wiring patterns 13a and 13b, the wiring patterns 13a and 13b can be made thin, and miniaturization of the integrated circuit can be achieved.

Although the metal casing 11 is made of carbon fiber reinforced aluminum alloy in the above embodiment, it may be made of aluminum silicon alloy.

Example 3. FIG. 4 is a sectional view showing a main part of a hybrid microwave integrated circuit according to the third embodiment of the present invention. In this case, the semiconductor element 17 is grounded on the back surface of the die. Further, in FIG. 4, reference numeral 31 denotes a region where the insulating oxide film is not formed on the inner bottom surface of the metal casing 11.

In this case, when the insulating oxide film 12 is formed on the inner bottom surface of the metal casing 11, the region where the semiconductor element 17 is mounted is masked. Thus, the region 31 where the insulating oxide film is not formed is formed. Further, since the metal case 11 can be used as a ground conductor, if the die of the semiconductor element 17 is joined to the region 31 thereof, the earth on the back surface of the die can be realized.

In each of the above embodiments, the metal casing 1
Although the case where the dielectric layer is obtained by forming an insulating oxide film on the inner bottom surface of No. 1 has been described, the dielectric layer may be formed of a high-dielectric-constant paste or the like, and similar effects are obtained in those cases as well. ..

Example 4. FIG. 5 is a sectional view showing a main part of a hybrid microwave integrated circuit according to the fourth embodiment of the present invention. In the figure, 32 is a region in which the semiconductor element 17 is mounted.

In this case, after forming the insulating oxide film 12 on the inner bottom surface of the metal casing 11, the film in the region where the semiconductor element 17 is to be mounted is scraped off. Then, the semiconductor element 17
By bonding the back surface of the die to the metal casing 11, it is possible to realize grounding on the back surface of the die. The height of the input / output electrodes of the semiconductor element 17 can be adjusted by adjusting the depth of scraping.

Example 5. FIG. 6 is a sectional view showing an essential part of a microstrip substrate according to the fifth embodiment of the present invention. In the figure, 21 is a metal base made of carbon fiber reinforced aluminum alloy, 22 is a dielectric layer such as an insulating oxide film formed on the metal base 21, and 24a to 24c are wiring patterns.

In this case, the metal substrate 21 serves as a ground conductor and also serves to assist the strength of the dielectric layer 22. Therefore, the thickness of the dielectric layer 22 can be made thinner than that of the conventional dielectric substrate, and as a result, the wiring patterns 24a to 24c can be made thinner, and the substrate size can be made smaller.

Most of the weight of the conventional substrate is occupied by the weight of the dielectric layer. For example, when alumina is used as the dielectric layer, its density is 3.7 g / cm ³ . On the other hand, in this embodiment, the weight of the substrate depends on the weight of the metal base 21. The density of the metal substrate 21 is about 2.5 g / cm ³ (at the point A ₂ in FIG. 2). That is, the microstrip substrate according to the present embodiment is lighter than the conventional one.

In each of the above-mentioned embodiments, the dielectric layer is made of an insulating oxide film, but other insulating films may be used. Further, in each of the above-mentioned embodiments, the hybrid microwave integrated circuit has been described, but the same can be applied to the hybrid integrated circuit used in other frequency bands.

[0041]

As described above, according to the first aspect of the present invention, since the hybrid integrated circuit is configured to use the header made of carbon fiber reinforced aluminum alloy, the line between the high power semiconductor element and the header is formed. Since the expansion coefficients can be matched, the semiconductor element can be directly bonded to the header, and there is an effect that a small structure, a light weight, and a high reliability can be obtained.

According to the second aspect of the present invention, the hybrid integrated circuit has a structure in which a metal housing made of carbon fiber reinforced aluminum alloy is used and the dielectric layer is integrally molded with the metal housing. What is possible is to match the linear expansion coefficient between the semiconductor element and the metal case, to make the dielectric layer thin, to be small and highly reliable, and to simplify the manufacturing process. There is an effect to be obtained.

According to the third aspect of the invention, since the microstrip substrate has the structure in which the dielectric layer is formed on the metal base made of carbon fiber reinforced aluminum alloy, the width of the wiring pattern can be made narrow and the size is small. It has the effect of being lightweight.

[Brief description of drawings]

FIG. 1 is a sectional view showing an essential part of a high-power hybrid integrated circuit according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing characteristics of a carbon fiber reinforced aluminum alloy.

FIG. 3 is a partial sectional view showing a hybrid microwave integrated circuit according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing an essential part of a hybrid microwave integrated circuit according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing an essential part of a hybrid microwave integrated circuit according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view showing an essential part of a microstrip substrate according to a fifth embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a main part of a conventional high-power hybrid integrated circuit.

FIG. 8 is a partial cross-sectional view showing a conventional hybrid microwave integrated circuit.

FIG. 9 is a cross-sectional view showing a main part of a conventional microstrip substrate.

[Explanation of reference numerals] 1 high-power semiconductor element 2 alumina substrate (circuit board) 3 header 11 metal housing 12 insulating oxide film (dielectric layer) 21 metal substrate 22 dielectric layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takefumi Ito 8-1-1 Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation

Claims (3)

[Claims] 1. A hybrid integrated circuit comprising a header made of carbon fiber reinforced aluminum alloy, and a high power semiconductor device and a circuit board bonded on the header. 2. A hybrid comprising a metal housing made of a carbon fiber reinforced aluminum alloy, and a dielectric layer having a wiring pattern formed on the inner bottom surface of the metal housing, the layer being subjected to an insulating film treatment. Integrated circuit. 3. A microstrip substrate provided with a metal base made of a carbon fiber reinforced aluminum alloy, and a dielectric layer having a wiring pattern formed on the surface of the metal base and having an insulating film treatment.