Leaky insulating paint for preventing discharge anomalies on circuit boards

• Published in: IEEE transactions on nuclear science Vol. 36; pp. 2405 - 2410
• Main Authors: Frederickson, A R, ENLOE, CLON, Mullen, E G, Nanevicz, J E, Thayer, J S
• Format: Journal Article
• Language: English
• Published: 01-12-1989
• ISSN: 0018-9499
• DOI: 10.1109/23.45359

A semi-insulating paint has been formulated and tested for preventing pulse discharges from causing damage to circuits on heavily irradiated circuit boards. The paint is tin-oxide-filled phenoxy resin with a bulk resistivity of 108 ohm-cm. A typical coating is then 10 to the 10th ohms per square. It is applied over the finished, conformally coated circuit board and connected to ground where possible on the board. It works by minimizing the stored electric field energy prior to the discharge. With such high resistivity it cannot load down most circuits. Tests were performed on circuit boards with and without the paint using energetic electron beams to simulate very high space exposure levels. Many potential damaging pulses were seen without the paint; application of the paint removed all large pulses, and only a few small pulses were seen. (I.E.)