We have occasionally used dryfilm to tent both sides of a via hole prior to applying LPI mask. Other than the added expense and additional steps, it works quite well and is cosmetically good. We have not observed any degradation or adhesion loss after multiple thermal stresses. Since the dryfilm is applied over high pressure areas you don't need to utilize a vacuum system when applying the film. If you have this equipment available, it does result in a slightly lower profile "bump" over the vis because the dryfilm is deformed into the hole. Be sure to use the .0015 film to avoid assembly issues with stencil interference during solderpaste application in high density component areas. ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################