In the field of low-power motor drive for consumer appliances and general industrial applications, the intelligent power module with transfer molded package is the current development trend. The smart power module (SPM) of Fairchild Semiconductor covers a power range of 0.05 to 7KW, which is compact, functional, reliable and cost-effective. Through the use of copper direct bonding (DBC) based conversion packaging, not only can improve the power density, but also in a single package can achieve three-phase inverter, SRM driver and power factor correction and other circuit topologies. This paper will introduce the advanced technology in SPM from the perspective of device, package and system configuration.
For companies serving household appliances and low-power industrial markets, the focus is increasingly shifting from vertical integration of manufacturing processes to the development of core competitiveness, such as brand development, customer service and logistics. Integrating discrete power semiconductor devices and drivers into a single package will enable these companies to reduce the time and effort spent on design and ensure that their electrical products have reliable power electronic components. This integration enables these companies to reduce time to market and bring innovative technologies to end users faster.
One driving force behind the demand for innovation is long-term energy-saving initiatives that force companies to adopt inverter driven technology. Different types of electrical appliances use different drive solutions, so the power level requirements of different types of systems are different, that is, circuit topology and power level. In this paper, several examples are listed, and different devices are successfully integrated into one module to meet these diverse requirements.
Since the first development of SPM in 1999, Fairchild Semiconductor has successfully developed a variety of SPM series, covering consumer appliances and low-power general industrial applications from 50W to 7KW. In this paper, the design concept of SPM and its semiconductor implementation (power device and control IC), packaging and system technology are introduced in detail.
Due to the progress of IGBT technology, SPM series has been continuously upgraded since it first appeared in the industrial market. With the introduction of submicron design rules, not only the speed of chip size reduction is accelerated, but also the current density is greatly increased. The latest generation of IGBT chips achieve a better performance balance between turn-off loss and on-off voltage drop, while ensuring adequate SOA. Figure 1 shows the improvement of IGBT technology. Obviously, V5 IGBT has excellent device performance, which can increase the power capacity in smaller package.
Low power operation often needs faster speed, which results in the increase of recovery current and DV / DT, which will bring greater electromagnetic interference (EMI), high surge voltage and motor leakage current. During the development of SPM series, EMI has been considered, and the design of gate drive has been optimized. High switch speed is sacrificed to control the switch speed of integrated IGBT. Because IGBT has low on-off voltage drop, it can keep the overall power consumption unchanged and realize low EMI characteristics. Figure 2 shows the typical DV / dt characteristics of SPM. At its rated current, DV / dt of opening and closing is less than 5kV / μ s.
In addition, in order to obtain better ESD protection, a polysilicon back-to-back diode with sufficient clamping voltage is used between the gate and the emitter. The chip area of 2350 × 2350 square micron can obtain the ESD level of HBM 2.5KV and mm 300V. With integrated protective diodes, all SPM products meet the industrial standard ESD level.
Due to the cost-effectiveness, HVIC and lvic are designed to have the least necessary functions, especially suitable for inverter driving of consumer appliances. The design considerations include: reducing the chip size with the help of fine process technology; directly driving the effective "high level" interface by 3V feed into the microcontroller; low power consumption; higher anti noise ability; better stability against temperature change, etc.
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