In the development of power semiconductor modules, with the increase in integration and the reduction in size, the power consumption per unit heat dissipation area has increased. Heat dissipation has become a key issue in module manufacturing. The traditional module structure (welded and crimped Formula) has been unable to successfully solve the heat dissipation problem. Therefore, new requirements are put forward for the thermally conductive insulating material between the heat dissipation base plate and the chip. At present, this kind of material used in the power electronics industry at home and abroad is generally a ceramic-metal composite board structure, referred to as DBC board (Dircet Bonding Copper).

The so-called DBC technology refers to the technology of directly bonding copper to ceramic materials at high temperatures. The DBC board mainly uses thermally conductive and insulating ceramic substrates such as Al2O3, AIN, and BeO. Because BeO contains toxicity, it is rarely used in industry. Although AIN has good thermal conductivity and a coefficient of thermal expansion similar to that of silicon, its price is too high. Therefore, Al2O3 has been widely used as a thermally conductive insulating substrate for DBC boards, and AIN is also under development.

At present, foreign DBC substrates have been put into industrial production and are widely used in power semiconductor modules, microwave transmission and sealing and other fields. Among the power semiconductors of the same power, the welded module of the DBC board, compared with the ordinary welded module, is not only small in size, light in weight, saving parts, but also has better thermal fatigue stability and higher integration. Domestic research in this area has just started, and industrial production has not yet been formed. The Institute of Electrical Insulation, Xi’an Jiaotong University, combined with the "Eighth Five-Year Plan" task of GTR module packaging structure, used DBC technology to develop Al2O3-Cu composite boards and provided them to Xi’an Institute of Power Electronics Technology, Beijing Power Electronics New Technology Research and Development Center, etc. Unit trial. Small batch production in the laboratory has been formed. The market prospects are impressive.

The role of the DBC substrate in the power module is as follows:

1) As the carrier of the silicon chip, and there is no other material and connecting wire between the two. Circuit wiring substrate, the function is similar to PCB board.

2) Good insulation performance, separate conductive parts and heat dissipation parts.

3) Good heat dissipation performance. The heat generated by the silicon chip is transferred to the heat sink through the thermal oil.

Therefore, DBC substrate is a substrate with excellent thermal conductivity and insulation performance.

Al2O3-Cu substrate has the following excellent characteristics:

1) The thermal resistance is small, and the thermal expansion coefficient is the same as Al2O3, which is similar to silicon (7.4×10-5K-1). No transition layer is required during use. The silicon chip can be directly soldered on the DBC substrate;

2) Has good mechanical properties, adhesion>5000N/cm2, peel resistance>90N/cm;

3) Corrosion resistance, no deformation, can be used in the temperature range of -55℃～+860℃;

4) Excellent electrical insulation performance, porcelain plate withstand voltage>2.5KV;

5) Good thermal conductivity, the thermal conductivity is 24～28W/m·K;

6) Good weldability, reaching more than 95%.

DBC board will be the basic material of structure and connection technology in future electronic circuits. When the traditional organic copper clad P.C. board cannot meet the thermal shock performance of the component, the DBC board will be used as the basic material for electronic components with high power dissipation. In use, because the thicker copper layer (0.3mm) can withstand higher current loads, under the same cross-section, only 12% of the conductor width of the usual PC board is required; good thermoelectric rate makes the dense installation of power chips become may. It can transmit more power in a unit volume and improve the reliability of the system and equipment. It can be widely used in the following related fields of power electronics:

(1) Power semiconductor devices, such as IGBT, GTR, SIT, etc.;

(2) Power control circuit;

(3) Hybrid power circuit and new power structure unit;

(4) Solid state relay and high frequency switch module power supply;

(5) Temperature control unit of electronic heating device;

(6) Inverter, motor speed control, AC non-contact switch;

(7) Electronic ceramic devices. According to our research, the use of DBC technology to make BaTiO3 burnt copper electrodes has low contact resistance and superior performance compared with ordinary burnt silver electrodes and copper-plated electrodes;

(8) Structural units in automotive electronics, aerospace and military technology. DBC technology is the foundation of the future "core-board" technology and represents the development trend of packaging technology in the future. With the application of DBC boards, it has taken a step toward the future "core-board" technology and also formed creative product ideas. And has the basis of highly integrated equipment design.

At present, with the development of new devices such as GTR, IGBT, and SIT, there are requirements for DBC boards with better heat conduction. Japan has developed AIN copper clad laminates and used them in IGBT packaging. my country has developed AIN ceramic substrates, our institute has carried out the research and development of AIN copper clad laminates, and is conducting research on bonding mechanism and process. It is expected that it will be obtained in the domestic power semiconductor industry during the "Ninth Five-Year Plan" period. application.