Summary form only given as follows. The semiconductor switch has been shown to be a realistic alternative to the thermionic device in pulse power applications. The introduction of new press-pack IGBT technology offers the opportunity to extend the range of high power applications for which a semiconductor switch may be considered. IGBT technology considerably simplifies the ancillary circuitry required to both trigger and protect the semiconductor switch, when compared to alternative technologies. However, conventional substrate mounted module packaging does not lend well to many of the requirements of pulse power. The pressure contact devices described in this paper are of an electromechanical design, which overcomes many of these limitations and these issues are considered in the paper. Highlighting the suitability of the packaging technology for series operation to achieve most desired circuit voltages. Issues of improved reliability and device failure mechanisms are also considered. Individual press-pack IGBT switches with pulse ratings up to several thousand amperes are now available with much higher currents anticipated for the future. The paper includes details of experimental testing of devices under a wide range of operating conditions, example waveforms as illustrated. Pulses from a few microseconds duration, with rates of rise of current of several thousand amperes per microsecond to pulses of several milliseconds are considered, as well as the requirements for series operation.