JPH06302721A - Substrate for high-power semiconductor module and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the productivity of a substrate for high-power semiconductor module without reducing characteristics, which are required in the substrate, by a method wherein a ceramic layer, a heat-resistant and thermoplastic resin layer, a ceramic layer and a circuit metal plate are laminated and formed in order on the surface on at least one side of the surfaces of base a metal plate. CONSTITUTION:In a substrate for high-power semiconductor module, ceramic layers are respectively formed on a base metal plate 1 and a circuit metal plate 5 by a general spraying method. A film 3 made of a heat-resistant and thermoplastic resin is made to interpose between both ceramic layers 2 and 4 and this film is made to thermally pressure bond to the plates 1 and 5 under a reduced pressure and is formed integrally with the plates 1 and 5. Therby, such a fine control as it is seen in the manufacture of a direct bonding copper substrate is not needed, the manufacture of the substrate for high-power semiconductor module is easy and the mass productivity of the substrate can be improved. Moreover, the substrate can hold high withstand voltage characteristics by stopping up voids in the layers 2 and 4 on the plates 1 and 5 with the heat-resistant and thermoplastic resin film 3 and can hold a high bonding force by an anchoring effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for a high power semiconductor module used in the field of electronic equipment, and a substrate for a high power semiconductor module which is excellent in easiness of manufacture, mass productivity and economy, and its manufacture. It is about the method.

[0002]

2. Description of the Related Art Conventionally, a substrate for a high power semiconductor module is required to have excellent heat dissipation and withstand voltage of an element to be mounted. Therefore, molybdenum is metallized on a ceramic plate and nickel is formed on the molybdenum layer. A plated substrate is used. In the case of this substrate, a molybdenum spacer for adjusting a thermal expansion difference between the semiconductor element and the silicon chip and a thermal diffusion plate of copper are required, and the structure and the mounting process of components are complicated. As a substrate to solve those problems, a direct bond copper substrate has been recently developed,
It is becoming popular as a substrate for high-power semiconductor modules.

The direct bond copper substrate is
Ceramic plate 1 made of alumina or the like as shown in FIG.
This is a substrate in which a copper plate 11 is directly bonded to 0. This direct bond copper substrate is manufactured by first punching a copper plate into a predetermined shape, arranging it on both sides of a ceramic plate, and heat-treating it in a nitrogen atmosphere at a temperature of about 1065 to 1083 ° C. In the above-mentioned manufacturing method, during the heat treatment, oxygen is controlled to be 0.008 to 0.39% by weight to generate a Cu-O eutectic liquid phase on the copper plate surface, which wets the surface of the ceramic plate to make the copper plate ceramic. It is to be bonded to the surface of the plate. The direct bond copper substrate thus obtained is compared with a conventional ceramic plate in which molybdenum is metallized and the molybdenum layer is nickel-plated.
Since there is no layer that hinders heat conduction, it has high heat dissipation properties and simplifies the process of mounting components.

[0004]

In the case of the above-mentioned direct bond copper substrate, the component mounting process is simplified due to the simplification of the substrate and module structure, as compared with the conventional substrate to which the molybdenum metallizing method is applied. However, the manufacturing process of direct bond copper substrate is complicated,
Moreover, in order to generate a Cu-O eutectic liquid phase which plays a role of a bonding agent at the bonding interface between the copper plate and the ceramics plate, it is necessary to finely control the oxygen amount, temperature, etc. in a nitrogen atmosphere, and the manufacturing conditions are severe. As a direct bond copper substrate, it is required that the copper surface retains the original characteristics of metallic copper such as excellent conductivity, thermal conductivity, solderability, and wire bondability, in addition to the uniform bonding of copper plates. It

That is, a Cu--O eutectic product which functions as a bonding agent is required at the bonding interface between the copper plate and the ceramics plate, but the surface of the copper circuit plate on which the plating and components are mounted is in the state of metallic copper. Is something that must be held. Therefore, in joining the copper plate and the ceramics plate, it is required to join under a condition of a range narrower than the theoretical range of Cu—O eutectic formation conditions. Moreover, even slight changes in process conditions cause unbonding or melting of the copper plate, which greatly affects the quality, which is problematic in productivity. In view of the above problems, the present invention is a structure of a substrate for a high power semiconductor module which solves the manufacturing difficulty found in a direct bond copper substrate without impairing the characteristics required for the substrate for a high power semiconductor module, and As a result of exploring the manufacturing method, the present invention has been achieved.

