Scotty: Circuit boards are in just about every piece of electronics in our lives. But how are they made? And why the heck is it so yellow in here? Today we're gonna find out. (music) Scotty: Printed circuit boards, or PCBs may look really complicated, but they're actually pretty simple. They're a bunch of tiny copper wires, sandwiched in between multiple layers of fiberglass. Now the wires are there to connect all of the various integrated circuits and other electronic components in an organized, repeatable way to make up an electronic circuit. Today, we're gonna see how they're manufactured. I'm here at the JLCPCB Factory in Huizhou China, which is outside of Shenzhen. and I'm here with Lilly who's a technical support representative that talks to engineers all day long Who sends you design files for PCB is to have you manufacture them. And so, you know everything about this process and you can answer any question I might ask, right? Lilly: Not every question
Scotty: Not every question Scotty: So you brought someone with you Lilly: Our engineer, Mr Liu. Great to have you mr. Liu, and you can answer any question that Lilly doesn't know the answer to? Mr Liu: (nods head) Scotty: Great! I'm really excited to see this process step by step, But first, we need to rewind a couple hour and go back to your main headquarters in Shenzhen to see the very first step. (Rewinding tape sound) Scotty: So we're here at your headquarters, and this is where the first stage in the process happens, right? Lilly: Yes. Scotty: Where the very first thing when a when a customer sends in their file to have a board designed, it happens here. Lilly: This is our engineering department. Scotty: And this is where they review the design files to make sure there are no problems.
Lilly: Yeah Lilly: He's checking whether this file is okay. For example, whether there is a layer missing, Lilly: Making sure there is a border on the file, whether the drilling file is there. Scotty: So he's just making sure that the engineer who designed this, the customer, Didn't design it in a way that you can't actually manufacture.
Lilly: Yeah. Scotty: so he makes the production file and then he sends that over the Internet to the factory?
Lilly: Yeah Scotty: And then the next step happens at the factory, right?
Lilly: Yeah. Lilly: Yeah. Scotty: Okay, let's go back to the factory, and see the next step! Lilly: Let's go! Scotty: So this, they're printing the design on to clear film here Scotty: Wow! Scotty: So now we're gonna go see where they take this film and they use light to project this image onto a board that has some photoresist on it that will then expose, similar to how you would expose a photograph. Scotty: Now, we've got the design, We need to transfer it onto a copper circuit board blank. But first we've got to prepare that blank. So let's go see where you guys do that. Scotty: Oh, wow! This is huge! Scotty: I have no idea it comes this big.
Lilly: So we have to cut it. Scotty: Of course, it's so big! Scotty: So this is your FR-4 fiberglass? Lilly: Yeah, you have two copper layers, one on the top and one on the bottom. And when we remove the copper, there's a yellow board (underneath). That's the FR-4 material. Scotty: Right, which is the fiberglass. So there's fiberglass in the middle, and then the copper is already sandwiched, already glued on the outside.
Lilly: Yeah. Yep. Scotty: And so this is the circuit board before anything's been printed on it. Scotty: This is the raw material.
Lilly: Yeah.
Scotty: That's really cool. So the next step is you cut this down. You take these big sheets and you cut it, right? Lilly: Yeah. Scotty: Oh, wow! Okay, this is crazy. This is the original size for this material. Scotty: And so you're picking this up here and then this is a cutter machine, here? Lilly: When it goes through this machine, it gets cut into smaller pieces. Scotty: So it starts out as one piece here and it's getting cut down the middle by a saw. Scotty: So what's going on here? Scotty: it looks like it's... Scotty: Cutting the edges? Lilly: Because the edge is rough, we have to smooth it. Scotty: So making the edges very smooth, got it.
Lilly: Yeah. Scotty: So next what are we gonna see?
Lilly: We will see how the inner layer is made first. Scotty: Got it. And so these are the wires that run in the middle of the board, where you can't see them.
Lilly: Yeah. Scotty: Okay, so we gotta put on outfits.
Lilly: Yeah. Scotty: This is like a proper clean room. Scotty: So we really don't want to damage the the boards that are being made right now By like bringing in too much dirt and dust?
Lilly: So we have to wear these things. Scotty: Tell your boss thank you for letting us come and see the inside. I've never gotten to see this. Scotty: Are you ready?
