Ryan

George Milad present a paper on this technology at IPC last February. You might want to discuss this with him. I have always always received a great deal of insight from George.

Best regards

Lee

J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389
  ----- Original Message ----- 
  From: Ryan Grant<mailto:[log in to unmask]> 
  To: [log in to unmask]<mailto:[log in to unmask]> 
  Sent: Wednesday, October 12, 2005 11:34 AM
  Subject: [TN] Direct Immersion Gold


  Hi Techies,

  Can anyone explain what direct immersion gold is?  

  My supplier gave me samples of several different board finishes, of
  which two groups were direct immersion gold from two different
  suppliers.  The gold over copper was 5uin and 7uin, which I was
  surprised the copper hadn't already diffused into the gold.  I told him
  I had no interest in direct immersion gold...but, since he gave me the
  samples, I might as well test them with the samples that I am interested
  in (immersion silver).  First, I baked the boards at 125C for 48 hours
  to kill the solderability.  Then they were reflowed twice to kill
  solderability, and checked for wetting.  Again, I expected the copper to
  completely diffuse through the gold, and/or the solderability to be
  dead.  To my surprise, the gold was still there and solderability was
  still good; whereas immersion tin and OSP showed evidence of dewetting.
  (ENIG and immersion silver still had good wetting too).

  So can anyone explain why the copper and gold didn't diffuse into each
  other?

  Thanks,
  Ryan

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