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How LEDs Are Made 93

Posted by Soulskill
from the when-a-two-flashlights-love-each-other-very-much... dept.
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 Ichijo (607641) on Friday May 30, 2014 @05:06PM (#47132021) Homepage Journal

    There's a surprising amount of manual labor involved with making LEDs.

    You have to expect that in a country where manual labor is cheap. In other countries, it makes more economic sense to automate or otherwise fix inefficiencies in the manufacturing process [theatlantic.com].

    • I'm suddenly thinking that my job isn't so bad... I would go insane after the first three minutes.
    • by roc97007 (608802)

      > You have to expect that in a country where manual labor is cheap.

      I'd say, you have to expect that if cheap manual labor exists in any part of the world. The areas where manual labor is cheap will naturally attract these kinds of jobs. Why bother building a machine to do it when people in abject poverty exist who will do it for a crust of bread?

    • You have to expect that in a country where manual labor is cheap. In other countries, it makes more economic sense to automate or otherwise fix inefficiencies in the manufacturing process [theatlantic.com].

      I'm not saying you're wrong, but I'd like to highlight that there is a second side to your coin. In other countries, it makes more economic sense to automate the manufacturing process so a larger percentage of the profit is converted to profit for those employees that remain, while those who would have done the inefficient manual assembly become unemployment statistics.

      Somewhere in between your statement and mine likely lies an ideal.

      • by Rockoon (1252108)
        In the world I live in, the wealth of a country is properly defined as the amount of goods and services that its people enjoy.

        Greater efficiencies is the road we should always be on.
    • 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.

    • by russotto (537200)

      Yes, the cheap labor in China (and other countries, but largely China) has probably set back industrial automation 20 years.

  • by rogoshen1 (2922505) on Friday May 30, 2014 @05:09PM (#47132041)

    The most striking thing to me about that .. article is that the factory was actually closed on a Saturday.

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

    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 Obfuscant (592200)
      I'm guessing for the same reason that the hundred of op amps on a wafer aren't all wired up on the wafer: the manufacturing process isn't perfect and you'd have a lot of nonworking or low output LEDs in the middle of your traffic lights, with modern pick and place machines it is automated to put them back into one device, and if you ever need to fix a failed LED it is cheaper to replace one than a whole wafer of them.

      Probably also for heat dissipation.

      And that traffic lights are a niche market so you'd be

    • Re: (Score:3, Informative)

      by Anonymous Coward

      Attach ONE set of leads to the LED silicon panel.

      LEDs emit light from the diode junction, not the surface. If you wired up the entire wafer, light would just come out only from the edge of the wafer and the rest would be trapped inside and turn to heat.

    • by Dan East (318230)

      All the value and cost of the LEDs is in the silicon dies they get from Taiwan. That's why they cram 4,000 dies onto a silicon sheet the size of a postage stamp. The labor required to manually pull them off is cheaper than the material and manufacturing process of the die.
      The surface area of a stoplight led panel would be at least 40 dies worth. That's 160,000 LEDs worth of silicon and production time in the fab plant. Just to get 200 LEDs worth of illumination using your technique. Plus, setting up the fab

    • by zmender (573290)
      First, LEDs are not grown on silicon. Most of the manufacturers in the world is based on sapphire wafers, and some U.S. based manufactures use SiC wafers.
      Second, consider the physics of LED: you have a lot more control over current spread and light extraction if each die is individually treated.
      Third, think of extra manufacturing technical difficulties as you saw through layers of different materials, each with different thermo and tensile properties.
    • by Anonymous Coward

      What you just described is called a Chip on Board (COB) LED. They are just coming out now with single units ranging from 10 - 150+ watts. They are designed for use in streetlights and high bay lighting.