Lilly: Yeah.
Scotty: So we'll go through here. Scotty: Oops, not here.
Both: (Laughing) Scotty: Two at a time? (More laughing) Scotty: So these are the boards that we saw being cut in the other room. Lilly: Yeah, so they have to load the plastic dry film on the top and bottom side. Scotty: Okay Scotty: So when they expose this material to UV light, it gets hard and it sticks to the board. Scotty: And in places where there's no light, where there's black in the image, this will wash off. Scotty: And that will protect the copper from being dissolved by the alkaline bath Scotty: we're gonna see later in the process. Scotty: so now that the film is on the blanks, we need to actually apply the design, right?
Lilly: Yeah. Scotty: So she's got like two films there sandwich together. Lilly: And then they put the PCB in the middle. Scotty: I see. Lilly: And then it exposes on both sides.
Scotty: At the same time? Lilly: Yeah.
Scotty: Oh wow, that's awesome. Lilly: It takes only a few seconds (to expose the image) Scotty: Oh I see, and it's doing it behind there, where we can't see it. Scotty: Oh I see the light in the corner. Oh and you could you can see the design already? Lilly: Yeah.
Scotty: Oh wow, I didn't think we'd be able to see it yet. Scotty: So, why are all the lights so yellow in there? Lilly: Because the film is light sensitive. Scotty: Ah.
Lilly: so we don't need the light so strong. If the light was strong, then the film could be exposed. Scotty: Because the film is sensitive to blue light and that will make it hard. Scotty: And so the yellow light doesn't effect it.
Lilly: Yeah. Scotty: So this stack of boards is ready to be developed, and they're gonna feed it through the wall. Scotty: So then that will go into the rest of the developing process?
Lilly: Yeah Scotty: okay, but I bet we have to take off the bunny suits and go outside to go see that. Scotty: All right, let's go. Scotty: This is like an activated charcoal mask. Scotty: This is where we just were. Scotty: And now the boards are coming through that have been exposed to the light, and now they're going through the developing process. Lilly: Yeah. Scotty: Everywhere that we can see copper, the copper is going to get removed. Scotty: So developing over here where we wash off the excess photoresist. Scotty: And then here is the actual etching process.
Lilly: Yeah. Scotty: And this is an alkaline solution That removes the copper chemically. Scotty: This is a whole bunch of chemicals going on here, we totally can't see inside. Scotty: But when they come out to this side, we'll have a look. Scotty: Now where there was copper back there, there's the yellow, which is the FR-4, right?
Lilly: Yeah. Scotty: That's the fiberglass that's in the middle. Scotty: And so underneath this blue is the copper that we want to keep. Scotty: so then it comes around over here. Scotty: It says here film stripping. So that's removing the blue layer on top of the copper?
Lilly: Yeah. Scotty: So it's a bunch of washing and removing. Scotty: The blue layer has been removed and it just leaves the copper that it was protecting. Scotty: And now we have our design in copper, so this is starting to look like a circuit board.
Lilly: Yeah. Scotty: And then drying, it looks like. Scotty: And then it's putting a protective layer in between the boards so they don't scratch each other. Scotty: Each one of these now is a finished inner layer, is that right? Lilly: It's done. Scotty: So next you need to inspect the etching on the inner layer and make sure that everything is okay, right?
Lilly: Yeah. Scotty: This is very cool. Scotty: This is an automatic robotic inspection, right? You guys call this AOI. Automatic Optical inspection. Scotty: And then it's scanning it with a light and a camera.
Lilly: Yeah. Scotty: It's so fast! Scotty: And so this is comparing what the board looks like with what the design file is supposed to look like. Scotty: And so then when this is done, then it goes to be sandwiched with copper on either side of it. Scotty: Let's go see that. Lilly: This is the clip vac. We call it PP. Lilly: We can see the light here. If the surface is too smooth, we call it round. Lilly: We add PP on each side to increase the binding force. Scotty: ...Binding force. Let me see if I can explain that a little differently. Scotty: This machine takes the smooth surface and makes it a little bit more rough. Scotty: So that when you put the pre-preg on, which is sort of like an epoxy glue, Scotty: So it can get into the surface and bind more strongly.
