PCB Assembly Basics: Parts and Terminologies

The PCB, or Printed Circuit Board, is one of the most important aspects of electronics. This is the reason why learning what a PCB is, its parts, and how it is made is extremely important for someone who’s delving into electronic engineering. If you’re a beginner in PCB assembly, don’t worry. In this article, we will provide you with everything you need to know about PCBs–their parts, how they’re made, and some of the important terminologies you need to learn to get started.

What is a Printed Circuit Board?

So let’s go ahead and get the most obvious question out of the way: What is a PCB? Well, way back when PCBs weren’t invented yet, point-to-point wiring is the only way to make a circuit. Aside from being an extremely tedious process, point-to-point wiring always led to short circuits and wire junction failures when insulation on the wires began to crack because of age.

Printed Circuit Board

To alleviate this problem, engineers came up with what they call “wire wrapping.” Wire wrapping is a process where a tiny wire gauge is wrapped around each of the posts found at the end of the circuit. This basically creates an easily changeable and highly durable gas-tight connection.

As electronics became widespread in consumer goods, the pressure to mitigate manufacturing costs and reduce the size of electronic devices drove developers to seek better alternatives. Thus, they came up with the PCB.

PCBs are electronic boards that have copper lines that connect various components and connectors to each other. It allows electrical current and signals to be routed between actual physical devices. The one that creates the connections between the electronic components and the surface of the PCB is called a “Solder.” Solders not only serve to connect components to the PCB, but also serves as an extremely strong adhesive.

PCB Composition

You can think of the PCB as a layer of lasagna or cake. They have alternating layers that are made of different materials. These layers are laminated together with adhesive and heat so that it will come out as one single object. Starting from the middle going out, the PCB layers are as follows:

FR4 – This is the PCB’s base material. This is typically made up of fiberglass. “FR4” is basically the designation given the fiberglass used. The FR4 core is the one responsible for a PCB’s thickness and rigidity. When you’re doing PCB assembly, you’ll most likely make use of different PCB thickness.

PCB assembly

Copper – The layer that comes after FR4 is copper. This copper layer is also laminated onto the board with adhesive and heat. With single-sided PCBs, the copper is only laminated to one side of the FR4 during PCB assembly. With a double sided PCB, however, the copper layer is laminated on both sides of the FR4.

Soldermask – This is basically the layer that’s place on top of the copper layer. The soldermask is the one responsible for the PCB’s green color. The soldermask is laid on top of the copper layer to prevent accidental contact with other circuits, metals, or bits of conductive material.

Silkscreen – The silkscreen layer is the layer that’s laid on top of the Soldermask. This is the one responsible for the symbols, numbers, and letters found on most PCBs. The silkscreen layer allows not only for easier PCB assembly, but also for easier understanding of the board.

Terms To Remember

DRC – This is actually an acronym for “Design Rule Check.” DRCs are basically computer software that cross-checks the PCB for manufacturing flaws, errors, and defects.
Annular ring – The annular ring is basically the copper ring around PCB through-holes.

Finger – Fingers are the metal pads found along the PCB’s edge. It is usually used to connect two circuit boards together.

Drill hit – Drill hits are places on the PCB design where the through-holes would usually go. Think of drill hits as drill hole markers manufacturers use to quickly identify where a through-hole should go.

Pad – Pads are basically exposed metal portions on the PCB surface where a component is soldered.

PCB assembly is rather easy, and can be done at home. However, if you plan to mass produce a particular electronic product, you can order a high volume of top-quality PCBs from pcbnet.com. They a fast, and reliable PCB supplier that will take care of all your PCB needs.