There's a component so useful, it's in every
single piece of electronics. It's so ingenious, it's been almost unchanged since World War
II. It's so important that every electrical engineer learns to design them. You won't find
this component anywhere on a board, because... it IS the board! I'm Zack Freedman, welcome
to Voidstar Lab, and today we're asking a big question about something that everyone takes
for granted - why are circuits on boards anyways? Every modern electronic device, whether
it's a nuclear-powered space probe from 1977 or a self-balancing rideable beer
cooler from 2020, has at least one printed circuit board at the center. It's the
most ubiquitous electronic component of all. It's the technology that literally
holds the world of electronics together, the printed circuit board. You might have
noticed that electronic components have become a liiiiittle more advanced over the last century.
This is a capacitor from the 1940s - it's made of foil and paper soaked in electrolytes. This
is the modern version - it's made of metallized film and a gel electrolyte. Electrolytes - they're
what electrons crave. This is Intel's cutting-edge 1971 processor that features a whopping 2,250
transistors. Here's their 2020 model with about three and a half BILLION transistors. This is
a printed circuit board from the 1950s - it's made of copper on fiberglass. This is a 2020
circuit board, made of... fiberglass and copper. Once upon a time, there were no boards at all.
Manufacturers glued or screwed components directly to the device's chassis, and then soldered the
wires to each other. Point-to-point soldering made early appliances possible, but it was crude.
That web of twisted leads was not a good use of space. It took a lot of manual labor to assemble,
it made complex circuits diabolically snarly, and it gave fork-wielding toddlers a buffet of options
to zap themselves into the shadow realm. Gosh! As time passed, devices grew more complicated
and wire wrapping was invented to cram more parts into the same amount of space. Technicians
stuck the components through a perforated wiring board - literally just a board with holes
- and they used a power drill to wrap little wires around each of the leads. They routed the
wire where it had to go, wrapped the other end, and bam! Connection made. It looks nice
and tight on top, but on the bottom... [Cliche screechy horror string music] This brings us to World War II. America had to
shove a ton of electronics into a bomb THIIIIIS big. Wire wrapping and point-to-point soldering
were not only too bulky, they were far too labor-intensive for wartime production. Instead,
the Army screen-printed metallic paint onto a pair of ceramic discs and soldered parts in between
them. This didn't just speed up production - this new so-called printed wiring board was more
compact, more durable, it was easier to repair, and it was harder to short, and these are all
features that you want in a warhead. By 1943, in the thick of World War II, the U. S. of A.
had covered the country in an entire industry of board fabricators just to make more of
these fuzes. Anyways, a couple years passed, America stuck 32 electronic detonators in a
different kind of bomb, and we ended World War II. As the war machine unwound, the birthplace of the
stuffed-crust pizza found itself dotted with a network of large-scale circuit board manufacturers
who had just lost their biggest client. Soon, cheap printed circuit boards were making their way
into industrial, and then consumer products, and a lot of former professional wire wrappers were...
were checking the help-wanted ads. PCB's really electrified the electronics industry. Before,
you needed an entire factory full of artisan wire wrappers and professional solderers just
to manufacture a piece of electronics, but now, all you needed was a stack of boards and a river
of solder. Companies could suddenly produce a wider variety of products, pack them with even
more components, and sell them at even more affordable prices. Parts manufacturing absolutely
exploded to keep up with this demand, which enabled even more consumer products, and that
in turn begat even more demand and even cheaper parts. The next thing you know, you're watching
YouTube in the bathroom and you forgot to wipe. Since 1943, electronics production has become
way cheaper, safer, easier, and sexier, but at the end of the day, circuit boards are
basically the same today as they were back then. They might be more angular and more green,
but a printed circuit board is still a thin stiff board with copper printing...