Lilly:Mm-hmm. Scotty: So this is like a like a sheet of fiberglass, But it's really thin, it's flexible. Scotty: And it has an epoxy already impregnated into it, already soaked into the fabric. Scotty: And then you're gonna put this here and then we're gonna put another piece of copper. Scotty: And then sandwich it all together.
Lilly: One PP and one copper layer on each side. Scotty: Wow, this is a huge machine. So this copper foil is the outside.
Lilly: Yeah. Scotty: There's only one worker for this whole area?
Lilly: Yeah.
Scotty: Only one person. Scotty: So that's the bottom copper, now the prepreg and the middle and the top. Lilly: The copper is on the bottom, then the PP, then the board we've been following. Scotty: Yep, and then PP and then another layer of copper, then one of these metal sheets. Scotty: That's a big sandwich!
Lilly: Yeah! Scotty: This is the room we were just in right?
Lilly: Yeah
Scotty: Okay. Scotty: Oh and he's about to bring some out right now. (alarm blaring) Scotty: Oh, OK. Scotty: These are the board's that we just saw being stacked together. Scotty: I'm glad he told me to move, I would have gotten run over. Scotty: Well, let's go chase that robot cuz that's got the other stack, right? Scotty: So there goes the first stack that we made. In here is the press, this is where they come next. Scotty: Definitely no safety rails here. You just have to be standing out of the way. Scotty: Oh, This is where he controls... Lilly: They will increase the temperature, some time later. Scotty: Okay. Lilly: And then increase it to 200°C. Scotty: I see, so this is the steps it goes through. Scotty: The basic deal Is you load this in the furnace, Scotty: pressure and heat up to 200 degrees C, Scotty: And 27 kgs of pressure, Scotty: And that will melt the epoxy in the prepreg, Scotty: And stick it to both sides, and then it comes out here and we can see the finished lamination. Scotty: Okay, let's go take a look. Scotty: So this is what it looks like when it's fully laminated. Scotty: This is the copper. Wow, that is super thin. Scotty: This is like, paper thickness, maybe even thinner. Scotty: So inside that is the inside layer that we etched, and now it's got two pieces of copper foil on the outside. Lilly: Now, it's four layers.
Scotty: Now it's four layers. Scotty: Now we need to drill some holes. All the holes.
Lilly: Yeah. Scotty: This is the drill room. Scotty: Oh my god, you guys have so many drilling machines. Scotty: Underneath all of this stuff is the circuit boards that we just saw, right?
Lilly: Mm-hmm Scotty: And they're in a stack, what they're stacks of like three? Scotty: And these are all the drill bits here. Scotty: These machines can automatically change what drill bit they're using.
Lilly: Yeah. Scotty: They they can drill all different size holes, depending on the design. Scotty, And they just come out here, put down the one they've been using, Scotty: and they pick up a new one and they go back in and keep drilling. Scotty: Oh, it's here! It's doing it! It's switching heads. Okay, it's switching bits. Scotty: So these boards are fully drilled. And, Wow! Scotty: These are tiny, these little tiny vias. Scotty: There are two kinds of holes, (thinking) three kinds of holes, in a circuit board. Scotty: There are vias, there's through-hole, and then there's just mechanical holes. Scotty: Right?
Lilly: Yeah.
Scotty: Like for putting screws. Scotty: So those are obvious, those are for putting screws and bolts and things through. Scotty: Those are these big holes around the outside. Scotty: Then through holes are for putting the legs of components through, like resistors and capacitors. Lilly: So you can solder the through hole components. Scotty: And then vias, these vias are the magic that makes circuit boards work, makes multi-layer boards work Scotty: When you've got wires on the top of your board and wires on the bottom of the board, Scotty: The vias are what connect those two sets of wires together. Scotty: So you drill a really tiny hole and then you have to plate copper in that hole so that it connects the two.
Lilly: Yeah. Scotty: I can't believe how big this drill operation is. So how many heads is this? This is one two, three, four, five six heads! Lilly: Yeah
Scotty: So they're all doing the same thing the whole time, and they're all working on their own stacks of boards. Scotty: Which all have to be perfectly aligned to each other. Scotty: So next we'll go see plating. Scotty: Where we actually put copper back in the holes?
