Fabrication of the monolithic polymer–metal microstructure by the backside exposure and electroforming technology

Abstract

Monolithic polymer–metal microstructures can be fabricated on the silicon or glass substrate using two kinds of photoresists and electroforming technologies for the inkjet and microfluidic application. However, it suffers from the high shrinkage problem of first SU8 resist after exposure and post exposure baking. This paper reports a novel approach to solve the shrinkage problem by introducing backside exposure of first SU8 resist for the fabrication of the monolithic polymer–metal microstructure. In combination with the light absorption layer coating on the unexposed SU8 resist, metal seed layer deposition, frontside exposure for second JSR resist on the seed layer and the nickel (Ni) electroforming together with release process, we have demonstrated a high physical resolution of 1,200 dpi monolithic Ni nozzle plate with negligible shrinkage. It also has the advantages of low cost and high resolution for the improvement of the traditional bonding of polymer and metal nozzle plate, which is generally in need of a complex alignment to stick the metal nozzle plate and dry film polymer on the heating chip together.