Electronics Forum | Tue May 22 06:28:50 EDT 2007 | aj
Hi All, I ran a prototype last week with one of the above mentioned connectors on board. During Inspection post reflow we noticed a solder ball had formed at the top of each leg. We used a 5thou stencil with 10% reduction on the width but it seems
Electronics Forum | Mon May 28 03:36:46 EDT 2007 | aj
Hi All, We have a QFP device that is struggling to achieve acceptable solder joints. I have noticed one or two of the components shifting during reflow. I can adjust the Blowers but I dont have any issues on other boards. This seems to be a straigh
Electronics Forum | Mon May 28 07:50:08 EDT 2007 | pavel_murtishev
Good afternoon, Have you checked placement accuracy? Is it installed without shift prior to reflow? Are you sure it shifts in the oven? I believe tension cannot cause QFP shift since QFP has quite low self centering ability. Such kinds of shifts are
Electronics Forum | Fri Jun 15 11:34:49 EDT 2007 | cman
What is the board finish? Did you profile built assy and get the temps on the board with a t/c in the board? DId you drill the BGA and get the t/c at the ball? When the parts came off the board did all of hte solder come off the pads and stay with th
Electronics Forum | Sat Jun 16 02:44:21 EDT 2007 | gsala
Hi Grant, it seams your PCBs are ENIG (Gold)finished, correct? If yes, did you considered the quality of PCB, for istance are you sure are there any black pad evidence on BGA pads? When BGA drops away like that, one of the potential cause can be a
Electronics Forum | Sat Jun 16 07:48:09 EDT 2007 | grantp
Hi, We are using emerson gold, and I have not seen any evidence of black pad, as the pads are clean and gold colored when the part comes off. That is what worried me, as I would have thought that if the solder melted correctly, it would have stuck t
Electronics Forum | Mon Jun 18 10:20:14 EDT 2007 | ck_the_flip
Grant, i have heard of a few cases where the PCB is "reworked" by the PCB house, where the immersion silver that did not wet to the base copper was reworked by just putting immersion silver on top of the non-wetted immersion silver. I know your PCB
Electronics Forum | Mon Jun 25 19:53:57 EDT 2007 | vlazern
Our Hellers exhaust has a range from 500 to 600 CFM, depending on model. I am aware that the profile will need adjustment due after reducing the exhaust air velocity, but i'm not getting a reply from Heller for power consumption specification. I will
Electronics Forum | Thu Jul 05 15:13:46 EDT 2007 | joeherz
We've seen non-functional QFNs cured by touching up the toe fillets. Especially with parts that are not plated on the edge/face where you get minimal/no wetting due to oxidation of bare copper. I'm not suggesting that you touch everything up but th
Electronics Forum | Thu Jul 05 17:10:29 EDT 2007 | arun2382
Thanks all! I'm facing this issue with one specific batch of QFNs. It could be a plating issue. But, nothing was evident from visual inspection,No sign of voiding or non-wetting. Cross-section images of solder joints were clean as well. Could this s
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