When using an OSP coating on a double sided circuit board (plated thru), should the topside annular ring of a via (not the area over the hole) be covered with soldermask? I am told by the designer that this is done to prevent the copper from corroding during the lifetime of the product (no conformal coat used). Is it acceptable to have the soldermask go to the edge of the via hole(over the annular ring) and allow some of the mask to coat the upper portion inside the via hole. I am having ICT failures on probes that probe the bottomside of the via hole. Soldermask either covers the via hole or bleeds down into the via hole, and then particles of this soldermask are trapped in the solder "fillet" on the bottom of the board that fills the via after the wave soldering process, and the probe does not make contact. Thanks Ed Holton Hella Electronics ################################################################ TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################