Browse Prior Art Database

Polyurethane Coating of High Voltage Power Supplies

IP.com Disclosure Number: IPCOM000051727D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Chacon, CC: AUTHOR [+3]

Abstract

Circuit boards containing the components of high voltage power supplies are coated with nonfoaming thermoplastic polyurethane resin to provide mechanical strength and protection, as well as dielectric insulation between the various power supply components. The resulting power supply is of lighter weight than conventionally potted power supplies.

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Polyurethane Coating of High Voltage Power Supplies

Circuit boards containing the components of high voltage power supplies are coated with nonfoaming thermoplastic polyurethane resin to provide mechanical strength and protection, as well as dielectric insulation between the various power supply components. The resulting power supply is of lighter weight than conventionally potted power supplies.

The circuit components are first mounted to the circuit board. The polyurethane resin is then applied by conventional techniques, such as spraying, to form a continuous coating. The resulting coating is then cured at ambient temperature, with air circulation, for about 10 minutes. A heat cure of 140 degrees F for an additional 10 minutes is then used. If desired, more than one coating can be applied in this manner. The resulting coating provides a dielectric strength in excess of 2,000 volts per mil.

The polyurethane resin is provided with a dye that is fluorescent under black light. If the resin has not adequately adhered to the circuit board, so as to leave voids as possible dielectric breakdown sites, the voids will appear as black spots during inspection, when viewed in black light.

Since the polyurethane is thermoplastic, the power supply is repairable because a hot soldering iron will remove the coating to facilitate replacement of a circuit component.

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