Greetings Technet.
 
I have an interesting problem that has developed since we converted to
our lead-free process.  We have been using an Electrovert Astrapak for
our wave solder operation for many years in our SnPb process.  A few
months ago, we converted the machine for SAC305 by installing new
titanium parts (solderpot, pumps, wave guides, etc) and loaded it up
with Alpha metals SAC305. We removed and cleaned up the transport
fingers in alcohol while the pot conversion was under way.  After
putting the machine back together our new lead-free process seemed
perfect -- except that now the SAC305 is sticking to the titanium
transport fingers- I mean really sticking to them.  The smooth wave
doesn't seem to affect the fingers as much as the chip wave- but after a
run of about 200 PCBs- the fingers are fouled with solder - to the point
that we have to stop and brush out the fingers with a rotary wire brush.

 
We never had this problem with leaded solder. We do not have an
automatic finger-cleaner installed on the machine (we never had this
problem before) and I cannot find one anywhere to retrofit.  But the
question still comes down to-- what is causing the solder to stick where
it did not stick before? 
 
We use a no -clean flux (Alpha EF2202 or Indium 1075, makes no
difference --the solder still sticks.) The fingers were not changed out
(only soaked and cleaned with alcohol) when the rest of the machine was
converted to lead-free.
 
Any insight into solving the problem would be greatly appreciated.   
 
Neil Maloney, Manufacturing Engineer
Contemporary Control Systems, inc
2431 Curtiss St Downers Grove, IL  60515
(630) 963-7070 x132
[log in to unmask]
http://www.ccontrols.com <http://www.ccontrols.com/> 
http://www.ctrlink.com <http://www.ctrlink.com/> 
 
 

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