      I just got done using one for my design project to make a tracking LED spotlight. You can watch a video of the light below.

      http://www.calvin.edu/academic/engineering/2013-14-team9/

      • Re: (Score:3, Informative)

        by b1t r0t (216468)

        I work in a part of the commercial lighting industry, and the current technology is indeed surface-mount LEDs, sort of like what you see on strip lighting, only on a metal PCB (for heat dissipation, naturally). Just run everything through a pick-and-place machine and roll it through the reflow oven. The lenses are clear plastic light pipes mounted through holes in a metal fascia. (And I was lucky enough to be able to pick up a bunch of LEDs that fell out of the PnP when we were making some a couple of years

    • by imsabbel (611519)

      They would be too bright, and too expensive. Those 5mm LEDs (outdated crap) have LED dies of a less than 1/20th of a mm^2 inside.

      High-end power LEDs that put out the equivalent of a 100W incan bulb are 2-4mm^2.

      A disk the size of a traffic light would be able to draw 10000s of Amps, and be bright enough to illuminate a stadium (if you could drain the waste-heat away). Driving it with lower currents would be a collosal waste of dies.

      So the wavers are cut into conveniently sized pices that have reasonable powe

      • I suppose that makes sense - if a CPU can have millions of transistors in less than one square inch, the wafer density is way to high to have only a few hundred diodes on a chip large enough to handle the heat. Unless of course much, much larger process sizes were much, much less expensive.

    • by thegarbz (1787294)

      I would say having to redesign a manufacturing system would essentially drive up cost, and then they'd have to compete with the existing products.

      Circuit boards are cheap, LEDs are cheap, pick and place and wave soldering is cheap. In the end you get a fully completed module. You're proposing a change in the LEDs that ultimately will still require circuit boards, pick and place, and wave soldering after to get the associated electronics working.

      Effectively you're looking at a fixed cost for the board and dr

  • Machines may be more efficient, but they would need to be manufactured and run on coal electricity. Perhaps we should encourage handmade electronics for the time being.

    • Yes. And we should wear homespun clothing, hew our own logs for our houses, and drink raw milk from Bessie out back. Its not green. It's stupid.
      • by iamacat (583406)

        Actually all of these things WOULD probably be green, if a local forest is not overexploited. You may not have time to do them, but people working in these factories have no better employment prospects. Else they would leave already.

  • 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 zmender (573290) on Friday May 30, 2014 @06:27PM (#47132629)
      Messed up my formatting.

      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 nmb3000 (741169)

        Interesting, thanks for sharing.

        If you happen to know, I noticed in the picture of the sheet of dies [sparkfun.com] that there are a fair number of gaps. Are these failures in the die manufacturing process, or something else?

      • 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.

        Waitaminute waitaminute waitaminute. You can't do that. This is Slashdot. You're violating time-honored tradition.

        First you have to tell us what you know without telling us how you know, so some dumbass can demonstrate the Dunning-Kruger effect. Then you tell us how you know what you know. It's only fair. Gotta keep the post count per article up ya know, or Dice will cry.

      • What's the best brand/model of LED bulbs to replace fluorescent ones? (classical 40 watts replacement)

    • by b1t r0t (216468)

      The articled failed to mention the most important aspects of the LED manufacturing: wafering and the MOCVD that deposits the light emitting materials

      It didn't "fail to mention" that, it started with the pre-cut dies. This place turns cut dies into finished LEDs, and they documented what they saw. This was in China, and the dies are apparently made in Taiwan (so maybe they are crap), and they weren't anywhere near there.

      And yes, fabs are serious alchemy. Like the time when Fairchild was a new company, and they found out that their transistor yields were being affected by workers not washing their hands after taking a leak. The chemicals in urine were fu

    • by afidel (530433)

      Why is the wafer size SO much smaller than in Silicon/SOI manufacturing? 200mm wafers for chips was early 90's tech and the standard has been 300mm for over a decade with 450mm slated to be coming online about now if it hadn't been for the great recession and the shift towards mobile (ie Intel Fab 42 which is now in mothballs).

      • by drinkypoo (153816)

        Why is the wafer size SO much smaller than in Silicon/SOI manufacturing?

        Because those gigantic wafers are very very expensive.

        • by afidel (530433)

          Not really, according to this [icknowledge.com] chart the raw wafers only cost $125.

