The use of heat pipes in the cooling of portables with high power packages-A case study with the Pentium processor-based notebooks and sub-notebooks

The continuous increase of the system power and the shrinking size of portables present increasing challenges in thermal management at component and system level. Among the various cooling techniques, heat pipe technology is emerging as a cost-effective thermal design solution due to its excellent heat transport efficiency and capability. In this paper, we start with the basics of heat pipes and review their performance, reliability and cost characteristics. The use of heat pipes in portables Is illustrated in the cooling of notebooks and subnotebooks using the recently introduced 75 MHz Pentium processor in Tape Carrier Package (TCP) with a design specification of approximately 6.5 W (depending on the system configuration) with Active Thermal Feedback (ATF). Tests were conducted using test boards and TCP thermal test dies in one reference notebook and sub-notebook. After the thermal characterization of TCP in the reference notebook and sub-notebook, three configurations using heat pipes were studied. In all three cases, results showed that the use of heat pipes enables the system to handle the 6.5 W of CPU power with 4 W of board power. Although the study is conducted in notebooks and subnotebooks, the analyses of heat pipes and their usage are also applicable to other portables.