Hence my last two sentences that are standard drawing notes for those who don't wear coats like the rest of us. Dewey -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Dean Stadem Sent: Thursday, June 25, 2009 2:39 PM To: [log in to unmask] Subject: Re: [TN] Conformal coating coverage But some conformal coatings do not adhere to certain materials, therefore a blanket declaration becomes problematic. To fully comply can be very costly, with no value added. R. Dean Stadem Consulting Engineer Analog Technologies Corp./Lumagine, Inc. 11441 Rupp Drive Burnsville, MN 55431 (952)894-9228 [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls Sent: Thursday, June 25, 2009 2:00 PM To: [log in to unmask] Subject: Re: [TN] Conformal coating coverage I agree with Richard who agrees with Dewey...... As others have indicated, it is very much an "it depends" type of proposition, including factors like design life, consequences of failure, hostility of the end use environment, the materials involved, etc. A generic document like A-610 or J-STD-001 can't address all the multitude of factors, so the engineering drawing has to predominate. That issue has come up here internally before. An example: If, in the process of machine spray coating, we leave a very narrow strip of the top of a ceramic DIP package uncoated. Is this a defect? Yes, per the drawing and our requirements. Will there be any degradation in reliability as a result of not coating that narrow strip. Probably not. Ceramic, or even the epoxy of plastic encapsulated microcircuits are better insulators than conformal coating. But, if you allow that narrow strip, you then have to determine how much you can leave uncoated without impacting reliability. What are the tolerances? How do you measure it? Does it depend on the application? Our engineering department does not want to spend the money for what would certainly be a massive study to determine this. Hence, 100% coverage is specified on our drawings. Doug Pauls Rockwell Collins "Stadem, Richard D." <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 06/25/2009 01:01 PM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to "Stadem, Richard D." <[log in to unmask]> To [log in to unmask] cc Subject Re: [TN] Conformal coating coverage Thanks, I like that language, Dewey. In any case, to help Ioan in his initial question; there can be no concrete, comprehensive standard that works for everything when it comes to conformal coating. The requirements need to be tailored AABUS. They seldom work perfectly as defined on the print during the first build, thus the "out card" where any deviations are documented, adjudicated, and approved by the customer before shipping the assemblies. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey (EHCOE) Sent: Thursday, June 25, 2009 12:33 PM To: [log in to unmask] Subject: Re: [TN] Conformal coating coverage I changed Richard's note to be in line with the new approach. After it I added a note I add to all drawings that may have need of the wiggle room or a get-out-of-jail-free card. The conformal coating requirements shall be defined and documented on the PBA (printed board assembly) drawing. Deviations to these requirements shall be AABUS. Conformal coating may or may not be present in non-critical laminate areas of the PB (printed board) or on the top and side of non-critical, non-conductive surfaces of large scale packages, unless otherwise specified. This exception is for the coating coverage requirement and shall not be used to accept uncoated areas due to bubbles, voids and other workmanship issues. Dewey -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. Sent: Thursday, June 25, 2009 9:28 AM To: [log in to unmask] Subject: Re: [TN] Conformal coating coverage That may not be covered under any standard, because the requirements for CC coverage vary by component, assembly, program, customer, and usage requirements. Usually, coating over the component body has no value added, as most component bodies are impervious to moisture. The primary purpose of the CC is to prevent moisture buildup on the metal terminations and solder connections on the CCA. The coating requirements need to be defined and agreed upon between the user and the supplier (AABUS) and documented on the CCA drawing. They are unique and specific to the product. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea Sent: Thursday, June 25, 2009 10:51 AM To: [log in to unmask] Subject: [TN] Conformal coating coverage Dear Technos, Since the PCB edges have been already discussed, I would like to get your input on tall components coverage. Do tall parts, like radial TH parts, inductors, electrolytic caps, etc. need to have the vertical sides coated? What about the coils with apparent windings? IPC-610 is not detailed at all at this level and I have quickly browsed IPC-HDBK-830 without being able to find anything. What would be the IPC or MIL standard covering this particular issue? Thank you, Ioan Tempea, ing. Ingénieur Principal Fabrication / Sr. Manufacturing Engineer 30 ans déjà! - Already 30 years! 950 rue Bergar, Laval, Québec, H7L 5A1 t : 450-967-7100 ext : 244 Mtl : 514-990-5762 f : 450-967-7444 [log in to unmask] <mailto:[log in to unmask]> www.digico.cc <http://www.digico.cc/> P N'imprimer que si nécessaire - Print only if you must --------------------------------------------------- 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 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