Hi everyone, I am studying the tool life of capillaries in the thermosonic gold wire bond process. The PCBs I used are low-end FR-4 or tetrafunctional for MCM packages and therefore the bonding temperature is kept at 120 degC max. The gold plating thickness varies from 0.5 to 1um or even less and the nickel is above 3um. The capillary has a matte finish. No matter which plating finish is used, I found that under the same bond schedule, a break-in is required for the stitch pull force to stabilize. I also found a layer of metal build-up at the tool tip and suspect that this build-up should enhance the reaction of the wire with the substrate metallization. I've asked the capillary vendor and he also realized this phenomenon as reported by his customers. Do you have the same experience? What is your observation and explanation for this? Regards, Benny. Wire Bonder Process Eng'g ASM Assembly Automation Tel :852-26192844 Fax :852-26192159 Email :[log in to unmask] ################################################################ 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 ################################################################