Meaning
Physical architecture and material set used to enclose high-power semiconductor chips while providing electrical insulation and heat dissipation. The power module packaging must manage high voltages and currents while protecting the sensitive silicon or silicon carbide dies from the environment. It acts as the primary thermal path from the heat-generating component to the cooling system (such as a liquid-cooled baseplate).
Die Interconnect
Connections between the semiconductor and the external terminals often utilize heavy aluminum or copper wires. In advanced modules, these wires are replaced by ribbons or copper clips to reduce electrical resistance and improve the reliability of the joint under thermal stress. The choice of interconnect material directly affects the power density and the switching speed of the finished module.
Insulating Substrate
Electrical isolation is achieved through the use of ceramic plates, typically made of alumina or aluminum nitride, which are bonded to copper layers on both sides. This direct bonded copper structure provides the necessary mechanical support for the chips while maintaining high thermal conductivity. The substrate must withstand thousands of volts of potential difference without dielectric breakdown.
Encapsulation Method
Silicone gel or epoxy resin is injected into the housing to cover the internal components and prevent moisture ingress. This soft potting material allows the internal parts to expand and contract during heat cycles without putting excessive stress on the bond wires. The durability of this material determines the lifespan of the module in harsh industrial or automotive environments.
