I've heard lots on my time Lee. The only reasons that resonated with me were: 1. To overcome moisture uptake of the boards between cleaning and coating if significant delay between 2 processes. High levels of moisture can create havoc with certain solvent-based materials developing their adhesion, or lead to blushing, where coating becomes cloudy, hazy or milky in appearance. Can lead to bubbling with moisture curing mechanisms occurring at a rate greater than the permeation of by products, eg CO2 thru the film. 2. To help prevent excessive capillary flow or dripping on inversion with low viscosity solvent-based materials, theory being drive solvent-off quicker, build viscosity faster. This works well with primer or 'dusting' layers, less well with traditional cc process. I don't see this 2nd reason cited much any more. Sure I missed some reasons though... Best Regards, Phil +44 7703 795422 Sent from my iPhone On 26 Mar 2013, at 17:39, lee Hitchens <[log in to unmask]> wrote: > Can I also ask a question. What is the purpose of baking a PCB before > coating, assuming that the cleaning process drying section is adequate? I > have never really got a good answer to this? > > Best Regards > > Lee Hitchens > Technical Director > > SCH Technologies is a Division of SCH Services Limited > Mob: +44 (0) 7862 25 33 21 www.conformalcoating.co.uk > > TECHNICAL SUPPORT SERVICE > > SCH Services Ltd offers a Technical Support Helpline to help address all > issues relating to reliability. This includes contamination testing, > cleanliness and cleaning issues, plus any coating related questions. > Please contact us via email or telephone: > > [log in to unmask] +44 (0)1226 249019 (office hours & answerphone) +44 > (0)7862 253321 (out-of-hours emergency) > > The opinions expressed in this e-mail are strictly those of the sender and > not of SCH Services Limited. This communication may contain information > which is confidential and may also be privileged. It is for the exclusive > use of the intended recipient(s). Unauthorised use, copying or disclosure of > any of it may be unlawful. If you are not the intended recipient(s) please > note that any distribution, copying or use of this communication or the > information in it is strictly prohibited. If you have received this > communication in error please notify us by e-mail or by telephone (+44 > (0)1226 249019) and then delete the e-mail and any copies of it. Virus > Warning - Although steps have been taken to ensure that all email and > attachments are virus-free, we cannot guarantee nor be held liable. > > Company Registration: 04043334 > Registered office: SCH Services Limited Newburgh Building McLintock Way > Barnsley South Yorkshire S70 6BF > > > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Fox, Ian > Sent: 26 March 2013 16:17 > To: [log in to unmask] > Subject: Re: [TN] Conformal Coat and Board Edges > > No we don't. Since the purpose of the coating is not to prevent moisture > ingress into the board (we all know that happens), but really to prevent > issues with condensation, and since there likely will be no exposed tracks > on the edge, there's no point. We typically have a ground/thermal strip > around the edge of the card anyway so the masking may sometimes cover, or > partially cover the edge. I couldn't tell you how many millions of on wing > hours our assemblies have accumulated over the past 30+ years, but we've > never had an issue in service as a result of uncoated edges, nor in the > umpteen unit qualifications we've carried out. In fact if you carry out > weight gain measurements with high (85%+) humidity exposure the laminate is > typically saturated after about 4 days and we always run the 10 day tropical > exposure test > > Regards > > Ian Fox > Lead Materials and process Engineer > > Aero Engine Controls > York Road, Hall Green, Birmingham B28 8LN | Tel: +44 (0)121 607 3763 | Fax: > +44 (0)121 607 3975 > Email: [log in to unmask] | Web: www.aeroenginecontrols.com > > Aero Engine Controls is part of the Rolls-Royce Group > > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls > Sent: 26 March 2013 15:43 > To: [log in to unmask] > Subject: [TN] Conformal Coat and Board Edges > > OK, the conformal coat question of the day: > > Do you conformally coat the edges of a printed circuit assembly? Why or why > not? > > OK, that is two questions, or perhaps a half fractional question..... > > Doug Pauls > > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > > ______________________________________________________________________ > This email has been scanned. > > ______________________________________________________________________ > Aero Engine Controls is part of the Rolls-Royce Group, whose legal entity is > Rolls-Royce Engine Control Systems Limited which is registered in England. > Registered office at Moor Lane, PO Box 31, Derby, DE24 8BJ. Company number > 6686268, UK VAT number GB 939 396 075 > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________