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Rigid PCB 15 Things We Should Know

A printed circuit board (PCB) electrically connects and mechanically supports electronic parts using conductive pathways, signal traces, or tracks etched from a single or multiple sheet layers of copper, laminated onto a non-conductive substrate. Most modern electronic devices have them as their foundational building block. PCBs can be used in various things such as circuit boards used in servers and computers, a smartwatch, and a garage door opener. Essentially, every electronic component is assembled on a PCB. There are different kinds of PCBs, flexible PCB, rigid PCB, and rigid-flexible PCB.

About 90% of PCBs that are manufactured worldwide are rigid. A rigid PCB cannot be folded or twisted, unlike a flexible PCB. Usually, the board’s base material is made from a rigid substrate, giving strength and rigidity to the board, for instance, a computer motherboard. A rigid-PCB consists of copper paths and trances incorporated on one board to connect the various components on the board.

Once manufactured, they cannot be folded or altered into a different shape. They are the conventional types of PCBs and are much cheaper than flexible ones. It is also worth noting that the project you are doing will determine whether you need to use 1 layer PCB, 2 layer PCB, four-layer PCB, or six layers , 8 layers PCB. 1 or 2 layer PCB are usually used in more simple devices. In contrast, multi-layered ones are used in more complex devices.

Rigid PCBs are made up of multiple layers that are put together using heat and adhesive, which gives the board material a solid shape. The layers used to develop a rigid-PCB include substrate layer, copper layer, solder mask layer, and silkscreen layer. Its auto-assembly process was invented by the US Army, specifically the army signal corps. The PCB auto-assembly process ensures that their creation is faster. The stream-lined production of PCBs is the leading cause of all the consumer products we currently have. Listed below are 15 things we should know about rigid-PCB.

01 Invention

Paul Eisler is an Austrian inventor who is accredited with the invention of PCBs in 1936. Although, note that the development that led to the invention can be traced back to the 1890s. The first-ever PCB was developed by Eisler when he was working on a radio set in 1936. Eisler had learned about printing technology, but he wanted to learn the possibility of using the printing process to lay down all the elements in an insulating base instead of using wires to connect them manually.

Even after his discovery, their mass usage did not start until after the 1950s, from which their popularity grew primarily. They are now used in multiple applications such as automotive, aerospace, medical, and industrial electronics and automation. They are also used in just about every device you own, your smartwatch, tablet, laptop, and mobile phone.

It is worth mentioning that a music printing company funded the first PCB. Eisler used to work in a music printing company. So when he came up with his invention, he shared the idea with the music company who agreed to bankroll his idea. This made it the first-ever PCB, and this first PCB is the reason we currently produce multiple different PCBs.

02 Their Green Color

You must have probably noticed that a lot of PCBs are usually green in color. It is worth noting that a PCB board is brown and not green. The dark green color you see is the solder mask’s color showing through the glass. Green is the standard solder mask color, but the solder mask does not have to be green. There are multiple theories about why the solder mask is green. However, its origin remains undetermined.

Some of the green color theories are that the green color was the original color of solder mask resins. Hence, people just kept using it because it was the conventional color used, even though these materials are no longer used. Some say that the human eye responds significantly to the color green, and besides, at the time, the laminates were green, so that is the color incorporated into every PCB. Others speculate that it was based on the military’s requirements and somehow just became a familiar concept from thence.

As mentioned earlier, a solder mask does not have to be green in color. In modern circuits, you can use any color of solder mask you would like to use. Green has been used conventionally and has worked exceptionally well. It is also worth noting that the green color makes it much easier for engineers to detect any faults in the traces. Therefore, most companies prefer to stick to working with the green color.

03 Their Design

PCBs are designed using computer-aided design (CAD). Technicians usually use CAD to design the layout and the schematic of the PCB. Using a CAD allows them to test the board’s design and check to confirm that all the traces are rightly connected before they can physically make the PCB.

Once the technicians have confirmed that the positions and traces of the corresponding parts are where they ought to be and there are no errors, they will use the layout to manufacture the PCB. There are multiple PCB services you could look into if you are planning to design a PCB. There is multiple software that you can select from to design your PCB.

04 Their Application

You may not be fully aware of this, but rigid PCBs are just about everywhere. As mentioned earlier, the majority prefer to use rigid PCBs. When you think about it, they are just about everywhere and probably within your reach or in your grip at this moment. Almost every device available uses a rigid-PCB. The laptop, tablet, or mobile phone you are currently using to read our article probably has a rigid-PCB.

Every electrical device uses a PCB because it can be used in different types of applications. It also saves space and energy. They have become and are an intrinsic aspect of modern technology. No other creation may be replacing PCBs soon, seeing as they are constantly evolving. For instance, rigid PCBs are conventionally used PCBs. Still, improvements have been made to them over the years, from having a single layer PCB to a multi-layered PCB and having different types of PCBs like the flexible PCB.

05 Traces

Most individuals assume that all electronic devices usually use wires to transmit energy. This may be true in certain instances, but this convention does not apply to PCBs. PCBs do not use wire for transmission. Instead, they use copper traces in transporting electrons. Since PCBs use copper traces instead of wires, they are much smaller because the flat traces occupy very minimal space. This also translates to through-hole technology that can be used to make PCBs because copper can transfer quickly through a hole in the circuit board.

