Evaluation of a Fast Prototyping Method: Thermal Damage in Pulsed Laser Micromachining

Abstract

The theories of energy harvester and complaint mechanism on micro scale have been developed vastly, however prototyping and realization of conceptual designs of such devices is difficult. Currently, micro scale prototyping devices can only be manufactured by means of lithography. However, lithography is expensive, both in terms of time and cost. Alternatively, laser micro machining is considered to be capable of precise manufacturing in micro scale, be able to bring down process time from months to a few days. Yet, thermal damage and mechanical performance of laser fabricated device have not been quantified and evaluated properly in literature, which are the challenge and goal of this thesis. The operation of laser system has been thoroughly studied , which enables replication of previous research in this area with a state-of-art quality.

Firstly, thermal damage was quantified by means of the piezoelectric property loss under high temperature. A set of taguchi process optimizations was conducted for optimal operational settings. Secondly, a micro double-flexure stage was manufactured by laser micromachining. Structural properties of the micro devices such as side wall surface roughness and beam geometry were measured, and stiffness in translational direction of the micro flexure structures were tested.

It is found that the piezoelectric property can be preserved by 99% by systematically optimizing the parameters. And it was found that stiffness of the laser micro machined silicon compliant mechanism is 16%-36% lower than lithography made ones due to thermal damage. Therefore a fast prototyping method for micro scale devices has been thoroughly studied and can be used for further researches and applications.