Electronics Forum | Wed Nov 07 11:27:28 EST 2007 | patrickbruneel
Grant, Thanks for sharing that experience with us; this comes to show what damage can be done when politicians make laws based on rumors instead of facts. New laws as drastic as removing lead in soft soldering should have been based on scientific e
Electronics Forum | Fri Nov 09 12:42:08 EST 2007 | wayne123
Smt paste= SAC305 Wave Solder= SN100C no real problems with either of these. good luck
Electronics Forum | Thu Nov 08 10:05:04 EST 2007 | pjc
I have not seen hold size as an issue when switching Sn/Pb to Pb Free wave soldering. Trying increasing your dwell time in the wave- typical for Sn/Pb is 2 to 3 seconds. Try 5 seconds to see what you get.
Electronics Forum | Thu Nov 08 07:33:23 EST 2007 | hussman
Why? Just use IPC on finished solder joints as your guide. I've seen groups of people puts hundreds of hours into this task and then tell me a 3 mil stencil is all I need. After reflow, none of the solder joints meet IPC Class 1 and a lot of tombs
Electronics Forum | Thu Nov 08 08:56:51 EST 2007 | hussman
Sorry Matt, Just hate when people use this site as their engineering bed. I believe you can weigh your board before and after reflow. It would have to be a sensitive scale though. From there you can calculate weight to volume ratios.
Electronics Forum | Thu Nov 08 10:14:43 EST 2007 | slthomas
"Their third attempt was a report that Process Engineering was being resistive and skewing the tests." Thanks for the early a.m. laugh. I needed it.
Electronics Forum | Thu Nov 08 13:00:33 EST 2007 | russ
Just how accurate do you need to be Matt? you seem to already know the answer, calculate the volume deposit from stencil aperture and divide x 2? that will get you very close wouldn't it? Russ
Electronics Forum | Sat Nov 10 23:10:13 EST 2007 | mika
Hi Real Chunks, Nice to meet you. Well, I certainly not agree with you. Sorry. Can You be a little more specific about your claims, about my statements? Do you know what you are talking about? I wish no polemic about this. Best Regards, Mika
Electronics Forum | Fri Nov 16 18:08:32 EST 2007 | mika
So you are saying that 0.13 mm stencil thichknes and 20% reduction of the middle cooling pad is working for you? Just as I said.. Best Regards, Mika Ps. Keep in mind that the QFN is designed to do some heavy work, while enough "heat transfer" occur.
Electronics Forum | Mon Jul 07 17:25:04 EDT 2008 | thughes
I'm curious to know what the pitch of the outer pads is/was on your device. Also, is this a general formula you use on all of your QFN devices or was this for one specific device?
