Hi Jeff, I think Sefika meant the ambient temp/humidity/barometric pressure that an assembled board can be stored in over time. Previous TechNet discussions have touched on this to some extent, especially when it comes to different board types, i.e. FR4 vs. Polyimide, etc. Some raw board types act like sponges and absorb water quickly, others take longer to suffer from high humidity or corrosive contaminants in the air around them. And assembled boards still suffer from this somewhat, but the inherent problems with raw boards are most apparent when trying to assemble boards, i.e. shrinkage during high reflow profiles, dewetting issues, contaminated pads, etc. Once a board is assembled most of these 'issues' go away - especially if the boards are conformally coated. However, I remain curious to see if anyone will wade into this issue with some good, solid statistics on the post-build side of the equation. Any takers? Dale Ritzen, CQA Quality Manager Austin Manufacturing Services -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Jeffrey Bush Sent: Wednesday, February 09, 2005 6:11 AM To: [log in to unmask] Subject: Re: [TN] storage temperature of assembled pcbs Maximum operating temp is generally 130 C for most /21 materials. At this temp the board an continuously operate and function electrically and mechanically as designed. Beyond this performance can become flakey. Jeffrey Bush Director, Quality Assurance and Technical Support VERMONT CIRCUITS INCORPORATED 76 Technology Drive – POB 1890 Brattleboro, Vermont 05302 Voice: 802.257.4571.21 Fax: 802.257.0011 http://www.vtcircuits.com -----Original Message----- From: Sefika ÖZKAL [mailto:[log in to unmask]] Sent: Wednesday, February 09, 2005 6:35 AM To: [log in to unmask] Subject: [TN] storage temperature of assembled pcbs Hi, How can we determine the storage temperature of an assembled pcb? What is the minimum temperature value which a laminate material (fr4 – tg 135°C ) can tolerate without experiencing any distortion on its construction? Best Regards Have a good day? Sefika OZKAL Design Engineer ASELSAN INC. MGEO Division Address : Cankiri Yolu 7. Km Akyurt Ankara TURKEY E-mail : [log in to unmask] Tel : +90 312 84 75 300 Ext: 4698 Fax : +90 312 84 75 320 --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------