Back to Basics: What is a Printed Circuit Board?

Let's discuss some basics of PCBs and their components.



Printed Circuit Board Uses
We use PCBs everyday, whether you realize it or not. They're used in medical devices, automobiles, flashlights, mobile phones, defense systems, computers and so much more. Literally, everything that is "electronically alive" probably has a PCB in it.

What is a PCB?
It is a board of non-conductive material, either glass or plastic, that has electrically conductive patterns printed onto it, using either copper metal or India ink. In the case of metal core boards, this pattern uses an aluminum core, copper core or a combination of substrates. India ink, in comparison, is low in conductivity.

The electrically conductive portion of the board supplies an electrical current to various components on the circuit board that are attached during the PCB assembly process. The electrical components of the board control the rate of flow and the behavior of the electrical current.

Printing Methods: Etching & Silkscreen Printing
A substrate is a material that does not conduct electricity. A PCB is a substrate that has a electrically conductive pattern printed on it. The pattern dictates the flow of electrons and is etched onto the bare circuit board.

The etching process begins with cutting copper sheet metal to the same size as the substrate. Epoxy is used on the board to bind the conductive portion to the board then an etching machine cuts the desired pattern in the copper sheet, leaving a pattern on the substrate.

Silkscreen Printing can also be used to print on the boards. With this method a silkscreen printer prints onto the board with an electrically conductive ink.

Components & PCB Assembly
PCB Assembly or PCBA is the process of attaching or embedding components onto the printed board. Common components are diodes, resistors, heat syncs (for high heat applications; common with metal core boards) and magnets.

Leads are common and important on assembled PCBs as they act as the connection between the board and another electronic device.