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 | Fri Apr 23 12:47:29 EDT 2004 | barry
I have increased my peak to 220, and Flow is better, but it still not quite a good fillet all around. The solder tends to kinda "bunchup" at the toe of the lead. If part is Pb free, would this affect adhesion and or flow?
Electronics Forum | Fri Apr 16 08:49:07 EDT 2004 | Chris Lampron
Hi Barry, Your best course of action is to perform a thermal profile and determine exactly what the times/temps are in these locations. Try to match your profile to the recommendations of your solder paste. (Time between 130-160, Time over 183 and m
Electronics Forum | Thu Apr 22 12:27:47 EDT 2004 | barry
I placed thermo's at 2 of the problem devices. Soak (time 150 to 180) 100 sec. Time above 180 =80 secs with 208 deg. peak. The solder appeared to flow at these pads, but little to no adhesion to the joint.Total time in oven was 5 min. All other joint
Electronics Forum | Fri Apr 23 13:31:20 EDT 2004 | russ
The toes of leaded devices are problematic in fillet formation. A lot of the time they have the copper from the lead exposed so it becomes oxidized and won't readily take solder. Normally this is of no concern if the heel and side fillets are forme
Electronics Forum | Sat Apr 17 17:08:22 EDT 2004 | finepitch
Russ has a hint by saying "too long of a soak at too high of a temp or being in reflow for too long/hot". I think the board should stay in the oven for 3-4 minutes, spending 60-90 seconds of which during reflow. in order to stay in the oven for 3 m
Electronics Forum | Tue Apr 11 10:30:46 EDT 2000 | Jeremy Smith
I am having a problem with some joints on a 100 pin pqfp and few different soics on one particular board. When viewed a 8x with a "Mantis" inspection scope the joints look as though they wetted to the ic leg but when probed the leg will pop loose.
Electronics Forum | Fri Aug 13 12:52:17 EDT 1999 | Steve Schrader
| Hello | | Having a problem with bridging on 20mil pitch qfp, only on the lead groups where squeegee goes over width of apertures. Using MPM sp-200 semi-auto, chem-etch stencil, 9-10mil width opening | 100 durometer blade. Getting "tails" on deposi
Electronics Forum | Thu Aug 12 22:38:44 EDT 1999 | Dave F
| Hello | | Having a problem with bridging on 20mil pitch qfp, only on the lead groups where squeegee goes over width of apertures. Using MPM sp-200 semi-auto, chem-etch stencil, 9-10mil width opening | 100 durometer blade. Getting "tails" on deposi
Electronics Forum | Fri Aug 13 13:50:53 EDT 1999 | Brian Wycoff
| | | | | | Hello | | | | | | | | | | | | Having a problem with bridging on 20mil pitch qfp, only on the lead groups where squeegee goes over width of apertures. Using MPM sp-200 semi-auto, chem-etch stencil, 9-10mil width opening | | | | | | 100 du
