Agree with George Black Nickel result form uncontrolled bath chemistry. My experience before, was that thick nickel have deposited on tank sidewalls (unpassivated) thereby Nickel metal content in the solution become not balance and deposit become black as you check the concentration of the solution it was no longer balance. So check out your tank passivation and dragging in of Di water onto your bath too. hope this helps George Milad <[log in to unmask]> on 06/01/2000 03:24:11 AM Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to [log in to unmask] To: [log in to unmask] cc: (bcc: Jonathan A Noquil/Cebu/Fairchild) Subject: Re: [TN] Black nickel barrier problem w/immersion Ni/Ag The Black Nickel issue is a very low level defect (ppm), with big ramifications when it is encountered. In absence of a good understanding of how this occurs, it has become a "Catch all" for any solderability issues associated with ENIG. Many defects that may have other explanations go un investigated once they are labeled "Black Nickel". The immersion gold step is a controlled corrosion reaction. Occasionally this could go out of control and may create a "Black Ni" pad, under the immergent Au. This gold will have a tendency to peel if tape tested, depending on the degree of severity of the corrosion. The underlying Ni is compromised and may not wet. Some of the ways that this can occur are: Uneven Ni deposit: An uneven Cu surface (pitted, corroded etc) Solder mask residues on the incoming Cu surface Cu/tin intermetallics as above Uneven catalyzation. Catalyst bath operated out of control. Ni bath chemistry out of the specified operating range Gold bath too aggressive: Excessive dwell time in the Au bath High Temperature (outside the control limits) Au bath chemistry out of specified range. Most board shops today are fully aware of this condition and are making sure that their ENIG processes are running within the specified vendor recommendations. George Milad Shipley ############################################################## TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ############################################################## ############################################################## TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################