For thermosonic gold ball bonding, you should have pure, soft gold. The problems that you are seeing are probably due to the materials added to harden the gold. Thallium, lead, nickel, copper, chrome, or titanium can all decrease bondability. Talk to your board vendor, and see if they can plate pure soft gold for the wire bonding. There is an article in Volume 20, Number 3 IMAPS Journal regarding thermosonic gold ball bonding to immersion gold, electroless nickel. Perhaps this metallization is a possibility. It is more difficult than bonding to soft pure gold, but it can be done. Dave Anderson Medtronic, Inc. Opinions are my own, and do not necessarily reflect those of my employer. >>> <[log in to unmask]> 05/29/98 08:08am >>> Everybody, good day. Does a woodpeck prefer hickory or limetree? And does a automatic wire bonding machine prefer hard gold or soft gold? From the metaphor to the problem: Our board supplier is a very good one, I think, but our special headache is not his, at least not yet. We design with Teflon-on-Brass plates (US-made). On the Teflon (in fact Teflon mixed with ceramic and glass etc) there is a Copper layer. This copper layer is etched and Nickel plated. Finally you put electrolytic Gold on. The process is such, that both the Nickel and the Gold becomes too hard for gold ball wire ultrasonic bonding. Wanted hardness is 100 HV. The hardness from supplier X is 450HV. The question is: what is possible to do in the board processing steps? I know that the chemistry of Nickel-and Gold baths is a mysterious world, current density plays a role, heat treatments also and a lot of other things. But we don't have the time to experiment weeks and months. Is there someone with a woodpeck's experience? Ingemar Hernefjord Ericsson Microwave Systems Sweden ################################################################ 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 web site (http://jefry.ipc.org/forum.htm) for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################