JP2002343935A - Power semiconductor module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that solder cracks causing poor connection when a large current is applied because the heat transfer effect is not good at an interval between a chip and a circuit board for a conventional power semiconductor module of resin molding, resulting in a larger power semiconductor module in quest of higher heat transfer effect. SOLUTION: An insulator of good heat conductivity and high heat-resistance is press-fitted in a gap between a chip and an electric insulating layer of a circuit board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power semiconductor module formed by soldering chip components such as a power semiconductor chip and a chip resistor in one module.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a conventional power semiconductor module, and the conventional structure will be described with reference to FIG. One surface of the metal substrate 1 is covered with an electric insulating layer 2 having a copper circuit 3 formed on the surface, and a chip component 4 is fixed to a land 5 of the copper circuit 3 with solder 8 to complete a circuit board 11.
1 is surrounded by a resin case 21 and is filled with a sealing material 22 such as an epoxy resin from above, and the completed power semiconductor module is used for applications such as power control. The gap 6 sandwiched between the lower part of the chip component 4 and the electrical insulating layer on the metal substrate is filled with air having poor thermal conductivity. The path in which the heat generated by the chip component 4 is mainly released by heat conduction is conducted by heat conduction to the solder 8, the land 5, the electric insulating layer 2, and the metal substrate 1 under the micro-section and from the metal substrate to the outside. Had released. When the power supplied to the power semiconductor module increases, the heat generated inside increases, the temperature of the solder 8 at the connection part of the chip component increases, and the temperature difference between when the power is supplied and when the power is stopped increases, causing solder cracks. As a result, the connection was poor and the reliability was reduced.

[0003]

SUMMARY OF THE INVENTION In a power semiconductor module for supplying a large amount of power, a solder crack is apt to occur and its life is shortened. Therefore, a power semiconductor module in which generated heat is effectively released is provided. Is an object of the present invention.

[0004]

Means for Solving the Problems In order to effectively release the heat generated from the chip components, the present inventors have focused on minimizing the thickness of the air layer having poor thermal conductivity. A power semiconductor module in which a chip component is soldered to a copper circuit land provided on a metal substrate via an electric insulating layer, surrounded by a resin case, and a sealing material is injected and cured inside the resin case. In the intermediate position between a pair of opposing lands, a high thermal conductive electrical insulating member is press-fitted into a gap sandwiched between an electrical insulating layer below a copper circuit and the above-mentioned chip component. A heat conduction path is formed directly on the metal substrate, and heat is released in addition to the conventional heat conduction path.

According to a second aspect of the present invention, the high heat conductive electrical insulating member is made of a rubbery organic compound having elasticity or a rubbery organic compound kneaded with an inorganic substance in order to adhere to the chip component and the component mounting board. The member was made of a compound. Organic compounds, which are solid electrical insulators, have higher thermal conductivity than air. Inorganic substances such as silicon carbide have a high thermal conductivity, and they are kneaded with silicon rubber to obtain an elastic, highly thermally conductive electrical insulating member, which is sandwiched so as to be in close contact with the chip component and component mounting board. Thus, an effective heat transfer path is formed.

According to the third aspect, the projected position of the chip component on the surface of the electrical insulating layer fixed on the metal substrate is raised to a height substantially equal to the projected area and substantially equal to the thickness of the copper circuit. The component mounting table, which is the convex part of the electrical insulating layer to be formed, is formed, and the chip components on the component mounting table are soldered to the lands to minimize the air layer between the chip component and the component mounting board. .

