- Today, we're gonna see how individually addressable
full-color LEDs are made. You can wire a bunch of them up and change each one to a
different color of the rainbow, many times per second,
creating amazing effects. They're in everything from LED
strips to computer keyboards to PC fans to architectural lighting. I'm here at World Semi, which is the first and arguably the most well-known
manufacturer of these LEDs. A huge thanks to them for
inviting me to their factory. They make over 2 million LEDs per day. So let's dive in and take a look. (energetic music) So why are these LEDs so famous, and why were they such a game changer? It's because they're the first smart LEDs. So prior to this, if you
wanted to have a bunch of LEDs like this that were
lighting up different colors, you had to have a driver chip
per LED, or per couple LEDs, and it was really complicated and required a lot more wiring and space. These have the driver
chip embedded inside them, and they only have to have
four wires connecting each LED, power, ground, data in, and data out, which makes them really
cheap and simple to assemble and allows you to space
'em a lot closer together. This is the first step in the process and one of the coolest. The LEDs start out as empty packages. So these might look like a finished LED, but all they are is metal
and plastic right now. They have an outsource factory
that makes these for them. It's basically a metal frame here. It's nickel with silver plating. On the backside are the four legs that will be soldered down to the PCB once the LED is finished. And then they just overmold plastic on to give it this housing. The first step here is
placing all of the silicon, all of the ICs inside the package. This machine right now
is placing a control chip that provides all of the smart
functionality for the LED, and then we'll see later
where they're placing the red, green, and blue LED dies. Over here is what's
called the tape and frame. This is the carrier for
the sliced silicon wafer that comes from the chip fab. When this is first made,
it's a single disc of silicon that goes through the standard
IC manufacturing process. That then goes to testing. They individually test
each IC on the wafer using really tiny needle probes. Then during that testing process, they mark which ones are good and bad. You can see on here there are
some marked with a black dot. Those are bad. This arm is then skipping those. And I don't know whether it's doing that just by visual recognition or if they fed in a digital
map of what was good and bad. Both are possible. This half is the frame
that I just showed you with those packages on it,
and it's doing two things. It has a little tiny needle that's moving small droplets of glue for where the IC is gonna go. This arm is moving individual chips from the tape and frame to the package. The arm is using a
little tiny vacuum needle similar to a pick-and-place machine that you would see in, like,
circuit board manufacturing. I've made videos about that as well. So if you wanna learn more about how pick-and-place machines work, you can go check that out. I'll place a link down below. Now, why do we use tape and frame? The tape is actually stretchy. So before they slice up the wafer, they place it on the tape. They slice it, kind of with
like a pizza wheel essentially, and then they stretch out the tape. And what that does is it
moves each individual die a little ways away from
each of its neighbors to make sure that when this
arm goes in to pick one up, it doesn't disturb anything around it. This is happening pretty quickly. There are some machines that
are going way, way faster that even have two arms that are picking up dies alternately. But this also needs to be very precise. This is a camera here
looking down on those ICs. This camera is looking at the destination. This machine wants to
make sure there are ICs where it thinks there should be and that they get placed properly and that it actually properly set it down. (energetic music) Next, they put carriers full of panels in ovens like this one and bake them for about two
hours at 170 degrees Celsius to cure the glue that's holding
down the ICs in the LEDs. Over the entire process, they'll go in these ovens five more times to cure any glue or epoxy
that they put on the LED. Next, let's go take a look at the machines that are placing the red,
green, and blue LED dies. Now, this machine is placing the red LEDs, same exact setup, just different dies. They are much, much smaller than those, which is saying a lot 'cause
those were really small. You can see here, this is the die. So this is from the tape and frame, and this is the destination. And the dotted blue is actually bigger than the LED die itself. So this here is the actual LED. I believe this white circle is where they're gonna bond a wire on top. We'll see that in one of the later steps. And down here it's placing
blue and green LED dies. Again, same machine, but you can see here
this is the control IC, this is the red one, this is the blue one, and then this here is the green one. And I believe, in between
each of these steps, they're going back to
the oven to cure the glue that's holding down each individual IC. They said that this machine can place up to 50,000 pieces per hour. (energetic music) The panels then get loaded in
this plasma cleaning machine, which cleans off any excess glue that's been left over
from the previous steps. It uses a high-voltage
arc similar to lightning to generate the plasma,
which cleans that glue off and prepare it to better
receive the adhesive that they're gonna apply next. This is a wire bonding machine, and it's gonna hook up all of the wires connecting all of the chips
to the LED package itself. So this is that circle on the LED package. These big planes here connect
to each of the four legs on the outside of the package that get soldered down
to the circuit board. This is the control IC, and each of these is the
red, green, and blue LEDs. These black things here
are the wire bonds. Now, it is important to know exactly how much this is magnified. These wires are 20 microns in diameter. That's 1/5 of a human hair.
