Electronics Forum | Mon Jul 07 13:33:40 EDT 2008 | realchunks
Most QFP 128s have a 0.16mm wide lead. Might have to modify your pads if you'r buying some odd ball part. But generally 0.2mm should be OK for this part. You may never get good toe wetting. Most QFPs are cut apart after plating, thus the toes are
Electronics Forum | Wed Jul 09 10:15:57 EDT 2008 | aj
I have carried out some further measurements on the device and the results are as follow: Component Lead width measures 183 microns. Actuals PAD width measures 158 microns. What I am thinking is that the lead is attracting the solder hence prevent
Electronics Forum | Tue Jul 08 15:37:14 EDT 2008 | realchunks
Volume that appears to be caused by wetting. Now remember most solder pastes will not "flow" across an entire pad. It will only flow where it is printed. In your pic, if the pad was covered and came out like this - it may be your pad. If it was
Electronics Forum | Tue Aug 12 07:35:23 EDT 2008 | stevezeva
Hi, Is the footprint per the component manufacturers recommendations? The reason I ask is because it kinda looks like the pads are extending beneath the component. Could cause the part to float up on top of the solder and not allow the leads to wet
Electronics Forum | Fri Sep 26 07:26:33 EDT 2008 | realchunks
Looks like lack of wetting. What is the BGA ball material? Could be high temp. Could be improper profile. Could be paste sat on board too long / flux dryout. Could be co-plane mount and this ball touched at the end of reflow curve. Could be cont
Electronics Forum | Thu Mar 05 17:49:57 EST 2009 | snsmt
i have been looking for masking tape as well. I just came across esdtapes.com and got a sample of one of there tapes "CM300." I tested a component by taping it completely off and submerging it in water, just to see if it will soak through. The resu
Electronics Forum | Thu Apr 16 10:08:56 EDT 2009 | waveroom
Sorry for the delay. We are actually pretty busy over here. We have found the Aim 257-2 no-clean sac305 paste offers very little if any voiding and better wetting in lead free terminated devices. My suggestion is contact your local Aim distributor fo
Electronics Forum | Thu Jun 04 14:35:11 EDT 2009 | floydf
We wound up using a ramp to spike profile with 50 sec. between 150C and 217C and 90 sec. above 217C. The idea being the flux is still active when it hits reflow, and it stays in reflow long enough for the weird alloy in the parts lead to wet. All par
Electronics Forum | Thu Jul 30 13:52:34 EDT 2009 | davef
Thoughts are: * 215-220 temperature at the leads is not real hot for leaded assembly. * It's peculiar for component leads to dewet. Sometimes non-wetting occurs along the edge of the lead where the lead is not plated. * How do the leads of a removed
Electronics Forum | Tue Sep 22 08:35:47 EDT 2009 | cman
Did you try pre-tinning your board on this suspect pad/s to see if it improved wetting/solderability prior to printing/SMT placement and reflow? Does the pad/s not soldering tie to a ground layer? I would connect a T/C to each pad of the same part an
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