Surface mounting the Teensy 3.2

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tenkai

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Hello!

I was thinking today, how to get access to ALL the pins, easily?

Has anyone tried to surface mount an entire teensy right on to a board?
I am thinking you could make a board layout with a cutout under the teensy, and castellation on an peninsula of the PCB to get to the underside pins...

Any thermal considerations which might cause problems? This would be a permanent attachment of course, but if a breakout board was made, you could get access to all of the teensy pins with much less work! (maybe)

Here is a relevant thread:
https://learn.sparkfun.com/tutorials/how-to-solder---castellated-mounting-holes
http://electronics.stackexchange.com/questions/35625/soldering-pcbs-directly-together
 
Yes, see Tindie. There are multiple add-on boards for sale there of various configs that allow access to all pins / pads.
 
All of the breakout boards I see on Tindie use header pins.

I am talking about soldering the teensy DIRECTLY to another board, no header pins.
 
I have done it for work in order to bring the bottom pads out and to a 2mm header to conserve PCB space. Unfortunately, whilst this works, they take a long amount of time to assemble and so I'm going to have to spin my own teensy variant at some point for this purpose. "/
 
Frank B said:
Like this ?
https://oshpark.com/profiles/FrankB
Click to expand...

I got some of these Frank did - used the first one the other day to get to under pins where ALTERNATE serial2 Rx2 & Tx2 appear and it was very easy and worked. Also going to use the underside I2C pins on that unit.

Frank made a drawing of bottom side showing pin numbers (right half) - I flipped it and translated the numbers for the top side and it looks like this to help with orientation and identification where the pins emerge:

connectorboard_PinNumsFlip.jpg
 
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tenkai said:
This is EXACTLY what I am thinking about!
Do you have this on OSH park shared? I would love to get a few!
Click to expand...
It is for Teensy 3.1 and not for 3.2. Somehow OSH park didn't made all needed cut outs and I don't know why - this is why the Program pad/pin is not connected.
It's not shared on OSH park and unfortunately I've removed the project, but I can re-upload the gerber files. Or I can upload the eagle pcb files.
 
HWGuy said:
It is for Teensy 3.1 and not for 3.2. Somehow OSH park didn't made all needed cut outs and I don't know why - this is why the Program pad/pin is not connected.
It's not shared on OSH park and unfortunately I've removed the project, but I can re-upload the gerber files. Or I can upload the eagle pcb files.
Click to expand...

I'd actually love the purple PCB's eagle BRD file, if you can HWGuy. I'm probably going to have to make something similar very soon, so it'd save some time. Thanks!
 
@HWGuy,

I'd like to apply your ...ahh... innovative reverse-castellation technique to a custom PCB. I'd like to live without the pin headers due to a space constraint.

The question is: How did you specify this in your board layout ?
Did you just draw a cutout on the board outline layer intersecting with the vias and OSHparks fab simply milled/routed it that way or did you need to specify it differently ?
 
The board outline is on eagle's "Dimension" (20) layer. The milled slots inside of the board are on the "Milling" (46) layer, but the "Dimension" layer would also be fine. One difference (for eagle) is: copper pours go to the edge of slots drawn on "Milling" layer, on the "Dimension" layer there is a margin (based on polygon isolate). In the CAM process (creates the gerber files), both layers are merged into the same board outline file. (Double check that the Milling layer is selected in the CAM process)

eagle_milling.png

The castellations are custom parts, but I think that vias can work too. They are simply placed on the board outline.

eagle_milling2.png

Your pcb manufacturer has a min size for milled slots. oshpark slots are at least 100 mil wide. (But sometimes they can do 40 mil slots). They recommend to put the text "CUt OUT" over the slot.

FAQ for oshpark: http://docs.oshpark.com/submitting-orders/cutouts-and-slots/
 
Thank you very much for the detailed reply!
I've had a number of boards made at OSH park including somewhat odd board shapes and cutouts.
I was not sure how they'd deal with cutting away vias or your custom parts. I can see the the elongated double-hole vias are custom parts.

I've worked with Eagle for all of my previous boards but decided to try CircuitMaker for this project, which is great!
For that software, according to the FAQs at OSH Park cutouts need to be on the outline layer. I'll report back once I've got boards in my hands.
 
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