Electronics Forum | Wed Aug 27 13:50:57 EDT 2014 | mcapizzi
The superior machines typically use only a split vision system which allows two pictures to be viewed simultaneously. The PCB (pads) and the underside (balls) of the BGA can be observed. By using micrometer screws, both exposures can be adjusted exac
Electronics Forum | Mon Feb 09 06:56:39 EST 2015 | saoasasd
What is the maximum PCB shelf life for double side PCBs after first reflow? I mean, after assembly bottom side, how long can I keep the PCB without solder paste waiting for the second reflow? (Considering exposure on production environment conditions
Electronics Forum | Mon Feb 09 09:45:16 EST 2015 | saoasasd
Thanks for the support Jax. Our current scenario: Baking - Not allowed for PCBs Washing - Not allowed Heat Cycles - 2 (Bottom and top side). It's a notebook board Our concern is related to solderability because OSP finishing will be seriously imp
Electronics Forum | Thu Jan 19 11:10:13 EST 2017 | rgduval
I'd start by checking the manufacturers documentation, and seeing if they have any application notes regarding reflow recommendations for the part. But, in general, make sure to bake the parts prior to assembly, they are notoriously moisture-sensiti
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 May 05 23:26:29 EDT 1999 | Dean
| OK, my manager read an article on printing glue (aaargghh!)and wants to know why we aren't doing it. We currently use Fuji GLs and GDMs to dispense glue. I've never done it, but have seen it done at NEPCON and other shows. It looks OK, BUT what
Electronics Forum | Wed May 15 13:11:26 EDT 2002 | fmonette
Hi Dason, Yes I was talking about the same paper. This is the best technical information available to clearly explain the physics of moisture diffusion inside a plastic package. Many of the guidelines contained in the current J-STD-033 are derived
Electronics Forum | Wed Aug 24 10:07:56 EDT 2005 | stepheniii
I think where the fuzzy thinking starts is by calling the recipe's; profiles. Or maybe I"m being too fussy. Idealy you want every solder joint to have the same thermal "profile" (not recipe). That is the temperature over time is best if identical fo
Electronics Forum | Tue Jan 23 09:03:00 EST 2001 | fmonette
This guideline is actually in the IPC/JEDEC standard J-STD-033, May 1999 (although it is not spelled out very clearly, thus the current confusion in the industry). The technical reason is that moisture diffusion is a very slow process. Once parts ha
Electronics Forum | Fri May 09 09:09:22 EDT 2003 | fmonette
Phil, here is why "dry cabinet storage may not stop the clock" : The moisture diffusion inside a component is actually quite complex. When previously exposed components are returned to dry storage, the moisture gradient that is already absorbed in
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