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Hardware Build Technology

How LEDs Are Made 93

An anonymous reader writes "The SparkFun team took a tour of a factory in China that manufactures LEDs. They took lots of pictures showing the parts that go into the LEDs, the machines used to build them, and the people operating the machines. There's a surprising amount of manual labor involved with making LEDs. Quoting: 'As shipped on the paper sheets, the LED dies are too close together to manipulate. There is a mechanical machine ... that spreads the dies out and sticks them to a film of weak adhesive. This film is suspended above the lead frames ... Using a microscope, the worker manually aligns the die, and, with a pair of tweezers, pokes the die down into the lead frame. The adhesive in the lead frame wins (is more sticky), and the worker quickly moves to the next die. We were told they can align over 80 per minute or about 40,000 per day.'"
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How LEDs Are Made

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  • by raymorris ( 2726007 ) on Friday May 30, 2014 @05:38PM (#47132223) Journal

    I suspect this story may draw comments from people who know something about LED manufacturing. If so, I hope someone can answer this question. I noticed that panels of LEDs, such as used for traffic lights or stage lights, are composed of 200 individual LEDs. So the process is:

    Cut one LED panel apart, into hundreds of LED cores.
    Glue hundreds of leads to the hundreds of fresh cut cores.
    Align hundreds of cores into hundreds of little molds.
    Inject resin into hundreds of little modes.
    Assemble all of the hundreds of resin-covered LEDs back into a panel again.

    Why not this?:
    Attach ONE set of leads to the LED silicon panel.
    Dip the whole dang panel in resin.

  • by zmender ( 573290 ) on Friday May 30, 2014 @06:17PM (#47132541)
    Note: I am speaking as a material engineer who spent about 6 years in R&D for the 65W LED bulbs you can now buy at HomeDepot. The articled failed to mention the most important aspects of the LED manufacturing: wafering and the MOCVD that deposits the light emitting materials (the PN junction) onto the wafer. In short, the steps would include: 1) Crystal growth / wafering / surface prep; (make the wafer) 2) Nitrite epitaxial growth; (grow the light emitting part) 3) Wafer fabrication (cut big wafers down to die-sized chunks) 4) Packaging and testing (encapsulating the die) -- what the article was describing The article only touched upon the 4th step of LED manufacturing, and concidently, the most automated aspect of manufacturing, as well as the part that contains the least amount of patents / trade secrets. The first 3 steps were marginalized as "This is a sheet of LED dies. YunSun buys their dies from a high quality Taiwanese company". To my knowledge, there is no high quality manufacturer in Asia outside of Japan. Samsung makes a great quantity of ok stuff, and China / Taiwan makes a great quantity of shitty stuff that is ruining the entire high profit margin products. Also, all of the major manufacturers of LED dies dare not introduce step (2) and (3) into China / Taiwan due to IP issues. Wafering is important because larger wafer sizes (2in to 4in to 6in) means more dies per area. However, crystal quality becomes harder to control as sizes go up, especially for US-based LED manufacturers that is based on silicon carbide instead of sapphire. The real issue is with the MOCVD, the deposition technique that grows the PN junction which actually emits light. In the world of deposition, MOCVD is archaic voodoo magic and we spent a lot of time praying to deities of deposition that our process would repeat for more than a day. Fab is more systematic than epitaxial growth, and the real science here has to do with light extraction. Again, big money is spent on R&D here, and we dare not bring the manufacturing process to Asia (except for Japan).
  • by TubeSteak ( 669689 ) on Friday May 30, 2014 @08:00PM (#47133219) Journal

    --American unions are changing their priorities. Appliance Park's union was so fractious in the '70s and '80s that the place was known as "Strike City." That same union agreed to a two-tier wage scale in 2005--and today, 70 percent of the jobs there are on the lower tier, which starts at just over $13.50 an hour, almost $8 less than what the starting wage used to be.

    --U.S. labor productivity has continued its long march upward, meaning that labor costs have become a smaller and smaller proportion of the total cost of finished goods. You simply can't save much money chasing wages anymore.

    Your article glides over this very quickly, but it's worth discussing further.
    Management has essentially halted the growth of wages for decades and this has allowed all the productivity gains to accrue to business profits.
    The knock on effects have ripped through the economy, from skewed stock valuations to screwed workers' debt loads.

    http://tcf.org/assets/images/blog_images/20120814-graph-of-the-day-does-productivity-growth-still-benefit-the-american-worker.png [tcf.org]
    You can find other graphs that break down the wage growth by percentile (20th, 50th, 95th) and it's pretty much exactly what you'd expect.

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