Polymer thick film resistor with a dual curing system

Abstract

Embedding polymer passive component is an inexpensive means of burying passive components into organic substrate. The polymer pastes for passive components contain several kinds of conductive powder and additives. This investigation presents a novel approach to manufacture environmental and process friendly polymer based resistor materials by developing a screen printable solventless resin system. The study included the following: polymerization kinetics, cure profile, conductivity during cure and glass transition temperature. The polymer thick film resistor (PTFR) materials are showing excellent performance that includes dimensional stability, UV hardenable resistant traces. The benefits incurred are achieved by combining a conductive carbon black with a low viscosity, fast gel times elevated temperature combined with a long storage life time and solventless epoxy resin formulation. This process is purely additive, non-polluting and not produce waste. How the process affects the electrical properties, screen printability, and cost of the composite at the loading required to achieve the desired conductivity level must be considered to properly select a conductive carbon black. The pastes can be printed on the 400 mesh count screens, and tested from the polymer composition with a sheet resistivity of paste ranging from 10 Ω/square to 10 M Ω/square when the surface of resist traces is hardened by UV radiation and bulk polymerized by heat.