EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: NorthernWing on May 05, 2021, 06:37:53 pm
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Anyone around here used these cheap Espressif wireless modules on anything? If so, how'd you dimension the center pad in your footprint?
Unless I'm an idiot, something is wrong here. Looking at the drawing of the module (first attachment):
Using the bottom left corner as a reference point (0,0), it looks like the center of that exposed pad should be at (8.3, 10.65). Mirrored, because bottom view. Simple enough.
Now looking at their PCB footprint drawing (second attachment):
Using the bottom left corner, the center of that pad is dimensioned at (8.0, 10.51).
I can't wait for the day when these manufacturers collectively hire at least one person that's even remotely competent for their datasheets, because these drawings look like they were made by a child even when they're not blatantly incorrect. Guess that's why they're $2/ea.
I don't think the 0.3/0.1mm will make much of a difference for something this big, but anyone that's used these have any thoughts on which one is correct?
Edit: Unrelated, but did Inline Thumbnail attachments break sometime in the last year?...
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Pretty much all footprints I've seen were bigger than IC/module itself and they expand a bit outside, otherwise you won't be able to easily inspect the solder joint and it will be hard solder with a soldering iron. So, mechanical drawing != land pattern.
(May be this also helps with component placement, idk.)
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I understand that, but what I'm saying is that the centerpoint of the exposed thermal/ground pad doesn't match between the mechanical and package drawing. That pad on the package drawing is off by (0.3,-0.14)mm relative to the pad on the mechanical drawing.
These seem popular, was just thinking someone that's done a production run/etc with them could chime in.
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I feel like the center pad is actually not in the center, but has an offset right (bottom view). The pcb footprint seems to have offset to the right because it's "top view". If you have the actual device it's easy to measure.
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Note some dimensions are referenced not to the outer pad's center but instead to the package outline i.e. "18x25.50" so the pads are inset.
There's many ESP32-WROOM variants (32D, 32E, 32U, IE, S2, ) etc. Which module are you dealing with?
Seeed (https://www.seeedstudio.com/ESP32-Breakout-Kit-p-2783.html) uses this ESP32 breakout (they have Eagle pcb files). It uses a rounded square pad and silksceen to protect traces and vias from shorting on the underbelly. I think the only danger is paste getting into the via's on the ESP32 MCU so that is why the 9 pads.
Another approach is to use the 3D models:
https://grabcad.com/library/espressif-esp32-wroomu-1#! (https://grabcad.com/library/espressif-esp32-wroomu-1#!)
https://esp32.com/viewtopic.php?t=9728 (https://esp32.com/viewtopic.php?t=9728)