Extreme PCBs for outer-space
Oct 25, 2006
As a printed circuit research and design company, we constantly receive requests for circuit boards that push the envelope - such as 30,000 volts to high temperatures and very thick copper (15 oz) for high-current applications. Through the years of manufacturing these different boards, we think we have seen it all...when along comes a new, weird application.
One such outer-space application was just that - printed circuits for outer space. We researched the environmental conditions, talked with some NASA guys and experimented with various solutions. An outer-space circuit must be able to withstand very low temperatures (- 173C), very high temperatures (180C), low atmospheric pressures (vacuum), high-voltage corona plasma fields, low outgasing numbers and the worst - repeated extremely-large delta temperature cycling - successfully. The laminate needs to have low-Caf resistance and high-volume resistivity to help stop corona damage from the high-voltage plasma fields encountered when the spacecraft passes through the atmosphere. The best laminate for low-Caf, low-moisture absorption and high-corona rejection was Panasonic 1755, but, true to the manufacturing world's ways, it suffered supply problems. We now specify Isola 410 as the laminate of choice for outer-space use.
Our next job was to eliminate the problems with extreme delta thermal cycling, which causes the copper vias to crack and open. We borrowed my patent-pending High Reliability technology from Sierra Proto Express lead-free applications. The barrel was further strengthened with a little plating trickery, and samples passed over 2000 thermal cycles of -65C to 145C with no reduction in the via's resistance, proving a very tough via indeed.