Lilly: Yeah.
Scotty: Okay. Scotty: So this is a copper plating process where every hole has copper plated on the inside. Scotty: This is a chemical process that I don't fully understand. Scotty: If you're a chemist and you understand this process better than I do, leave a comment down below and I'll make sure to pin it. Scotty: I'm not sure I fully understand what all is going on here. Scotty: But the important takeaway is that we're putting copper in the holes. Lilly: (laugh) Scotty: So we talked to Mr. Liu and it turns out we only saw half the process.
Lilly: Yeah. This is the other half. before, it was doing copper plating, but it was just putting a really thin layer on. Lilly: Yeah, it's not thick enough. Scotty: Right, not thick enough for soldering and for current to flow through. Lilly: Right, so we have to plate again. Scotty: Right, so this is an electroplating line, but in order to electroplate you actually need to be able to run electrical current through the board. Scotty And the first step gave us enough copper to be able to do this and then this will grow the thickness of the copper in those holes. Scotty: So now we're back in the dark room Scotty: And this time we're putting the traces on the outside of the board.
Lilly: yeah. Scotty: Okay. So this process is exactly the same as what we saw for the inside layers? Lilly: Mm-hmm.
Scotty: So let's go ahead and just skip ahead to the next step. Lilly: This is out AOI Room. Scotty: So this is AOI again. We saw AOI for the inner layer. Lilly: Yeah, this is for the outer layers. Scotty: Are these machines any different than the ones downstairs? Lilly: No, they are the same. Scotty: Same exact thing?
Lilly: Yeah. Scotty: This is where you apply the solder mask which gives circuit boards that unique green color.
Lilly: Yeah. Scotty: So far they've been yellow, turning them green. Scotty: You can do other colors too, but green is what everybody thinks of when they think of circuit boards. Lilly: It's the standard color. Scotty: Yeah. (music) Scotty: This is liquid solder mask?
Lilly: Mm-hmm. Scotty: And your squeegee-ing it on with these squeegees? Scotty: It goes back and forth. So we're putting it everywhere here. And then in the next step, we're gonna remove some of it. Lilly: Yeah.
Scotty: On this machine. We're only putting solder mask on one side of the board, right? Lilly: Yeah.
Scotty: But we want it on both sides. Lilly: Yeah. So we have to print it on the other side next. Scotty: Right, okay Scotty: So let's go down here. Oh, I see. So you've got two machines that are exactly the same. Scotty: Oh and you've got you've got a robot arm that flips it over in the middle. Scotty: That is super cool!
Lilly: Yeah. Scotty: And then next where do we go? Lilly: We have to make the solder mask dry. Scotty: So you've got these big industrial dryers here. Scotty: Oh, I see. Okay. So all the boards are vertically stacked up here. Lilly: Yeah, it is an air drier.
Scotty: That just makes the solder mask kind of tacky dry so that it doesn't run off. Scotty: So next we need to go see how we remove the solder mask off the pads where we don't want it. Lilly: They cover it with film. Lilly: On this PCB, the film has the openings for the solder mask. Lilly: That shows which needs to be removed. Scotty: These films are printed out the same way as the film we say for the traces. Lilly: Yeah
Scotty: And anywhere, there's black, the solder mask is going to be removed. Scotty: They put black where there are pads or other things where we don't want solder mask to stick.
Lilly: Yeah. Scotty: So he's taking boards that have solder mask everywhere, and he's putting the films on both sides. Lilly: Yeah.
Scotty: So I think this solder mask is UV curable. Lilly: Yeah.
Scotty: And so when you expose this solder mask to UV light, it hardens. Lilly: Yeah.
Scotty: So that's what this bright purple light is over here, it's a UV light. Scotty: We're just curing the solder mask, Scotty: Everywhere that the the film is clear. And anywhere it's black, it's staying uncured. And then we can wash it off. Lilly: Uh, yeah. Scotty: That's the washing line in there?
Lilly: Yeah. It's the developing line, and on the other side, it goes to be washed. Scotty: This is the other side of the clean room, where the boards were going into the wall.
Lilly: Yeah, it comes out through here. Scotty: And this looks just like the developing line that we saw on the in the etching process.
