It is true that sulfamate nickel inherently has less stress than sulfate nickel. The main reason is that sulfate nickel plating chemistry contains nickel chloride. The chloride itself has been proven to cause more stress in the deposit. You may also want to make sure that any organic additions agents used in the process do not contribute any significant amounts of stress. If sulfate nickel is employed, use an additive that only imparts a semi-bright finish to the nickel, such as the sodium saccharin type additives. -----Original Message----- From: Au Po Lam, Benny [SMTP:[log in to unmask]] Sent: Wednesday, March 31, 1999 8:24 PM To: [log in to unmask] Subject: [TN] Ni Plating for wire bond Hello Everyone, What kind of chemistry do you recommend for electrolytic Ni plate, sulfamate or sulfate nickel, as applied on thermosonic wire-bond PCB? I was told long time ago that sulfamate nickel is a 'low-stress' nickel being used in various metal finishing jobs, including PCB; while the latter comes from a Watt nickel bath. Some BGA designers says that as long as the metal surface is clean, the two nickel types should work equally well. I recently tried both and found that the sulfate nickel has a better bondability, despite the fact that they come from two different vendors. Can anyone tell me about the surface topography of each type of nickel? Do they have different atomic packing in the plated layer? What actually does low/high -stress mean, something related to hardness? Assuming they have the same amount of gold plated on top, which one is more suitable for gold wire ball bond? Thanks in advance! Regards, Benny. Wire Bonder Process Eng'g ASM Assembly Automation ################################################################ 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 ################################################################