Fabrication and test of enhanced boiling heat transfer copper surface with micro-structure

In order to meet the efficient heat dissipation requirements of electronic chips, an enhanced boiling heat transfer copper surface was fabricated based on UV-LIGA and micro-electroforming technologies. Aiming at the removal difficulty of SU-8 photoresist in fabricating process, a method of preset swelling gap was proposed, simulated and experimented. Simulation and experimental results indicated that the optimal gap dimension is 14 μm. Then isolation layer material to fabricate the enhanced boiling heat transfer copper surface was discussed and BN308 photoresist was selected. Furthermore, surface condition was improved by oxygen plasma treatment. Finally, the enhanced boiling heat transfer copper surface was fabricated and tested. The statistic results demonstrated that the number of micro-columns with complete structure on the enhanced boiling heat transfer copper surface is 39,986 and the proportion is about 99.97%. The contact angle measurement results of the fabricated enhanced boiling heat transfer copper surface is 135°, illustrating that the surface is hydrophobic. The heat transfer performance testing results showed that the heat flux and the heat transfer coefficient of the fabricated enhanced boiling heat transfer copper surface is respectively 3.10 and 3.11 times than that of smooth copper surface. The fabricated enhanced boiling heat transfer copper surface has a relatively great heat transfer performance.