Printed circuit boards (PCBs) are among the key items in the field of electronics. These are so fundamental and yet a lot of people do not know what they are. In this article, the basic definition and composition of printed circuit boards will be discussed.
Definition and Origin
Also called printed wiring cards or printed wiring boards, printed circuit boards are created through a rigorous process of wiring. In time, the point-to-point method of wiring ended up in short circuits and wire junction failures as soon as the insulation of the wiring started to crack and age.
The development of the process of wire wrapping served as a huge advancement in the creation of PCBs. Here, a tiny gauge wire is wrapped around a post on every connecting point. This created a connection that is gas-tight, easily modifiable and extremely durable.
Over time, even more advancements and improvements in the field of electronics surfaced. What started from relays and vacuum tubes soon moved to silicon and then to integrated circuits. At the same time, the cost and size of the components needed began to decrease. More and more consumer goods incorporated the use of electronics, which led to a high demand in reducing – even more – the costs of manufacturing and the sizes of the electronic products. In turn, manufacturers had to find better and more effective solutions. This is when printed circuit boards were born.
A PCB is a board with pads and lines that connect different points to each other. There are traces in the board that connect different components and connectors to each other via electricity. The PCB lets power and signals to be routed through various physical devices. The metal that creates these electrical connections on the PCB’s surface and in other components is called “solder”. Because it is a metal, it is also an efficient and durable mechanical adhesive.
Think of printed circuit boards like an electronic type of lasagna or layered cake. It has various materials layered in alternating fashion, laminated together using adhesives and heat. In order to understand how it works, it’d help by knowing the layers in a common board.
The following are the layers of PCBs, starting from the inside out:
The PCB’s substrate or base material is commonly fiberglass. FR4 is the most common designator for this material. It makes for a solid core, giving the board great thickness and rigidity.
A thin copper foil forms the next layer. It is laminated to the PCB using adhesive and heat. Double-sided PCBs have copper on both of the substrate’s sides. Cheaper gadgets may have copper on just one side. There can be as few as one or as many as 16 layers in the PCB.
The soldermask is the layer found on top of the copper layer. It gives the board its signature green color (although some manufacturers have begun creating other colors). The layer is overlaid onto the copper foil so that it can serve as insulation to the copper traces, in case accidental contact with solder, metals or conductive bits take place. The soldermask helps in soldering at the right places and in avoiding solder jumpers.
On top of the soldermask layer is a white silkscreen layer. This one adds the numbers, letters and symbols seen on the board. These are essential for easier assembly. Users understand the board better, too, using these indicators. Silkscreen labels are commonly used to indicate the function of each LED or pin on the board.
By learning the fundamental composition and functions of PCB parts, it’s easier to understand the way they work – and even more helpful in trying to solve any possible problems like malfunctions and defects.