for your circuits. Let's snoop around! These are the traces, which carry electric
current just like flat wires. This is a via, a little tube-shaped wire that connects a trace
on top of the board with a trace on the bottom. This is a through-hole pad and this is a surface
mount pad; components get soldered onto these pads to connect them to the circuit. But the
board also physically carries the components, too - soldering a component onto the
board makes a mechanical connection as well as an electrical one. The board itself is
made of an insulating high-dielectric material. That means it doesn't conduct current or allow
high-voltage arcs to punch holes through it. The first commercial circuit boards were made
of cardboard hardened with phenolic resin; it turns out that running electricity over
paper soaked in tree sap is actually a really bad idea. Nowadays, we usually use fiberglass
because it's tougher and it's heat resistant. In fact the most common material is called
FR4 - that's flame retar[REDACTED] type 4, which actually extinguishes itself if it catches
fire. Fun fact: Nearly every modern circuit board actually fluoresces green under a blacklight.
The manufacturer mixes a glow-in-the-dark dye into the fiberglass so that assembly robots
called pick-and-place machines can easily see the board. Pick-and-place machines are really
cool and they're going to get their own video, and if you want to see that video - call to
action - subscribe and hit notifications. [Bling!] The board begins life as a sheet of copper clad
- that's a stiff backside with copper foil glued to it that covers the entire board edge to edge.
The PCB fabricator, AKA the fab house, draws the circuit onto the board using a chemical-proof
paint called resist. Then, the board is dunked into etchant, which dissolves the exposed copper.
Only areas covered by resist stay on the board. A technician washes the board off, drills holes for
the components, and bam! Printed circuit board. Back in the day, an engineer would literally
paint the traces, by hand, with a brush, onto the screen used for printing. This is why
old-school circuit boards have those whimsical curvy traces and those teardrop-shaped pads -
because those organic shapes are easier to paint. Artwork for modern boards, with all the angles,
is generated by an EDA program - that's electrical design assistance - instead of by a steady-handed
engineer. A photolithographic printer applies the resist, and a computer controlled CNC mill, not a
grizzled chain-smoking machinist, drills holes and mills slots. But what's really neat is that even
though the manufacturing has become a lot fancier, modern PCB's are still like old school
PCB's - they're still thin, stiff cards, they got copper printed on them, they got holes
drilled in them, and we stick stuff to the copper. Since World War II, we have made some
improvements. The most important is solder mask, which is this enamel-like paint that protects
copper traces from corrosion and prevents stray solder from shorting circuits. That was a tongue
twister! Most circuit boards are green because they have green solder mask. It's... it's just...
it's just green paint. Isn't that a letdown? On top of the solder mask, there's markings,
part numbers, etc. called an overlay; it's screen-printed on to make life easier for jabronis
like us to hack stuff. One set of wires is nice, but what if we need even more wires? Let's
double the fun by putting another set of traces, mask, and overlay on the bottom side too!
Now we got ourselves a dual-layer board. Need even moooore wires? Just laminate a
bunch of extra-thin boards together into a Scooby-Doo sandwich and you got yourself a
multi-layer board! [Cartoonish munching noises] Most modern devices actually still use
double-layer boards because they're cheap, but some PCB's, like the ones in computer
motherboards, can have more than 20 layers! So now we need to connect these layers of
traces together. Solder a wire from the top to the bottom nah? Drill a hole and electroplate
it? Yeah. The same way that steel rusts, exposed copper will corrode in air; we might as well
gold plate the entire board while we're at it! I love goooooold! Finally, those big through-hole
components with those wires that have to be jammed through holes? Yeah, they gotta go. We replaced
them with teeny-tiny surface-mount components that use conductive pads on the ends. This
is called surface mount technology because they're soldered directly to the surface
of the board as if the solder were glue. They don't have wires that punch through the
board and get soldered on the other side. Manufacturers continued to make chips smaller
even as they crammed in more and more features. Some parts now have so many signals and need so
many wires, they can't physically fit the pins, so we've changed the connecting pins from metal tabs
around the edge of the chip into a grid of metal balls on the bottom of the chip. These ball grid
array parts can expose hundreds of electrical signals in only a few square millimeters,
so modern boards need ultra-thin traces that run in three dimensions just to spread those
signals out far enough to wire up the part! But what about those fancy flexible circuit boards
the kids keep talking about? Will we ever be able to roll up our iPads and smash a mosquito with
Reddit? Flexible circuit boards are actually really common nowadays. The only difference
between a flex board and a rigid board is that the flex board replaces that fiberglass with layers
of a thin heatproof rugged plastic called Kapton. Flex PCB's are way thinner than fiberglass and you
can integrate cables into the board itself. Flex PCB's are great for bending around obstacles and
for tucking electronics into nooks and crannies. What they're not very good at... is flexing.