[0006]

That is, as shown in FIG. 1, a high power semiconductor module substrate of the present invention has a ceramic layer 2 and a flow starting temperature of 200 ° C. or more on at least one surface of a base metal plate 1. The heat-resistant thermoplastic resin layer 3, the ceramic layer 4, and the circuit-forming metal plate 5 are sequentially laminated. Further, in the method for manufacturing a substrate for a high power semiconductor module of the present invention, a base metal plate 1 having at least one surface provided with a ceramics layer 2 by thermal spraying, and a circuit formation having at least one surface provided with a ceramics layer 4 by thermal spraying. And the metal plate 5 for use between the ceramic layers 2 and 4 have a flow starting temperature of 200 ° C.
The above-mentioned heat-resistant thermoplastic resin film 3 is arranged and laminated, and the films are thermocompression bonded under reduced pressure to be integrated.

The base metal plate 1 used in the method for manufacturing a substrate for a high power semiconductor module of the present invention is not particularly limited, and may be, for example, a copper plate, an iron plate, an aluminum plate, an Invar alloy plate or a metal plate of these. A metal plate plated with nickel or the like or a copper clad plate can be used. A copper plate for a heat sink may be soldered to the base metal plate 1 if necessary. As the circuit-forming metal plate 5 used in the method for manufacturing a substrate for a high power semiconductor module of the present invention, a copper plate, a copper alloy plate, a copper clad plate, an Invar alloy plate or the like having a thickness of 0.2 mm or more is used. . In addition, if the thickness is less than 0.2 mm, the handling property is very poor, and even if it is slightly bent, the ceramic layer provided on one side thereof is easily cracked and the insulating performance is deteriorated, which is not preferable.
On the copper surface of the metal plate 5 for forming a circuit, which is opposite to the side where the ceramic layer 4 is provided, copper, nickel, gold, or the like is used in order to facilitate soldering mounting of components or aluminum or gold wire bonding. It is good to apply the plating.

In the present invention, the type of ceramics provided by thermal spraying on the base metal plate 1 and the circuit forming metal plate 5 is not particularly limited, but alumina or a mixture of alumina and silica has a relatively high thermal conductivity. It is preferable because it has excellent electric insulation and is low in cost. Also,
As a thermal spraying method for forming the ceramics layer 2 on the base metal plate 1 and the ceramics layer 4 on the circuit forming metal plate 5, a general gas flame spraying method or an electric plasma spraying method can be applied. . At the time of ceramics thermal spraying, in order to strengthen the adhesion of the ceramics thermal spray coating obtained, the base metal plate 1 and the circuit forming metal plate 5 may be previously subjected to surface roughening treatment such as degreasing or blasting, Preheating to 100 to 200 ° C is effective. Also, a bonding coating method in which nickel-aluminum, nickel-chromium, molybdenum, etc. are thinly sprayed and then ceramics is sprayed is also an effective method for improving the adhesion of the ceramics sprayed coating. The thickness of the ceramic layer formed by thermal spraying varies depending on the rated voltage and thermal resistance of the target module, but it is generally 0.1 to 0.5.
A thickness of about mm is preferable in terms of uniform film formation and adhesion.

In the method of manufacturing a substrate for a high power semiconductor module of the present invention, a heat resistant thermoplastic resin used for joining the base metal plate 1 with the ceramic layer 2 and the circuit forming metal plate 5 with the ceramic layer 4 to each other. Film 3
Is a heat-resistant thermoplastic resin film having a flow starting temperature of 200 ° C. or higher because it is easy to manufacture during thermocompression bonding and solder heat resistance during component mounting, and has a glass transition point of 14
It is desirable to use one having a temperature of 0 ° C. or higher. Preferred examples include polyether ether ketone, polysulfone, polyetherimide, polyether sulfone, and polyphenylene sulfide.

