Powdered iron cores for RF magnetics

Abstract

Investigations were made to determine what are the effects of varying specific materials and conditions during manufacturing of powdered iron magnetic cores on the initial permeability and Q of the core. Discussions are limited to core material mixes used for RF frequency applications. The following are discussed: (a) the effect of different binder resins on Q and T/sub c/; (b) the effect of differing proportions of insulating acid and resin on inductance and Q; (c) comparison of inductance and Q produced by different material mixes; (d) the effect of pressure applied during molding (material density) on inductance and Q; and (e) an example of improving Q for production cores. This study was proposed to provide information that could be used to improve production yields when winding on powdered iron cores. Improvement of these yields was to be made by improving the performance of the core itself. Specifically, by determining means by which higher Q could be obtained from the core material and how tighter control of initial permeability of the core (and hence inductance) could be achieved.