If you carry out weight loss trials you will find that temps above 105 degC and dwells of approx 4 hours are required to fully remove moisture from saturated PCB's, but in practice 2-2.5 hrs is usually sufficient to dry a board prior to coating. These times and temps will not impact on the reliability of product. Ian Fox TRW AS -----Original Message----- From: Phil Nutting [mailto:[log in to unmask]] Sent: 08 April 2002 17:13 To: [log in to unmask] Subject: [TN] Bake before Conformal Coat Good day, Technet After reviewing past threads regarding baking boards before conformal coating I come up with quite a varied selection of ideas. I found 1 hour @100°C, 4 hours at 150°C, and 4-5 hours at 125°C. My design engineer is concerned about the boards being exposed to this temperature for an extended time. Yes, in the wave solder it sees much higher temperatures... for a short period of time. Our aqueous wash system dries at about 65°C for 20 minutes. Our product normally is tested to 40 - 50°C depending on the customer needs. The past threads suggested raising the temperature above 100°C to "boil off" any remaining water. Can this time/temperature be narrowed down any? And if we use a lower temperature are we possibly trapping moisture? How will the reliability be affected by these elevated temperatures. Thanks in advance, Phil Nutting ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or 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 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL 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/scripts/wa.exe?S1=technet Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------