Wow! Such a simple question has so many answers. A wedge void occurs usually at the prepreg inner layer interface. It is due to plating salts or desmear product being trapped at this interface and "poisoning" subsequent plating operations. As for the cause: 1) Uncured prepreg 2) Too much resin "squeezed out" of the prepreg 3) Drilling feeds and speeds not optimized (usually indicated by the presence of nailheading) 4) Too aggressive of a desmear or etchback chemistry 5) Adhesion promoting properties of the inner layer foil being attacked more aggessively by the desmear or etchback chemistries These are just a few of the causes. Unfortunately there are as many causes as you have steps in the process Susan Mansilla Technical Director Robisan Lab --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------