Lilly: Yeah. Scotty: Right, so it's basically just water sprayers that are moving back and forth, and spraying off all the excess solder mask, right? Scotty: The solder mask that didn't get hardened by the light. Scotty: So we can see here that the boards have the solder mask removed from the pads so we can see the copper pads showing through. Scotty: That's awesome. Scotty: Now it's time to put some markings on these boards. Scotty: This is your silkscreen process. And this is just what you would expect. This looks exactly like a t-shirt silkscreen. Lilly: Yeah.
Scotty: It's a big frame, and it's got a piece of silk stretched in the middle, and then on that is the design. Scotty: from the design files of where the engineer has drawn silkscreen. Why do engineers put a silkscreen on the board? Lilly: Because some designers have something they want on the PCB. For example, their logo, maybe the date, or any special text. Scotty: Yeah, so they'll put text that says like what each component is, Scotty: Alignment lines for where components should be on the board, Scotty: It's purely for humans, right? It has no electrical purpose. Scotty: But it's purely for humans to know what goes where, how it should be aligned, logos, Scotty: Part numbers, things like that. Lilly: Yeah, anything you like. Scotty: Now, this is not the only way you do this. You have a different machine. Scotty: So this looks like a giant inkjet printer, like what you would have at home. Scotty: But maybe with a UV cured... looks like a UV cured Inkjet printer. Scotty: Why do you use the old method at all? Why not do it all with this machine? Lilly: It's only available for those PCBs with lower quantity. it requires more. Because this one is much slower than silkscreen on both side. Scotty: Ah, I understand. Scotty: So if they only have a few they use the slower machine that doesn't require making silk screens. Scotty: But if they're gonna make a lot then it's worth making a silk screen and they can do it much faster. Scotty: So now we've got all the labels and the outlines printed on our board, let's go see the next step. Scotty: The boards are coming out of the ovens that finishes the silkscreen, hardens it. Scotty: And now they're coming into surface treatment. Scotty: The service treatment on the copper that makes it easier to solder. Scotty: right?
Lilly: Yeah.
Scotty: so it makes it perfectly flat, Scotty: And makes the solder stick better. Scotty: So there's a couple different options here, but this one is called HASL, Hot Air Service Leveling, right?
Lilly: Yeah, that's right. (whoosh of air) Scotty: Wow. Scotty: So the board is dipping down into the liquid solder, and then they pull it out. And there's hot air blades that blow off all the excess. Scotty: You can see it goes in copper and it comes out silver. Scotty: Onward! (music) Scotty: Okay, so this looks like the drill machines we saw before. Scotty: We're not drilling holes anymore, right? Lilly: No, no holes. You can look at this PCB, there's many different PCBs on here. Lilly: That may be from many, many customers. Lilly: Several customers.
Scotty: On one big panel. Lilly: yeah, so we have to cut it into pieces. Scotty: So we have to cut out each PCB according to the shape the designer specified.
Lilly: Yeah. Scotty: These are basically cutting bits that are cutting around the edges of each circuit board. Scotty: So what is this room? Lilly: This is the V-score. Scotty: Okay, so this is related to what we just saw, cutting out the profiles but it's a little different. Lilly: Yeah, some customers will decide they want their PCB in one small panel so it's easier for assembly. Scotty: So each of these is a separate board, right, but they receive it like this, Scotty: They'll place all their components on there, in their pick and place machine or whatever, Scotty: And then snap it apart.
Lilly: Yeah.
Scotty: Okay. Scotty: So the V-score here, this machine, makes that scoring cut, so that it's easy to break it.
Lilly: Yeah. Scotty: He's getting a stack ready to go into the machine here. Scotty: Wow, that's so fast! Scotty: We have our finished boards, we're done, right? Lilly: No, we have to test whether the PCB is all okay, for example if there are any short circuits or open circuits. Scotty: That's the most important part, right?
