MINIATURE THIN FILM INDUCTORS (MODIFICATION NO. 2).
Interim rept. no. 3, 1 Dec 63-1 Mar 64,
MOTOROLA INC PHOENIX ARIZ
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A program is described for fabricating miniature thin-film inductors. These inductors use flat spiral conducting paths on bulk ferrite substrates encapsulated with depositied ferrite film. The period covered from 1 December 1963 to 1 March 1964. Four tasks, all directed toward the problem of obtaining larger inductance values, have been pursued during this period. They are 1 Study the effect of ferrite material thickness on the inductance of an encapsulated coil it was determined that a 40-mil 1000 micron thick layer of material is required for maximum permeability effect. 2 Fabricate spiral coils of increased air core inductance The 1.8 microhenry 23-turn coil has not been completed. 3 Fabricate spiral coils of a gold-rhodium alloy so that a ferrite film deposited encapsulating these coils can be annealed or sintered at elevated temperatures, i.e., greater than 1050 C. 4 Study techniques for fabricating two coils in a mutually aiding inductive geometry on a single substrate. The coils are separated by a ferrite film deposit Absorption of the gold plating solution by the ferrite has been a problem. This prevented the fabrication of a complete unit for evaluation. Author