Here is the abstract you requested from the HiTEC_2012 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.
|Extreme Thermal Transient Stress Analysis with Pre-Stress in a Metal Matrix Composite Power Package|
|Keywords: power, extreme temperature, MMC|
|This paper describes the culminating results of a six-year development of an aluminum-based metal matrix composite power package that used cast aluminum interconnects on a cast-in AlN ceramic substrate. The harsh environment package houses a SiC semiconductor used as a solid-state circuit breaker for aerospace applications. The package was targeted for -65 ˚C to +105 ˚C ambient operation with the semiconductor generating a transient +245 ˚C increase in <1 microsecond when interrupting fault currents in excess of ten-times normal operation. Previously reported design results used a 4.1mm X 4.1 mm SiC semiconductor chips. Final test results are reported for 48A/chip clearing current from a 300 Vdc bus with a di/dt of 2.1 kA/us (in 390 ns). The chip absorbed ~4.6 J inducing a transient junction temperature increase of ~245 °C from a +25 °C and +105 °C ambient. The junction temperature conservatively exceeded +350 °C during a 5 ms fault-current conducting pulse at the 105˚C ambient. The electrical testing demonstrated acceptable performance for over 750 cycles, most from 105 ˚C ambient. Earlier publications reported on electro-thermal performance. The final work added here, used extensive FEA modeling to show substantially increased electrical power performance for 7mm X 8mm SiC chips replacing the small chips described above. Thermal profiles are provided for transient performance for 96A/chip clearing current during a 3 ms fault-current conducting pulse at 105 ˚C ambient. The majority of the analysis is focused on thermally induced stresses in the package as the larger chips undergo simulated operation down to -65 ˚C ambient. Coupled with the analysis is an FEA of embedded pre-stress from the casting process while the composite package was fabricated. The analysis shows the composite structure needs reformulation to reach -65 ˚C.|
|Douglas C. Hopkins, Professor
North Carolina State University