Electronics Forum | Tue Jan 15 12:20:16 EST 2002 | cfraser
This sounds like it could possibly be a case of Black Pad. We have had a few issuses with this in the past as well. Who the PWB vendor? I also recommend searching the archives and doing some solder samples with nonpopulated boards
Electronics Forum | Tue Jan 15 09:42:40 EST 2002 | davef
Here's two choices. 1 Before accepting a lot of boards from your supplier: * Print some paste on a board * Reflow the paste * Inspect the quality of the solder connection * Make a decision on accpting the board based on that observation. 2 Have yo
Electronics Forum | Mon Jun 12 06:45:10 EDT 2000 | kim ji tae
Hi! Thanks all who upgrade these pages. I have some questions. Is there any answer? I do double-sided reflow solderig, with 0.4% AG solder cream. with AU finished pcb. First I do reflow solder bottom side where 0.5pitch TQFP locates. Second I do re
Electronics Forum | Fri Feb 01 11:58:28 EST 2002 | Romain
the PCB vendor is Multek in germany he made some measures about P content in Ni layer. What is the normal level of Phosporous and what is the upper limit ? thanks Romain
Electronics Forum | Wed Jul 28 17:34:27 EDT 2004 | Steve Stach
Hi Ralf, This discoloration may be re-oxidation. Fluxes are supposed to do three things (1) remove oxide, (2) promote wetting, and (3) protect surface from reoxidation. The solder paste possibly is not protecting from reoxidation. Best Regards, St
Electronics Forum | Wed Jan 16 20:06:09 EST 2002 | davef
No, not as such. Consider: * Using the IPC calculator [free at http://www.ipc.org]. It allows you to consider / assess the amount of solder when designing pads. * Reviewing IPC-7525 - Stencil Design Guidelines. It gives general aperture guidelines.
Electronics Forum | Mon Jun 12 22:00:51 EDT 2000 | Dave F
Could be. What are your profiles? 2) Au finish fail => Could be, but that the connections can be made with hand soldering makes this a low probability cause, assuming the activity of the flux used in hand soldering is not significantly different fr
Electronics Forum | Wed Jun 14 18:21:23 EDT 2000 | Robert Moore
It has been our experience that the problem you have discribed was not solder process related. We had two such instances in the past and both were component related. The first case involved a PLCC28 that failed test. Reflowing the solder seemed to co
Electronics Forum | Wed Jan 16 15:22:29 EST 2002 | Terry Burnette
In his book titled "Manufacturing Techniques for Surface Mount Assemblies" author R.J. Klein Wassink describes the relationship between solder land dimensions, component lead coplanarity, board warpage, solder volumes, and solder paste flux wetting b
Electronics Forum | Tue Dec 14 11:08:19 EST 1999 | John Thorup
I think you're on the right track Paul. You didn't mention what type of solder mask was used but I'll presume that it was LPI (liquid photo imagable). If development of the image is incomplete some mask can remain where it is unwanted. Sometimes im
