Hi Ian - boy, that's a million dollar (or maybe a billion pound) question that many of the JSTD-003 committee would love to have a definitive answer on! The information/opinion that seems most agreed to within the JSTD-003 committee is that a printed wiring board that is keep in a 75 +/- 10F, 30-60% RH that has been produced in a well controlled, HASL process should be solderable after 12 months of storage. The "well controlled HASL" process refers to a consistent solder coating thickness across all features of the printed circuit board. However, humid conditions and/or elevated temperature conditions have a definite impact on the printed wiring boards. The level of impact will depend heavily on the process conditions (flux type, process parameters, etc.) that the printed wiring board assembler uses. The TechNet suggestion of bagging/sealing boards has been shown to extend storage durations in some cases. The JSTD-003 committee is attempting to better address this issue with the use of "durability" ratings - anyone with information on the subject should forward it to the committee to help them in their efforts. Dave Hillman JSTD-003 committee chair [log in to unmask] [log in to unmask] on 04/21/98 12:10:00 PM Please respond to [log in to unmask]; Please respond to [log in to unmask] To: [log in to unmask] cc: (bcc: David D Hillman/CedarRapids/Collins/Rockwell) Subject: [TN] Storage conditions of pcb Good Day! Could anyone advise me on the specification to adopt ( temperature and relative humidity ) for the optimium storage conditions for bare printed circuit boards. These boards are typically overmakes which we store until our Customers can place their next order. What length of time do you think the solderability of solder levelled boards would remain excellent in these conditions. Best regards Ian Parker Prestwick Circuits Scotland ################################################################ TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################ ################################################################ TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################