Currently, unlike AMCA 210's test methods for fan, AMCA 220's test methods for air curtain units, AMCA 300's sound testing of fans, ASTM D5470's test for thermal conductivity for measuring the thermal conductivity K of thermal interface materials, and TTMA-HP-2012-1.0V's standard testing method for the performance of miniature heat pipes, no real standard for thermal resistance testing is available to date that can serve as a reference for industry.

Theoretically, thermal resistance testing should be done on real machines to get the most realistic results, but in practice, there are many difficulties in designing a mechanism. Take a computer system for example. The first problem that must be addressed is the heat dissipation of the central processing unit (CPU), which is manufactured by Intel, AMD and Cyrix.

Data shows that for every 10 degrees Celsius rise in CPU socket temperature, the life of the CPU chip is reduced by about one-half. If the average life expectancy is 30,000 to 50,000 hours, that's a decrease of 15,000 to 25,000 hours of usage time and a significant drop in economic efficiency. Since the thermal resistance of the heat sink determines the junction temperature (TJ) of the chip in question, the heat sink must be designed according to the CPU specifications. However, for testing purposes, the specifications of next generation CPUs, such as power density, chip size and available cooling space, can be accessed from the official files published by Intel, but the actual next generation CPU heatsink are not always available to manufacturers. Do I need a fastener even if I have a real CPU? Do I need a motherboard afterwards? With a motherboard in place, how can other peripherals be configured? If all of them are tested in a physical configuration, it is not possible to do so in terms of time and cost. Therefore, the industry must design a heat sink based on the official information published by Intel to meet the needs of system manufacturers.

Author

Professor Wei-Keng Lin

Education｜Ph.D., University of Maryland

Occupation｜Professor, National Tsing Hua University 

Specialty｜Electronic package heat dissipation, Heat pipe, Loop heat pipes(CPL，LHP，PHP), Energy-saving design, Solar heat storage and cooling, Heat flow system, Cooling of electronic components, Two-phase flow, Heat transfer elements of artificial satellite and high-altitude flying object