In the method for manufacturing a substrate for a high power semiconductor module according to the present invention, a base metal plate 1 having a ceramics layer 2 provided on at least one surface thereof by thermal spraying, and a circuit formation having a ceramics layer 4 provided on one surface thereof by thermal spraying. And the metal plate 5 for use between the ceramic layers 2 and 4 have a flow starting temperature of 2
The heat-resistant thermoplastic resin film 3 having a temperature of 00 ° C. or higher is arranged and laminated, and the heat-resistant thermoplastic resin film 3 is thermocompression-bonded under a reduced pressure near the flow start temperature to be integrated. Here, what is defined as being thermocompression-bonded under reduced pressure is that the ceramic layer 2 and the ceramic layer 4 provided by thermal spraying on the base metal plate 1 and the circuit-forming metal plate 5.
Since many pores exist in the ceramics, when they are thermocompression-bonded under normal pressure, the pores remain in the ceramic layer, which causes deterioration of withstand voltage characteristics and peeling at the interface with the heat-resistant thermoplastic resin film 3. This is because, when thermocompression-bonded under reduced pressure, the fluidized heat-resistant thermoplastic resin film closes the pores in the ceramic layer and improves the adhesive force by the anchoring effect.

[0011]

In the high power semiconductor module substrate of the present invention, a ceramic layer is formed on the base metal plate 1 and the circuit forming metal plate 5 by a general thermal spraying method, and heat resistance is provided between the ceramic layers 2 and 4. Since the thermoplastic resin film 3 is interposed and thermocompression-bonded under reduced pressure to integrate the film, it does not require the fine control as found in the production of the direct bond copper substrate, and the production is easy. Excellent mass productivity. In addition, the substrate has a high withstand voltage characteristic because the heat-resistant thermoplastic resin film 3 closes the pores in the ceramic layer on the base metal plate 1 and the circuit-forming metal plate 5, and maintains a high adhesive force by the anchoring effect. is doing. Examples of the present invention will be described below.

[0012]

【Example】

Example 1 As a base metal plate, a 2.0 mm copper plate was used, the surface of which was roughened by sandblasting, degreased with chlorocene, pickled, washed with hot water, and then preheated to about 150 ° C., which was 98%. Alumina particles with a thickness of 0.1 mm under the condition of 30 kW
Plasma sprayed so that. Next, as a metal plate for forming a circuit, a 0.2 mm copper plate was used, and the surface to be sprayed was soft-etched with an aqueous solution of cupric chloride at about 60 ° C. and then preheated to about 150 ° C., which was 98%. Alumina particles were plasma sprayed to a thickness of 0.1 mm under the condition of 30 KW. Next, a heat-resistant thermoplastic resin film having a thickness of 7 is formed between the alumina layers of both the alumina-sprayed base copper plate and the alumina-sprayed circuit-forming copper plate.
A 5 μm polyetherimide film is sandwiched, and this is vacuum hot-cold pressed to a vacuum degree of 14 Torr,
Thermocompression bonding was performed under the conditions of a pressure of 4.9 MPa and a temperature of 300 ° C.
For the manufactured substrate, thermal resistance as a measure of heat dissipation,
Insulation durability for 1000 hours at a temperature of 85 ° C, relative humidity of 85%, which is a measure of withstand voltage, and a 260 ° C solder bath, which is a measure of adhesion, and delamination occurs, which is a measure of adhesion. Was checked for. The evaluation results are shown in Table 1.

Each evaluation test was conducted as follows. [Thermal resistance] Solder the power transistor 2SC2233 on the substrate cut into a size of 40 mm × 30 mm,
It is mounted on a heat dissipation block via a heat dissipation grease, the transistor is energized, and the rise value (° C.) of the transistor temperature with respect to the power consumption (W) is obtained. (0.65 mm
The thermal resistance of a direct bond copper substrate using thick alumina ceramics is 0.8 ° C./W, and if it is equivalent, it can be used as a substrate for high power semiconductor modules. ) [Withstand voltage] A circuit is etched in a circular pattern having a diameter of 15 mm, and the positive side is used as the positive side, and the base metal plate is used as the negative side.
Exposed for up to 1000 hours in an environment of ℃ and relative humidity of 85%,
Measure the time until dielectric breakdown occurs. (1000
It can be used as a substrate for high-power semiconductor modules as long as no dielectric breakdown occurs until the time. ) [Adhesiveness] A substrate cut into a size of 50 mm × 50 mm is immersed in a solder bath at 260 ° C. for 20 seconds and examined for the occurrence of delamination. (It can be used as a substrate for high-power semiconductor modules if no peeling occurs between layers.)

