Patty - good reading material - unfortunately haven't read till u mentioned. would like to dispute Lenny's views - have seen too many cross sections to know otherwise. Whenever pinkring occurrs - look at those cross sections carefully - u will notice some sort of copper folding after plating - means had to be minor space - most llikely filled with air - then solution - whether plain shifting or whatever - the wall has either a gough in it - or minute fracture in the oxide layer. Reduced oxide is nice - but is the oxide layer reduced chemically or is it being chemically etched back - be careful when ur chemical supplier says " we have reduced oxide".Can SERA determine breakdown product is left in? When does the reducer have to be changed? And when we speak about multi-layers - 4 - 6 - 8 - 10 - what happens on 16 layer boards - 20 layers? Saw some occurances happen this year on some pretty thick boards - hydrolization of the reducer - ain't a pretty sight when a 20 layer board seperates. Final conclusion as to how and why? Will know in a month or so .... will try to remember to pass info on. Little pressed for time these days .... once i get freed up will try to forward this info through the net. Yes - reduced oxide does help out when using DM - to an extent - but drilling is still where it starts - from there - your guess is as good as mine as to where the acid attack occurrs. best regards Richard Fudalewski Atotech Canada Ltd *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************