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Thermal management of through-hole leds

Discussion in 'Electronic Basics' started by Lauri Alanko, Jul 30, 2013.

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  1. Lauri Alanko

    Lauri Alanko Guest

    I have some leds in 8 mm through-hole packages, rated for 0.5 W,
    maximum steady current 100 mA. The legs are extra wide at the top, but
    there is no other built-in heat sink. These are chinese cheapos from
    ebay and no proper datasheet was supplied.

    I intend to lay these out in a lattice on a stripboard, but I'm
    worried about thermal issues. How closely can I position the leds? Do
    copper strips provide enough additional heat dissipation area, or do I
    need to etch and drill a PCB? At the very least I suspect I should
    leave the legs sticking out from the board instead of cutting them.

    Also, is there some way to measure the temperature of the led to check
    if heat dissipation is sufficient?

    Typical through-hole leds are low-power so heat isn't much of an
    issue, and typical power leds are SMD and have dedicated heat sinks.
    0.5 watt through-hole leds seem to be in a grey area and I can't find
    much information on them. Any advice is appreciated.


  2. I don't know about the 8mm leds. But for the 5mm ones if you look into thepackage you can see that the lead going to the anode (more positve end in normal operation) is mounted right to the device, whereas the cathode lead is a wire bound. (I don't know if this is universal or just the most common configuration). So I'm thinking that if you make a big copper pour for the anode side of the led that will help conduct some of the heat out of theled. Of course you still need to get rid of the heat in the copper on thepcb. To measure the temp you might try sticking a little thermocouple on the same anode leg.

    George H.
  3. From the period reading electronic hobby magazines from the UK,
    "stripboard" is perfboard with strips of foil along the holes along one
    axis. So it's not perfboard with copper all over, but perfboard with
    strips of copper. You cut where you don't need continuity.

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