It's 0.02 millimeters. These are made out of a
gold-and-silver alloy. They also do gold. It depends on the customer
requirements, they said. The wire bonding machine
uses a combination of heat, pressure, and ultrasound to melt the gold wire into a ball here and stick it to the pad
wherever it's connecting to. So here it's connecting
to bond pads on the IC and on the LEDs, and then they're connecting
directly to the pads that connect to the
legs on the LED itself. Of course, this has to
be incredibly precise. So the camera is coming in and looking for each individual pad where it's gonna place a wire bond, to make sure that it's perfectly aligned both on the IC and on the LED dies, but it's also going incredibly fast. I'm blown away by how
fast this machine runs. The boss said that this
can do 3,000 LEDs an hour, and it's 10 wires per LED. That's 30,000 wires per
hour and 60,000 bonds. That is incredibly fast, and these machines are running nonstop. Wire bonding is notoriously
a finicky thing to get right, and these machines are chugging along. There's one person manning
this entire two rows of 20 machines. (energetic music) They use an automatic glue dispenser to dispense a few drops of clear epoxy in every well of every LED. Wire bonds are really fragile, so this protects the
wire bonds and the chips from any mechanical damage either during the rest of
the manufacturing process or during the life of the LED itself. For the smaller LEDs, they
actually add the package later, after the wire bonding. So they put the wire bonded panels in an overmolding machine. This is essentially a
heat press with a mold. It's got a mold on top and bottom. They put the individual panels in after they've sprayed
it with a mold release so nothing sticks. And then they insert the
raw material pellets, plastic that will get squirted
over the top of the LEDs. This takes about 10 minutes
with pressure and temperature, and then they come out in these sets of four with
the excess plastic flashing. Most importantly, the
plastic has been overmolded over the wire bonded LEDs. He then trims these with a knife. And then finally, these
finished overmolded panels get sent out to another factory to get sliced into the individual LEDs. Next, the panels come up here. He's doing a final inspection on them, making sure there's no obvious defects, there's no bent legs or
bent part of the frame, no obvious glue defects. They then get loaded into this machine, which uses this sharp roller here to cut the tabs holding
the LEDs in the frame. And then finally, they get
put in this vibration sieve that removes any dust or metal shavings before they get shaken down here into a bin of finished LEDs. For the smaller LEDs, they
actually send them out to be cut, and then she is removing
them from the backing, I think it's like a rubberized material, inspects them, and then finally
is loading them into jars, which look like jam jars. And then she loads the
jars in this machine, which rotates them as it
blows in compressed air to clean and dry them. This is an automated LED testing machine, and it's quite cool in its design. It uses a bunch of relatively
off-the-shelf parts that are used in all sorts
of manufacturing lines for small parts like this. They're testing a bunch
of different things here. They're testing, one, does
the LED turn on at all? Two, does the red, green,
and blue LEDs light up? Does the smart chip work correctly both in terms of turning on the LEDs, but also is it sending
the right signal out, which would go to the next LED? Also, they are testing the
color accuracy of the LED. Are the red, green, and blue
LEDs the right brightness? Are they the right color, et cetera. So let's walk through this step-by-step, and I'll explain what's going on. First, they load the LEDs to
be tested into this hopper. It's basically a funnel which feeds down onto this little vibration shoot, which periodically turns on and moves the LED into a vibration pot. Now, vibration pots are really cool. They're used to load any
kind of small part like this onto a line where we
need them to be oriented in a specific way. It's a really clever design. They have essentially a
spiral ramp on the inside and a vibration motor, and that vibration motor
shakes them in a way that the parts work their way up the ramp. And then usually, they're
designed in such a way that there are a lot of passive features that any part that's not sitting
in the correct orientation will just get knocked back
into the center of the pot and will get a chance to try again to get into the right orientation. This one also has some active features. It has some light
sensors and some air jets that will detect components
that are upside down or backwards or sideways and blow them back into
the center of the pot. Finally, they get loaded
onto this rail here, in the right orientation, and loaded into the
main testing apparatus. So this is like a rotary
conveyor belt that spins and has one LED per position. It has a few sensors to make
sure that there is an LED where it thinks there is, and then it loads it into a testing jig that comes in and touches
all four contacts on the LED and powers it up, sends it
data, tells it to turn on, as well as measuring the
data that's coming out. The testing jig is
underneath this black ball. The LED shines up into that, and this is a color sensor, so it's white on the inside,
