Electronics Forum | Thu Nov 01 17:40:52 EST 2001 | davef
Listen to Wolfgang. Your dull solder connection is a process indicator. Some 63Sn / Au solder connections look grainy, depending on how your process them and the materials involved. Gold dissolving in tin forms an intermetallic compound [AuSn4] th
Electronics Forum | Fri Jun 25 15:48:55 EDT 2004 | tcp
The potting definitely is a factor in fracturing the grainy joints, but does not seem to damage a "good" solder joint.
Electronics Forum | Tue Apr 10 11:39:29 EDT 2001 | brownsj
One of the reasons for a grainy joint is the cooling of the joint after reflow. Check your reflow profile, not just the preheating and reflow section but also the cooling zones. It works the same way as molten rock. If it cools slowly you get pumice
Electronics Forum | Thu Nov 21 01:40:11 EST 2002 | ruimsig
The cause of grainy joints is either too high reflow max 225�C, 90 seconds or the reflow temp was tp low
Electronics Forum | Tue Feb 07 16:45:32 EST 2006 | Mike
Can someone point out what sort of defects at the joint I can expect if solder is above liquidus for 3-4 minutes rather than the typical 1 - 1.5 minutes. Voids? Grainy joints? Poor wetting? Thanks
Electronics Forum | Tue Apr 10 10:41:23 EDT 2001 | GregH
What's wrong if my solder joint is grainy ? what will be the effect on its strength ? what process problem is causing that ? regards
Electronics Forum | Tue Nov 05 22:19:07 EST 2002 | Victor Salazar
I am seeing quite a bit of grainy solder joints. I am told this can be from being in a liquidus state for too long. Does anybody have any information on this defect?
Electronics Forum | Thu Apr 15 16:07:37 EDT 2004 | barry
Hi there all, we are having problems with 2 qfp devices. grainy poorly reflowed solder joints. One 100 pin .5mm pitch, and one 64 pin .5 mm pitch . Both of these devices have a thermo pad on the back of them (pad area soldered to back of device)which
Electronics Forum | Tue Apr 10 13:12:41 EDT 2001 | davef
You've told us nothing about your situation, process, boards, or anything!!! If you leave some boards with very fine solder connections on the shelf for a cuppla years, the grain will become coarse. What do you mean when you say "grainy"? What is
Electronics Forum | Fri Jun 25 16:18:26 EDT 2004 | waveroom
For what its worth. Even though you are potting the boards. If for whatever reason flux residue (OA) was left on the board prior to potting this flux could migrate and cause embrittlement problems with the solder joint. I would definately inspect for
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