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. 1 and FIG. A copper circuit 3 is formed on a metal substrate 1 with an electric insulating layer 2 interposed therebetween.
Lands 5 to which the chip components 4 are soldered are provided on the copper circuit. The cream solder is printed and applied to the land, and the terminal of the chip component is irradiated with a light beam on the portion placed on the cream solder, whereby the solder is locally heated and melted. When the solder 8 is hardened and then bonded to the required portions with the bonding wires 7, the circuit is connected and the circuit board 11 is completed. The circuit board is surrounded and fixed by a resin case 21 so as to be the bottom, and a sealing material 22 such as an epoxy resin is injected from above and cured by heating. Since the power semiconductor module formed in this way generates a large amount of internal heat as the power used increases, the following steps must be performed before the chip components are fixed to the copper circuit in order to effectively dissipate this heat. Do. A highly thermally conductive electric material formed by kneading a rubbery organic compound with a highly thermally conductive inorganic material, for example, silicon carbide or beryllia ceramic, between a pair of lands 5 and the lands 51 to which the chip parts 4 are fixed. The chip component is placed so as to sandwich the insulating member 9 (hereinafter, referred to as the heat transfer member 9), and the cream solder on the land is irradiated with a light beam and heated to complete the soldering. A heat transfer member 9 having elasticity is interposed in the gap 6 between the lower part of the fixed chip component 4 and the circuit board, and the temperature rise of the chip is lower than that in the case where the conventional heat transfer member 9 is not provided. This contributed to the improvement of the life and reliability of the semiconductor module.

In another embodiment, as shown in FIG.
The electrical insulating layer 2 fixed on the metal substrate 1 is made of beryllia ceramic and has a thermal conductivity of 0.58, which is at least 8 times higher than the thermal conductivity of alumina of 0.070. (The unit of thermal conductivity is kilocalories / square centimeter-second- ° C.) This focuses on mounting chip components in contact with such an electrical insulator. A copper circuit 3 is formed via the layer 2, and a component mounting table 10 having a height corresponding to the thickness of the copper circuit is formed on the electrically insulating layer 2. The chip component 4 is mounted on the component mounting table and soldered to the land 5. A cream solder may be printed and applied to the land, and the terminals of the chip component may heat the entire substrate placed on the cream solder,
Since the insulator is only an inorganic material and withstands high temperatures, it is not necessary to perform local heating by irradiating a light beam. Thereafter, the circuit is connected by bonding to a necessary portion with the bonding wire 7, and the circuit board 11 is completed. The circuit board 11 is surrounded and fixed by a resin case 21 so as to be the bottom, and a sealing material 22 such as an epoxy resin is injected from above and cured by heating.

In the embodiment shown in FIG. 3, in order to loosen the dimensional accuracy and reduce the cost, a gap is formed on the component mounting table 11 with which the chip component 4 is in direct contact. It is also effective to fill a heat-resistant liquid that can be sucked up and held by a simple capillary phenomenon.

[0010]

According to the present invention, the thermal conductivity is improved in a portion where air is insulated in the gap between the chip component and the circuit board, so that the size of the circuit board of the module with the same power capacity as the conventional one can be reduced. As a result, costs were reduced and resources were saved. Since the temperature of the chip components could be kept low, it contributed to the improvement of the life and reliability of the entire semiconductor module.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part showing an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing another embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a structure of a conventional circuit device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 metal substrate 2 electric insulating layer 3 copper circuit 4 chip component 5 land 6 gap 7 bonding wire 8 solder 9 high heat conductive electric insulating member (heat transfer member) 10 component mounting table 11 circuit board 21 resin case 22 sealing material 51 land

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hidehisa Tachibana 3-1-156 Nishi-Awaji, Higashi-Yodogawa-ku, Osaka-shi, Osaka Inside Sansha Electric Works, Ltd. (72) Inventor Seiji Tanaka Nishi-Higashi-Yodogawa-ku, Osaka-shi, Osaka Awaji 3-chome No. 1-56 Sansha Electric Manufacturing Co., Ltd.

Claims (3)

[Claims] 1. A chip component is soldered to a land of a copper circuit provided on a metal substrate via an electrical insulating layer, surrounded by a resin case, and a sealing material is injected and cured inside the resin case. In the power semiconductor module, a high thermal conductive electrical insulating member is press-fitted into a gap between the lower electrical insulating layer of the copper circuit and the chip component at an intermediate position between a pair of opposing lands. A power semiconductor module characterized by the above-mentioned. 2. The power semiconductor module according to claim 1, wherein the high heat conductive electrical insulating member is a member formed of a rubbery organic compound having elasticity or a rubbery organic compound kneaded with an inorganic substance. 3. A component mounting table which is raised at a projection position of a chip component on a surface of an electrical insulating layer fixed on a metal substrate to a height substantially equal to a projection area and substantially equal to a thickness of a copper circuit. 2. The power semiconductor module according to claim 1, wherein the chip component on the component mounting table is soldered to the land.