JPH08167762A - Thick film hybrid integrated circuit - Google Patents

Abstract

PURPOSE: To improve the heat conduction from the joining section of a board to its heat sink, by forming a plurality of protrusive thick film conductors between the heat sink and board over nearly the whole rear surface of the board. CONSTITUTION: On the surface of an insulating board 1 made of aluminum, etc., conductor patterns and electronic part mounting lands are formed, and in the places neighboring one side edge of the surface of the board 1, lead mounting lands 2a are formed. Subsequently, in the places of the rear surface of the board 1 which are opposed to the lands 2a, lead mounting lands 2b are formed out of thick film conductors, and over the nearly whole residual section of the rear surface of the board 1, a plurality of thick film conductors 4a having e.g. protrusive-bar shapes are formed. Therefore, the most of conventional bonding resin is replaced with the thick film conductors 4a formed on the rear surface of the board 1, and as a result, the effect whereby the heat conduction from the joining section of the board 1 to its heat sink is improved largely.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to thick film hybrid integrated circuits. The thick film hybrid integrated circuit is, for example, a device in which a passive element is formed on a substrate such as a ceramic by a film technique and an active element made by a semiconductor technique is mounted on the substrate.

More specifically, the present invention is a thick film passive element such as a thick film conductor or a thick film resistor or a thick film capacitor formed on a substrate such as a ceramic by a screen printing technique or the like. The present invention relates to a thick film hybrid integrated circuit in which individual passive elements, semiconductor elements which are active elements, and the like are mounted on a film circuit.

More specifically, the present invention relates to a thick film hybrid integrated circuit using semiconductor components such as power transistors and field effect transistors (FETs), which is a thick film hybrid integrated circuit equipped with a radiator plate for cooling. Regarding the improvement of heat dissipation.

[0004]

BACKGROUND OF THE INVENTION Thick film hybrid integrated circuits have traditionally been used, for example, in
As shown in the perspective view of the front side of FIG. 4, the perspective view of the back side of FIG. 5, and the side view of FIG. 6, a thick film conductor circuit ( (Not shown) is formed, and in the formed conductor circuit, electronic parts 3a, 3 including semiconductors such as power transistors and FETs are provided.
b, 3c are mounted.

The plurality of lands 2a and 2b on one side of the front and back surfaces of the substrate 1 are a part of the conductor circuit and are used for attaching leads.

Reference numeral 6 in FIG. 6 is a radiator plate made of a metal such as aluminum, which is joined to the back surface of the substrate 1 by an adhesive 5 or an adhesive means such as soldering.

Therefore, the electronic component 3a including the semiconductor,
The heat generated from 3b and 3c is applied to the substrate 1 and the adhesive 5
The heat is dissipated from the heat dissipation plate 6 via the above.

[0008]

However, in the conventional hybrid integrated circuit described above, when the adhesive 5 such as a silicone resin is used for joining the substrate 1 and the heat sink 6, the adhesive is resin. In addition, there is a drawback that the thermal conductivity becomes poor.

Electronic parts 3a, 3 which generate a particularly large amount of heat
b, 3c, etc., the electronic components 3a, 3b, 3
There is a problem that an adhesive such as a silicone resin cannot be used because the temperature of c is too high.

When metal solder is used as the bonding means, the heat dissipation is good, but when a temperature cycle test or the like is performed, due to the stress generated by the difference in the thermal expansion coefficient between the materials, the solder or the substrate 1 However, there is a problem that cracks occur, and therefore, there is a problem in that it cannot be used for a device that requires high reliability, such as a device mounted on an automobile. The present invention was developed for the purpose of eliminating these drawbacks and problems.

[0011]

A hybrid integrated circuit according to the present invention includes at least an insulating substrate, a conductor circuit formed on the surface of the substrate, an electronic component mounted on the conductor circuit, and the substrate. In a hybrid integrated circuit consisting of a heat dissipation plate bonded to almost the entire back surface with an adhesive interposed, a protruding thick film conductor for heat dissipation is formed on substantially the entire back surface of the substrate, and further, It is characterized in that the projecting thick film conductor for heat dissipation is formed in a plurality of pieces so as to increase the overall area.

[0012]

Therefore, according to the present invention, the protruding thick film conductor formed on the back surface of the substrate replaces a part or most of the conventional adhesive resin.

In other words, the projecting thick film conductor containing a metal having a good thermal conductivity replaces the part which was a resin having a poor thermal conductivity, and as a whole, the joint between the substrate and the heat sink is formed. The thermal conductivity at will be greatly improved.

Further, the joint between the substrate and the heat sink is
Although the bonding area with the resin does not change on the heat sink side, the bonding area with the resin on the substrate side increases significantly due to the presence of the thick film conductor, and as a result,
The bonding strength between the substrate and the heat sink is greatly improved.

In addition, since the resin exists between the substrate and the heat radiating plate having different thermal expansion coefficients, cracks due to thermal stress are eliminated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings with reference to its embodiments.

