| More details: sites.google.com The SU-8 is a negative, epoxy-type, near-UV photoresist (365 nm). This photoresist can be as thick as 2 mm and aspect ratios up to 25 have been demonstrated with a standard UV-lithography. Photoresists such as the SU8, are based on epoxies. The term epoxy is a prefix referring to a bridge consisting of an oxygen atom bonded to two other atoms, very often carbon, already united in some way. Such a structure is called 1,2-epoxide. ler.gutierrez.googlepages.com An epoxy resin is defined as a molecule containing one or more 1,2-epoxy groups.Such molecules are capable of being converted to a thermoset form or three-dimensional network structure. This process is called curing or crosslinking. The term curing or crosslinking is used to describe the process by which one or more kinds of reactants, ie, an epoxide and a curing agent, are transformed from a low-molecular-weight material to a highly crosslinked network. Photoepoxies, such as the SU8, are normally polymerized by a cationic photopolymerization. Cationic polymerization is induced by Lewis acids. The general mechanism is represented at figure 3.1. The Lewis acid is generated during UV illumination. The polymerization is done by the ring-opening of the 1,2-epoxy. The SU8 photoresist is an epoxy based photoresist. The main part is the EPON SU8 epoxy from Shell Chemicals. It is a highly functionalized molecule with 8 epoxy groups. The polymerisation is done by a cationinc photopolymerization ... |
