Gold surface contam after prebake 150C for 3 hrs

We're not familiar with the AUG5 from Taiyo. [It doesn't show on their US site.] Is it liquid photoimageable? Printed solder masks are more likely to bleed. But you wouldn't have any solderability with bleed.

Your plating seems acceptable [if that's what you're receiving]. * Poor coverage at the edge of the gold pads (exposed Cu or Ni) sometime will result Cu/Ni migrated to Au surface under humidity condition. (surface diffusion is 2 orders of magnitude higher than the bulk diffusion). * Insufficient final rinse (or delay of the final rinse, e.g. "went for lunch") after the plating may cause residue on the gold pad (oxidation of residue...e.g. brownish look Au for KCN based plating). * Good reference: "The Auger Analysis of Contaminants that Influence the Thermocompression Bonding of Gold" G.E. McGuire et. al, Thin Solid Films Vol. 45, 1977. p. 59 * Plating condition [e.g. current density, PH, additive concentration variation] can entrap impurities (co-deposit), sometimes the Au deposit becomes porous. A good reference paper for Au plating is: "High-Performance Gold Plating for Microdevices" A. Gemmler et.al. Plating and Surface Finishing, Aug. 1994, p.52; Publisher - Association of Electroplaters and Surface Finishers (AESF) Printers

Whem wire bonds don't stick when bonded: * Check pull and shear strength * Review machine setup parameters, depending on point of failure * Listen during bonding, if there is a high pitch buzz, there is vibration in the system somewhere, "seek and destroy" * Get the plating analyzed, and look for high surface contaminants.

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Can someone explain what full body gold is ?

Any reference material to read from ?

Thx

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