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Thread: Which side of driver board to stick to heatsink?

  1. #1
    Flashaholic* Mr_Light's Avatar
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    Default Which side of driver board to stick to heatsink?

    Hopefully this is a simple question. From a thermal transfer point of view, which side of driver board to stick to heatsink? The two choices are component side or PCB. I plan on using Arctic Alumina epoxy (no turning back!). The specific boards in question are the new 5-mode driver boards at DX.

  2. #2
    Flashaholic* Long John's Avatar
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    Default Re: Which side of driver board to stick to heatsink?

    It depends on the light and the location for the driver.
    I.e. at a Mag, you can sink the driver with its own heatsink.
    At an Aleph, McGizmo or other common location, you will need the +connection of the backside of the driver-board for the +contact to the batts.

    Best regards

    ____
    Tom
    It's cheaper to get a high quality light than spending money for many cheap lights.

  3. #3

    Default Re: Which side of driver board to stick to heatsink?

    *
    Last edited by macforsale; 08-28-2007 at 06:39 AM.

  4. #4
    Flashaholic* Mr_Light's Avatar
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    Default Re: Which side of driver board to stick to heatsink?

    A little background info:
    I have used several of the following DX boost converters in 2D Maglites using Litemania heatsinks and SSC emitters. I discovered that these boards will fail if not heatsinked when left on for 1+ hours. I have tried attaching the driver board (PCB side, yes there are wires soldered to that side) to the back of the heatsink using Arctic Alumina Epoxy. Using this heatsink setup the driver board survives a 3+ hour test. My question is for these type of driver boards would I be better off epoxying the component or PCB side of the board to the heatsink?
    700mA 2.5W Regulated Circuit Board for DIY Flashlights (3V Input) 5-Pack
    http://www.dealextreme.com/details.dx/sku.4382

  5. #5
    *Flashaholic* greenLED's Avatar
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    Default Re: Which side of driver board to stick to heatsink?

    Some random thoughts:

    Putting a blob of thermal epoxy doesn't do much in terms of enhancing heatsinking off components.

    If you epoxy the PCB side of the board onto the heatsink, how are you feeding power into the board?

    Whatever you do, make sure that you "pad" that inductor so it doesn't break with use.

  6. #6
    Flashaholic* Mr_Light's Avatar
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    Default Re: Which side of driver board to stick to heatsink?

    "If you epoxy the PCB side of the board onto the heatsink, how are you feeding power into the board?" I have soldered the power wires flat to the face of the of the PCB and have epoxied the PCB (wires and all) to the heatsink. Not exactly a tight connection! This leaves a large gap to bridge with AA epoxy, not the best....

  7. #7

    Default Re: Which side of driver board to stick to heatsink?

    Pure speculation, but I would try to identify the component(s) that are getting warm and concentrate on sinking those. You can pickup heat sinks to fit any size part and then try sinking that also to the body.

    I haven't seen that particular pcb but I would think it is possible to attach to + from both sides which would help if you mount from the pos side.

    Fact is the board doesn't create heat, components do so try to isolate.

    Lets see some pics of these torches..

    GL
    X..
    So much to learn, so little time.. ')
    DFW Texas Spring Fling CPF and LPF Flashapalooza, TBA? ')

  8. #8
    Flashaholic* FirstDsent's Avatar
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    Default Re: Which side of driver board to stick to heatsink?

    Originally Posted by X_Marine
    Fact is the board doesn't create heat, components do so try to isolate.
    Ditto that. The PCB won't conduct heat effectively to the body. Phenolic boards like those are actually good thermal insulators. Sink the hottest components if you are concerned about heat. I'm not aware of another flashlight application where the driver is heat sinked.

    Per your post above, are you really going to leave the light on for over an hour? If you need a light for long night hikes, or most other applications where you want it on for extended periods of time, do you need it on max power/max heat?

    Bernie
    Last edited by FirstDsent; 08-15-2007 at 10:29 PM.
    If it's worth driving, it's worth overdriving!

  9. #9
    Flashaholic* Essexman's Avatar
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    Default Re: Which side of driver board to stick to heatsink?

    Maybe (just a idea) try and simulate how the board/driver is installed in the type of torch it came out of? Most of those AA type lights are the same type of design.

    The component side is mounted in a hollowed out round bit of Alu like a can. That can is then screwed into the body of the light. That small body then has the heat coducted away by the users hand !

    So I would agree with the above ideas, i D the hot parts first and work from there.

    Hope that makes some sense, let us know how you get on.

  10. #10

    Default Re: Which side of driver board to stick to heatsink?

    Hi,

    really old thread, maybe earth turned around many times? But i have also a question regarding the heatsinking of the board.

    If i have to glue the driver with the outer ring, wich is also ground, to the aluminiumtube using arctic alumina will it still be connected to the tube? Or will this arctic shield the current, insulate? How do you do that?
    I ordered a typical Kaidomain 3040mah driver board with a spring in the middle. The instructions manual says to glue it. If i would press it down onto its seating and would glue it from the topside, do you think there is enough heatsinking, and also resistance is low enough alos over time to guarante proper connection?
    Is there anybody who already tried? I think so...
    THX a lot..
    regards
    Henning

  11. #11
    Flashaholic* kosPap's Avatar
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    Default Re: Which side of driver board to stick to heatsink?

    what I did with such a driver and a other liek this is place the driver ina P60 dropin pill and attatch this to the heatsink with thick aluminum strips (D Mag H22 heatsink) or straight to it (H22 C mag heatsink)

    Last edited by kosPap; 06-26-2012 at 12:28 AM.

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