Evaluation Methods on Adhesion Property between SU-8 Photoresist and Metal Substrate

During the fabrication process of metal microdevice by SU-8 UV-LIGA technology, due to the poor adhesion strength between SU-8 photoresist and metal substrate it is common for interface separated and bind failure. In this paper pull-off test, scratch test and indentation test were performed to evaluate the adhesion property between SU-8 photoresist and metal substrate, and the feasibility of these three methods was compared. The result shows that the pull-off test fails to evaluate real interface adhesion strength because of the great possibilities of mixed debond appearance which makes the experimental data discrete and inaccurate. The scratch test and the indentation test can efficiently and accurately evaluate the interface adhesion strength between SU-8 photoresist and metal substrate and are demonstrated two preferable methods.