Good Morning TechNet!
     
     To my knowledge there is not a specification requirement for the 
     "thickness" of the tinning of gold plated components. The MIL STD 2000 
     and the JSTD-001 specifications were/are focused on the removal of the 
     gold rather than getting a specific tinned thickness and I would focus 
     more on that aspect also. Both specifications endorse either a double 
     dip (two solder pots) emmersion or the use of a flowing solder wave as 
     proven methods for removal of the gold plating and replacing it with 
     tin/lead. JSTD 001 goes further in that it promotes the development of 
     documented data showing that your method of removing the gold is 
     sufficient for allowing reliable assembly operations. One industry 
     number that has been suggested is 60 microinches of tin/lead on the 
     leads is sufficient to insure solderability (I think this number may 
     have come out of the old WS6536 specification). Keeping 60 microiches 
     of tin/lead on the corners of square leads can sometimes be a problem. 
     I suggest working with your vendors to evaluate how they propose to 
     remove the gold and either through microsection or electron microscopy 
     document that the gold is gone. How much solder you want to have left 
     on the leads will depend on how fast your process consumes the 
     components. Good Luck.
     
     
     Dave Hillman
     Rockwell Collins
     [log in to unmask]
     


______________________________ Reply Separator _________________________________
Subject: ASSY: Pre-tinning of Gold Leads
Author:  [log in to unmask] at ccmgw1
Date:    1/14/97 3:13 PM


     
Technetters
     
We use a lot of components that come with gold plated
leads (gull wing, J-leaded, castellations..).  We are currently 
asking our vendors to pre-tin these leads if possible and one 
such vendor wants to know the exact mil-spec that he can
look up to know the thickess of the tinning that is required.
     
Can anyone point me to the exact document that spits out 
recommended tinning thicknesses based on the thickness 
of the gold on the lead??
     
Thank you
________________________________________________ 
Sanjay Rajan        RF Communications Division 
Harris Corporation  Product Design Engineering 
1680 University Avenue   Phone:    (716) 242-3923 
Rochester, NY 14610 Fax: (716) 242-3174 
________________________________________________
     
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