At 12:35 AM 3/13/02 -0600, Nick Veys wrote: >What would be some good, yet inexpensive ways to ruggedize PCBs? We >want to be able to tolerate water, vibration and moderate impacts. >Without breaking into MILSPEC components of course! The project I'm >involved in is 100% donation funded, and as a result our budget for >things like this is quite limited, and we like tricky methods that get >the job done. :) We do this regularly for many of our projects. 1) avoid IC sockets. Solder the chips directly to the board. There are two reasons: the conformal coat gets into the pins and causes bad and/or intermittent contacts *and* the chips can work their way out of the sockets. The pin contamination problem is by far the worst thing you have to deal with. Use a flash PIC and include an ICSP connector so that you can upgrade the code without having to remove the chip. 2) glue or otherwise fasten large components to the board. All electrolytic caps should be glued (Plyobond (sp?) or contact cement applied around the perimeter with a syringe works well and is quick. The glue you choose should shrink somewhat upon drying and remain flexible. Silicone sealant is NOT a good choice here. Large power resistors are mechanically strapped with wire loops. 3) Use a GOOD liquid conformal coating. The spray stuff just doesn't cut it for extended periods. We use two different types from GE and Dow Corning. The Dow stuff is by far the better of the two. Apply the coating by either brushing or dipping. If you dip, you can also use a vacuum pump and bell jar to get rid of air pockets (I normally don't bother). dwayne Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 18 years of Engineering Innovation (1984 - 2002) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads