Packaging Evolution: 50 years of the isolated power module

This year, we celebrate the 50th anniversary of SEMIPACK, the world’s first isolated power module. Since revolutionizing power electronics in 1975, SEMIPACK has continuously evolved. Today, the 6th generation is available, with 6 different housing sizes. It has become the standard in 50/60Hz rectifiers and AC controllers and is widespread in markets such as motor drives, UPS systems, and process control. These modules are configured for uncontrolled (diode/diode), half controlled (thyristor/diode), and fully controlled (thyristor/ thyristor) rectification. Thyristor/thyristor modules are also easily configurable for AC control (anti-parallel connection).

New power semiconductor technologies don’t always require a completely new power module. Improvements can be implemented in time-tested packages. This allows designers to improve the performance of their products without major redesign. It also enables the retrofit and repair of fielded products with the latest technology. Procurement benefits from the continued use of a standardized form factor as it allows for multiple sourcing.

The SEMIPACK is the ideal example of evolution in action. This industry standard package has improved over six generations and grown into six housing sizes. Advances in internal design, materials, and chips allow for higher current in the same footprint.

The 6th generation of the SEMIPACK 1 utilizes a new internal material stack-up with an improved baseplate — while maintaining the existing external mechanical and electrical connections. These improvements allow a mean on-state current of up to 145A, making it the most powerful 20mm module available on the market.

The SEMIPACK 1 module utilizes the well-established construction of lead frame, chip-on-substrate, and baseplate. The use of a copper baseplate in these 20mm-wide modules improves thermal spreading as well as providing a robust mounting surface across different heatsink types. For the 6th generation SEMIPACK 1, the internal construction has been changed. These changes improve thermal performance and reduce materials, significantly improving the cost/performance ratio.

The newest SEMIPACK 2 incorporates the latest generation of Semikron Danfoss diode and thyristor chips. This allows the SEMIPACK 2 Performance to achieve junction temperatures of up to 150°C. Improvements to chips provide enhanced humidity robustness without modifying the housing. All of this means an unrivalled power density and reliability in the class of 34mm modules.

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