Mike The best one I've come across is a triply envelope: a very thin unplasticised polypropylene on the inside (to provide heat-sealing without evaporating contaminants onto the contents, like PE does); the middle one is a thin Sendzimir-rolled aluminium foil (to provide perfect barrier for moisture and chemical contaminants: do NOT use evaporated aluminium) and a thicker polyethylene layer on the outside to make it robust. Vacuum-sealing a bare PCB in that will give you virtually perfect protection and conservation. We used these for individually packing m/ls and had no blow-hole and no solderability problems with just Sealbrite on the copper for years (both guaranteed for 6 months, provided soldered within 48 hours after opening). This was 30 years or so ago, when I was in charge of a PC fab shop. The bags I describe are sometimes used for the long-term conservation of food without freezing, where cans are otherwise unsuitable or undesirable for whatever reason. Brian "Mcmaster, Michael" wrote: > There's been a lot of talk about baking and packaging boards to avoid > problems from moisture sorption. Does anybody have any recommended sources > for moisture barrier packaging for PWBs? > Mike McMaster > RF Product Engineer > Merix Corporation > Forest Grove OR > 503-992-4263 > > ############################################################## > TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c > ############################################################## > To subscribe/unsubscribe, send a message to [log in to unmask] with following text in > the body: > To subscribe: SUBSCRIBE TECHNET <your full name> > To unsubscribe: SIGNOFF TECHNET > ############################################################## > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional > information. > If you need assistance - contact Keach Sasamori at [log in to unmask] or > 847-509-9700 ext.5315 > ############################################################## ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################