Electronics Forum | Sat Mar 24 00:50:24 EST 2001 | PeteC
Fresh paste from a factory sealed container. Should paste be scrapped out altogether if left on the stencil for too long (length-of-time?)? Our paste is Multicore CR39. Multicore reccomended the print chamber be around 22C @ 50%-60% RH. Our plant is
Electronics Forum | Fri Apr 13 14:08:53 EDT 2001 | CAL
Proper setup and cleaning of stencil helps ensure repeatable printing performance. Cleaning processes need to be compatible with materials used in the manufacturing of stencils and solder paste. IPC 7525 should also help you out. We here would Inspe
Electronics Forum | Thu Nov 21 07:57:37 EST 2002 | gramsey
The information you are seeking is found in IPC-7525. Section 3.3 describes an equation for calulating the solder paste volume required to produce a desireable fillet. I simplified it a bit. V=1/s[Tb(Ah-Ap) + Ft + Vp] - Vh V is the volue of paste
Electronics Forum | Mon Oct 25 21:19:06 EDT 2004 | davef
Q1: I thought we have a industry standard for this. A1: We're unaware of such a standard. IPC-7525 - Stencil Design Guidelines has a brief section on stencil inspection. We've talked about it previously on SMTnet. If you can't find it in the Archiv
Electronics Forum | Wed Dec 14 08:21:25 EST 2005 | tk380514
good points but to answer your questions... Although i am aware of most of those potentail problems we havent had most of them, fingers crossed. Unfortunately we have 2 sub-contractors doing the PCB palnning and design which mean i have to solve ther
Electronics Forum | Fri Mar 23 09:28:46 EST 2001 | PeteC
Well, it's hard to say what it started out as, a smear, splash or ball cause the solder formation on the finger after reflow is spread out ya know. I looked at an archive for possible causes and one was printer operators with paste on their fingers.
Electronics Forum | Mon May 21 17:34:22 EDT 2001 | davef
Continuing the line of Michael's, the previous poster, comments ... The more Krispy Kremes, the better. Yeth!!! The more beer, the better. Yeth!!! The more epoxy, the better. Uh, I don think so!!! We look at this from a papa bear, mama bear, bab
Electronics Forum | Mon Oct 15 10:51:49 EDT 2001 | davef
On over printing, the general issues are: * Paste deposits being so large that when reflowing, collapse onto many, rather than a single solder mass. * Paste expanding during heating and being close to other solder deposits and bridging [as you say].
Electronics Forum | Wed Nov 07 11:56:44 EST 2001 | mparker
Pad spacing is just one element to consider. Your pad spacing is determined by the pitch (center to center distance between the leads). There are several good resources to find the appropriate pitch per device. Search the archives here or refer to th
Electronics Forum | Thu Apr 11 14:31:15 EDT 2002 | aaelect
We're having some problems with 0402's tombstoning. On a board with about 300 parts we're getting about 12 to 20 tombstones per board. The caps seem to do it more often than the res. The pads appear to be in accordance with IPC SM 782 amendment 1, S