Al2O3/Cu Composite-Layered Structures of High Thermal Spreading Capability Formed by Plasma Spray Coating

• Main Authors: Tzu-hao Hsu, 徐子浩
• Other Authors: Shun-tian Lin
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/477nx5

碩士 === 國立臺灣科技大學 === 機械工程系 === 95 === Thermal spray coating of alumina onto copper offers a new alternative in the production of substrates for high power modules.The particle size of alumina, the coating thickness, and the consequent surface roughness if the alumina layer were found to play important roles on the thermal resistance and breakdown voltage of the substrate of composite-layered structure. In the process variables investigated in this study, the combination of a lowest surface roughness, a lowest thermal resistance, and a highly reliable breakdown voltage was attained when spray-coated layer of about 20 μm in thickness was achieved by spray coating an alumina powder having particle size ranging between 22 and 45 μm under the conditions of a power of 40 kW, a spraying velocity of 750 m/s, an argon flow rate of 45 L/min, a praying distance of 140 mm, and a spraying angle of 90◦. It was also found that the thermal resistance of the composite layer increased with the increase in surface roughness. Even with a coating thickness as large as 40 μm, the breakdown voltage was still greatly influenced by the moisture content in the alumina dielectric layer.