What are the common automotive IGBT module packaging types?

The current module system of new energy vehicles is composed of many parts, such as batteries, VCU, BSM, motors, etc., but these are relatively mature products. Domestic and foreign module manufacturers have developed many, but there is a module that needs to be paid attention to in the industry, that is, the core component of the motor drive part, IGBT (Insulated Gate Bipolar Transistor). As the "CPU" in the power electronics industry, IGBT (Insulated Gate Bipolar Transistor) is internationally recognized as the most representative product in the electronic revolution. Integrating and packaging multiple IGBT chips together to form an IGBT module has greater power and stronger heat dissipation capabilities, and plays an extremely important role and influence in the field of new energy vehicles.

What are the “three-electric system” and “electric drive system”?

Under simple popularization, the three-electric system that is also familiar to everyone, namely the power battery (referred to as battery), the drive motor (referred to as motor), and the motor controller (referred to as electronic control), are also called the three major parts. Together, they account for more than 70% of the total cost of new energy vehicles and are the core components that determine the vehicle's sports performance. For the electric drive system, we generally simply refer to the motor, electronic control, and reducer as the electric drive system. But strictly speaking, according to the prospectus of Jinjing Electric, the electric drive system includes three major assemblies: the drive motor assembly (which converts the electrical energy of the power battery into rotational mechanical energy and is the source of output power), the controller assembly (based on the hardware and software design of power semiconductors, real-time control of the working status of the drive motor, and continuous enrichment of other control functions), and the transmission assembly (reducing the output speed and increasing the output torque through the gear set to ensure that the electric drive system continues to operate in the high-efficiency range).

Figure: Schematic diagram of electric drive system How the electric drive system works: When driving a new energy vehicle, the motor controller converts the direct current (DC) released by the power battery into alternating current (AC) (this process is called inversion), which allows the drive motor to work. The motor converts electrical energy into mechanical energy, and then uses the transmission system (mainly the reducer) to make the wheels of the car run. Conversely, the process of converting the mechanical energy of the wheels into storage in the battery is kinetic energy recovery. The schematic diagram of the electric drive system is as follows:

How exactly do IGBT modules work?

The standard package of IGBT modules is a flat rectangular block. The following figure shows the top view of the HP1 module. The outermost white part is the plastic shell, and the bottom is a metal base plate (usually copper material) for heat conduction and heat dissipation. You can see that there are many terminals and pins outside the module, each with its own function:

Figure: HP1 module equivalent circuit diagram

Figure: HP1 module equivalent circuit diagram In the electric control module, the IGBT module is the core component of the inverter. To summarize its working principle: Through the semiconductor characteristics of either on or off, without considering the transition process and parasitic effects, we regard a single IGBT chip as an ideal switch. We build a parallel and series structure of several IGBT chip units inside the module. When direct current passes through the module, the outflow direction and frequency of the current are changed through the rapid opening and closing of different switch combinations, so as to output the desired alternating current.

IGBT module production process

The threshold of the IGBT industry is very high. In addition to the design and production of chips, the development and production of IGBT module packaging and testing also have very high technical and process requirements.

Figure: Cross-section of IGBT standard package structure As shown in the figure above, you can see the interface of the cross-section of the IGBT module. The basic structure of the modules of the current shell sealing process is not much different. The process of IGBT module packaging is roughly as follows: SMD → vacuum reflow soldering → ultrasonic cleaning → X-ray defect detection → wire bonding → static test → secondary welding → shell glue filling and curing → terminal forming → functional test (dynamic test, insulation test, reverse bias test) SMD, firstly, each die on the IGBT wafer is SMDed to the DBC. DBC is a copper-clad ceramic substrate with ceramic in the middle and copper on both sides. DBC plays the role of conductivity and electrical isolation similar to PCB. Commonly used ceramic insulating materials are alumina (Al2O3) and aluminum nitride (AlN); Vacuum welding, after SMDing, the die and DBC are fixed by vacuum welding. Generally, the solder is tin or solder paste; X-ray void detection, it is necessary to detect the bubbles that appear during the bonding process, that is, voids. The existence of voids will seriously affect the thermal resistance and heat dissipation efficiency of the device, resulting in problems such as overheating, burning, and explosion. Generally, the void rate of automotive IGBT modules is required to be less than 1%; the next step is the wire bonding process, in which the die and DBC are bonded with metal wires. Aluminum wires are the most commonly used, and other commonly used materials include copper wires, copper tapes, and aluminum tapes; there will be a series of appearance inspections and static tests in the middle, and modules with problems in the process will be scrapped directly; the above steps are repeated to weld and bond the DBC to the copper base plate, followed by processes such as glue filling, shell sealing, and laser coding; a final functional test will be performed before leaving the factory, including dynamic testing of electrical performance, insulation testing, reverse bias testing, etc.

