Parylene-N Precursor Chemistry

The starting material for the deposition of parylene film is a dimer in the form of a white powder. This dimer can be purchased through a number of companies in the US and abroad, including Para Tech Coating, Inc. (visit http://www.parylene.com) and Speedline Technologies (visit http://www.scscookson.com). The dimer for parylene-N, which is also called di-para-xylylene and [2,2]paracyclophane was first reported by Brown as a product of xylene pyrolysis and later was synthesized with high yield by Cram [77]. According to Beach et al., there are two common routes to the synthesis of the dimer, di-para-xylyene; the direct pyrolysis of p-xylene and the 1,6 Hoffman elimination of amine from a quaternary ammonium hydroxide [1]. Beach et al. also state that purification of the dimer is often accomplished by recrystallization from the solvent xylene.