Adhesion Improvement of Polyimide/PDMS Interface by Polyimide Surface Modification

Silicon wafers coated with a 5μm thick layer of polyimide were treated with different surface modification techniques such as chemical adhesion promoters, oxygen plasma and an Ar+ sputter etch. After surface modification, the wafers were molded with a 1mm thick layer of PDMS. The adhesion of the PDMS was tested by peel testing and by using a Nordson DAGE wedge shear tester. It was found that commercially available chemical adhesion promoters and oxygen plasma treatment resulted in a very poor PI/PDMS adhesion, whereas the Ar+ sputter etch resulted in an adhesion so strong that the PDMS could not be delaminated from the PI surface without the failure of the material.