an increase of soldering top temperature by some 30 Centigrades, or a slight increase in humidity absorption (0.01 %), does that motivate such a dramatic extension of bake out procedure? Is it proven bytests or is it an assumption based on maths? I can't see the reason to increase bake out to +150 Centigrades. Why not keep the ordinary std temperature and extend the oven time? Inge -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Fox, Ian Sent: den 24 augusti 2007 08:53 To: [log in to unmask] Subject: Re: [TN] Baking out board moisture Typical values for Novolac cured materials eg IS410/415, PCL370HR, are declared by the manufacturers to be between 0.15-0.3%, ie bridging the gap between polyimide and traditional FR4. If you are processing at Pb free temps then bakeout becomes much more important than it is at traditional SnPb levels. We usually bake 4hrs at 125degC with no impact on ENIG solderability Regards Ian Fox -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar Sent: 24 August 2007 07:03 To: [log in to unmask] Subject: Re: [TN] Baking out board moisture "higher" says nothing, they should be more precise.Here are some examples on moisture absorption: ISOLA std FR-4 Tg130 : 0.2 % GE std GETEK Tg180: 0.12 % Polyclad BT-Epoxy : 0.2 % Nelco PI : 0.35 % GIL GML 1000 : 0.02 % nn PTFE : <0.01 % nn Cyanate Ester : 0.3 % Taconic all products : <0.01 % Rogers Ro group : <0.1 % Rogers RT/duroid : 0.015 to 0.6 % Rogers TMM : 0.010 to 0.16 % Arlon DiClad : < 0.1% Metclad all products : < 0.08 % Would be interesting to know why your Tg170 has higher moisture absorption and also how much higher in percentage. Inge -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Rob Strecker Sent: den 23 augusti 2007 20:04 To: [log in to unmask] Subject: [TN] Baking out board moisture Hi All, We are having an issue with boards delaminating post oven (oven profiles are good). We brought the issue up with our PCB manufacturer and they said "The absorption of moisture on Tg170 laminate (Lead Free) is higher than Tg130 laminate." Their corrective action is to increase the bake time of the inner layer as well as additional drying process of 60min at 150oC before packing. I am concerned with regards to the high bake temperature and what it will do to our ENIG finish. This is also the recommendation they have given us to bake our existing stock before running. Could this reduce the solderability of our boards? I know with Tin finishes you would definitely have a problem with the Tin degrading. One other odd thing about this is we have been soldering lead free for about 2 years now and started seeing issues in Jan of 07. Rob Strecker --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 15.0 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 ----------------------------------------------------- -------------------------------------------------------- Goodrich Control Systems Limited. 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