Main Types of Electronic PCB Boards
A printed circuit board (PCB) is a rigid or flexible circuit that connects electronic components using one or more layers of copper and an insulating substrate. Rigid PCBs have a fixed shape, while flexible PCBs are made from a stretchy material such as teflon, polyphenylene oxide (PPO) or polyethylene (PE). The choice of insulating materials depends on the needs of the circuit. Typical insulators include glass epoxy, FR-4-graded fiberglass, cotton paper impregnated with phenolic resin, tan or brown phenolic, or woven glass and epoxy. High-frequency PCBs are designed to transmit signals above 1 GHz and require low loss dielectrics like FR-4 or teflon.
Integrated circuits and other discrete components are mounted on the PCB using either through hole or surface mount technology. Through hole technology uses holes in the board to pass wires through to connect components, while surface mount utilizes a conductive paste or solder to hold the component in place. A PCB can be single-sided, double-sided or multilayer.
The most common electronic pcb board are single-layer, which have a thin layer of conductive metal, usually copper, applied to only one side of the board. Holes drilled through the board allow circuits on one side of the board to connect to those on the other using vias (vias are also known as plated through holes). Single-sided boards are the most popular because they are simple to design and manufacture.
What Are the Main Types of Electronic PCB Boards?
Double-layer PCBs have the conductive copper and components on both sides of the board, which allows for much higher component density than single-sided boards. The outer copper layers are connected to the inner layers by way of vias, which is what makes them so versatile.
Multilayer PCBs have more than two copper layers on each of the outer substrate layers. They can be single-sided, double-sided, or four-layer, and they have an option of including power and ground planes on the inner layers. The purpose of these planes is to allow signal traces to be routed closer together, which reduces parasitic effects and improves electrical performance such as noise suppression, signal integrity, and high frequency transmission.
The copper used in a PCB is deposited on the board using a process called additive manufacturing. This process starts with the unpatterned board being coated with a reverse mask that exposes only those areas that will become traces. Then, a layer of copper is added to the unmasked areas using either an additive or subtractive process. This is followed by a final mask and silk-screening to mark out the pads that will be used for through hole or surface mount components.
Before the finished product is shipped, it’s often subjected to several inspection processes. These include visual inspection, automated optical inspection and JEDEC standards for component placement and soldering. In addition, a number of tests are conducted to determine the quality of a PCB. These can include a thermal shock test to simulate the mechanical stress of vibration and humidity tests to measure moisture content.
