Hi again,
Thanks for all the input as it has now directed me towards fluxes (and
control thereof) and ICT.
Leading from one of the members advice of low residue flux I stumbled across
this Kester comment:
'Flux selection does have some play as to the occurrence of solder balls. A
rule of thumb is that the lower the solids content of the flux is the more
solder balls will be noted when all other parameters are held constant. This
is sort of a dilemma for us as a flux manufacturer in that if we increase
the solids content, we will more than likely have an adverse impact on probe
testing of final soldered assemblies. The aesthetics of the final soldered
assembly will also be affected as you can imagine.'  This was posted in 1993
so any idea on what has since transpired and is this statement still valid
wrt the solids content?
Geez, my research thusfar has brought an array of variables to this party
such as test pin profiles and type, gold plating vs gold alloy, pin base
material hardness, spring force etc. on the ICT aside. Nevertheless it is
now beginning to get interesting.
As a comment, I hope my research drives me away from introducing another
process i.e. cleaning of assemblies hence and control of flux effluent (we
are coincidentally reviewing ISO14000) etc. and rather focus on improving
the existing process i.e. flux residue reduction (without cleaning) and ICT
issues.
Thanks again to all,
Grant

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