The first problem is that the board can bend but the components can't. The second problem is
that flexible PCB's take damage every time they wiggle. Eventually the layers of plastic and metal
will delaminate and the board will peel apart. The thicker the board is, the
more it strains when it flexes, so we can't pile up multi-layer flex boards
the same way we can stack up rigid boards. [Canine ingestion] Modern devices combine a stiff main board
that has the most intricate circuitry with flex PCB cables and modules wherever
the engineer can tuck them. Flex PCB's are really designed to flex just a single time,
and that's when the device is assembled. But can't we just go back to sticking components
right to each other, or even integrate every single component into one giant mega-chip?
That way, we could trim off most of the board and make the device that much smaller. Well,
not really. The ability to put off-the-shelf parts on custom boards, even though it makes the
part a bit bulkier, is actually a good thing. Modern devices have a lot of parts - you got
processors, memory, modems, transceivers, sensors, secret government espionage chips, security chips
to protect you from secret government espionage chips, and blinky blinky lights. Getting all those
manufacturers to combine all their parts together would be an absolute nightmare, and even if you
managed to pull it off, you'd never be able to make any design changes because everything's fused
together into one chip! Integration is risky - the more stuff you cram into a single package, the
higher the odds that a single defect breaks the entire thing. Stuff breaks - if everything is in
one place, the device is impossible to repair. This is still a big deal. Like, some hardware
is always dead on arrival and it's cheaper to repair it than to replace it. Manufacturers have
also stopped making super-low-end devices because they can refurbish last year's
model and sell it at a discount. If everything was integrated into a
single part, that wouldn't be possible. On top of that, integrating everything makes
you your suppliers' bitch because all it takes is a single supplier to threaten to revoke
their license and your entire product is trashed. Some components need to maintain social distance
from other components. Antennae, for instance, pick up interference unless they've got breathing
room, and in a high-voltage board like this power supply, arcs will jump between traces and blow
[REDACTED] up unless they're a certain distance apart. Some parts also need special packaging; this is
a pressure sensor that needs a little breathing hole to allow the air to flow in. This
is a pulse oximeter that's in a special glass capsule so that it can see the skin
clearly. There's just no getting around it; you need a bunch of parts to make electronics,
the best way to put a bunch of parts together is on a board, and the best way to make a board
is to print it. No matter how many parts are in your design, no matter how exotic they
are and which suppliers are involved, pretty much anyone can put anything into any
project as long as they can mount it on a PCB. Any parts can be combined in any configuration,
and you'll always know you'll have this thin, sturdy board, keeping everything
together, with convenient mounting holes. Integration is kind of happening in a way, but
instead of putting every component into one chip, manufacturers are integrating many
components into one module. For instance, the camera module compresses images. The
fingerprint reader handles your security. The display has the drivers embedded right into
the glass. The wireless modem, processor, RAM, graphics chips, are all integrated into a single
part. This is really the best of both worlds, because the manufacturer has already done a bunch
of your engineering, and if something breaks you just replace the module. This
is great for the user because, like, anybody with a screwdriver can replace a broken
camera if the new one just pops into place. So what's the future of the PCB? Are we still
going to be using copper and fiberglass when Brooklyn is under eight feet of water? Yeah,
I think we probably will. The PCB production process is just so well-established and so cheap
that, like, boards are already as accessible as they ever need to be. There have been some
nitty-gritty technical advancements; like, you can have a sheet of aluminum laminated
onto your board to help spread heat; you can add plugged vias, which
are sort of vertical wires, to route super duper dense components; oh,
and now you can get FULL COLOR SILKSCREEN! [Wolf whistle] Electronics are becoming cheap enough that
we can actually embed them straight into some devices - this is a bunch of RFID tags,
which are a tiny foil antenna and a teeny-weeny microcontroller built directly into a sticker.
