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 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 ..
Electronics Forum | Mon Mar 26 20:55:16 EST 2001 | davef
Two things: 1 IPC pad calculator is an excellent resource for you and your board layout staff. Consider that working together with the calculator may allow you both an opportunity to balance your interests. 2 It's unlikely that the ceramic parts h
Electronics Forum | Tue Mar 27 02:57:32 EST 2001 | Ken S.
Have you a reflow oven that has upper and lower heaters? Have you a reflow oven that uses hot air as well as elements to control the transfer of heat to various areas? If yes to these, I would suggest increased air flow or change in direction of
Electronics Forum | Thu Mar 22 21:10:42 EST 2001 | dblsixes
Ah ha! ... You hit upon something that I discovered earlier today ... As I said in an earlier post, I was going to experiment with dog-boning the solder paste ... But upon further review, I discovered that our customer removed 75% of the pad behind t
Electronics Forum | Tue Mar 27 09:06:10 EST 2001 | dblsixes
We have tried to adjust the upper and lower heaters. We have a dillema in this area however. The power supply portion of the assembly has thermal vias in the solder pads underneath larger pads. We have a problem with solder wicking through these h
Electronics Forum | Thu Mar 22 17:31:08 EST 2001 | davef
Hold off on the sharp knife for little bit. [Yano, I get "queasy" when I see much of my blood, but other people�s blood doesn�t bother me much. Weird, eh?] [Oh bye-da-bye, I didn�t win the bar bet on "Ground Hog Day". I didn�t loose it either. T
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
