
How LEDs are Made - yror10
https://learn.sparkfun.com/tutorials/how-leds-are-made/all
======
HeyLaughingBoy
_I could do this in my basement!_

Years ago I answered a "for sale" newspaper ad for used office desks and some
test equipment. I showed up at the address and it was a small dingy old
building and most of the employees seemed to be 55+ year-old women. When I
asked what they did and was told they made diodes, you could have knocked me
over with a feather. Like he did, I assumed that all electronics parts
manufacturing was high-tech, cleanroom work, etc. But here were little old
ladies putting pieces together.

I had a similar epiphany years later when a friend told me he was buying a
thermocouple manufacturing business for $20,000!!! The business consisted of
two senior citizens who wanted to retire. No high-speed pick&place robots
working in inert argon atmospheres, just two old people putting wire in jigs
and spot-welding them together (probably in an inert atmosphere, though).

The same thing repeats itself over and over: a huge amount of what we think of
as sophisticated technology is being done by hand, or by ancient machinery, in
dirty, poorly lit corners of the US.

~~~
DanBC
I ised to work in electronic subcontract engineering. They had some automation
(little pick and place machine with oven and screen printer; a flow oven for
populated PCBs) but there was a lot of work done by hand.

It was a terrible time of my life and it informs a lot of my opinion about
poor management and inefficient working and about ISO900x quality assurance
systems.

~~~
madengr
ISO9000 just means you must document that management crap on it's employees.
As long as your crappy processes are documented, you are good-to-go.

~~~
ttflee
Passing these management craps are not completely meaningless. Sometimes,
people do realise what was the problem during the process of producing these
management craps.

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carrigan
The title here is slightly misleading- this isn't how LEDs are made, it is how
LED dies are packaged. The more difficult part of all of this is creating the
dies themselves, which is requires a clean room and all the automated tools
I'm sure most people here were expecting to see.

~~~
DigitalJack
this is a good link, although still high level:
[http://www.edisontechcenter.org/LED.html](http://www.edisontechcenter.org/LED.html)

and a lab to get a better feel for how band gaps affect the spectrum:
[http://electron6.phys.utk.edu/phys250/Laboratories/Light%20e...](http://electron6.phys.utk.edu/phys250/Laboratories/Light%20emitting%20diodes.htm)

~~~
johnohara
Good links indeed. And interesting. Thank you.

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leoedin
I'm surprised by how manual the whole process is. I think labour is so
expensive in the west that any manufacturing of small low value items is
incredibly highly automated (see youtube for lots of videos of how huge
automated production lines work). There's no way you could employ someone to
manually bond 80 LEDs a minute in the west and still have a competitive
product.

~~~
HeyLaughingBoy
I'm not so sure. Let's assume you're paying someone $15/hour and she actually
costs you $25/hour. Assuming a 10 minute break every hour (that's gotta be
tiring work and you want to hold onto your employees), then that's 2500/(80 *
50) = 0.625 _cents_ of labor cost per LED. I don't know what all the other
costs are, but that one operation seems surprisingly cheap.

~~~
DanBC
I'm stupid. EDIT: I am! Thanks for the corrections!!

~~~
johnchristopher
> We were told they can align over 80 per minute or about 40,000 per day.

~~~
parker94
Wow that's impressive

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xedarius
Trick of the eye there for a moment. I thought that girl in the photo had a
robot LED making arm.

~~~
brc
Yeah me too. I had to do a double take.

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coreymgilmore
Very surprising how manual this is, unless this is just for the purpose of
showing how the LEDs are made. I would have expected everything in this
process to be automated since electronic component manufacturing is very high
volume.

Also amazing how small the components (LED dies) are.

~~~
joezydeco
Everyone else has moved on to 0402-sized surface mount LEDs a long time ago.
Could this manual process just be because nobody is building the old through-
hole LEDs in massive quantities?

~~~
DanBC
For people who don't know 0402 is:

> 0402 (1005 metric): 1.0 mm × 0.5 mm (0.039 in × 0.020 in).

~~~
HeyLaughingBoy
And they suck to do manually. I started this morning off by hand-stuffing some
PC boards with (among other parts) 19x 0402 resistors per board.

There was a reason I did it before I had any coffee!

~~~
DanBC
The company I ised to work for would sometimes buy components from RS. They'd
supply them in strips of 10, 50, or 100.

The pick and place machine needed blank strip of about ten components (just
for lead-in on the cassete).

Transfering components from one tape to another was really annoying. And one
of the bosses just did not understand that the fractions of a penny saved were
obliterated by time wasted moving components over.

And until you've had to do something like that you can't really understand the
benefit of $60 Swedish tweezers.

~~~
madengr
Yep #00 Swiss tweezers. Nothing like them. The feel of the #00 is just right.

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chrisBob
Am I the only person that thought the shape of the metal inside an LED was a
significant part of the function?

I am sure if I thought about it I would have realized that it is just support
for the silicon. I guess I never thought about it that much until today.

