Circuit Board vs. Motherboard: How Do They Differ?

Here’s a detailed circuit board vs. motherboard comparison.

Circuit boards and motherboards are words often mentioned when dealing with electronics and computers.

But do they mean the same thing? Let’s define the two terms to see how they differ. 

What Is a Circuit Board?

A circuit board or printed circuit board is a solid or flexible sheet with conductor and insulator layers.

These layers sandwich each other, creating a compact electrical circuit with conveniently-placed pads for attaching electronic components.

These components get hooked to the circuit board via soldering, which creates a solid mechanical and electrical joint.

So an unassembled circuit board is a flat or flexible sheet that cannot function.

It requires circuit components to be fully functional.

You can use copper wires to create the circuit, but this approach is impractical for modern-day electronics; they must be compact.

So the primary reason for using circuit boards is to pack large electrical circuits in a tiny package.

These boards make the circuits:

  • Easier to handle
  • Cheaper to build
  • Take up less space

Additionally, you can layer the board to have several optimized electrical connections in 3D space, creating a highly compact circuit.

These boards come in different types and categories, which we have demystified below.

Circuit Board Types (By Layer)

According to layers, PCBs are available in the following types.

Single-Sided/Single-Layer PCB

A single-sided board contains only one conducting copper layer and an insulating layer (substrate) measuring 0.2-5mm thick.

The printed circuit or copper foil gets formed on the substrate via etching and printing.

Although this circuit board is simple to fabricate and assemble, it is not ideal for complex or high-density circuits.

And in most cases, you’ll find this PCB in electronics like TVs and radios.

A TV’s printed circuit board

A TV’s printed circuit board

Double-Sided/Double-Layer PCB

As the name suggests, these circuit boards have two copper layers, one on each side of the substrate.

This insulating layer has the same thickness range as in the single-sided PCB.

But you can mount components on both sides, creating a denser circuit.

So the board can be more compact.

These PCBs are typical in electronic meters, instruments, and computers.

Multi-layer PCB

Multi-layer circuit boards encompass those with more than two conducting copper layers, with the substrate insulation in between.

So technically, the board is a combination of multiple slim single or double-sided PCBs.

And to reach the inner layers, the holes for soldering components must be metalized.

So whenever you see a circuit board with metalized holes, it is a multi-layer type with one or more hidden copper layers inside.

A PCB with metalized vias

A PCB with metalized vias

The overall thickness for such boards is usually 1.2-2.5mm.

Circuit Board Types (By Substrate)

We can also differentiate circuit boards based on the substrate.

Rigid Board

These boards have a flat, solid design, with the FR4 substrate providing mechanical strength to the circuit.

However, some rigid boards have a metal core instead of FR4.

This material gives mechanical strength, dimensional stability, and heat dissipation from components.

For instance, LED circuits usually have aluminum-core PCBs to maximize heat dissipation.

But remember, metal is an excellent electrical conductor.

So the electrical pathways must not touch the metal core.

There must be an insulation layer between the two.

LEDs mounted on a white aluminum PCB

LEDs mounted on a white aluminum PCB

Another benefit of using a metal core is the prevention of mutual interference.

Metals like iron and aluminum have magnetic properties that can provide a shielding effect.

Flexible Board

A flexible printed circuit board does not have a solid FR4 or metal core.

Instead, it features a soft material like plastic as the insulating layer.

So you can stretch or bend the PCB to fit the installation requirements.

A flexible board for a membrane keyboard

A flexible board for a membrane keyboard

These boards are typical in mobile phone buttons and flat panel displays, especially where the screens need rotational adjustment along an axis.

Rigid-Flex Board

These PCBs are combinations of rigid and flexible circuit boards.

This design provides the required mechanical strength to parts of the circuit and flexibility where you need stretching and bending.

Circuit Board Types (By Frequency)

When comparing frequency, printed wiring boards fall into these two categories.

Low-Frequency PCB

These circuit boards carry low-speed, low-frequency signals.

They are common when dealing with analog, reference voltage, analog power supply, and control signal circuits.

High-Frequency PCB

As the name suggests, these PCBs can handle high-speed, high-frequency signals and are typical in modern-day electronics.

