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Organic Electrocoating for Ferrite Device

IP.com Disclosure Number: IPCOM000087597D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Washo, BD: AUTHOR

Abstract

Ferrite cores for magnetic deflection yokes and the like are customarily given a thin coating by electrophoretic polymer deposition to eliminate sharp edges that might otherwise cut into the insulation of wire that is wound on the core. A porous ferrite can absorb moisture and the moisture may cause the coating to blister during the high temperature cure that follows the polymer deposition. The problem can be solved by gradually drying the core after the polymer deposition, but the drying step adds significantly to the production time for the ferrite devices.

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Organic Electrocoating for Ferrite Device

Ferrite cores for magnetic deflection yokes and the like are customarily given a thin coating by electrophoretic polymer deposition to eliminate sharp edges that might otherwise cut into the insulation of wire that is wound on the core. A porous ferrite can absorb moisture and the moisture may cause the coating to blister during the high temperature cure that follows the polymer deposition. The problem can be solved by gradually drying the core after the polymer deposition, but the drying step adds significantly to the production time for the ferrite devices.

Good adhesion between the ferrite and the polymer coating can also be obtained by a pretreatment of the ferrite core with a solution of a fluorocarbon and an organic fluoroacid having four to eight carbon atoms. The core is placed in this solution of the fluorocarbon and the fluoroacid acid at room temperature for about four minutes with ultrasonic agitation and the core is then air dried for about thirty seconds. The usual polymer coating is then applied to the core.

The preferred fluoroacid (heptafluorobutyric) has the following structured formula. CF(3)CF(2)CF(2)COOH.

The carboxylic acid group (-COOH) causes the substance to be attached to the metal oxide of the core by electrostatic attraction as a molecular monolayer. This thin layer does not interfere with the subsequent electrodeposition operation. Fluoroacids with fewer than four carbon atoms would have poor ...