Electronics fuel the modern world, and at the heart of these devices is the printed circuit board (PCB). Whether you realize it or not, you may use dozens of PCBs a day. These tiny technologies are everywhere, and just as there are countless different gadgets, there are several different types of circuit boards. Whether you’re pursuing a career in electrical engineering or just like electronics, you may want to know these different types. It would take forever to run through every single option, but here are a few of the most common PCBs.
As the name implies, single-sided PCBs are those with all of their electrical components on one side. These boards only use a single layer of base material, called a substrate. The side with the electrical components has a thin layer of conductive metal, usually copper. These boards are inexpensive but have limited functionality. Because of this, you’ll find them in cheaper devices like calculators or simple radios.
A double-sided PCB is similar to if you took two single-sided boards and attached them back-to-back. A layer of substrate is in the middle with conductive layers and electrical components on the top and bottom. Small holes called vias go through the substrate to connect the conductive layers.
Double-sided PCBs can do more work at once, but having conductive layers on both sides can make them tricky to handle. You can find these boards in everything from hard drives to vending machines.
Some circuit boards have far more than just two or three layers. Multilayer PCBs can have dozens of different layers, but most only have a few. Layers of substrate separate the conductive ones. Because they can handle numerous tasks at once, multilayer PCBs find use in complex machinery. Satellites, medical equipment and servers in hi-tech data centers all typically use these types of circuit boards.
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Layer count isn’t the only way you can distinguish between different circuit boards. PCBs also come in varying degrees of flexibility. What you probably think of when you hear circuit board is a rigid component. Unsurprisingly, a rigid PCB is stiff, unmoving material, usually fiberglass, and they tend to have longer lifespans due to their strength. Computer motherboards are a common example of these PCBs.
A flex PCB is effectively the opposite of a rigid one. Instead of fiberglass, these boards use flexible plastic materials like a polyester film as a substrate. This pliability offers greater versatility and less weight at the cost of a higher price tag. Just like their rigid counterparts, flex PCBs can be single-sided, double-sided or multilayer. You can see these PCBs in both computer keyboards and TVs.
Rigid-flex PCBs combine both rigid and flexible circuit boards. The most basic example is two rigid PCBs connected by a flex one. As you can imagine, these boards are more expensive and complicated than other types, but they’re also more versatile.
These PCBs offer the reliability of rigid boards with the convenience and weight reduction of flexible ones. You’ll find rigid-flex PCBs in a growing number of applications, from pacemakers to cell phones to cars.
High-Density Interconnect PCBs
People define some newer forms of circuit boards by their functionality. High-density interconnect (HDI) PCBs offer more wiring in the same area, meaning smaller boards can do more. These boards weren’t possible until advanced, highly precise manufacturing techniques came along.
All of the electrical components in an HDI PCB are smaller, so more of them fit in a tighter area. HDI PCBs allow you to do complex tasks with tiny devices. You use them whenever you use a modern video game controller or your smartphone.
Sometimes you need to get a job done as quickly as possible — that’s where high-frequency PCBs come in. These circuit boards use hi-tech substrate materials like Teflon to handle frequencies over one gigahertz without overheating.
These types of circuit boards are ideal for devices that require speedy signal transmissions, such as radar systems and GPS receivers. As the demand for faster electronics grows, high-frequency PCBs have become more common.
Choosing Between Different Types of Circuit Boards
When picking a PCB, there’s a lot to consider. A large electronics company may be able to afford to produce high-frequency, rigid-flex HDI PCBs comfortably, but the same probably isn’t true for an electronics hobbyist. On top of the needed function, you have to think about how complex or expensive it might be to design and build a PCB.
The most technologically-advanced boards may offer more functionality, but they’re not always necessary. Just because people can do more with PCBs than they used to doesn’t mean they have to.
Circuit boards today are far more varied and useful than their dated counterparts. The next time you use any electronic gadget or appliance, think of all the thought that went into something as small as its PCB.