Can you provide mechanical drawings with tolerances for the heights of the heat generating ICs? The tolerance for the mating height between the boards is important as well. I need the overall height tolerance for any heat generating component with respect the mounting surface on the baseboard when the two are mated together.
Thanks for the request, our mechanical engineer will work on that drawing, we’ll post it here in a few days.
Here you go
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That is most of the information I need I am only missing two critical tolerances regarding the relationship between the two boards. I just need the tolerances on these two dimensions in order to do a complete tolerance stack up. Can you provide the dimensions for the dimensions I labeled A and B below?
I don’t have the tolerances, but the dimension you labeled as A is nominally 3mm, not 2mm. The solid model of the bare board is (or in the past, was) off from the delivered hardware on thickness.
Is this a permanent change? This dimension was pulled from the CAD model downloaded a couple of months ago can you check that the CAD model currently posted on GrabCAD is correct? It just so happens that I am currently mounting the baseboard from the face closest to the module otherwise this could have caused some significant issues. Are there any other inaccuracies in the CAD that I should be aware of? We were planning on ordering hardware on Monday.
I think the CAD we have was from GrabCAD, but downloaded a couple years ago (probably BB-UD1-A-1). The physical boards of BB-UDI-A-1 and BB-UD1-C-1 are both 3mm (at least the samples I have in front of me at the moment). The shape, hole size and location, connector locations are all accurate, but we light-weight the models by stripping off a lot of the other components, so I can’t address those.
I’ve been taking some measurements and it looks like the thickness of the module board is closer to 2mm but the CAD and the drawing you sent earlier has it as 1.6mm.
Do you have the correct CAD files that you can send me or should I just correct the files that I have manually?
The file I have is stripped down and then saved as a single .sldprt file (SolidWorks), so you probably could easily modify what you have. To update, the process (in SolidWorks) was a “Move Face” on the body (or part file) to thicken the PCB, then a “Body-Move/Copy” to shift the SFP cage (and any other components on that side) appropriately. The second step shouldn’t be required if you still have it as an assembly.
Can you confirm the board thickness for BB-UBS-B-1. Is 2mm the correct board thickness?
I measure from 1.99-2.05mm around the perimeter of the BB-UBS-B-1 I have. Also, your dim B is approximated by the two threaded standoffs on the BB-UD1-A1, which I measure at 7 and 7.1mm.
A - 2mm ± 0.1mm
B - 7.05mm ± 0.13mm
Nominally it is 3mm on both the NDAA and non-NDAA versions. That being said, there’s about a ±5% tolerance on that, and that tolerance is usually skewed negative because the laminate pressing process squishes it all together.
I just checked the 3D CAD models on GrabCAD, I can see they’re 2mm which is incorrect. Not sure how that’s happened. I believe we initially planned to make the boards 2mm in our design, but we changed that to 3mm in production to improve rigidity.
We’ll have our MechE make the fixes to those models and reupload to GrabCAD in about a week. Sorry for the confusion and thanks for bringing this to our attention.
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The 3mm versions of the baseboard models are now uploaded to GrabCad.
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