Juergen Dr Ing Wilde

Moisture-resistant properties of SiNx films prepared by PECVD

The barrier properties of silicon nitride films prepared by plasma-enhanced chemical vapor deposition (PECVD) against moisture penetration were studied, with emphasis on the correlation of deposition parameters and moisture permeation rate. The moisture resistance of films have been characterized using infrared spectroscopy and determination of water vapor permeation (WVP) rate. Our results indicate that the gas flux ratio and discharge frequency are the most important factors in controlling the moisture resistance of these films. The best moisture-resistant property in terms of WVP and stability of the film is found in the film deposited in a low frequency (LF) process with lower ratio of silane to ammonia although the general trend is toward decreased WVP with a higher ratio of silane to ammonia in the films deposited freshly by both high and low frequency processes. Too high a ratio of silane to ammonia in LF processes leads to instability of the film after long exposure in a high humidity environment.

An integrated design approach for the hardware optimization of electrical power modules for automotive electrotraction

In this paper, a systematic approach is presented for the design and optimization of forced liquid cooled electronic modules with high power dissipation. The steps of the design cycle include hydrodynamical evaluation of the heat sink, thermal management, thermomechanical optimization and especially lifetime prediction of soldered joints. Utilized engineering tools comprise computational fluid dynamics, finite differences and finite element programs. These are coupled via software interfaces in order to enable data exchange as well as efficient cooperation of the designers. Applying these means, performance, reliability and costs of a certain module have been optimized. By use of a design-for-reliability procedure substantial savings with regard to development time, prototyping effort and consequently costs can been achieved.