Kevin, The definition of wedge voiding that I'm familiar with is a defect located at the plated through hole where the oxided layer meets perpendicular to the plated barrel of the hole. (I have never heard of the ends <or tails> of nailheading called that before) --[===| |===]-- | | | | ======|< >|===== ========<| | | | ^Oxided | | ======|< >|===== InnerLayer | | Wedge void @ PTH interface --[===| |===]-- On this <crude> 4 lyr diagram the "<" and ">" would indicate where the wedge void could be. An improperly drilled hole may produce a small gap at that location as attempted to depict above. During <acidic> wet processing solution works it way up the innerlayer oxided copper area surrounding the drilled hole and can dissolve oxide <hence pink ring but lets leave that one alone>. If the size of the gap <or wedge> is sufficient to trap air bubbles or chemistries, there would not be ample coverage for proper copper plated through holes. Cross section analysis could produce circumferential voiding or copper plated through hole thickness less than .0008" <isolated>. Are others calling the <absence of> ends of the nailheading not taking plating wedge voids? Groovy ______________________________ Reply Separator _________________________________ Subject: Re: Fab-Re: More nailheading Author: [log in to unmask] at SMTPLINK-HADCO Date: 5/4/96 2:42 AM Dear Phil: As you indicated, the potential for circumferential voiding exists in any direct plating process that would remove the underlying copper from the conductive deposit. This condition is commonly referred to as wedge voiding, as it exhibits itself as a wedge shaped defect in cross sectional examinations. Further, this condition manifests itself typically on the oxide treated surface of the foil only. Actual production using palladium based direct plating systems can occasionally exhibit this defect, but the liklihood is not very great. Further, because palladium systems can modify the process sequence to incorporate microetching prior to conditioning, the chance of the defect occuring is further reduced. Finally, substituting double treat foil for oxide treated foil will eliminate the chance of wedge voiding in all but the most severe cases. Kevin H. Baranowski Atotech USA Inc.