You could try buying some composite material (pallet and fixture materials)
and having replacement fingers machined for you..expensive solution but it
would work...

Kevin Glidden
Manufacturing Engineer
Luminescent Systems Inc.


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Neil Maloney
Sent: Thursday, August 03, 2006 5:05 PM
To: [log in to unmask]
Subject: [TN] SAC 305 solder on TI wave solder machine transport fingers

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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