Example 2 As a metal plate for forming a circuit, a 1.0 mm copper clad Invar plate was used, the surface of which was roughened by sandblasting, degreased with chlorothene, pickled and washed with hot water. A substrate was prepared in the same manner as in 1. An evaluation test similar to that of Example 1 was performed on the manufactured substrate. The evaluation results are shown in Table 1. Example 3 A substrate was produced in the same manner as in Example 1 except that a 2.0 mm aluminum plate was used as the base metal plate. An evaluation test similar to that of Example 1 was performed on the manufactured substrate. The evaluation results are shown in Table 1. Example 4 A substrate was prepared in the same manner as in Example 1 except that a polyphenylene sulfide film was used as the heat-resistant thermoplastic resin film and the temperature was 285 ° C. as the thermocompression bonding condition. An evaluation test similar to that of Example 1 was performed on the manufactured substrate. The evaluation results are shown in Table 1. Comparative Example 1 A substrate was produced in the same manner as in Example 1 except that thermocompression bonding was performed under normal pressure. An evaluation test similar to that of Example 1 was performed on the manufactured substrate. The evaluation results are shown in Table 1.

[0015]

[Table 1] * 1 Time until dielectric breakdown * 2 ○ Without delamination

As is apparent from Table 1, the substrate for high power semiconductor module manufactured by the method of the present invention has the same performance as that of the conventional direct bond copper substrate, and the manufacturing method is direct bond copper. It is extremely simple without the need for fine control as found in the substrate manufacturing method.

Example 5 A metal plate for forming a circuit having a thickness of 0.175 mm and a thickness of 0.15 mm.
Four kinds of substrates were prepared in the same manner as in Example 1 except that four kinds of copper plates of 2 mm, 0.3 mm and 0.5 mm were used.
The relationship between the thickness of the metal plate for circuit formation and the withstand voltage was examined. The obtained results are shown in FIG. From FIG. 2, in the high power semiconductor module substrate of the present invention, a metal plate having a thickness of 0.2 mm or more is used as the circuit forming metal plate.
It can be seen that this is preferable because a substrate having excellent voltage resistance can be obtained.

[0018]

The high power semiconductor module substrate of the present invention has the same performance as that of the conventional direct bond copper substrate, and its manufacturing method is the same as that of the conventional direct bond copper substrate. It does not require the strict fine control required, is easy to manufacture, and excels in mass productivity.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view of a high power semiconductor module substrate of the present invention.

FIG. 2 is a table showing the relationship between the thickness of a circuit-forming metal plate and the withstand voltage in the high-power semiconductor module substrate of the present invention.

FIG. 3 is a cross-sectional explanatory view of a conventional direct bond copper substrate.

[Explanation of symbols]

 1 ... Base metal plate 2 ... Ceramic layer 3 ... Heat-resistant thermoplastic resin film layer 4 ... Ceramic layer 5 ... Circuit forming metal plate 10 ... Ceramics Substrate 11 ... Copper plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumiha Osawa 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (3)

[Claims] 1. A base metal plate on at least one surface thereof,
A substrate for a high-power semiconductor module, comprising a ceramic layer, a heat-resistant thermoplastic resin layer having a flow starting temperature of 200 ° C. or higher, a ceramic layer, and a circuit-forming metal plate, which are sequentially laminated. 2. A base metal plate having a ceramics layer provided on at least one surface thereof by thermal spraying, and a circuit-forming metal plate having a ceramics layer provided on at least one surface thereof by thermal spraying. Is 200
A method for manufacturing a substrate for a high power semiconductor module, comprising arranging and stacking a film made of a heat-resistant thermoplastic resin having a temperature of ℃ or higher, and thermocompressing the film under reduced pressure to integrate the films. 3. A heat-resistant thermoplastic resin film having a flow initiation temperature of 200 ° C. or higher and a glass transition point of 140 ° C. or higher is used as the heat-resistant thermoplastic resin film having a flow initiation temperature of 200 ° C. or higher. The method for manufacturing a substrate for a high power semiconductor module according to claim 2.