Electronics Forum | Wed Mar 21 16:32:03 EST 2001 | mparker
The root cause is dependant on the type of solder "splash", ball, whatever, that you are seeing post reflow. If it is smears, then cleaning the stencil underside is probably the answer. Are you using automatic wipers? How many print cycles between w
Electronics Forum | Wed Jul 14 19:15:59 EDT 1999 | JohnW
| Can plcc's be glue on the a board if not why? | Ron, The biggest problem you have with PLCC's is the hieght of the base of the component from the board, if you can get a glue dot high enough then yes you could do it. Probably the best method is d
Electronics Forum | Wed Dec 15 16:20:48 EST 2004 | darby
I read with interest in September Circuits Assembly magazine an article entitled "Reducing Variation Through 'Intelligent' Stencils. In this the authors propose that by REDUCING stencil thickness from 0.005" to 0.004", the paste deposit volume will I
Electronics Forum | Thu Dec 08 15:27:54 EST 2005 | Samir Nagaheenanajar
Yes, yes, I agree with American man, URL, on all his points about having to know the overall process 1st. I'm surprised he doesn't have his own free consulting website. Other things you can try are: * "Dog-bone" apertures... taper down the apertur
Electronics Forum | Thu May 24 08:55:25 EDT 2007 | ck_the_flip
Here's some quick things to look for: 1. Does your solder paste feel like concrete, does it roll-up into your squeegee blades, and stick to your stencil? If so, your problem is the solder paste. The mixture of powder and flux, or metal load is ou
Electronics Forum | Fri Feb 22 14:22:07 EST 2008 | stevek
Are you using nocleans, especially when you get to SMT? Years ago, I had OA wave flux get into vias that were plugged from the top under parts. It is really difficult to clean small, high aspect ratio vias. Cross sections showed that the copper in
Electronics Forum | Wed Jul 23 08:18:29 EDT 2008 | davef
Q1. Is this a standard process for plugging? A1. Not as such. We checked both IPC-6012 and IPC-SM-840. Neither comments on plugging. So, your fabrication notes rule the day. Q2. Is this okay for such thick PCB's or is it mandatory to use a special pl
Electronics Forum | Tue Dec 23 17:34:07 EST 2008 | davef
We hear you talking two main issues: 1 Solder paste release 2 Thoughts on using two passes of solder paste on the stencil 1 Solder paste release * Check your aperture & aspect ratios [Search the fine SMTnet Archives for more] * Do a better job with
Electronics Forum | Wed May 30 21:16:05 EDT 2001 | davef
MPM AP-27 preferred over MPM AP-20 The issue is release of paste from the stencil. A vertical lift printer kinda snaps the stencil away from the board to complete the print cycle. The inertia and the rheometric properties of the paste make it rele
Electronics Forum | Wed Jun 20 12:07:13 EDT 2001 | Steve
I would suggest getting a copy of IPC-SM-782A, Surface Mount Design and Land Pattern Standard, and IPC-7525 Stencil Design Guidelines. My experience is that reflow does not cause tombstoning very often. Pad and land design, paste volume, and placemen