What are the common automotive IGBT module packaging types?

Econodual series half-bridge package is mainly used in commercial vehicles, with main specifications of 1200V/450A, 1200V/600A, etc.; HP1 full-bridge package is mainly used in small and medium-power models, including some A-class vehicles and most A0 and A00 vehicles. The peak power is generally within 70kW, and the model is mainly 650V400A, and other specifications include 750V300A, 750V400A, 750V550A, etc.; HPD full-bridge package is used in medium and large power vehicles, most A-class vehicles and above, with 750V820A occupying the mainstream of the market, and other specifications include 750V550A, etc.; DC6 full-bridge package is an integrated packaging solution based on UVW three-phase full-bridge, with the characteristics of compact packaging, high power density, and good heat dissipation performance; TO247 single-tube parallel connection, there are also a small number of electronic control system solutions using TO247 single-tube packaging on the market. There are two main advantages of using a single-tube parallel solution: ① The single-tube solution can achieve flexible line design. You can use the corresponding single tube in parallel according to the current required, so the cost also has certain advantages; ② The parasitic inductance problem is easier to solve than the IGBT module. However, there are also some difficulties to be solved when using single-tube parallel connection: ① It is difficult to equalize and balance the current between each parallel single tube, and it is difficult to ensure consistency, such as achieving simultaneous disconnection, the same current, temperature, etc.; ② The customer's system design and process are very difficult; ③ There are many interfaces, and the requirements for the production line are very high.

China's automotive IGBT situation

With the rapid development of the domestic new energy vehicle industry, the upstream of the industry chain is gradually completing domestic substitution and even leading the world trend, such as vehicle brands, power batteries, battery materials, etc. have already taken a relatively advanced step. The automotive electronic control IGBT module is the core power device of new energy vehicles. It has been monopolized by foreign suppliers such as Infineon, ON Semiconductor, Semikron, Mitsubishi Electric, etc., but with the rise of domestic suppliers such as BYD Semiconductor, Star Semiconductor, CRRC Times, Silan Microelectronics, Cuizhan Microelectronics, etc., it can now meet domestic demand to a certain extent. I believe that in the near future, domestic automotive semiconductor companies will be bigger and stronger!

Figure: Market situation of automotive electronic control IGBT modules

Introduction to major automotive IGBT module suppliers

Infineon Technologies was formally established in Munich, Germany on April 1, 1999. It is one of the world's leading semiconductor companies. Its predecessor was the semiconductor department of Siemens Group. It became independent in 1999 and went public in 2000. Infineon's business is spread all over the world, with 56 R&D institutions and 20 production plants around the world.

Main Products:

Microcontrollers, smart sensors, RF transceiver ICs, radars, discrete and integrated power semiconductors, charging modules, chargers, controllers, DCDC, IGBTs, smart network processors, gateway chips, AI chips

Supporting customers:

Toyota Motor, Continental Electronics, Volkswagen, Hitachi Cable, BMW, Audi, etc.

BYD Semiconductor Co., Ltd. is a leading semiconductor company in China. It was established on October 15, 2004. It is mainly engaged in power semiconductors, intelligent control ICs, intelligent sensors, optoelectronic semiconductors, semiconductor manufacturing and services, covering the sensing, processing and control of optical, electrical, magnetic and other signals. Its products are widely used in the fields of automobiles, energy, industry and consumer electronics, and have broad market prospects. BYD Semiconductor is determined to become a new type of semiconductor supplier that is efficient, intelligent and integrated.