If you get dewetting from plastic components, then they are dirty, or you are using the wrong coating. This can pose a reliability issue. An extreme example is a fin pitch J lead. If the coating dewets the body, are the leads covered adjacent to the body. Will the dewetting prohibit coverage of the solder joint under the component body? I have tested and qualified coatings. This was found on some, but not all coatings, and usually upon one specific part or supplier. I disqualified all coatings that exhibited this problem from the matrix, and implemented a coating that does not dewet from them. It is acceptable to leave plastic bodies uncoated using masking or a Nordson, since plastic is generally inert relative to tin/lead, but don't allow dewetted coating. It can result in catastrophic failure. Aric Parr [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: FWD: pwb-cca : conformal coating Author: [log in to unmask] at internet Date: 10/23/96 7:01 AM Technet, I'm forwarding this from a colleague. Cindy Kemp Lockheed Martin Orlando, FL ******************************************************************************* From: [log in to unmask] Date: Tue, 22 Oct 96 16:35:22 EDT Message-Id: <[log in to unmask]> To: [log in to unmask] Subject: pwb-cca : conformal coating Sender: [log in to unmask] Precedence: bulk hi group; We are finding that in designs using conformal coating (UR) over plastic parts that the cc is dewetting on the parts. Question - is this seen as a problem ? I am proposing that a note should be added to our designs as follows: CONFORMAL COAT DEWETTING ON PLASTIC ENCAPSULATED MICROCIRCUIT COMPONENT BODY IS ACCEPTABLE. If there is a better way please let me here from you. What is the real would doing ? thanx; Skip Greb ======================================================================== To learn more about this email exploder (majordomo), including how to unsubscribe from this list, send e-mail to: [log in to unmask] and place the command "help" in the body of the message - subject may be left blank. Help can also be obtained on the WWW at http://www.epic.lmco.com/Majordomo ======================================================================== *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************