ADDRESSING THE CHALLENGES IN LASER MICRO-MACHINING AND BONDING OF SILICON MICROCHANNEL COLD-PLATE AND 3D-MANIFOLD FOR EMBEDDED COOLING APPLICATIONS: PERFECT DEBRIS REMOVAL

摘要

Laser machining is an inexpensive and fast alternative to conventional microfabrication techniques that produce complicated three-dimensional, hierarchical structures. One of the major issues plaguing the use of laser micromachining to manufacture commercially usable devices is the formation of debris during cutting and the difficulty in removing these debris efficiently after the machining process. For silicon substrates, this debris can interfere with surrounding components and cause problems during bonding with other substrates by preventing uniform conformal contact. This study summarizes several post-process techniques that can be employed for complete debris removal during etching of Silicon samples using an Nd/YVO_4 pulsed (～ 1 - 3 kW) UV laser, detailing the advantages and drawbacks of each approach. A method that was found to be particularly promising to achieve very smooth surfaces with almost complete debris removal was the use of PDMS as a high rigidity protective coating. In the process, a novel technique to strip PDMS from Silicon surface was developed and a study was carried out to optimize the process. The result of this study is very valuable to the micro-fabrication industry where smooth and clean substrate surfaces are highly desirable. This work could facilitate adoption and significant improvements to the process of using UV lasers to create microstructures for commercial applications as well as in a research environment.