Phil, I have read the mentioned paper. Indeed one can simulate the effect with +1V charge application during IG. Is this a normal occurrence? On page S18-5-6 the mechanism of black band formation is given as depletion of surface nickel with "no gold, being deposited during the defect corrosion process." It is then stated on page S-18-5-8 that "while this hypercorrosion is taking place a thicker than normal layer of IG is also plating on top." Perhaps this is a typo, but one might suggest that there are other mechanisms of nickel starvation that lead to black band including thermal characteristics at reflow. Does anyone have information as to black pad formation versus type of solder paste and reflow temperature? Do different cycles give different defect rates or is 63/37 the only used paste? Perhaps the root cause is nickel starvation in the bath or during assembly, but the side effect is the black pad? Speculating some more, Paul -----Original Message----- From: Phillip E Hinton [SMTP:[log in to unmask]] Sent: Wednesday, March 31, 1999 1:32 PM To: [log in to unmask] Subject: [TN] Black Ni/Au pads All interested in black-pad phenomena The root cause and explanation of the the black pad condition is well explained in Nick Buinno's (Hadco) paper published in the IPC Printed Circuit EXPO Paper No. S-18-5. Get a copy from IPC if you did not attend. Phil Hinton . ################################################################ 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################