Electronics Forum | Fri Jan 14 12:59:07 EST 2005 | Dan Mendoza
I have used the rectangle shapes and round shapes with no noticible difference. The idea is to design the pads to accept the same solder volume per component. Components over two size pads will favor the higher solder volume side during reflow.
Electronics Forum | Mon Sep 21 21:21:32 EDT 1998 | Steve Gregory
| am working on the design of a showboard to demonstrate our | assembly capabilities. we are working with double sided assemblies involving BGAs and CSPs. could someone suggest | types of BGAs/ CSPs (type, name, I/O, etc)that would be a challenge t
Electronics Forum | Fri May 26 05:54:40 EDT 2000 | Sal
For the past year now we have been printing adhesive with no real problems. Our printing ranges from 0603's to SOIC using a variation of aperture sizes and metal thickness foils. The crucial parameters are : aperture sizes : These obviously depend o
Electronics Forum | Fri Apr 21 18:43:23 EDT 2006 | SD
Sorry, I have not read the article. However, I do have five years experience constantly tweaking an AOI system that ran ONE product! The strength of the machine was solder inspection. The biggest problem was component color variation and shadowing
Electronics Forum | Thu Jun 24 09:24:03 EDT 2004 | Rob
The smallest component we use is 0402. Solder paste is Kester 256. Printer is MPM Ultraprint 2000. Stencil is 6 mil. I didn't here anything bad (rework or whatnots) in terms of soldering of those components.
Electronics Forum | Thu Jun 24 16:14:04 EDT 2004 | buki
I used an old camalot 1818 with solder paste dispener system to do 0402 components on LTCC. It worked very well, but there are tricks that you have to learn. Volume and placement of the dots is critical. I am sure the latest dispense equipment have s
Electronics Forum | Wed Jul 22 11:27:25 EDT 1998 | Russ Miculich
I agree with the response and strongly recommend that you use the "home plate" design to reduce solder ball entrapment, and that the under cut for the 0402's in particular be 80% of the pad size. Solder slump is typically about 1.2 to 1 so spread wi
Electronics Forum | Tue Jan 12 10:18:36 EST 1999 | Russ Steiner
| Any idea what the "industry standard" is for fall out on assembled PCB's? I realize that the controls put in place in your processes will effect your overall quality. But I'm trying for a general answer. On pre-tested assemblies, should you exp
Electronics Forum | Thu Nov 02 03:42:49 EST 2000 | CHRIS MAY
Tombstoning primarily occurs due to the fact that the paste may melt and wet the metallized face of the chip earlier or better at one end than the other. This could be due to a difference in heat capacity (thermal shadowing ?) or that one end of your
Electronics Forum | Mon Nov 06 10:29:28 EST 2000 | Dean Stadem
All of the replies have merit. Here is another one. Because the cause of the tombstoning is wetting forces that are imbalanced, and one end wets faster or more readily than the other, the 0402 lifts up on that end easily because of its low mass. Incr
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