HELP - What's the secret to making wire-bondable gold? Our ppm failure rate on wire bond sites is a little too high for our customer. Smallest wire-bond pad is about .014"x .050" and wire mat'l is Al (generally higher failure rates on smaller pads). The highest percentage culprit has been described as an [arguably] visible "orange stain" - very thin with a Carbon/Oxygen signature. Board is double-sided with the following route: Drill, panel plate Cu, image & plate gold (DuPont 9020), strip resist (RR3), image (cover gold), cupric etch circuitry, pumice w/brushes, LPISM (Probimer-65), solvent develop, bake & UV cure, legend, ET, Entek 56. Gold parameters: 83-85 knoop, Ni content: 30-40ppm, As,Cu,Pb,Co, all less than 3 ppm, Gold conc. is on low side: Au strike: 0.15-0.25 tr.oz./gal, Au Plate: 0.4-0.6 tr.oz./gal @ ~2 ASF. Questions: - What are the most common contributors to wire-bond failures? - Is LPISM residue one of them? - Are aqueous developable LPISMs generally more successful? - What are the, say, 3 most critical parameters to control at deep gold? - How critical is gold surface topography (roughness)? - Are ET pin dents a failure cause? - Can pumice operations be detrimental to the gold surface? - Is low Au concentration necessarily a liability? Any input will be greatly appreciated. J.Felts PC World, Toronto *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************