Electronics Forum | Thu Apr 03 09:27:04 EST 2003 | davef
First, welcome to SMTnet. On your question, are you talking about control charts? If so, here's some background on control charts http://deming.eng.clemson.edu/pub/tutorials/qctools/ccmain1.htm What are you plotting: * Independant variables? * De
Electronics Forum | Mon Apr 07 09:52:07 EDT 2003 | kmorris
I have just started an assembly which uses a 16 mil pitch QFP. We ran on Saturday, using a type 3 solder paste. (working Sat's really sucks) We really struggled with paste release after the stencil sat for 15 minutes without printing. Apertures clog
Electronics Forum | Mon Apr 07 12:21:02 EDT 2003 | davef
Russ is correct. A 5 thou thick stencil should give good release. Here's how you run through it: * You want at least 5 solder particles across the smallest aperture. So in your case, 8 thou wide, which equals to 0.20mm gives us 0.20/5=40 microns.
Electronics Forum | Mon Apr 07 14:03:27 EDT 2003 | ksfacinelli
We have a client we would like to have switch from leaded can components to surface mount versions. We currently are utilizing these on a number of designs but his concern is in the area of reliability of the solder interface. The caps generally ha
Electronics Forum | Mon Apr 07 16:42:49 EDT 2003 | jax
You will not see any reduction in quality. Some of the only reasons to hold off on converting to SMD packaging is Cost and availability. The cost normally runs about 30% more and the lead times are about 2 times as long for SMD. For that reason you w
Electronics Forum | Wed Apr 09 15:05:45 EDT 2003 | russ
Probably of no help but here it is anyway This is a tuff one. Attrition is due to many factors. You have machine rejects (visual fail, no pick), feeder set-up loss each time a reel is removed you lose X number of parts depending on feeder design (w
Electronics Forum | Wed Apr 09 11:23:02 EDT 2003 | davef
Nice pix. The pebbly texture that you're seeing is aptly called "orange peel". Temperature appears to significantly influence the appearance of solder spheres during soldering. Indeed, when the reflow temperature is high, tin continues smelting long
Electronics Forum | Wed Apr 09 13:30:20 EDT 2003 | davef
In order to get reliable reflow, you need to be at or higher than [liquidus + 20*C] for about 5 to 10 seconds. [I said 25* in a earlier post, but in an effort to stay on message, I'll stick with 20*] Don't forget that your liquidous is probably NOT
Electronics Forum | Thu Apr 10 19:21:02 EDT 2003 | tony_sauve
Kevin, One point that I'd like to make is that in order to get an accurate reading of the solder joint temp's you need to have the thermocouple right at the ball/PCB interface. I'd recommend precision drilling a mechanical sample of the unpopulated P
Electronics Forum | Wed Apr 09 05:55:05 EDT 2003 | Chrissie
We've encountered a little problem with BGA's. There was a process problem in the build of the boards which has ment the BGA are failing open circuit due to the lack of solder paste. Any-one else had this problem? Any suggestions on solutions? We've
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