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Thread: Castellated PCB Pads

  1. #1
    Junior Member
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    Castellated PCB Pads

    We are starting to use more Teensy's in low volume commercial products, as the saving in development time outweighs the component savings of placing a conventional MCU on the board and creating firmware from scratch.

    However we try to maximize the use of surface mount components as we have 2 large pick-and-place machines and vapor phase reflow equipment. The adding of the headers for the Teensy and soldering both sides top and bottom is very time wasting.

    It would be good if the most commonly used Teensy's came in a castellated PCB pad option, so that the Teensy could be placed straight onto a PCB and re-flow soldered in place. I suspect the castellated pads could be added to the existing footprint so that the two existing outside rows of through holes could be retained, OR, as an alternate make the Teensy slightly narrower and sacrifice the through holes.

    We use mostly Teensy 3.2 but I expect we will do more volume with the Teensy LC in the future.

    Does anyone know if this has been considered ?

  2. #2
    Senior Member
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    As you are concerned with time-wasting and have all equipment for production in house, maybe you could consider designing your own Teensy PCB (getting the bootloader chip from PJRC).
    Schematics and reference board are available. Other have done it.
    As long you are using PJRC bootloader chip, you can find SW support on this forum.

  3. #3
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    Thanks for the suggestion. We could do that, but it kind of defeats the purpose of what we are try to achieve, which is an accelerated PCB design for non-complex low-volume products. Often they are as simple as a customized front panel interface. I don't really want to throw an engineer at designing our own Teensy, as the volume wouldn't make it worthwhile and the time we would save by removing the soldering process would be consumed by the time to design the Teensy lookalike and put the tooling in-lace to make it.

    Another example is the Teensy 4, whereby we are not setup for BGA production. A castelated version of the Teensy 4 would be a great way for businesses like ourselves to embed a high end CPU using relatively modest production technologies.

    I do believe there is an opportunity for PJRC to have a castelated version of some common products. Lots of modules such as Bluetooth and Wi-Fi are now castellated.

  4. #4
    Have you considered just milling the edges off the Teensy? I wouldn't expect any traces to be running outside the outer holes.

  5. #5
    Senior Member
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    Quote Originally Posted by Ausplex View Post

    Another example is the Teensy 4, whereby we are not setup for BGA production. A castelated version of the Teensy 4 would be a great way for businesses like ourselves to embed a high end CPU using relatively modest production technologies.
    There are multiple threads that use Teensy4 as is and make the carrier PCB with castellated connection to teensy. Through-holes are also easy connected.
    I plan t do similar for my boards.
    Note, you cannot mount T4 flush at it has bottom components, which need internal PCB cutouts.

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