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Thread: Non-permanent LED mounting?

  1. #1
    Flashaholic
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    Default Non-permanent LED mounting?

    I just ordered 6 XM-L's and 6 XP-G's on 20mm stars (with various drivers, both AC/DC and DC/DC) as a way to experiment and learn about wiring different numbers of LED's with various drivers. Is there a good way to temporarily mount the LED's (for heatsinking purposes) so I can change them out in order to experiment with different configurations? In the future I'd like to mount them permanently for various fixed lighting projects I have in mind.

    I don't need to run them for long (a couple minutes max) and I'd like to be able to drive at various levels but no more than, say, 70% of the max. I could run them at a lower current without needing any heatsinking other than what the 20mm star provides but I would be worried at higher currents. The other option I see is to buy several small heatsinks that are pre drilled for 20mm stars but was hoping there was a cheaper option.

  2. #2

    Default Re: Non-permanent LED mounting?

    In a pinch I use a dab of superglue on the star. And I mean a *small* amount..just enough to be visible on the star bottom. Press the star firmly to a heat sink about 30 seconds and it should be a pretty tight bond. Make sure the sink is clean first. A large razor blade is a superb scraper to keep both surfaces clean. Avoid super glue gels because they take longer to set. Again, just a tiny dab on the bottom of the star.

    You should have no problems popping the star off with a plastic wedge of some sort and a decent tap on the end. Avoid screw drivers because metal will often gouge your heat sink. Use the same razor to scrape off any residue, and you're all set. Pretty much any glue will work for this but super glue is the fastest.

    For permenant mounts I now use you regular, clear epoxy, and even then I can pop them off later, and a few scrapes with a razor I'm good as new. The trick for a good thermal adhesive interface is to use a tiny bit of adhesive and lots of pressure, not over-priced thermal epoxies. When you push the star around before the glue sets, and can feel metal scraping metal, the only way to achieve a better interface is with lithium grease and screws.

  3. #3
    Flashaholic Mooreshire's Avatar
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    Default Re: Non-permanent LED mounting?

    I have experimented with swappable stars by wiring a plug to each star (I used JST and XT-60 plugs from my r/c gear) and a matching plug onto the driver. I attached them to an old computer heatsink using some of the HexaTherm brand tape they sell at LEDSupply. The taped star isn't very hard to remove from the heatsink (or star from tape, whichever) and the plugs made for easy rewiring. The tape is made to fit the stars and comes pre-cut with ten pieces on a sheet, so if I messed up the removal I just got a new piece of thermal tape. This was just for casual testing on my workbench, but I bet you could implement the same thermal-tape-and-cable-plugs approach in a more permanent housing.
    Headlamp appreciator - favorites: CustomDuo modified Petzl Explorer, Zebralight H600W, Kavelight by KevinM.

  4. #4
    Flashaholic
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    Default Re: Non-permanent LED mounting?

    Thanks! I felt odd about asking such a basic question but the suggestions are a huge help! I wasn't online over the weekend and was thinking about drilling holes (spaced for 20mm stars) into an aluminum strip and then using small bolts to secure each star. That way I could at least tighten them a decent amount to get good contact and swap in new stars as needed (although all those small bolts would be a pain).

    I'm going to try the small amount of superglue first b/c it's the cheapest route. I'll make sure to make it a VERY small amount as suggested. I ordered the 20mm LED stars through LEDSupply (VERY fast shipping btw) and also picked up a pack of the pre-cut thermal tape but only got a sheet due to the expense. ...ok it's not that expensive but it will definitely add up.

    Also, I have a lot of the JST plugs (previous RC helicopter obsession) and I think the suggestion of using them will be good for my case since I want to easily change the number of LED's running on the driver to learn more about voltage/current/etc.

    Thanks again!

  5. #5

    Default Re: Non-permanent LED mounting?

    Just remember to never connect a hot driver to a string of LED's. Even bucks will kill LED's this way.

  6. #6
    Flashaholic* georges80's Avatar
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    Default Re: Non-permanent LED mounting?

    I use a tacky thermal pad material (TGF150 by Ferrishield) from Mouser. It is sufficiently tacky to 'stick' to a hunk of aluminium and to 'stick' to a star. I can then hook leds in series/parallel as needed and also 'stick' the driver down. The material is tacky enough to hold things in place and provide a very good thermal path for short term tests.

    For longer term test I use BP-100 (Bergquist Bondply 100) from Digikey. This is a double sided adhesive thermal pad/tape material that will permanently hold a star/driver in place. With a bit of leverage (screwdriver etc), the adhesive bond can still be broken easily enough.

    A sheet of either (enough for a lifetime of 'average' tinkering) costs about $20. I provide the BP-100 material with my drivers and it has proven to be reliable and stable for permanent LED or driver mounting, so I buy 5 to 10 sheets at a time. It is easy to cut with scissors or guillotine paper cutter.

    cheers,
    george.
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  7. #7
    Flashaholic*
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    Default Re: Non-permanent LED mounting?

    Quote Originally Posted by georges80 View Post
    I use a tacky thermal pad material (TGF150 by Ferrishield) from Mouser. It is sufficiently tacky to 'stick' to a hunk of aluminium and to 'stick' to a star. I can then hook leds in series/parallel as needed and also 'stick' the driver down. The material is tacky enough to hold things in place and provide a very good thermal path for short term tests.

    For longer term test I use BP-100 (Bergquist Bondply 100) from Digikey. This is a double sided adhesive thermal pad/tape material that will permanently hold a star/driver in place. With a bit of leverage (screwdriver etc), the adhesive bond can still be broken easily enough.

    A sheet of either (enough for a lifetime of 'average' tinkering) costs about $20. I provide the BP-100 material with my drivers and it has proven to be reliable and stable for permanent LED or driver mounting, so I buy 5 to 10 sheets at a time. It is easy to cut with scissors or guillotine paper cutter.

    cheers,
    george.
    the bondply is great stuff if your looking to temporarily stick a LED to a heatsink. I have been using it for a long time now for testing.

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