Nicolas Heuck

Lifetime analysis of power modules with new packaging technologies

Several novel packaging technologies for power modules have been recently introduced to meet the future requirements of higher reliability and temperature stability. Using copper wire bonds for the top-side interconnect and silver sintered or diffusion soldered die attach layers led to a significant increase of lifetime. It was subsequently shown that the power cycling lifetime of modules without a baseplate is mainly limited by the substrate metallization, while modules employing a baseplate and a substrate-to-baseplate solder interconnect fail due to degradation within the solder layer. The investigations in this paper continue with the description and systematization of degradation effects in new interconnect technologies of power modules. As a result first lifetime models for modules with and without baseplate are provided. Thereby, accepted lifetime models for standard technologies are adopted to the degradation patterns of the new technologies.

Reliability aspects of copper metallization and interconnect technology for power devices

Abstract The introduction of thick copper metallization and topside interconnects as well as a superior die attach technology is improving the performance and reliability of IGBT power transistor technologies significantly. The much higher specific heat capacity and higher thermal conductivity increases the short circuit capability of IGBTs, which is especially important for inverters for drives applications. This opens the potential to further optimize the electrical performance of IGBTs for higher energy efficiency. The change in metallization requires the introduction of a reliable barrier against copper diffusion and copper silicide formation. This requires the development of an efficient test method and reliability assessment according to a robustness validation approach. In addition, the new metallization enables interconnects with copper bond wires, which yield, together with an improved die attach technology, a major improvement in the power cycling capability.

History and Recent Developments of Packaging Technology for SiC Power Devices

Packaging plays an important role to allow the full potential of silicon carbide devices to be realised. The physical properties of silicon carbide will allow devices to operate with junction temperatures well above 200 °C, but today standard-packaged SiC products are limited to a maximum junction temperature of 175 °C. The limitation lies in the packaging, because a power device package is a complex structure consisting of many components of different materials and with correspondingly different thermal properties. As such, the assembly technologies define both the performance and lifetime of discrete packages and power modules. In this paper we give an insight of packaging technology for SiC devices from the beginning in the mid-1980s through to the state-of-the-art of today. In addition, new packaging technologies to enable power SiC devices to operate up to 200 °C are discussed.

Determination of parameters with high impact on fatigue of new Interconnect Technologies

The point of highest mechanical load in an interconnect layer, where crack propagation will start, depends strongly on geometry and material of the attached die as it was already indicated by the CIPS08 lifetime model for insulated models [1]. Therefore, simulations with the following varied geometry parameters were conducted: thickness, area and material of the die as well as thickness of the interconnect layer. Subsequently, the impact of each parameter on the fatigue of the interconnect layer will be discussed.