The IPC Solderability task groups and the Alternative Solderable 
     Finishes task group are currently looking at a number of non-tin/lead 
     finishes in relationship to solderability requirements. The committees 
     have not brought anything to the discussion table yet but some 
     proposals should be forth coming. Traditionally, the specifications 
     have required that gold pass a one hour steam age conditioning 
     followed by 95% minimum coverage with a dip and look test. The IPC 
     Steam Aging Task group will be publishing a report this fall at IPC 
     Techworks that shows gold finishes can pass 8 hours of steam aging 
     without failing. However, industry in general and I personally don't 
     think that steam aging is the finish durability conditioning method of 
     choice. It has been my experience that there is good gold and bad gold 
     - you need to work closely with your plating source to understand 
     their plating process/chemistry and characterize how that fits your 
     product and the product use environment. I have found that in some 
     manufacturing environments that your 150 Ni and 5 Au thicknesses would 
     be adequate.
     
     
     Dave Hillman
     Rockwell Collins
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: IPC specs for e'less Ni/imm Au
Author:  [log in to unmask] at ccmgw1
Date:    4/24/96 9:19 PM


     
Is there an IPC specs for the minimum thickness of electroless Ni/immersion 
Au PCB finish for solderability application? Is 150u" for electroless Ni & 
5u" for immersion gold the norm in the industry? Please advice. Thanks in 
advance!
     
B.H. Lee
Process Engineer
Singapore