You use a computer every day. You know the motherboard is the big green (or sometimes black or blue) board inside the case. But have you ever stopped and asked: what is it actually made of?

It’s not just plastic. It’s not just metal. A motherboard is a carefully layered sandwich of different materials, each chosen for a specific job. Some parts conduct electricity. Some parts insulate. Some parts hold everything together.

Let’s open one up – in our minds – and see what’s inside.

The Main Body – The PCB Substrate

The first and biggest part of any motherboard is the board itself. That flat, stiff sheet that holds everything. Technically, it’s called the substrate.

Most motherboards use a material called FR4. That stands for “Flame Retardant 4”. It’s a type of fiberglass cloth soaked in epoxy resin. Think of it like a super hard, heat-resistant plastic with glass fibers inside for strength.

Why FR4? Because it’s strong, it doesn’t catch fire easily, and it’s a great electrical insulator – meaning electricity stays in the copper traces, not leaking into the board.

Some very cheap or very old boards might use paper-based materials, and high-end boards sometimes use special low-loss materials for high-speed signals. But for 99% of desktops and laptops, it’s FR4.

The Copper Traces – The Nervous System

If you peel off the green solder mask (more on that in a minute), you’ll see thin, shiny copper lines running everywhere. Those are traces. They’re the wires printed onto the board.

A typical motherboard has multiple layers of copper – sometimes 4, 6, 8, or even more. The top and bottom layers have visible traces. The inner layers are buried inside the FR4.

What does copper do? It conducts electricity. When your CPU needs to send a signal to the RAM, it travels through a copper trace. When power comes from the power supply, it flows through wider copper areas called planes.

The copper is incredibly thin – usually measured in microns. One ounce of copper per square foot gives you a thickness of about 35 microns, roughly a third of a human hair.

The Solder Mask – The Protective Paint

That green (or blue, red, black) coating you see on top of the board? That’s the solder mask. It’s a layer of liquid photoimageable ink that’s applied and then hardened with UV light.

What does it do? It covers all the copper except the little pads where you need to solder. It prevents accidental shorts (copper traces touching where they shouldn’t), protects the copper from oxidation, and makes the board look pretty.

The classic green color comes from a pigment added to the ink. But manufacturers can use almost any color – blue, red, matte black, even white.

The Silkscreen – The Labels

If you look closely at a motherboard, you’ll see white text and outlines. “CPU_FAN”, “PCIE_1”, “JFP1” – those little labels are the silkscreen. It’s a special ink printed on top of the solder mask.

The silkscreen tells you where to plug things in, which way a component faces, or what a jumper does. For automated assembly lines, it also helps with orientation.

Sometimes it’s not white – it could be yellow or black – but white is the most common.

The Solder – The Glue That Holds Components

Motherboards aren’t just copper and plastic. They’re also covered in hundreds of tiny components – resistors, capacitors, connectors, chips. And those components are attached using solder.

Solder is a metal alloy – a mixture of metals that melts at a relatively low temperature. Most modern motherboards use lead-free solder, typically a mix of tin, silver, and copper (called SAC305). It melts around 217–220°C (423–428°F).

Before about 2006, motherboards used leaded solder (tin and lead), which melts at a lower temperature (183°C). Lead-free is better for the environment, but it needs higher heat to work.

The Components – What Are They Made Of?

The motherboard is empty without its parts. Let’s look at what those are made of:

CPU socket – usually made of special plastic that can handle high heat, with hundreds of tiny gold-plated or tin-plated metal pins or pads.

Capacitors – small cylinders or tiny rectangles. They store a little bit of charge. The cylindrical ones have aluminum cans with a rubber seal. The tiny rectangular ones (ceramic capacitors) are made of barium titanate or similar ceramics with nickel-tin terminals.

Resistors – tiny black rectangles with numbers on them. They’re made of a ceramic body with a carbon or metal film, and metal end caps.

Inductors (coils) – those little square boxes often labeled “R22” or “1R0”. They’re copper wire wrapped around a ferrite (iron-based magnetic) core, all encased in plastic or epoxy.

Chips (integrated circuits) – the big one is the chipset or the CPU itself. These are made of silicon – a sand-derived element that’s been purified, grown into crystals, and sliced into thin wafers. The silicon die is connected to metal leads or balls (solder balls for BGA packages) and then encased in black epoxy plastic.

Connectors – RAM slots, PCIe slots, SATA ports. They have a plastic frame (usually high-temperature nylon or LCP) with metal contacts made of copper alloy, plated with gold or tin for corrosion resistance.

What About Gold? Does Motherboard Have Gold?

Yes, there’s gold on a motherboard – but very, very little. You see it on the contacts of RAM slots, PCIe slots, and sometimes on CPU pads. Why gold? Because it never tarnishes or corrodes. Copper would oxidize and cause bad connections.

But the amount is tiny. A whole motherboard might have a few dollars' worth of gold at most. That’s why people don’t just melt down old boards for gold – it’s not worth it unless you have tons of them.

What About Lead? Is Motherboard Toxic?

Modern motherboards are mostly lead-free (due to RoHS regulations), but they still contain small amounts of hazardous stuff. The solder mask and silkscreen contain solvents and hardeners that aren’t great to breathe during manufacturing. The plastics can release nasty fumes if burned.

So don’t burn motherboards. And don’t eat them. But if you’re just using one in a computer, it’s perfectly safe.

How Thick Is a Motherboard?

A typical motherboard is about 1.6mm thick. That’s the standard for most PCBs. But the board itself is made up of multiple layers:

• Top solder mask: ~25 microns

• Top copper layer: ~35 microns (1oz)

• FR4 prepreg (insulating layer): ~0.2mm

• Inner copper layer: ~35 microns

• FR4 core: ~0.6mm

• ... and so on until the bottom.

So it’s a sandwich of copper and fiberglass, pressed together under heat and pressure.

A Quick Summary Table

The Bottom Line – What Are Motherboards Made Of?

So when someone asks you “what are motherboards made of?”, you can say:

“A motherboard is mostly fiberglass and epoxy (FR4) with thin layers of copper traces. The green coating is a protective solder mask, the white labels are silkscreen ink, and the components are attached with tin-silver-copper solder. Chips are made of silicon, connectors have gold-plated contacts, and everything is held together with various plastics.”

Now you know what’s inside that green slab that runs your computer. Pretty cool, isn’t it?