Printed circuit boards are everywhere! You probably use one more often than you might think. But what exactly are they and how do they work? Printed circuit boards, more commonly referred to as PCBs, are thin boards made from an insulating material, with a coated metal surface, sometimes on both the top and bottom. Small etches are created in the metal, which allow pathways and various metal components for electricity to travel through various components. These are mounted on the board with solder. But just because PCBs are found virtually everywhere doesn’t mean you’re the PCB expert! Here are a few interesting facts about PCBs that you probably didn’t know!
- Their green color.
The majority of PCBs are an iconic, dark green color. Why? The green you see is actually the soldermask that is showing through the glass, not the color of the PCB itself. While no one knows for certain where the use of green came from, there are a few theories.
The American military initially used PCBs. Therefore, some people speculate that green was regulation standard when being used by the military, and has spread from there. Others think that green could have been the color of the residue from the original soldermask that was used to create PCBs. We continue to use green as a matter of convention, even though the original materials are not still used today. The third theory that some people believe is that the color green makes it easy for engineers to find faults in the traces, so many companies tend to prefer green to other colors. But modern PCBs can be made in almost any color!
- It was invented by an Austrian!
Paul Eisler, an Austrian inventor, is credited with the invention of the PCB. However, even though Eisler is given credit for the invention, development that ultimately led to the invention dates as far back as the 1890s. In 1936, Eisler was working on a radio when he first invented the PCB. They didn’t really take off and see mass usage until the 1950s, but their popularity has grown significantly from there!
- They are everywhere!
Today, pretty much every electronic appliance that you use on a regular basis contains a PCB of some type. Computers, printers, cell phones, digital clocks, microwaves, televisions, stereos—the list goes on! PCBs are so common, that you probably don’t even realize that you are using a device with one most of the time!
- Tracers, not wires.
Most electronic devices are composed of wires, as a means of transmitting energy from one component to another. However, PCBs are different. PCBs use copper tracers instead of wires to transmit energy. This allows PCBs to be a lot smaller, because tracers take up less space.
- Designed using CAD.
Before PCBs are physically made, they are designed using computer aided design (CAD) software. CAD software prepares the specific layout data for the prototype PCBs. This allows the board to be tested, and to check that all of the tracers are properly connected. CAD programs are used to design not only the layout of the PCB, but also the schematics of the board.
- Several components.
PCBs are made up of several components, probably more than you ever imagined! Each component of a PCB has their own individual properties, including resistors, potentiometers, capacitors, inductors, relays, batteries, ruses, and transformers, to name a few!
- Can be personalized.
PCBs can be fully customized to fit whatever specifications you need. However, fully customizing a PCB can be very costly to ensure that every aspect is customized to your specific requirements.
- Technology is always changing!
Since the first PCB was invented in 1936, PCBs have changed immensely. Modern PCBs are smaller, faster, and more efficient to build. The technology that goes into building PCBs is ever changing. PCBs are just getting better and better!
- Getting smaller?
With the advent of smaller and smaller electronics, PCBs have had to keep up by becoming smaller as well. Surface mount PCBs can be up to 1/10 the size of through-hole circuits.
- Ohm’s law.
PCBs are strictly governed by physics. Electrical engineers must keep Ohm’s Law in mind when designing a PCB. This law dictates the relationship between current, resistance, and voltage. In other words, Ohm’s Law is the principle that electrical current is proportional to voltage, and inversely proportional to resistance. The different laws of physics strictly dictate the ways in which prototype PCBs can be designed and built.