Tom - I don't recommend using polyimide as a standard for the following reasons: 1. Cost -- the last time I checked polyimide was 20-50% more than FR-4 2. Fabricators -- not all fabrication houses can produce polyimide boards requiring you to qualify more suppliers. 3. Assembly issues - polyimide seems to require more process control than FR-4 to achieve the same results ( pre-bake, etc.) If you need dimensional stability over a wide temperature range, I suggest you look at G-tek or other tetra-functional FR-4 materials they may be a better choice. Jeffrey McGlaughlin Designer Battelle Memorial Inst. Columbus Ohio -----Original Message----- From: Tom Lambert [SMTP:[log in to unmask]] Sent: Friday, March 13, 1998 4:58 PM To: [log in to unmask] Subject: [TN] FR4 vs Polyimide > >Am trying to decide which to standardize on - would appreciate info, pros >and cons, for each. > ################################################################ 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 ################################################################