What Are the Functions of a Circuit Board?

By David Kennedy

Circuit boards or printed circuit boards (PCB) are thin plates containing electronic components mostly found in electrical and communications devices. The plate allows circuit components to transfer information and signals between each other as well as information to external devices. Circuit boards can be found in computers, televisions, cell phones, and other telecommunications devices. There are also different types for circuit boards, from traditional computer motherboards to tiny flexible boards used in mobile phones and PDAs.


PCBs are made of different parts and resins with circuitry on the surface to connect parts to one another. A PCB will usually have components for memory chips, processors, input/output devices, and then electrical components like resistors and capacitors. With the progression of technology circuit boards have become smaller while accommodating more components. Capacitors are now embedded into circuit boards which increase circuit performance and allow circuits to become smaller.


Motherboards can be found in computers and laptops. They are the large circuit boards with circuitry connections for a CPU or central processing unit, memory like RAM, input/output devices and USB connections, and a graphics processing unit. Motherboards allow all the electronic devices to communicate with one another.

Daughter Board

Daughter boards, or expansion boards, in desktop computers have generally been replaced by PCI type devices, but some examples of daughter boards include sound cards and modem cards. A daughter board is a device that extends the capabilities of the motherboard by providing an external hardware feature, like graphics, networking, or sound.


Circuit boards can be found in many electronic devices and are integral to the electronics industry. They can be used to connect LCD monitors to computers, disk drives and hard disk drives, and read and write drives like CD-ROM and DVD drives. In telecommunications systems, circuit boards are attached to metal plates to create a metal-backed assembly.

Flexible Circuit Boards

Flexible circuit boards are made of a laminated material that has insulation to resist heat, electrical properties, metal foil, and adhesive. Usually, conductive bumps allow conductivity between the flexible circuit board and another circuit board by pressing the bumps to pads with pressure. This creates electric flow between the systems. Flexible circuit boards are known for their lightness, thinness, flexibility, and convenience in size.