Please humor my question regarding coating thickness. Besides adding weight to the end product, what is the significance of listing a maximum thickness to conformal coating? Why would 0.010 be less reliable then the maximum thickness of 0.005? Joel Alexander Quality Assurance Manager TT APSCO, INC. Edward Mines <[log in to unmask]> 04/29/2007 12:54 PM To [log in to unmask] cc Subject Re: [TN] bubbles in conformal coating Joel- The thickness you are using is far greater rthan the maximum coating thickness called out by MIL-I-46058 & IPC-CC-830. Some customers would reject the coating for that reason alone. Contact Dymax. Ed [log in to unmask] wrote: We are using Dynamax Multi-Cure 984LVUF and it is about 10 mils thick on the flat section. I know this sounds thick but the machine drop dispenses so the coating will not run into keep our areas. Joel Alexander Quality Assurance Manager TT APSCO, INC. Edward Mines <[log in to unmask]> 04/27/2007 10:17 AM To [log in to unmask] cc Subject Re: [TN] bubbles in conformal coating Joel- You're right. 830 (the son of MIL -I-46058) is used by manufacturers to qualify the material. As a former employee of a manufacturer I know this document very well. I am less familiar with IPC-A-610. 46058 used to be on the internet. The versions of IPC-CC-830 that I am familiar with (there may be a newer one) followed the same format as 46058. Near the very beginning in MIL-I-......it states something like "the coating must be free from etc." Our interpretation was that this applied to the users too.That MIL SPEC is vague on many other things like thickness. Our interpretation was that the thickness the SPEC called out was on flat area of the board. I think foam is mentioned in the statement "the coating must be free from....." I know of many instances where coaters did things that weren't specifically prohibited that would adversely effect coating performance. Which coating are you using? Is the thickness on flat sections within the 1-3 mil range? Some HumiSeal polyurethane coatings do not cure properly if they are too thick. To the best of my knowledge no document says you have to follow the manufacturers instructions but if the don't the coating may not provide the protection for which the coating was designed. Ed [log in to unmask] wrote: IPC-CC-830 is a standard used by the manufacturer of the conformal coating to qualify their material. Can these also be applied to the application by the end user. IPC-A-610 states that bubbles are acceptable as long as they do not bridge adjacent conductors. Also is there a specific reference that states anything about the appearance of foam? Joel Alexander Quality Assurance Manager TT APSCO, INC. Edward Mines <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 04/25/2007 10:26 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to Edward Mines <[log in to unmask]> To [log in to unmask] cc Subject [TN] bubbles in conformal coating MIL-I-46058 & now IPC-CC-830 say conformal coatings should be "bubble free". Some have interpreted this as meaning that a few small bubbles away from components are acceptable. Foam is not acceptable. Some polyurethane conformal coatings generate gas as they cure. They should not be coated on very humid days. Bubbles are also apt to form in conformal coatings when the coating is too thick. I've seen this happen in between closely spaced tall components even when the coating on most of the board is within customary limits and has no bubbles. The solution was to change the application technique. Get the coating and equipment manufacturers involved. They want your future business. Ed Mines Ahhh...imagining that irresistible "new car" smell? Check out new cars at Yahoo! Autos. ForwardSourceID:NT000B489E Ahhh...imagining that irresistible "new car" smell? Check out new cars at Yahoo! Autos. ForwardSourceID:NT000B49D2 --------------------------------------------------- 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 -----------------------------------------------------