Lilly: Yeah, yeah. Scotty: We have to make sure that the things that should connect do connect, and the things that shouldn't connect don't connect. Scotty: So this is your E-testing room. Lilly: So we use flying poke testing. Scotty: This is one of my favorite machines in a PCB Factory. They've got little tiny needles on the end of these arms, right? Lilly: Yeah
Scotty: and those touch each of the pads on the circuit board where a component is going to be soldered down. Lilly: Yeah, that's why they're called flying poke. Scotty: So they're testing the electrical connection between two arbitrary pads, right? Scotty: And the computer knows where all of the pads should be, because it has the design. Scotty: And it knows what should connect together and what shouldn't connect together. Scotty: And it tests all of Combinations of that one by one. Lilly: Yeah.
Scotty: That's amazing. (music) Scotty: We're finally there!
Lilly: It's done! Scotty: We have finished circuit boards here, fully tested, fully manufactured, and ready to go to the customer. Lilly: Yeah.
Scotty: So what's the last step? Lilly: Package
Scotty: Packaging and shipping. So this is a an example ready to ship. It's got a label on it. Lilly: Yeah
Scotty: Ready to go out to the customers Scotty: Once it's all packed up and ready to go. It gets shipped out to the customer. Scotty: So it gets packing labels and and on its way. Scotty: So how long- We've seen this whole process, this is the very last step of shipping it out to a customer. how long from when the customer submits their design until it gets shipped out? Lilly: When it's put into production, normally it's maybe 24 hours. Scotty: 24 hours.
Lilly: Yeah. Scotty: That's so fast!
Lilly: Yeah! Scotty: So in the US, sometimes weeks is typical to wait from the time that you submit your order to the time that it's ready to ship. Scotty: I know you have customers in the US and Europe, how long does it typically take for shipping on top of that? Lilly: Maybe 3 days for DHL shipping. Scotty: DHL shipping, three days. So you're looking at, you know, four days from the time Scotty: You submit your file to the time you have your boards? Lilly: Yeah
Scotty: four days. That's pretty darn fast. Scotty: Well, I think that about does it for this time. I really enjoyed that. I enjoyed seeing the full process. I had a couple interesting takeaways from that. I think the biggest one was just how complex this process is. There are so many steps and you have so many different boards, so many different designs flowing through your factory. it's amazing that you guys keep all of this straight, that you keep track of whose orders are what, And there are so many details you have to get right. There's there's keeping things aligned, and keeping things clean. I'm so impressed. I hope you guys enjoyed this tour as much as I did. I wanted to thank JLCPCD for sponsoring this video and making it possible. But more importantly I wanted to thank you guys for giving me such deep access to your factory, such complete access. You in particular, Mr. Liu have been very accommodating, and letting us go into all of the clean rooms and see all of the different areas. It makes a big difference. and Lilly and mr. Liu, thank you so much for taking the time to show me around and the rest of your team. I really appreciate it. If you guys want to learn more about JLCPCB and their capabilities and potentially order a board design and have them manufacture it, you can find a link to their website in the description below. I hope you guys enjoyed this factory tour. I want to do a lot more of them this year. So leave a comment below with what factories you'd like me to go see, and I'll see what I can do. But for now, I'm Scotty from strange parts. If you enjoyed this video, hit that subscribe button down below and Hit that Bell icon next to it if you want to be notified about every video I upload But for now stay tuned for more adventures. I'll see you next time.
Strange Parts! This guy is awesome and I love his silly ambitious projects.
JLBPCB are really running quite the advertising blitz. I have seen their ads and sponsored videos on a ton different youtube channels recently. I am going to try them out pretty soon but I am warry. 10 5x5cm 4 layer PCB's for $15 and $9 shipping seems a bit too good to be true. I assume that they aren't impedance controlled and the 10% thickness tolerances might be trouble for RF designs (why I need 4 layers) but hey, for that price it is worth a shot. Congrats to their marketing team I guess.
That new green meth
I subscribed to Strange Parts several months ago, this guy is going places. Personally I think he needs his own show on the Travel Channel where they let him do whatever the fuck he wants
Dude come on, you don't just ask "why the heck is it so yellow in here?". Not cool.
Clean Manufacturing environment. Interview hosted in the fab with three people not wearing clean room suits? Handling transparencies without gloves.
What the fuck? You'd get kicked out of our ISO 5 for either of those things. Sure the litho they're doing is pretty laughingly easy but still it's a bit shocking to see.
i love that the camera follows the host and not the process.
I'd love to see a silicon foundry tour from this guy, love his work
I wondered who makes these robots