In a message dated 12/14/00 8:22:48 PM Eastern Standard Time, [log in to unmask] writes: << 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 >> Mr/Ms Yeo - I would like to amplify Susan Mansilla's response above. "Wedge Void" is the discriptive term for a hole wall plating failure where something has been removed from the hole barrel through chemical attack. It is selective at the B stage to copper conductor interface. The cross section of the missing area is a "wedge" showing preferential chemical removal of either the resin or the copper. Removal of resin indicates undercure or too agressive desmear, but is not as common as copper "wedge voids". Some copper is removed by the microetch in either the plated-through-hole line, or in the preplate to copper electroplating. Copper and copper oxide are both available to the microetch solution, and copper oxide (if thick) is removed faster. Hence, you see the attack travelling back along the conductor/cured B stage interface, forming the "wedge". Drill fracture can cause this, as well as poor control of the copper oxide process at inner layer manufacture. Extra care is taken with direct metallization systems, as the copper oxide/cured B stage line is avialable for attack at both through hole processing and electroplating. This interface is inherently covered during electroplating when using electroless copper through hole processes. Dennis Fritz MacDermid --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------