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.