Electronics Forum | Wed Mar 04 15:26:07 EST 2009 | clampron
Hi Jorge, Take a bare board and measure over the same pad. We have had similar issues with a higher deposition than the stencil thickness. In some cases, we have found that the top of the pad was higher than the solder mask. Our inspector uses the b
Electronics Forum | Mon Jan 04 21:03:22 EST 2010 | cman
1) I'm not familiar with the acronym CAF. Could you spell that one out for me? 2)Why do you feel they need to be baked? Are they in a high humidity enviornment? the only time we bake is when we are dealing with moisture sensitive components. Do you b
Electronics Forum | Sat Feb 27 01:16:16 EST 2010 | jmelson
I had a batch of Xilinx chips that I believe had microscopic hairs of the lead frame left as slivers on the leads. These maybe got encapsulated by the solder plating, and then were free to move when the chips were reflowed. You could see the tiny h
Electronics Forum | Fri Jun 11 03:14:03 EDT 2010 | muarty
Thanks Dax, We currently employ a stencil aperture design pretty much similar to that you describe. And you are correct in what you say about the thermal demands almost dictating the allowable voiding level. We have suggested to our customer that th
Electronics Forum | Wed Dec 08 09:53:23 EST 2010 | fönsi
Hello Because of the cold weather, we had some troubles with drying out of printed solder paste on the pcb's. The relative humidity in the air declined below of 20%. We have a process window of store the printed board for maximum 24 hours, but with
Electronics Forum | Mon Jul 23 05:40:58 EDT 2012 | franks
We are having a problem with a 601 pin BGA in that the corners of the BGA are lifting and taking the pads with them. Faults are not always seen straight away so we are not sure at which point the fault is happening. So far it looks as though flexing
Electronics Forum | Tue Sep 25 11:50:37 EDT 2012 | davef
Ken ... I resized your picture so that it fits on the page better. Continuing with your outgassing through the solder pads theory, how thick is the copper on the pads? I don't expect to see outgassing through pad that are a thou or more in thickness
Electronics Forum | Mon Apr 01 17:20:45 EDT 2013 | davef
In thinking about troubleshooting tombstoning {TS} defects, seek balance: * Pads the same size * Same amount of paste on each pad * Component placed with the same amount of contact on each pad * Heating the same on each pad, no via connection to a gr
Electronics Forum | Tue May 21 15:37:36 EDT 2013 | armelinda
I am looking for a service providing non contact PCB flatness measurement for open board SiP assembly. It was returned for failure analysis with complaint that assembly does not solder properly onto customer system board. Since there are remnants o
Electronics Forum | Thu Nov 07 15:33:02 EST 2013 | mleber
Below are a few photos of an ongoing issue we are having with 1 pwb style. Some of the pads appear to have contamination that appears after the selective solder step. The joints are extremely hard to rework - almost impossible. We had the joints anal
