Your lifted wedge bonds could have a number of causes. You don't
say if it is the gold, the aluminium wedges, or both that lift.
What is the gold thickness and what metal is underneath it. Very
thin immersion deposited gold (0.1 to 0.3 microns) are not gold
ball/wedge bondable with reasonable yields. I've not tried
wedge/wedge bonding gold, but this may well be the same. 









         Wire bonding requires cleanliness from the substrates. The 
         residues form no clean paste are difficult to remove. The alcohol 
         wash probably isn't making much of an impact. If these residues 
         are getting on the wire bond sites they can interfere with the 
         bond. Can you reverse the process flow and do the COB die attach 
         wire bond and glob top before attaching the SMD components?
         If you do this and the COB components are on the same side of the 
         board as the SMT then you can't stencil print solder paste. You 
         will have to dispense solder paste instead. Reversing the flow 
         could also interfere with your test strategy as well, so it needs 
         some thinking about. Given the choice I would COB first, then 
         attach the surface mount parts. 
         
              Plasma cleaning can be used to improve COB yields by removing 
         organics from the metal surfaces. Epoxy die attach materials can 
         out gas during cure, the molecules depositing themselves on the 
         wire bond sites. I don't know if plasma will remove no clean flux 
         residues. 
         
              Look at the surface roughness of the wire bond sites. If the 
         surface is too rough then you will get some bonds lifting.
         
              A final set of causes could be the wire bond process itself. 
         Process parameters, wire and capillary selection, or a machine 
         fault could all contribute to the problem. 
         
         Hope this helps.
         
         Jeremy Drake
         Design to Distribution Ltd
         Stoke on Trent 
         England.