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 | Tue Dec 14 10:36:42 EST 1999 | Paul Peterson
I recently encountered reflow soldering defects on a pair diode package, the smd pad had a green contamination, I'm convinced that this is not oxidation. The no-solder condition appears to be caused by a sloppy soldermask process, although over the y
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
Electronics Forum | Fri Sep 29 13:51:46 EDT 2000 | C. Ortner
We work in a "low" volume high reliability house building mixed tech double sided multi layer CCA's for long lived space applications. Our present problem is inspection questioning every dimple/anomaly on every leadless part(we put passives only thr
Electronics Forum | Wed Jun 14 08:08:56 EDT 2000 | Wolfgang Busko
Hi ji tae, we had a similar problem with QFPs 0,5 pitch processed by one subcontractor. The symptoms we noticed were: - the solderjointshape and wetting looked normal - the surface had a dull gray appearance - by pushing a lead sideways with a tweez
Electronics Forum | Tue Dec 14 11:08:59 EST 1999 | Wolfgang Busko
Hi Paul, you got to find the reason first before any measures can be taken. You have to determine wether it happend somehow at your site or at the boardhouse, you can�t blame them without reason. As long as it is suspected that more of those panels
Electronics Forum | Tue Dec 14 11:13:43 EST 1999 | Chris May
Paul, I have (as many have) come across this problem due to misregistration of resist at the PCB fab. You didn't say if these boards are inexpensive double sided or costly multis. I know this shouldn't make a difference on quality but I would tend t
.gif)
