Electronics Forum | Mon Sep 17 03:59:52 EDT 2012 | stivais
Hi guys, We have an interesting case we haven't seen before (see the picture below) http://postimage.org/image/lu2f4ae55/ Solder balls form on unpopulated pads after reflow. 1. Reflow profile is fine. 2. Stencil thickness / paste volume is also f
Electronics Forum | Mon Sep 23 10:45:34 EDT 2019 | slthomas
I have seen similar things happen with over etching and bridging but frankly the most common mistake that gives us grief is a failure to use the component manufacturer's recommended land pattern and/or aperture designs. As opposed to generating a n
Electronics Forum | Tue Jun 27 11:16:33 EDT 2000 | Christopher Lampron
Hello Bill, Ioan's idea's are good. One more thing that you may want to consider is using a "Home Plate" aperture on your stencil for the aforementioned caps. The idea is to put a smaller amount of solder paste directly underneath the component. This
Electronics Forum | Thu Jul 16 09:22:18 EDT 1998 | Aaron Delfausse
My question is in regards to how exactly temperature and humidity affect the stencil printing process. If temperatures here at the plant in the summer are 70-73 degrees F. and relative humidity is 60-65%,to what extent will the results of the steci
Electronics Forum | Mon Aug 14 15:09:14 EDT 2017 | charliedci
In my experience, in a temperature/humidity controlled environment, 1 hour, no big deal. 4 hours still ok. Overnight your pushing the limits but will probably reflow without issues. Any longer, could be a problem. Again, a lot depend on type of past
Electronics Forum | Fri Feb 19 09:14:52 EST 1999 | Justin Medernach
| During inspection and test we find leads which do not get soldered. Some are because of insufficient paste, but with others everything looks right. This will only happen on 1 to 2 pins, and it is not isolated to a specific type of ic or location o
Electronics Forum | Mon Nov 19 20:10:49 EST 2001 | davef
We print glue with a thick stencil on one product. Although it works �correctly�, we don�t like it because the process flow is goofy. So on a high mix line, it ends-up being a burden. Also, there is no rocket science behind making the stencils for
Electronics Forum | Fri Jun 04 11:54:22 EDT 2021 | cbart
We do this quote often with our older Summit machine. there are a few ways to do this. all of these are assuming you have parts on the boards already and are working around them. 1- if you have a good tech that can add solder to the pads on the PCB a
Electronics Forum | Sat Jun 05 13:38:22 EDT 2021 | ppcbs
For Linear Tech LGA's we solder bump the LGA using a .30mm solder ball then reflow with a tacky flux. This will provide a void free solder joint and adds a little height to the solder joint in case you use a flux that you want to clean from under th
Electronics Forum | Wed Dec 13 19:40:38 EST 2000 | Jerry Wetzel, SME, EM/SME
Your profile must be precise, your stencil aperture sizes and shapes are very important, and the size of the pads on the boards should be very close to what the part manufacturer recommends. We had some trouble with hi-temp paste, and discovered tha
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