reflecting all the light, and has a color sensor in the top of it. That color sensor measures the frequency of light across the spectrum. So you can see here this is a graph showing the frequency of light, the wavelength of light
along the horizontal axis and the brightness on the vertical axis. So you can see this peak
here is blue, green, and red. In addition, they're
plotting the color out on this point graph here, and the red dot is where the color for the current LED
being tested is sitting. Now, their target is to get everything within this center square, but they will accept anything
in this general clump. This clump up here are all rejects. So periodically, you'll see this flash red when one either doesn't turn on or is too far outside
the acceptable color. Finally, based on the
results of the testing, an air jet blows it
into one of these tubes which go down into these bins below. A worker periodically comes
by and empties those bins. The good chips then go
on to the next step, which is packaging. This machine tests
about 10 LEDs per second and is pretty much automated. Every, I don't know,
20 minutes, 30 minutes, a worker has to come by and unclog a jam, but it pretty much works on its own. Their success rate right now is about 95.6%, and their fail rate's about 4.4%. They did say that they
don't throw away the LEDs that they're marking no good. They sell them off at a much reduced price below actually the cost
it takes to make them, but they get to recoup
some of their costs. Let's go see the next step,
which is packaging the LEDs. Now, the final step is to
load those fully tested LEDs in what's called tape and reel packaging. And this is pretty
standard in the industry for any electronic components. They're gonna be placed by
a pick-and-place machine. These sprocket holes are pretty standard. The width of the tape is pretty standard. But the wells here are custom-made
for this particular part. They're a little bit bigger than the LEDs. The LEDs start, again, in a hopper that leads into a vibration
pot, same as before. They get fed onto a rail and then the same sort of
rotary assembly line holder that's going around. These are suction tips,
so this is a suction line. As the LEDs go around, they're mainly focused on aligning them and making sure they work one last time. So we've got an alignment step here that's got four fingers
that are pushing the chip into the center of the suction head, then another electrical
test jig just to make sure that electrically it's
working like it's supposed to. But, also, I think that
step's figuring out whether it's rotated 180 or not. Because when you load these in the tape, you want them to be all
facing the same direction so that when they get to
the circuit board assembly, the pick-and-place machine knows which way to place them on the board. I think they are testing with
four prongs, one on each leg, electrically to see which one is data in, which one's data out, which
one's power, which one's ground. Then they've got a rejection step. If any don't test electrically, they kick 'em out into a reject bin. And they actually have
something here labeled short. It says zero, so it sounds like they're not getting many rejects. This might be a rejection as well. Then they have a step here that
looks like it rotates them. So it's figuring out,
if it is rotated 180, it spins them around so they're
all facing the same way. Then we've got another set of fingers that's aligning them back
onto the suction head. And then they have a simple
light sensor that just checks, is there a chip still
attached to the suction head, making sure that they're not gonna leave any spaces open on the tape. And then finally, it gets
placed in one of these wells. That's the bottom of the tape. The top of the tape is here, and it's just a clear
plastic, flat piece of tape that has some heat-activated
glue on the bottom of it. That gets put over the top. And then this here is a heat stamp that is gluing down the glue
on either side of the wells. And then finally, it ends up here, fully enclosed in the tapes
and loaded onto a reel. And this is what will get loaded into the pick-and-place machines. And finally, the finished
reels of 4500 LEDs are packed in antistatic
bags to be sold to customers. A huge thank you to WorldSemi for letting me look around their factory and show you how all of this works. I'll put a link to their website, if you want any more
information about their LEDs. But this is not the only
factory I'm visiting this trip. One of my next videos is going
inside a Chinese CNC factory. We'll see how they go
from a customer drawing and raw stock to a finished part. You can watch it right
now, early, on Nebula. I'll put a link down in the description. But today's sponsor is an even more impressive
machining operation. Prior to the pandemic, they were a family-owned
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Parts" at checkout, and you'll get the blades for free. I've put a link down in the description. Thanks again to Henson Shaving
for sponsoring this video. And lastly, I'd like to
give a big thanks to JLC for introducing me to WorldSemi and for flying me out to China this trip. WorldSemi is a supplier of lcsc.com, which is JLC's electronics
components e-commerce site, and it's a great place to buy
any of the LEDs you saw today. I'll see you again soon.
