LED Encapsulation for Outdoor Light Element

Discussion in 'The Projects Forum' started by 69morpho, Apr 20, 2015.

  1. 69morpho

    Thread Starter New Member

    May 17, 2014
    4
    0
    Hello-

    I have a project in which I am seeking some technical advice. I will be building 400-500 light elements. The elements will be used outside exposed to sun, wind, snow and rain. The light elements are a 2 inch diameter sphere that will be suspended from a cable. I plan on using high brightness LEDs that would illuminate the balls. The LEDs are mounted on a small star metal clad PCB for heat dissipation (MCPCB). I think it is best that the LEDs and all connections be encapsulated or potted in some kind of UV, weather resistant and non-electrically conductive crystal clear resin or rubber within the ball. The bottom hemisphere of the ball will need to be water transparent to a slightly translucent red or blue. The top half would be clear and does not need to be illuminated.

    Some of our ideas include:

    1) Making a 2 part mold and pouring the first half with color, then putting the LED in and the pouring the top half with clear. Wires and suspension hook coming out of the top.

    2) Buying some of those 2 piece acrylic balls. (Kind of like plastic easter eggs or toy machine balls only perfectly round.) Perhaps we can find them with transparent color and could interchange them with the clear. We could then use this as a mold and clear encapsulate LED within.

    My concerns are:

    1) Heat dissipation from the LED itself. We would attempt to engineer a heat sink that protrudes outside the ball.

    2) Durability of potting material. Material must be UV and weather resistant, it must have to be able to handle heat from LED, must not yellow over time and be crystal clear or perhaps the colored part have some slight translucency to grab some light.

    Any advise?
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    Do you intend these balls to actually provide "usable" light.. (aka light up a pathway or something) ?
    Typical LED Christmas lights sold in the US do not feature "high power" LEDs and still provide plenty of light while virtually eliminating any thermal challenges that one would encounter with "high power" leds.

    Finding an optically clear yet thermally conductive potting material may provide difficult.

    Personally for the low volume I think I would cast a 2 part mold (your idea #1)
    Then even if you need to attach a small heatsink to each of these balls you could easily leave it partially exposed to drastically aid in heat dissipation.

    First one I ran across
    http://www.intertronics.co.uk/products/opt4200.htm
    I'm sure Henkel/Masterbond,etc.. have some too.
     
    69morpho likes this.
  3. 69morpho

    Thread Starter New Member

    May 17, 2014
    4
    0
    These spheres are for aesthetic only not for usable light.
     
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,791
    945
    pure mineral oil is cheaper. MUCH cheaper and has the added benefit of aiding heat dissapation.
     
    69morpho likes this.
  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    Then absolutely NO reason to use metal clad mounted LEDs..
    A $0.05 regular LED/resistor will be all you need.
     
Loading...