Think of wireless network device PCBs for fast voice, audio, and video data transmission.

A high-power radio frequency PCB

A high-power radio frequency PCB

The boards must have an insulation layer with a small dielectric constant and dielectric loss.

Materials fitting this description include:

  • Polyethylene
  • Polytetrafluoroethylene
  • Polyurethane
  • Polystyrene

What Is a Motherboard?

A motherboard is a type of PCB that is the primary board in a computer or smartphone.

These devices contain several internal and external components, and the motherboard is the centralized hub that connects all these devices.

A personal computer motherboard

A personal computer motherboard

And if you recall, the primary components of a computer are the following.

  • Central Processing Unit (CPU)
  • Power Supply Unit
  • Memory
  • Storage
  • I/O devices

The CPU is the computer’s brain because it provides all the processing power.

It communicates with all the other components using high-speed data connections (buses), such as data and address buses.

On the other hand, the power supply unit provides regulated power to the board to run most of the components inside.

Usually, the power supply unit uses an eight or 24-pin connector to deliver power to the motherboard.

A power supply unit’s 24-pin connector

A power supply unit’s 24-pin connector

Motherboard Components

Since it is the primary PCB in a computer, a motherboard must have the following components.

  • CPU Socket: This socket holds the CPU. It provides the mechanical and electrical connections between the board and the CPU.
A CPU mounted on a motherboard’s CPU socket

A CPU mounted on a motherboard’s CPU socket

  • Power Connectors: Provide the link to the power supply unit.
  • RAM Slots: Sockets for holding the memory sticks.
  • BIOS Chip: Stores the firmware required to run essential motherboard functions. Also, it initializes the hardware when booting.
  • Chipset: Manages data flow between different connected/attached components.
  • USB Headers: Links USB devices (peripheral devices) via the USB ports to the motherboard.
  • Expansion Slots: These sockets help attach hardware components like sound cards, graphics cards, TV tuner cards, and network cards to the motherboard.
  • SATA Ports: These slots connect Solid State Drives, Hard Drives, and other storage devices to the board.

Motherboard Form Factors

Motherboards are available in various sizes or form factors, including the following.

ATX (305 x 244 mm)

ATX is an acronym for Advanced Technology eXtended, and the ATX standard form factor is the most common in desktop computers.

It features multiple connectors and expansion slots.

E-ATX (305 x 330 mm)

E stands for Extended. So this board is larger than the standard ATX.

Although more expensive, it has more connectors and expansion slots, making it ideal for high-performance builds.

Micro ATX (244 x 244 mm)

This motherboard form factor is smaller than the standard ATX.

So it offers fewer expansion slots and connectors, making it ideal for building compact, budget computers.

Mini ITX (170 x 170 mm)

ITX is an acronym for Information Technology eXtended, and it is a form factor developed for tiny computer motherboards by VIA technologies.

This board features only one expansion slot with fewer connectors than the ones above.

Others include:

  • Nano ITX (120 x 120 mm)
  • Pico ITX (100 x 72 mm)
  • Mobile ITX (75 x 45 mm)
  • Mini ATX (284 x 208 mm)
  • WTX (356 x 425 mm)
  • Flex ATX (229 x 191 mm)

What Is a Backplane?

You might have encountered the term backplane when reading about motherboards.

Backplanes are more closely linked to circuit boards because they lack onboard processing and storage hardware.

Instead, you must plug these hardware components in via an expansion adapter card on an expansion slot.

A single-board computer undergoing testing on a backplane board

A single-board computer undergoing testing on a backplane board

Also known as passive backplanes, these basic versions only contain the primary circuitry.

But active backplanes have slightly more features (bus controls and other circuitry).

So such boards are ideal for server computers where you must frequently change/upgrade the processor and storage components.

Wrap-Up: Are PCBs and Motherboards The Same?

As you can see, they are not the same. Motherboards are PCBs, but PCBs are not motherboards.

So you can define a motherboard as a PCB subset because it is the largest circuit board in computers/smartphones. 

But you can find PCBs in all electronic equipment, including cell phones, medical devices, etc.

The good thing is that we can make either board for you.

So contact us if you need a PCB/motherboard for your project or for further clarification.