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 | Thu Nov 07 10:59:11 EST 2002 | pjc
IPC-7525 "Stencil Design Guidelines" is a good reference document to have. Here are notes from a Tessera, (a major mBGA mfg.), study- "Application Note Solder Stencil Requirement for mBGA" The stencil aperture is to be square, equal in size to the l
Electronics Forum | Thu Nov 07 09:23:05 EST 2002 | russ
What would the considerations be in utilizing a type 4 paste as opposed to type 3? We have an assembly that has a large amount of uBGAs (12 mil diam pad)along with 50 mil pitch BGAs assorted fine pitch etc... We are experiencing difficulty in paste
Electronics Forum | Fri Jul 08 09:14:49 EDT 2005 | Jason Fullerton
I've tested boards with SN100C HAL finish, and wetting to the PCB finish was poor at best, using a no clean SAC305 paste.
Electronics Forum | Fri Aug 17 12:03:46 EDT 2001 | davef
We knew they�d make you use those boards, didn�t we? Your boss could be correct, but then again, you might get away with baking. Entek coating thickness is often poorly controlled by fabricators. But if sample boards that you ran are OK, why not g
Electronics Forum | Fri Jan 28 12:29:01 EST 2005 | Bob R.
We use the exact same method Chunks outlined for evaluating just about anything we're going to roll out worldwide, whether it's a material or a machine. List your factors (print speed, solder spread, etc), assign each a weight, evaluate each paste a
Electronics Forum | Thu Oct 08 22:32:58 EDT 1998 | Dave F
| | | | I am trying to find out, what possibilities I have, to print solder paste on a board, when the task is to have 120 Microns thickness for the biggest part of the board (85% of the real estate), and then have 250 Microns of thickness on the re
Electronics Forum | Thu Oct 08 03:27:00 EDT 1998 | Thomas Blesinger
| | | I am trying to find out, what possibilities I have, to print solder paste on a board, when the task is to have 120 Microns thickness for the biggest part of the board (85% of the real estate), and then have 250 Microns of thickness on the rema
Electronics Forum | Tue Mar 21 08:22:11 EST 2006 | jdengler
If you usually get good release on other products with your paste, I would try a different batch of paste. The batch you are using may have a problem that contributes to the beading. Jerry
