Craig Take a bare piece of copper or aluminium and measure its thickness using a micrometer. Now apply the coating as per your normal method and leave it to dry for around 1 hour. Now re-measure the sample and subtract one from t'other et voila: you know the thickness you have applied. If you now apply a second coat you will not get the same thickness added to the first because the solvents in the coating will partially dissolve the existing coating. Of course you will experience some RF loss with a ticker v a thinner coating, but they should not affect the end performance once the data has been "dialled in". When you qualify a conformal coating for an RF application, it is assumed that you would actually determine the maximum thickness allowable on that circuit design. When you make your measurement first make sure the coating is FULLY CURED. In the case of an acrylic I would recommend baking at 80C overnight or leaving it for 1 week at room temperature before measuring. Hope this helps Graham Naisbitt On 8 Jul 2008, at 16:53, Craig Sullivan wrote: > Hi Everyone, > > I have a few questions about conformal coating. Specifically > acrylics. For > reference, we apply the coating manually. > > What are the average coating thicknesses that you see after 1 coat? > After 2 > coats? Are you getting more than 0.001" of coverage in 1 or 2 coats? > > Given that soldermask is very lossy when it comes to SI, I would > assume the > coating has similar properties (still waiting for vendor data). Have > you had > any odd failures (from an RF stand point) with a 0.001" coating > thickness > versus say 0.002" or 0.003"? > > The data sheet specs a Dk and Df @ 1 MHz, but I am extremely > interested in > these at RF frequencies. > > Has anyone done any studies about this that can share the findings? > > Thanks, > Craig > > --------------------------------------------------- > 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 -----------------------------------------------------