I’ve been wondering this for years. Like, I look at a motherboard and think, okay, this motherboard connects all pieces together. But HOW?! Watching a video of machines solder small bits of metal onto a board doesn’t help me understand it.
How does each individual piece get made first? It all just looks like metal to me. If you were to make a motherboard from scratch, what would the process be?
In: Technology
TLDR the mother board is just a copper road map on a silicon sheet.
The motherboard isn’t just a flat sheet of silicon. it has copper lines running along the back side, some times covered by another layer of silicon sometimes not. where the lines end it has a (usually gold)contact point poke through the silicon to the front. this is part the chips are soldered to. the solder bonds the circuit to the board and the circuit uses Logic Gates to determine which contact point to send power to(which other chip/circuit). the motherboard doesn’t do anything on it’s own it could just be replaced by a crap-ton of wires but that would be a pain in the ass to setup/repair, and very very expensive. the motherboard can be printed with a some chemical help fairly cheaply. the pattern of the copper lines is much easier to repeat for mass production and create for developing a new board. because the copper lines are fixed into the silicon they are much less likely break than the chip on the boards so maintenance costs are down too.
A motherboard (or any circuit board) is a “printed circuit.” It’s a layer of non-conductive material (these days, usually glass fiber) covered in ultra-thin copper wires. These copper wires are placed in specific ways to connect different parts together. The whole assembly is then coated in resin and heat-treated to cure the resin. This protects the wires from oxygen, so that the copper won’t corrode.
Soldering means putting a tiny dot of melted metal on an actual “chip” (the real integrated circuits that do the *calculation*) to connect the chip to those wires on the motherboard. Without the solder, it’s possible the chip could disconnect, or just have a flaky connection that could cause serious faults or actual damage. With the solder, the chip is securely connected to the specific wires it needs to be connected to.
Different chips need different wiring, which is why (for example) you can’t plug an Intel processor into a motherboard designed to use an AMD socket. It’s not just that they wouldn’t fit right, it’s that all the connections are very different; one part might be a power source on one chip and just an ordinary data connection on the other. You’d probably damage (=burn out) part of the processor even if you *could* somehow connect it to the socket.
Just putting solder onto a completely blank circuit board, one with no internal copper wires, would be completely pointless. It wouldn’t do anything except hold the chip in place. You need the internal wires inside the printed circuit in order to get any benefit.
If you have a printed circuit board handy (doesn’t have to be a motherboard, it can be any type), get a magnifying glass and take a look at the “back” or “bottom” side of the board. You’ll see many, many tiny wires just below the surface, and all sorts of little pins. The wires are the ones I mentioned above, that connect the different parts together. The pins are soldered bits from the chips on the circuit board.
Components like ICs, resistors, capacitors and everything else you see on a PCB are made separately. The same components can be used for all kinds of things – not just the computer you are looking at.
Electrical Engineers work on first creating a schematic that lays out what needs to be connected to work, they’ll test it etc, and then translate it into a PCB layout. There they design the physical layout that you see – there are PCBs in pretty much everything electronic – they can be very small or very large. It’s purpose (the PCB) is to provide electrical connections between components. It’s actually a lot more complex than that, but fundamentally it’s its purpose.
While you didn’t ask specifically, you should know that there’s a lot more to a PCB than you can see with your eyes. Most motherboards have 4 or 8 layers – meaning there’s a ton of connections you cannot see. Still the idea is to connect everything with the right electrical and thermal properties so it will work. In your computer, you want the CPU connected to memory, the PCI bus which connects to sound, network, video and more – it’s all about connections and electricity, and dealing with the heat that it generates.
Before we had PCBs you would see a nest of wires connecting everything. It didn’t take a lot of components before that was just a big mess hard to figure out. It is however doing exactly what the PCB does – connect things electrically. If you google “wire wrap” you’ll see early designs of computer components where it’s nothing but a lot (thousands) of little wires that are dragged from component to component. This was done MANUALLY and was considered a job for mainly women as they were seen as having steadier and more nimble hands. PCBs today are mostly soldered and fabricated entirely by machines – it’s designed on a computer and robots and machines create the PCBs, put the solder and components on, solder (using heat – not from a soldering iron), and test it before it leaves the factory. No human touch needed at all.
The solder is electrically conductive. Today most components are what we call “surface mount” and the solder connects the little legs/edges (lots of components have connections on the bottom that you cannot see) on the component to the surface of the PCB where the track (the thing that is conductive) and because it’s conductive it’s a good connection. Some components are still thru-hole meaning they have legs that go through little holes in the PCB, and the solder holds them in place while also ensuring there’s connectivity between the pin that goes into the hole, and the track that the hole is part of. It simply connects the PCB to something else. It’s like glue, but glue that conducts electricity.
Any circuit board is just a giant piece of fiberglass and copper, including a motherboard. It only consists of electrical connections that link together all the components of a circuit including various chips and plugs. Manufacturing the circuit board itself and putting all the chips on the board are two totally separate processes that are highly specialized, so the two parts generally happen in different factories. Solder serves as the “glue” that connects chips and other components to the circuit board. Solder is metal that is easier to melt than things like iron, copper, or gold so it conducts electricity and won’t melt under normal operating temperatures of an electronic device so it’s perfect to hold components to the circuit board.
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