To Ioan The thermal mass of the lead is much hotter than the point SMT pad and the profile is allowing enough time for solder to wick up the lead. You don't list the type of reflow oven and whether your soldering with or without nitrogen.
Some ovens allow you to set the convection fan speeds as well as the top and bottom IR temperatures.
Then there are the maintenance issue especially on ovens prior to flux management systems where a working profile months ago is no longer then same. Everything from clean top heaters, exposed thermocouples to holes in the flex line of the bonnet will cause major changes of the actual profile. We keep a thermocoupled profile board in our large library of profile boards to retest against the original profile.
Since SAC has less wetting than a eutectic solder unless the profile is too hot for the part, due to the needed heat for other parts.
The wetting away from the solder pad is more typical on device with long leads when using a eutectic solder.
Once the PM condition of the oven is known and acceptable, you will need to perform a DOE of the ovens parameters and select the temperatures and conveyor speed, and convection fan speed with nitrogen on or off to optimize the profile unique to this board.
----- Original Message -----
From: "Ioan Tempea" <[log in to unmask]>
To: [log in to unmask]
Sent: Wednesday, October 6, 2010 4:06:17 PM
Subject: [TN] Solder wicking up on the leads of Kyocera connector
Dear Technos,
Having this connector, http://www.kyocera-elco.com/prdct/pdf/6281.pdf <http://www.kyocera-elco.com/prdct/pdf/6281.pdf> and for a while we have been fighting with insufficient solder. After a closer look I realized that solder goes really high on the leads, probably through capillary action, and away from the joints. Please see this gallery http://ipc-technet.groupsite.com/gallery/15945
Are you familiar with this component/phenomenon and how can I fix it?
Needless to say, the board has many fine features, so the stencil is 5 mil e-formed and I simply cannot add more thickness. On top of it, I have 44 of these babies on one board, 81 pins each.
Thanks,
Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
T | 450.967.7100 ext.244
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