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Alden Hart, one of our LED gurus at HacDC (that’s right, we have several — we’re geek like ‘at) sent out a memo about how impressed he was with the latest issue of Digi-Key’s TechZone magazine.

I got a Digi-Key TechZone magazine in snail mail the other day and it has a lot of good and very detailed info on LEDs and lighting, including how specs are measured, circuits, and some theory. It looks like an advertisement for CREE, but what the hey… It’s available here. I’ll be digesting this for a few days.

[Thanks, Alden!]

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner’s Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.


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Comments

  1. Cephas says:

    How did you obtain a hard copy of the techzone magazines? I tried to get a PDF of the lighting issue and it came up with an error during the export process.

    1. Digi-Key says:

      Hi Cephas,
      Thank you for your interest in our Tech Zone magazines. You can start receiving the Digi-Key Tech Zone magazines by emailing your contact information to techzone@digikey.com. Please include your email address so we can send you a PDF version of the magazine. The issue you tried to export is Flash based which means you’ll need to install Adobe Flash Player to view. You can find the install here: http://get.adobe.com/reader/. If you have any further questions please do not hesitate to contact us.

  2. SilverAdept says:

    Gareth and Alden,
    Thanks for putting this up, the TechZone mag has some great information in it on this topic.
    One thing that I didn’t see, but I was skimming, was a suggested way to mount Cree X-Lamps that have the PCB mounted on an aluminum disk. Admittedly I ordered them about a year and a half ago, so I’m not even sure if they are still in production or not. I’m thinking that I would want to just mount them with thermal tape to a larger aluminum heat sink from a CPU(thank you salvage of old Pc’s at work). Does this sound like something that would be a good idea to do if I’m running these at about 80% power? Oh yeah, the LED is Cree XLamp(TM) 7090WB.
    Any input would be welcome on this.
    Thanks
    Silveradept

    1. Alden says:

      I have not worked with these myself, but I’d start here:
      http://www.cree.com/products/pdf/XLampXM_SolderingandHandling.pdf

      The doc provides the drive and thermal pad layouts CREE recommends for mounting this lamp. It requires some blind surface mount reflow soldering, but that should be achievable using a skillet and some due care with the solder paste.

      Alden

    2. Digi-Key says:

      Hello SilverAdept,
      Any time you are considering thermal management for any high power LEDs there are certain considerations you will want to look at. You will need to look at the wattage of the LED, the thermal resistance, as well as the maximum junction temperature of the LED. If the LEDs are already mounted on a aluminum board you will be able to use thermal tape to mount the aluminum to the heat sink without a problem. The next consideration you will want to be sure of is that you have good contact between the aluminum and the heat sink via the thermal tape, this way you will have maximum thermal transfer from the die to the heat sink. You will also want to be sure that the thermal resistance (or size) of the heat sink is low (large) enough and meet the specs of the junction temperature in relationship to the ambient temperature of the air surrounding the heat sink. However if these LEDs are just being slapped on a large heat sink as you are indicating the calculations would not be as crucial since the LEDs would be able to be cooled with out a problem.

      If you have any further quesitons please contact webmaster@digikey.com.

      Thank you,
      Digi-Key