Effect of thermal contact resistance on high power solid-state laser

• Main Authors: Li, Yuan-Chih, 李元植
• Other Authors: 劉耀先
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/80319694480113552703

碩士 === 國立交通大學 === 機械工程系所 === 105 === In the solid-state laser systems, high power laser slab must be cooled to avoid failure. Normally a buffer layer is incorporated amid laser slab and the cooling cold plate. This buffer layer has two functions, i.e. to absorb the thermal expansion by laser slab and to reduce thermal contact resistance. Since the laser power is quite enormous, hence effective reducing the contact resistance becomes very important. In this thesis, the measurement of thermal contact resistance of thermal interface materials applicable for a solid-state laser system is made available. This experiment complies with ASTM D5470-12 test specifications. In this study, ways to reduce thermal contact resistance are conducted in two different approach. Firstly, the study examines the performance of soft metal buffer layer like copper, lead, tin and indium. Test results indicate that the thermal contact resistance of the tested four soft metal decrease with the rise of contact pressure. It is found that the indium shows the lowest interface contact resistance, and the lowest thermal contact resistance is 0.076 (℃∙cm^2/W) at the highest supplied contact pressure. Secondly, by utilizing a low melting temperature alloy (LMTA) with the upper and lower surface being accompanied with the buffer layer, the contact resistance can be significantly reduced. However, the LMTA may cause additional problem of overflow after melting. To resolve this problem, a new design with indium encircling LMTA is proposed. This design features two outstanding characteristics. The overflow is eliminated and it is quite effective at a very low supplied pressure. In fact, the thermal contact resistance is reduced more than 95%.