~~~
morcheeba
If you look closely, you'll see it's actually in the shape of a reflector -
usually a cone. Also not shown is that some higher-power leds use a blob of
silicone around the chip to protect the bond wire during thermal expansion --
the cone helps hold the silicone while curing.

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userbinator
Similar process, but for USB drives:
[http://www.bunniestudios.com/blog/?p=2946](http://www.bunniestudios.com/blog/?p=2946)

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sparkman55
This is clearly an old process - when was the last time you saw a 7-segment
display, or those big red round thru-hole LEDs, outside of hobby electronics?

I'd be very curious to see how this process differs from the high-power
lighting LED manufacturing process (e.g. CREE), which is a more modern
technology by several decades. I would guess there is much more of the
automation people are expecting...

~~~
pmorici
"when was the last time you saw a 7-segment display, or those big red round
thru-hole LEDs"

Every HP common slot server PSU has one of those round through hole LEDs on
it. I have an HP server sitting here (DL580) that has two 7 segment displays
on its motherboard. These things are definitely still used in modern products.

------
danvoell
Am I the only one that thought Alicia had a bionic arm at first glance?

~~~
fideloper
I want those short ties. That's awesome.

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ChuckMcM
And so this makes an interesting point, LED shapes are controlled by the mold
makers, but when do we get just a flat thin LED and you can 3D print the shape
you want on top? :-)

~~~
HeyLaughingBoy
Make a trip to your local Michael's or other art/craft store and you can do it
today. Silicon sealant to make a mold + liquid molding acrylic and you're off.

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mrfusion
I wonder how the LED dies are made?

~~~
jmpe
Same as regular chips: in a grid on a wafer, then cut and pick&placed.

Don't forget: yield goes up when the die shrinks because the defects are
typically small spots. The smaller the die the better you pixelate the
defects.

The wafers are only 2 inch diameter to avoid yield loss due to edge effects:
at the edge of the wafer you have lowest quality components (optical ring
effects)

~~~
tedsanders
I doubt that they 2-inch wafers to avoid yield loss from edge effects. The
ratio of area to perimeter _rises_ as you increase the wafer size. Perhaps the
reasons they use 2-inch wafers are for better uniformity, better flexibility,
or lower capital investment.

~~~
jmpe
Probably uniformity & capital. The profit margins on LED aren't what they used
to be.

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Eliezer
If this is the manufacturing process and its price, why are LED light bulbs
still expensive? (Serious question.)

~~~
nkurz
These are not the type of LEDs used in modern light LED light bulbs. They
produce a tiny amount of light (maybe 5 lumens each, with a 60W equivalent
requiring 800 lumens), don't work well with a heat sink, and aren't
particularly efficient. Separately, a lot more goes into an LED light bulb
than just the LED.

Here's a teardown with cost estimates for a recent 800 lumen Cree 60W
equivalent, where they come up with an $8 Bill of Materials for a bulb that
retails for $13: [http://electronics360.globalspec.com/article/3212/cree-
ba19-...](http://electronics360.globalspec.com/article/3212/cree-
ba19-08027omf-12de26-1u100-led-light-bulb-teardown)

~~~
sokoloff
Home Depot has been selling those lamps for $4.97ea for quite a few months
now. They're a very nice replacement for the traditional A19 60W
incandescents.

My only complaint, and it's a tiny one, is that they only dim to about 10%
before cutting off entirely. There's also a small dark spot on the spot of the
bulb opposite the socket, but in practice that's been a non-issue for all my
use cases.

~~~
nkurz
In the US, the price varies state by state, and reflects a variety of
subsidies used to encourage the switch over from incandescents. Thus for
certain bulbs (like this one) the production cost is often higher than the
selling price. Some details for California here:
[http://www.designingwithleds.com/rebated-cree-philips-led-
bu...](http://www.designingwithleds.com/rebated-cree-philips-led-bulbs-8-ca-
temporarily/)

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NIL8
Neat!

Now, I'd like to see someone do something like this for solar panels.

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rikacomet
Isn't the word "dyes" the right one to use here? Instead of "dies"?

~~~
Figs
They're talking about this kind of "die":
[http://en.wikipedia.org/wiki/Die_%28integrated_circuit%29](http://en.wikipedia.org/wiki/Die_%28integrated_circuit%29)
; "dyes" are substances used to color things. (See:
[http://en.wikipedia.org/wiki/Dye](http://en.wikipedia.org/wiki/Dye) )

The book referenced as the first source on the "die" wikipedia link claims:

> The plural of die is dice. However, it has become standard practice in the
> industry to use "die" as the plural.

As a native speaker of English, I'd find any of "die", "dies", or "dice" to be
pretty reasonable as long as it's clear what's referred to from context. (I'd
prefer "dies" over "dice" if it's not immediately clear that you're not
talking about playing dice, for example.)

