Development and fabrication of microjet array package using LTCC for IC cooling

This dissertation is the part of the ongoing research at the University of Arkansas for developing and understanding a compact air jet impingement device, used for cooling high power electronics. In this dissertation, the author as been able to develop a packaging solution for the IC cooling, this also will provide the cooling solution for the chip. This has been made possible with the integration of air jet impingement cooling with a packaging solution for microprocessor type application using Low Temperature Cofired Ceramic (LTCC) MEMS. In this work, a microjet array cooler package has been fabricated and integrated with the active Integrated circuit chip using flip chip bonding technique. This microjet array has been integrated with the electronic device to be cooled with the air impingement type cooler forming a single cooling package with no need of any additional packaging. The air for cooling is introduced at the inlet on top of the package. The plenum under the inlet spreads the air into the microjet array. Through the micro jet array, the air is distributed and impinged onto the backside of a flip chip bonded IC chip where micro channels are etched to enhance the heat transfer. The chip cavity and micro jet cavity are located at the bottom side of the package so that a desired distance between the micro jet array and the IC chip can be achieved. This package can directly cool the IC chip on the printed circuit board without encountering any other thermal resistances associated with the package. No other packaging is required for the IC chip using the cooled package as it does both the jobs of a conventional IC package as well as the thermal management solution. This device is able to effectively remove 68 watts of power, which corresponds to the power density of 15W/cm2 at 70 scfh, with the average chip temperature no more than 102°C.