One of the key concepts in electronics is the printed circuit board or PCB. It’s so fundamental that people often completely don’t understand what the basics of PCB are. In this blog, we’ll discuss the basic fundamentals of a PCB.
What’s a PCB?
Printed circuit board is the most common name but may also be called “printed wiring boards” or “printed wiring cards”. Before the advent of the PCB circuits were constructed through a laborious process of point-to-point wiring. This led to frequent failures at wire junctions and short circuits when wire insulation began to age and crack.
PCB is an acronym for printed circuit board. It is a board that has lines and pads that connect various points together. In the picture above, there are traces that electrically connect the various connectors and components to each other.
A PCB allows signals and power to be routed between physical devices. Solder is the metal that makes the electrical connections between the surface of the PCB and the electronic components. Being metal, solder also serves as a strong mechanical adhesive.
A PCB is sort of like a layer cake or lasagna- there are alternating layers of different materials which are laminated together with heat and adhesive such that the result is a single object.
Substrate
The base material, or substrate, is usually fiberglass. Historically, the most common designator for this fiberglass is “FR4”. This solid core gives the PCB its rigidity and thickness. There are also flexible PCBs built on flexible high-temperature plastic (Kapton or the equivalent).
Copper
The next layer is a thin copper foil, which is laminated to the board with heat and adhesive. On double sided PCB’s copper is applied to both sides of the substrate. Lower cost electronic gadgets the may have copper on only one side of the PCB. When we refer to a double sided or 2-layer board we are referring to the number of copper layers in our lasagna. This can be as few as 1 layer or as many as 16 layers or more.
Soldermask
The layer on top of the copper foil is called the soldermask layer. This layer gives the PCB it’s green color. It is overlaid onto the copper layer to insulate the copper traces from accidental contact with other metal, solder, or conductive bits. This layer helps the user to solder to the correct places and prevent solder jumpers.
Silkscreen
The white silkscreen layer is applied on top of the soldermask layer. The silkscreen adds letters, numbers, and symbols to the PCB that allow for easier assembly and indicators for humans to better understand the board. We often use silkscreen labels to indicate the function of each pin or LED.
Stay Tuned for further details regarding PCB’s!
ALSO READ: Perpetual Motion
Follow us on: Twitter
Follow us on: Facebook
