In the IPC soldering flux spec J-STD-004 there are a couple of
non quantitative tests, IPC-TM-650 method 2.3.33 Silver Chromate
for Halides and method 2.3.35.1 Fluoride spot test. If these
tests are pass then the flux is Halide and Flouride free. If
they fail then there are quantitative tests that can be used to
determine the Halide and Fluoride concentration. My question is









         what is the limit of detection of these qualitative tests? What
         concentration of halide or Fluoride in the flux would just pass
         the silver chromate or fluride spot test?

              I'm planning on using a water wash flux that passes these
         tests for placing solder balls on silicon wafers. My semiconductor
         assembly experience with die attach materials and epoxy
         encapsulants makes me very wary of halides. How concerned should I
         be if the Aluminium bond pad is protected by good subsequent
         metallisation and chip passivation? Data sheets for most
         semiconductor assembly materials will give ppm of Chloride, etc
         with "good" values being below 10 or 20. Is there a direct
         comparison possible with fluxes?

         regards,  Jeremy Drake
         Design to Distribution ltd
         Stoke on Trent
         England