Would suggest making sure the mask thickness if sufficient, and may required 2 coats of material. Adhesion can be also improved by the micro-etching process similar to inner layers, or oxide if a replacement is not being used. Jeffrey Bush Director, Quality Assurance and Technical Support 76 Technology Drive - POB 1890 Brattleboro, Vermont 05302 802.257.4571.21 http://www.vtcircuits.com -----Original Message----- From: John Parsons [mailto:[log in to unmask]] Sent: Wednesday, November 17, 2004 2:08 PM To: [log in to unmask] Subject: [TN] Alternatives to Conformal Coating? Greetings all, We are a fab shop and are looking for a solution to a problem being experienced by one of our customers. They have a board which resides in a somewhat hostile environment - steam/salt water vapour - board carries 20Amp current - susceptible to multiple thermal excursions which put further stress on the unit The problem, as one might expect, is that the soldermask is not man enough for the job. Some units have exhibited significant solder mask flaking from the conductors after as little as 4 hours of operation. FYI, board is double sided with 3oz base Cu. The product is currently only in the prototype stage but production volumes are expected to be in the 100,000-250,000 units annually. We have proposed the obvious solution of utilizing a conformal coating post assy but that is an option they would initially prefer to avoid due to the inherent costs involved. They would like us to first exhaust any possibility that the problem can be averted from the pcb fabrication level. I should also mention that the expected lifespan of the unit is a maximum of 1000hrs and likely only several hundred hours. Some options that have been discussed are; (in no particular order of likelihood to succeed of fail!) - multiple coating of soldermask - micro etch of copper prior to mask application (currently pumice scrub) - conductor pacification with oxide alternative. If this does not provide additional bite for the mask it may provide additional protection from corrosion once the mask has pealed off. Any ideas from the lot of you? Are there properties to specialty solder masks which might be beneficial in this application? Any options to conformal coating?? Regards John Parsons --------------------------------------------------- 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 -----------------------------------------------------