Remember the production stop and the unique veils and crystal on the boards? This came to me from the guy who was invited to help us solve the problem. (a 'casette' is a PWB mounted on a metal cooler with channels for forced air circulation) > The lacquer problem is solved. I believe that the crystal > on lacquer surface is salt from our cleaning system. The cleaning > agent Vigon in the system normally has a solid content 0.5%. The BFB > cassette, after machine cleaning, still remained a pretty amount of > Vigon on inside. It is also very common that the cassettes are often not > completely dried before being lacquered. The salt within Vigon left > inside cassette is believed to have diffused to the surface of lacquer > following the water/moisture migrations. When water moleculars > evaporated, the salt left on the surface form crystals. This > assumption can also explain why the crystal patterns are always > initiated at short edges of the cassette, where the moisture content > is normally slightly higher because the water absorption is more >pronounced along the edge of boards. Recommended not to use Vigon. > > With best regards > > Qiao Wang PhD So, as many of you suspected, the higly alcaline Vigon200 was the root case, or rather the cleaning machine maintenance. Thank you all for good advice. Ingemar Hernefjord Ericsson Microwave Systems --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 -----------------------------------------------------