Ultra thick epoxy-based dry-film resist for high aspect ratios
This work presents a new type of high-resolution dry-film resist laminates for the fabrication of extremely thick epoxy based polymer structures. Via a lamination process a resist thickness of up to d=360?m can be applied by one single process step. Afterwards, the dry-film resist is patterned by standard UV-lithography. An epoxy based resist mixture which contains epoxy resins, reactive diluents, additives, and a photo acid generator is deposited onto a PET supporting film by doctor blading for fabrication of the resist film. The films can be cut defect-free into favoured sheet sizes. Currently, dry-film resists with a layer thickness of up to 400?m can be produced reproducible. With the tested d=360?m thick dry-film resist an aspect ratio of 15:1 (height:width) has been achieved. By lamination and UV-patterning of two layers resist a master for 700?m thick electroplated Nickel structures was fabricated. Thereby, steep side walls with an angle deviation of ?<1 have been generated.
dry-film lamination electroplating su-8 photoresist