Hi Doug -
     
     True, but one could also take some "unsoldered" phenolic, lacquer, and 
     soldermask samples, run them through the wave solder profile used on 
     the assemblies and use them as the "baseline" samples for comparison. 
     You are right, the decomposition via the molten solder will change the 
     material's character scans but these "baseline" samples could give you 
     a close enough match to help.
     
     
     Dave Hillman
     Rockwell Collins
     [log in to unmask]
     


______________________________ Reply Separator _________________________________
Subject: Re: Brown resin like residue in solder bath
Author:  [log in to unmask] at ccmgw1
Date:    12/12/96 3:39 PM


In a message dated 96-12-11 19:49:54 EST, you write:
     
<<   I haven't the foggiest idea what your brown residue is but you could 
      conduct a Fourier Transform Infrared (FTIR) analysis to pinpoint its 
      identity. FTIR analysis is the organic material analysis counterpart 
      to Scanning Electron Microscopy (SEM) analysis for elements. With the 
      FTIR analysis you can compare the residue scan with a phenolic scan, a 
      solder mask scan, and a lacquer scan to see if any match. Good Luck. >>
     
A good start Dave, but I don't think that FTIR will show much in this case.
 Since the residue is in the solder bath, I don't know of many organic
materials that would survive prolonged exposure to molten solder 
temperatures.  The SEM would be a good choice.  He might also try inductively 
coupled plasma (ICP), which is often used on plating bath residues.  Another 
possibility would be mass spectroscopy, although somewhat expensive.
     
Doug Pauls
CSL
     
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