Analysis and Design on the thermal Performance of a Desktop Computer and electronic Packaging.

• Main Author: 林冠甫
• Other Authors: H.C. Tien
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/47459363910044323976

碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 100 === As the semiconductor manufacturing processes advance, the IC chips are getting more sophisticated and miniaturized. Ball grid array (BGA) and Flip Chip BGA (FC-BGA) have become the main-stream IC packaging technology due to better electric conductivity, more I/O pins, and faster computational speed. As such, sufficient cooling of the electronic components is crucial. This study conducts cooling experiment, numerical simulation, and thermal analysis of the electronic packages of the IC chips in a desktop computer using a commercial code FLOTHERM. It is found that since the ICH chip is in the form of P-BGA (plastic BGA), the thermal conductivity of the package material is low and most heat generated in the chip is transferred through the thermal vias and the solder balls of the substrate down to the PCB. The air flow passage is redesigned by employing the partition and openings, and moving the front fan under the heat sinks of the ICH and MCH chips in order to increase the air speed in the flow passage a well as at the backside of the PCB. Thus the operating temperatures of the ICH and MCH chips drop 12.09℃ and 11.42℃, respectively. Moreover, if one attaches a heat sink in the same size and material as the junction at the backside of the PCB, the MCH temperature can further drop 8.68℃. We also adopt the concept of the suction fan for heat transport. Otherwise the impingement of the air flow on the fins may occur, the flow might diverge, and air speed might drop down. In addition, the rear fan is replaced by the CPU heat sink fan, and therefore the total number of fans in the computer decreases from 4 to 3. It is found that the operating temperatures of the key components are almost the same as those in the aforementioned design. Consequently, the design goal of lower power consumption, lower noise, and better cooling is achieved. To accommodate the change of electronic packaging technology, the cooling design in a desktop computer needs to consider the heat transfer characteristics of the IC packages. Other key issues may include: (1) The flow direction of the inlet fan are in parallel with the heat sink fins or not. (2) The distance of the air flow passage is long or short. (3) Does any obstacle exist at the entrance of the fin passage? These factors need to be considered and handled properly for obtaining good performance of the heat sinks in the desktop computers.