Ingemar,

Wow!  Can't bond with heavy aluminum?  Stuff must be really bad!  Actually, it appears as though you are able to bond, just don't like the pull values - correct?  Is the area depicted a region which was bonded?  

Are you using 127µm or 254µm wire?  If the image depicts an area that was bonded, it certainly does not appear to show evidence of adhesion.  Are the areas that Yoda speaks of regions of intermetallic formation, or something else?  What does the pulled bond [residual on the board] look like?

We assume that part clamping has not changed, etc.  

Just imagine how much fun someone would have with 25µm wire!!!!  

Thin coating of flux or organics on the board??

Steve - not Yoda

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ingemar Hernefjord (KC/EMW)
Sent: Tuesday, October 17, 2006 10:05 AM
To: [log in to unmask]
Subject: [TN] ENIG problem

 
Hi amigos,
I should never said that we had no ENIG problems. Now we seem to have
one. Chinese board supplier. Problems with heavy wire aluminum bonding
on the ENIG pads. Too low pull test values. Possible reason: pad surface
invaded by copper particles after the bake/reflow/mounting. Sending
picture to Mr Yoda. Never seen this before. Gold is too thick for being
ENIG (>1um), Nickel about 6um. Can't see how Copper could diffuse to the
surface so rapidly and at those low temperatures which are typical for a
general assembly process. Any clue? Graham? You seem to be sitting at
the keyboard just now.
Ingemar Hernefjord
SAAB MICROWAVE SYSTEMS



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