Polymer encapsulation of linear ferrite cores

A vapor deposition process was evaluated for encapsulating ferrite cores. The process consists of 1) subliming diparaxylylene, 2) pyrolysis of this dimer to form a monomer, paraxylylene, and 3) subsequent condensation of the monomer to form a polymer known as Parylene (Union Carbide Corporation). The process parameters and factors affecting thickness of the coating, the number of cores of varying size which may be processed per unit time, and the deposition rate of the parylene were evaluated. In addition, the degree of protection afforded by the polymer to insulative coated wire windings on the cores was evaluated.