Electronics Forum | Fri Apr 06 11:10:43 EDT 2012 | cadco
We are a PCB design house/CM and we have found that if you elongate the QFN pads to the outside of the part by .025 to .030 you then have the opportunity of doing touch-up manually with a soldering iron should there be a voiding issue. This would hav
Electronics Forum | Thu Jun 28 09:57:50 EDT 2012 | mosborne1
blow holes and via holes are almost always caused by moisture and in PTH they could be moisture and improper drilled holes. If you are seeing solder balls next to the parts than I would say you have a reflow profile problem. Are you using any kind of
Electronics Forum | Thu Jun 28 16:43:51 EDT 2012 | ssupertuba
Yes I have a KIC and have checked the profile often. I just changed the reel of the parts that are causing problems and it went away. Now what am I suppose to say? I have made an NCMR for the parts but I'm sure they would work in an environment of
Electronics Forum | Thu Oct 25 14:15:18 EDT 2012 | kkay
Yes it looks like I attached the wrong reflow profile and I'll get the new one in there. Our TAL should be between 60-90 sec over 217. I'm not sure the embrittlement would be an issue as we have seen this issue across at least 3 different board vendo
Electronics Forum | Mon Jan 19 05:02:07 EST 2015 | gertjannus
I've some troubles with LGAs components. i try to create void free results. so far i have no problems with dpacks, i think i do something wrong with the vacuum time. The padcoverage of my lga is very bad the vacuum creates solderballs under the compo
Electronics Forum | Wed Mar 04 13:06:45 EST 2015 | cyber_wolf
A full blown analysis could become very expensive. There are many test that can be performed. 3D acoustic microscopy, X-ray, Dye and pry,and I'm sure the list goes on. Typically, a micro-cross section report of the BGA solder joints will show you w
Electronics Forum | Fri Mar 27 13:08:14 EDT 2015 | ppcbs
We reflow solder balls to the LGA using a tacky paste flux. Then we install the LGA to the PCB using a tacky paste flux. This will result in zero voiding and is a preferred method of our Military and Space clients. Be sure to read your spec sheet
Electronics Forum | Wed Aug 09 11:59:19 EDT 2017 | dleeper
As you already know, it depends on the paste. There isn't really a rule of thumb, but less time exposed it better. The issue is the flux exposure to the air and ambient conditions. The flux can evaporate or absorb moisture from the air. If the paste
Electronics Forum | Wed Nov 21 06:07:20 EST 2018 | robl
Hi Prem, Voiding has lots of causes, but boiling off flux to quickly really doesn't help, so maybe a more gentle profile. Also you do not need to print a solid block of paste, you can print a window pain style pad to help the flux escape. Also, th
Electronics Forum | Mon Nov 26 13:40:40 EST 2018 | robl
Hi Prem, Yes, the flux in the Cobar paste helped with wetting and joint strength, as does reducing voids as there is more solder in the joint, as does cooling rate. Regarding peel test in KG, it depends on the pad size and volume of solder in the j
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