Thermal modeling and design of liquid cooled heat sinks assembled vvith flip chip ball grid array packages

Abstract

Development of advanced cooling techniques is required for electronic packages with high power dissipation such as microprocessors. In this paper, a liquid cooling setup is proposed and the thermal modeling and design of a liquid cooled microchannel heat sink assembled with a flip chip ball grid array (FCBGA) package are addressed, with an emphasis on the removal of a heat flux beyond 100W/cm2. A full model, which includes the microchannel heat sink with inletloutlet manifolds, the package and thermal test hoard, is developed. To reduce the overall modeling efforts, a compact package model is used. Two different flow pattems, the liquid flow through the microchannel heat sink populated with microchannellfms and the natural convection of air surrounding the package, are modeled simultaneously. The full model is compared with the heat sink model without the package assembly. Parametric studies are conducted on the effects of the channel width, the heat sink base thickness and the heat sink material. In line with the modeling analysis, a microchannel heat sink with a f m e d array compatible with the FCBGA package was developed. The measurements show that the current liquid cooling setup can achieve 'a power dissipation of 130 W/cm2. The comparison with simulation shows agreement within 11% in pressure drop and 5% in thermal resistance.

Thermal management of high power dissipation electronic packages: from air cooling to liquid cooling

“…The adoption of vapor chamber heat sink (VCHS) significantly reduces the spreading thermal resistances at the heat sink base and, correspondlyg, facilitates the use of large heat sinks [7-81. Another altemative and promising way to handle the large amount of power dissipation is to use liquid cooled heat sinks (LCHS) with microchannel structure. Studies on the liquid-cooled microchannel heat sinks only can he found in literature, for instance, [4, [9][10][11], This indirect liquid cooling technology can be used when the power dissipation exceeds the air cooling limit, with the least modification in the electronic system compared with other high flux thermal management techniques such as direct liquid cooling and refrigeration cooling. However, the study of the microcha~lel heat sink assembled on the electronic packages, which aims at immediate assessment of the chip to the ambient thermal performance and the cooling loop behavior, has not been well addressed.…”