FIG. 1 is a perspective view of an embodiment of the present invention viewed from the front side, FIG. 2 is a perspective view of FIG. 1 viewed from the back side, and FIG. 3 is a side view of the same embodiment. Is.

Here, a method of manufacturing the hybrid integrated circuit according to the embodiment of the present invention will be schematically described.

First, a conductor pattern (not shown) and lands (not shown) for attaching electronic parts are formed on the surface of the insulating substrate 1 made of alumina or the like by a thick film technique, and at the same time, one surface of the substrate 1 is covered. A land 2a for attaching a lead is formed near the side.

Next, as shown in FIG. 2, the land 2a of the substrate 1 is formed.
A land 2b for attaching a lead is formed of a thick film conductor on the back surface corresponding to the above, and a thick film conductor 4a in the shape of, for example, a ridge is formed over almost the entire back surface of the remaining substrate 1.
Are formed in plural.

In the case of FIG. 2, the thick film conductor 4a is formed in the form of a large number of parallel ridges, but as shown in FIG.
It goes without saying that the thick film conductor 4b may be formed in the shape of a large number of square plates.

Therefore, the thick film conductors 4a and 4b may be projections having a shape having a large surface area in order to improve the heat radiation effect and the bonding strength, and are not limited to the above-mentioned embodiments. Of course not.

The thick film conductors 4a and 4b are made of silver, silver palladium, silver platinum, copper or the like.

After forming a plurality of thick film conductors 4a on almost the entire back surface of the substrate 1 by the thick film technique, resistors, solder resist and the like (not shown) are formed on the surface of the substrate 1,
Further, as shown in FIG. 1, electronic components 3a, 3b,
3c is mounted and joined. In addition, these electronic components 3a,
Soldering or wire bonding is used for joining 3b and 3c. After that, the lands 2a, 2b on the front and back surfaces of the substrate 1
Then, a clip-type lead (not shown) is soldered, and as shown in the sectional end view of FIG. 3, the heat dissipation plate 6 is joined with an adhesive 5 such as silicone.

FIG. 7 shows an enlarged cross-sectional view of the joint portion including the substrate 1, the heat dissipation plate 6 and the resin 5 between them. The thickness A of the thick film conductor 4 is A = 12 μm, the gap B between the substrate 1 and the heat sink 6 is B = 15 μm, and the gap C between the thickness A and the gap B is C (= A−B ) = 3 μm.

[0026]

As described above, according to the present invention, in a hybrid integrated circuit including a heat dissipation plate bonded to almost the entire back surface of a substrate with an adhesive, a thick film for heat dissipation is provided over almost the entire back surface of the substrate. Since the conductor is formed, the thick film conductor formed on the back surface of the substrate replaces most of the conventional adhesive resin, and as a result, the thermal conductivity at the joint between the substrate and the heat sink is greatly improved. On the side of the substrate, the presence of the thick film conductor significantly increases the bonding area with the resin, and the effect of significantly improving the bonding strength between the substrate and the heat sink is obtained. Since the resin is present between the substrate having a different thermal expansion coefficient and the heat sink, a great effect that cracks due to thermal stress are completely eliminated can be obtained.

In other words, by adopting the present invention, it is possible to easily and easily manufacture a thick film hybrid integrated circuit required to have high heat dissipation and to manufacture a hybrid integrated circuit excellent in temperature cycle resistance. It will be easy and easy.

In addition, according to the present invention, since the thick film conductor can be formed simultaneously with the land for attaching the lead on the back surface of the substrate, there is an advantage that the number of steps is not increased.

[Brief description of drawings]

FIG. 1 is a perspective view of a thick film hybrid integrated circuit according to an embodiment of the present invention viewed from the front side.

FIG. 2 is a perspective view of FIG. 1 viewed from the back surface side.

FIG. 3 is a side view of the above embodiment.

FIG. 4 is a perspective view of a conventional thick film hybrid integrated circuit as viewed from the front side.

FIG. 5 is a perspective view of FIG. 4 viewed from the back side.

FIG. 6 is a side view of the above conventional example.

FIG. 7 is a side view showing an enlarged main part of the embodiment of FIG.

FIG. 8 is a perspective view of a thick film hybrid integrated circuit according to another embodiment of the present invention viewed from the back surface side.

[Explanation of symbols]

 1 Substrate 2a, 2b Land 3a, 3b, 3c Electronic component 4a, 4b Thick film conductor 5 Adhesive 6 Heat sink

Claims (2)

[Claims] 1. An insulating substrate, a conductor circuit formed on a front surface of the substrate, an electronic component mounted on the conductor circuit, and a heat dissipation plate bonded to almost the entire back surface of the substrate via an adhesive. A thick film hybrid integrated circuit comprising a plurality of projecting thick film conductors formed between the heat sink and the substrate over substantially the entire back surface of the substrate. 2. The thick film hybrid integrated circuit according to claim 1, wherein the thick film conductor for heat dissipation is formed in a plurality of pieces so as to increase the overall surface area.