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Thread: Bootloader soldering with a DIY hotplate

  1. #1
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    Bootloader soldering with a DIY hotplate

    I'm quite used to soldering small SMD parts on prototype boards but those QFN chips like the Teensy bootloaders are a borderline experience for me and my soldering iron. I therefore wanted to give one of those hotplates from China a try. For the fun of it I decided to build one myself and see how that works out.

    I used two cheap standard heating cartridges (24V, 50W each) for 3d printers and a 24V 120W power supply. The heaters are switched by logic level MOSFETS (IRLML6344). The heating plate is a 10mm aluminum plate from the scrap box and the white posts are Teflon (PTFE) rods. The green base is 3d printed.

    Here the simple schematic:
    Click image for larger version. 

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    And here a video showing more information and a first soldering test using my DIY microMod T3.2 board. I used low temperature (138C) solder paste.



    All in all this first soldering experiment worked quite well. Also the bootloader was easily soldered and worked without problems. (The fiddling with the bootloader chip in the video was not really necessary, I just wanted to see if it moves back into position when touched). I designed the board with large hand-soldering pads which I assume is not so good for reflow soldering (not all parts swim into place).

    Anyway, looks like this hot plate method is much more convenient and quicker than soldering with the iron. I need to practice a bit more and want to test various solder pastes. Does anyone has experience with a good (and affordable) solder paste, ideally low temp?

    (EDIT: Applying the paste and placing the parts is of course heavily accelerated in the video...)
    Last edited by luni; 02-07-2021 at 04:48 PM.

  2. #2
    Senior Member PaulS's Avatar
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    Nice job!

    Paul

  3. #3
    Senior Member+ KurtE's Avatar
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    Looks like fun,

    May have to see where to get all of the parts My 3d printer is needing work/replacement but...

  4. #4
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    That is really nice. I use a toaster oven for reflow but it is a bit of a hassle and takes up a lot of bench space.

    What are you using to measure the temperature? Is the quad encoder built into the LCD panel?

  5. #5
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    Quote Originally Posted by KurtE View Post
    Looks like fun,
    May have to see where to get all of the parts My 3d printer is needing work/replacement but...
    Yes, was quite some fun and turns out to be quite useful. I bought the heater cartridges and the NTC from Amazon. The rest was just stuff lying around.

    Quote Originally Posted by PhilB
    That is really nice. I use a toaster oven for reflow but it is a bit of a hassle and takes up a lot of bench space.
    Thanks, the small size was a design goal indeed, sits besides my iron now for quick use :-)

    Quote Originally Posted by PhilB
    What are you using to measure the temperature? Is the quad encoder built into the LCD panel?
    I used this NTC https://www.amazon.de/gp/product/B07...?ie=UTF8&psc=1 because it has a convenient screw end, but any other "3d extruder NTC" will do as well. These are the heaters I used https://www.amazon.de/gp/product/B08...?ie=UTF8&psc=1. I didn't want the standard 12V types since I couldn't find a small desktop 12V 120W power supply. Here the 24V 6A supply I use: https://www.amazon.de/gp/product/B07...?ie=UTF8&psc=1

    The LCD panel is a standard 1.3" SH1106 OLED, the encoder is not integrated. Here a view from behind and below:
    Click image for larger version. 

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    You can access the complete mechanical design here: https://cad.onshape.com/documents/7b...421d571f8cc87e


    And now for an automatic paste dispenser... I still have this transport system which I built for a completely different project some years ago. Might be not too difficult to add a dispenser to it :-)

    Last edited by luni; 02-08-2021 at 08:37 AM.

  6. #6
    Senior Member fdaniels's Avatar
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    You Sir, are crazy!

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