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Date: | Thu, 19 Sep 96 09:11:07 cst |
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Solder preferentially wicking up the leads rather than uniformly over
the lead foot and pad sometimes is an indication that the component is
reaching reflow temperature much earlier than the printed wiring
board. Try hooking up some small thermocouples on both the lead and
board pad to see if a change in the heating profile will remedy the
problem. A second possibility is that your baking operation is
oxidizing the board pads to the point the component lead is more
wettable than the board pad. Good Luck.
Dave Hillman
Rockwell Collins
[log in to unmask]
______________________________ Reply Separator _________________________________
Subject: ASSY:Solder Wicking,Fine Pitch Leads
Author: [log in to unmask] at ccmgw1
Date: 9/19/96 7:37 AM
We are seeing instances of solder wicking up our fine pitch leads and
causing minimal solder left in the joint to wet the board. What do most
companies do about solder wicking up fine pitch leads? What can be done to
minimize this phenomenon? Does anyone have suggestions that have been
successful for you?
Some background process info:
We profile at approximately 215-220 degrees c.
We are using RMA solder paste.
We are baking our boards (multilayer) prior to reflow soldering. They are
cool for the print cycle.
We are over 183 degrees c for approximately 70-80 seconds.
We are using a Vitronics 722 IR oven.
Any comments would be appreciated!!! Thanx!
----------------------------------
Jeffery L. Hempton Phone: (219) 429-7335 Fax: (219) 429-4688
Hughes Defense Communications Mail Stop: 25-31
1010 Production Road, Fort Wayne, IN 46808-4106
Email: [log in to unmask]
"The reason most people do not recognize opportunity is because it is
usually wearing a pair of bib overalls and disquised as hard work." -
-Thomas Edison
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