Electronics Forum | Thu Mar 22 16:06:22 EST 2001 | dblsixes
Our next plan of attack is to dog-bone the solder aperature. By reducing the width of the solder paste at the heel, we hope to slow the flow up the leg of the pin while the temperature of the pad catches up. We have boards that were HASL ...
Electronics Forum | Fri Mar 23 18:55:30 EST 2001 | davef
Consider posting actual measurements of your pads, component leads, and apertures.
Electronics Forum | Wed Mar 21 20:40:28 EST 2001 | dblsixes
We are building a monster ... Dimensions are 10" x 7" ... 12 layers ... A Logic Assembly with a Power Supply all rolled into one ... The Power Supply is in one section of the board, the logic in the other section ... The Power Supply obviously has a
Electronics Forum | Thu Mar 22 21:53:49 EST 2001 | davef
Don't mess with the doggie stuff until you get longer pads [and then you won't have to mess with it] because you'll just ruin your lead definition with more paste and still not have the heel fillet you desire.
Electronics Forum | Thu Mar 22 21:59:55 EST 2001 | dblsixes
ah ... but we had insufficient heel fillets in the old design toom when we had more pad area ... just not as bad
Electronics Forum | Sat Mar 24 16:34:06 EST 2001 | Stefan
Can you increase the placement force on your P&P machine? It should squeeze the solder paste to all sides including the heel.
Electronics Forum | Mon Mar 26 11:20:39 EST 2001 | dblsixes
The pads are 0.070 x 0.012 ... as spec'ed, and as measured. The pad extends approximately 0.017 behind where the Class 3 fillet is required to be. (It used to be 0.037 on an older design that exhibited similar, but not as bad of heel fillets.)
Electronics Forum | Thu Mar 22 08:07:41 EST 2001 | CAL
Selective Laser Soldering? Beamworks and Speedline Electrovert Both demo'd units at APEX. I am partial to the Beamwork machine cause it was able to do BGAs. Are the QFPs acceptable? You mention cleaning the pads, Stencil aperture enlargement could t
Electronics Forum | Thu Mar 22 08:54:06 EST 2001 | dblsixes
I'm not familiar with Laser Soldering. I don't believe it to be a problem with the QFP themselves, since the two plastic parts are from different vendors in the same package. We also are having similar problems with other plastic parts on other boa
Electronics Forum | Thu Mar 22 16:02:37 EST 2001 | dblsixes
In the end, we may have to go to our customer to see if we can get Class 3 relief ... We actually did an experiment by adding a ceramic cap to the top of the part, using a thermal paste to improve the thermal connection. It didn't do much for us ..
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