          • by drinkypoo (153816)

            Not really, according to this chart the raw wafers only cost $125.

            The wafers go up in price with their size, and the price goes up more than linearly. If it made economic sense to use larger wafers, you can be sure that they would be doing so unless there was a production issue.

      • Two factors:

        - size doesn't matter (that much): For CPUs, you are creating large (relatively speaking) rectangular
        objects on a circle. Thus, the closer your circle outline approaches a straight line (i.e., the larger the circle is),
        the less waste silicon you have to cut away. For tiny LED dies, you can basically use the full circle even on
        smaller wafers.

        - For CPUs, the price is in the processing; for LEDs, it's the materials: LED structures are gigantic compared
        to those found on a CPU. They are built
  • Not just the production way is low-tech, this type of LED is depricated for everything but the cheapest crap available.

    Modern LEDs are basically all SMD, the high power ones typically mounted on a solid metal core PCB. And those are acutally manufactured in a more modern type of way.

    • Hey hey easy there, my Sky King coaxial remote control helicopter is filled with these LEDs. It looked great for the 15 seconds it flew before it crashed.

    • by goodmanj (234846)

      Sparkfun is a hobby electronics company. Surface-mount LEDs are a pain to solder by hand, and impossible to prototype.

  • ...squinting at tweezers day-in and day-out for most of your life and the toll that would take on your eyes. It must be even harder for tall people with long arms.

  • I never did look into how LEDs are made (hey, I just buy and put them to use) and that it is a "cottage industry." And LEDs are made in open air facilities instead of clean rooms. I can start my own LED factory but unlike the author I don't have a basement.
  • by s122604 (1018036) on Friday May 30, 2014 @07:03PM (#47132887)
    More liberal propaganda to justify our loss of lightbulb freedom
  • When I was last involved with lead it was treated as a hazardous material, gloves and a gas mask at the minimum were required when working with it, or around it.

    • Gas mask- a common term used for any full face breathing protection.

    • by imsabbel (611519)

      When was the last time you have seen somebody use a soldering iron with has mask and gloves? In contrast to europe, american solder is still lead based.

      • A lot of 'American Solder' is actually also available as RoHS, simply because it ends up getting used for the manufacture of items that need to be exported outside the U.S.
        Similarly, I can walk into a local electronics store in Europe and get plain ol' 63/37 just fine for my own hobby use

        Not that the lead in the article has anything to do with the lead we're discussing here.

    • by MattskEE (925706)

      The lead frames are not typically made with any lead, it is just a case of easily confused homonyms.

      In "lead frames", "lead" refers to the metal pins coming out of the packages, which are connected to the LED die. It not typically made with any lead content (Pb, element 82) due to RoHS restrictions. It could be made of tin-plated copper, or various alloys of tin, copper, and silver. Older ones would likely have been Pb-plated copper.

    • They were referring to "lead frames", the wire terminals and internal die supports used in a semiconductor package (before the plastic overmolding is done).

      Nothing to do with the toxic heavy metal with the symbol Pb.

    • by goodmanj (234846)

      "Lead" pronounced "leed", meaning something used to guide (electric current, in this case).

  • Go to a foreign country, get invited to take a rare trip through a valuable suppliers factory.

    This supplier carefully dresses up for his guests, and makes sure his factory is spotless for the important, honored visitors.

    And you show up in a ratty t shirt and wtf are they,capri shorts?

    Nothing like showing respect for your hosts. What did you bring as a gift, a used newspaper you read last week?

    • by goodmanj (234846)

      Seriously. Adapt to the local social norms, moron, you're making me embarrassed to be an American.

      (Well, okay, that's far from the most shameful thing we Americans have done overseas, but still.)

  • by Anonymous Coward

    this is another factory with more automation.

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

  • make light work!
  • I never knew this style of LEDs were mostly made by hand.

    I always assumed it was done by an automated assembly line, like how (mostly) CDs and DVDs are created on automated assembly lines.

    Now would enjoy it, if someone could tour a LED light bulb factory, and share how those are made.

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