The Dummies’ Brief Guide to Printed Circuit Boards

Posted on by Elsie Hamilton

Ever since they were first introduced in 1936 by Paul Eisler and later on popularized for their use in bomb detonators in the 1950s, printed circuit boards have become highly popular, so much so that they are now considered the standard for supporting and connecting electronic components that are necessary for running almost any electronic device from mobile phones to cars.

Manufacturing Process

The first step in creating printed circuit boards is the designing phase. This is done with the help of Computer Aided Design (CAD) software and other electronic design automation (EDA) tools. This phase will basically dictate how the PCBs will turn out, as many decisions are made during this phase, such as the card dimensions and template, the boards’ stack layers, the layout of how the electronic components will be placed, and how the signal traces or pathways will be routed.

Afterwards, a prototype is produced using Computer Aided Manufacturing (CAM) software. This begins with inputting the so-called Gerber data, which will lead to the generation of digital tools necessary for producing the prototypes (e.g. drill files, layer images, electrical test files, etc.), until finally the copper patterns are produced and then replicated.

pcbOnce the copper traces are ready, the components are assembled by soldering them onto the board. There are two ways in which these are done: either holes are drilled into the board so the components are soldered through them or the components are directly soldered on the boards’ surfaces. Often, a combination of these two methods is used for a single board.

Once the board and its components have been assembled, the printed circuit board assembly (PCB) is then coated with masking materials such as lead-free solder, lead solder, immersion gold or silver, deep or hard gold, and a lot more.

Once the above processes are done, the final step is to print the legends and texts to properly label the PCB and its parts.

Types of Printed Circuit Boards

PCBs are classified depending on the number of sides in which the copper traces are placed.

o Single-Sided PCB

This is the most basic type of PCB. It only has a single layer of substrate on which the electrical components are assembled on one side while the copper traces are etched on the other.

o Double-Sided PCB

This type of PCB is the most common type of PCB as it allows for higher automation without having to add more layers of substrate. As the name suggests, the electrical components are assembled on both sides of the board, and there are copper traces on either side as well. This usually uses THT together with SMT for the assembly process.

o Multi-Layered PCB

More complex PCBs under this type commonly have anywhere from four to forty-two layers of substrate, though there are some PCBs that may go beyond this number. These PCBs use insulation to separate one substrate from another. Multi-layered boards are used for equipment and devices that require highly complex electronic circuits for their sophisticated functions.

Application and Use

Printed circuit boards were first used by Paul Eisler for radios in 1936. It was not until the 1950s, however, that his invention became popular after having been mainly used by the US Military for bomb detonators that they had intended for countering the German Military’s technological advancements. After the war, the US government had allowed the PCBs to be used commercially, particularly in industrial applications. Today, however, PCBs are used for practically any electronic device. These include computers, mobile phones, cameras, radios, music players, television sets, and basically anything that relies on electricity for it to function.

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