These things don't need a circuit board because the sticker holds the thing together. Your bank
might have also given you a special bank card that displays a security code, and that is also
an electronic device with no circuit board. The electronics are embedded directly
into the plastic of the card. There are some interesting rumblings in
the hackersphere, where toxic chemicals and electroplating tubs are kinda
impractical. 3D-printed circuits are this idea that just won't die; the idea is, you
print the circuit board out of regular plastic, and then you print the traces on top of it using
a special conductive material. There's also the inkjet circuit maker, which uses basically a
modified inkjet printer to draw the circuits on a sheet of paper using conductive ink made of
silver. Finally, you have the desktop board mill, which is like a tiny cute little CNC machine
that you put on your desk and it mills you circuit boards out of copper clad. CNC board mills
have recently become affordable and practical, and if you're okay with the lack of
solder mask, you can make simple boards right there on your workbench. Give me
$2500 and I'll do it on video! But what about the super-sci-fi future? Well, there's vitrionics, or embedding electronic components into panes of glass. This is already
used to make capacitive touchscreens for cell phones and those super-thin OLED televisions.
If you want to make transparent electronics, this is how you'll do it... after you invent
a transparent battery, of course. There's also optronics, which replaces traces carrying
electricity with fiber optics carrying light. These could run way faster and way cooler
( temperature and awesomeness) but there are severe practical problems that have to
be overcome. The main one is that even though you can easily send data through a fiber optic
line, you can't send much power, so ironically, you'll have to run wires in addition to your
fiber optic traces to feed power to the chips. [Geordi getting pwned noises] Data?
Yes? What happened?
Any answer would be mere speculation. Decades of experience have proven that
the best shape for a circuit is a board, and the best kind of board is a printed circuit
board. Printed circuit boards are still the most common electrical component, even though they're
basically unchanged since we used them to blow up the Wehrmacht. I think they'll maintain their
position as the literal foundation of electronics deep into the future. Hopefully you've
learned something about how they work and why we use them. Thanks so much for watching,
and I hope I've inspired you to bust open your electronics and dig into the PCB's around you.
Are you interested in exactly how engineers design these things? Maybe you're really interested in
those part-placing pick-and-place machines we talked about earlier? Well, I make videos about
all of those, and if you like the sound of them apples, why don't you... uh... why don't
you give me a little subscription? Thank you so much for watching! Voidstar Lab is still
a new channel, and every single view and comment gives me the warm and fuzzies. May your
boards not catch fire unless you want them to. I'm Zack Freedman, this is Voidstar
Lab, and I'll see you in the future.
Great pacing. I learned a lot, fast.
It's good! Those cyborg glasses are a bit districting, as are all those flappy hand movements. But the content is great!
I read it as “why is citrus on boards” and thought he was smelling it in the thumbnail
Noice
You sir are a good teacher!
Does anyone else see Adam Sandler in the still shot? Lol Great technique, was easy to follow without any IT background.
Great, i learn alot.
Around 5:20 did he beep out "retardant" as a joke?
Yeah, I found this channel a few months ago and it rocks. I didn't go very far into past posts, though. I hadn't caught this one. Nice!