How LEDs are made (2014)

(learn.sparkfun.com)

116 points | by smig0 2 days ago

10 comments

  • jrmg 7 hours ago
    Man, I miss photo articles like this that I can read at my leisure, without sound. Nowadays this would likely be a (probably frantic) video.
    • js2 4 hours ago
      A non-frantic (related) video worth the watch:

      Why It Was Almost Impossible to Make the Blue LED

      https://www.youtube.com/watch?v=AF8d72mA41M

      • dylan604 1 hour ago
        I remember reading about the Blue LED when it first started to appear. It was interesting reading what they thought how it would be used at the time with being able to do true R/G/B the thing everyone was talking about. Not sure how much later before they were used for shiny round discs but it wasn't part of the article's prognostications. This is all a bit nostalgic as I read about that in a printed magazine when those were still a thing.
  • WalterBright 2 hours ago
    Back at Caltech, one of the students realized that the only thing limiting the brightness of an LED was heat dissipation. So, he dipped an LED into liquid nitrogen, and cranked up the current. It got pretty bright before it melted.

    Naturally, he realized that the clear plastic blob it was inside was an insulator. How to fix - he filed it down to the bare minimum that would hold it together. This time, it would light up a whole room!

    Liquid nitrogen is all one needs to make bright LEDs.

    • ProllyInfamous 41 minutes ago
      >... to make bright WHITEish LEDs.

      While I'll readily admit to remembering nothing from her class, I took physical chemistry [πchem] from one of the co-inventors [2] of white LEDs. This is where my own limited fleshtelligence began searching for Heisenberg's god...

      [πchem] e.g: how metals behave when struck with electron[-like thing]s)

      [2] ONE of two known-methods, then

      ----

      But yes, once any process exists, it's usually only a matter of heat management to keep it working full wall-slam-ed-ly [ƒpu]

      [ƒpu] which is why to run GPU fanspeeds high enough to keep <65°C – don't care about the noisiness if they'll then last forever; change your car's oil (and keep topped-up)

    • prism56 1 hour ago
      People dedome their LEDs regularly these days for a different colour tint and beam profile. I never considered what it did to the thermal profile.
    • joe_mamba 37 minutes ago
      > Back at Caltech, one of the students realized that the only thing limiting the brightness of an LED was heat dissipation

      It takes studying at Caltech to realize semiconductors output are limited by their heat generation? I thought everyone knew this.

      • Kirby64 24 minutes ago
        The average person knows literally nothing about semiconductors. I would say it’s not very intuitive how diodes work, unless you’re an electrical engineer.
  • NikolaNovak 7 hours ago
    1. Fascinating overall

    2. "they can align over 80 per minute or about 40,000 per day." - terrifying, as I assume this is a metric workers are held against :O

    80 per minute is less than a second for what sounds like several movements - move the die over, align, push down, move it out. While your eye is stuck to the microscope.

    • throwup238 7 hours ago
      For context this is a 12 year old article about an outdated factory before LED die bonders got cheaper. The humans are working as glorified pick and place machines doing very repetitive motions, not manually aligning each die through a microscope. This only works because the tolerances on the placement between the die and anode/cathode are huge and the surface tension of the adhesive does most of the work.
  • bhagyeshsp 5 hours ago
    I guess I had read this article 12-13 years back. I think it was this same article.

    One of the things I vaguely remember was reading somewhere that working on this LED manufacturing severely damages the workers' eyes. I don't know how much of it is true and if it is, whether that is still the case.

  • mrheosuper 3 hours ago
    China has improved a lot in commerical, high power LED. 10 years ago, they could not even touch the performance of CREE or Luxeon or Osram LEDs, now thay are on par in term of performace, and much cheaper.
  • londons_explore 7 hours ago
    So every LED die is manually aligned?

    Surely 10 years on that isn't true anymore??

    • sitzkrieg 6 hours ago
      no longer true indeed. comment a bit above mentions more modern automated alignments. this and things like blue leds coming down in price
    • mrheosuper 3 hours ago
      I doubt it would even be true 10 years ago. This article is from small-mid scale led production.
  • s0rce 4 hours ago
    Neat, I was expecting more about how the semiconductor part is made. I toured the Lumileds/Phillips fab that closed in San Jose but you can't really see much.
    • QuinnyPig 4 hours ago
      You could probably see more if they used their own product.
  • pedroneto3 5 hours ago
    I wonder why some leds have a high TDP and if even that it is efficienty and how it could be fixed...
  • cowthulhu 7 hours ago
    This was a lot lower-tech than I was expecting. Very cool!
  • dekdrop 6 hours ago
    [dead]