It is pretty fascinating how PCBs do not need wires, as most technologies and electrical devices have to use wiring. The copper traces in PCBs allow them to connect all the components. Wiring can limit your design since it takes up so much space, but you no longer have to worry about that. As mentioned earlier, PCBs take very minimal space, and you can use them to make very complex boards.

06 Surface Mount Technology

Surface mount technology (SMT) is one of the most popular manufacturing techniques for modern PCBs. This technique started being used widely in the 1980s and replaced the through-hole method, which was its predecessor, quickly. The through-hole method used to be relatively slow and involved many errors whenever it was used. For instance, when the through-hole method was used, the parts had to be inserted into holes to attach them to the board. However, with the SMT method, these parts are instead glued onto the pads on the PCB surface, making it much more efficient.

SMT has multiple advantages. The main ones are reduced weight and smaller size since the elements will be closely aligned, meaning the end products are more lightweight and compact. They are also more affordable, flexible, have higher circuit speeds, lower resistance, allow multitasking, and are much more stable. SMT is hands down the better alternative since it uses automatic machinery to attach the parts to the PCB.

07 Silkscreens

The silkscreen layer is usually on top of the solder mask layer. A silkscreen layer is usually used to add a symbol or characters to the board, providing an understanding of the board. The most common color used for silkscreens is usually white, but you can use other colors such as yellow, black, red, and grey.

When you look at a PCB, you will often notice small white etchings on top of the solder mask, and those are what are referred to as silkscreens.
Silkscreens are usually used on the circuit board’s element side to identify PCB information and components. The name silkscreen is derived from the fact that the white components are usually silk screen printed. However, it is also common for them to be printed by ink-jet printers.

08 Multiple Other Components Are Involved

There are a lot of components on PCBs than you can imagine possible. What is even more fascinating is that all these components have their unique properties. For instance, some of the components include:
Transistors usually amplify the charge.
Diodes only allow the current to pass in a single direction while blocking the other.
Batteries provide the circuit with voltage.
Inductors usually store charge and also change and stop in current.
Capacitors usually harbor electrical charge.
Resistors often control the electric current passing through them, and they are color-coded to ascertain their value.
Switches usually block or allow current depending on whether they are open or closed.
Light-emitting diode or LEDs usually light up when current flows through them and only allow the current to flow in a single direction.

The above listed are some of the main components found on PCBs. However, there are so much more components found in PCBs, including but not limited to transistors, transformers, and potentiometers. PCBs are pretty complex, and without a specific component, a PCB may not function since they all contribute to the overall functioning of a PCB. All these multiple components are essential.

09 Size

PCBs are getting smaller. As time goes by and technology keeps evolving, developers are under pressure to make smaller electronics. The smaller an electronic gets, the smaller the PCB also has to be since the size of an electronic directly impacts the size of a PCB. For instance, the size of a PCB on a smartwatch is not similar to that on a laptop.

With every advancement made in technology and every improvement being made, PCBs will keep getting much smaller. It is also worth noting that PCBs are now about a tenth of the through-hole circuits’ size. Their reduction is because developers would like to save more space and the fact that the devices we are using have become much smaller, more compact, and lightweight. As time goes by, the trend will keep going since the goal is to get more work done in a brief form.

10 Rigid PCBs are Evolving

As with everything else, PCBs are evolving. The current rigid PCBs cannot be compared to those used back in the 1980s. So many changes have been made, and they have also evolved. For instance, one of the notable features, as mentioned earlier, is that PCBs are getting much smaller. The current PCBs we have cannot be compared to what Eisler had in 1936.

Other than being so much smaller, it is also that much more efficient to build them, and they are faster. PCB technology will keep evolving. Another notable thing is that when designing a PCB now, you can choose to have a rigid-PCB, a flexible PCB, or a rigid-flexible PCB depending on the kind of PCB your project requires and the functionality you would like to have.

It is also worth noting that scientists are currently working on making biodegradable PCBs to avoid contributing to environmental pollution. The way our electronics function can also be changed by the development of the ‘graphene’ material. Rigid PCBs will keep advancing with every technological advancement that is made. They are that much more reliable now and are also that much easy to repair now.

11 Personalization

Another notable thing we need to know about rigid PCBs is that they can be personalized. Multiple companies make PCBs, and as mentioned earlier, there are different software you can use to make a PCB. You can also order a PCB and have everything customized to your liking. For instance, some companies make circuit boards based on a client’s order. Therefore, if you would like a PCB, you need to contact them and place your order. You are at liberty to make an order that suits the specification that will best suit your needs.

However, it is worth noting that every PCB does not have to be made to a specific specification. As with almost everything bespoke, custom order PCBs tend to cost so much more than regular PCBs. Luckily for you, you do not have to worry about incurring these expensive charges. Because you can specify the majority of PCBs purchased within specific parameters offered by the company, you are buying from. When you buy PCBs with standardized specifications, the cost will be much lower.

12 Laws Guide PCBs

Physics rules strictly govern PCBs. For instance, among electrical engineers, the most popular physics law they use is Ohm’s law. This law dictates how voltage, current, and resistance relate. The principle states that the electrical current is inversely proportional to resistance and proportional to the voltage.

Therefore, these laws command how we can build and design our PCBs, meaning that an electrical engineer or developer must have an excellent understanding of these laws and their implications. Anyone without a good understanding of these laws cannot design a fully functional PCB. All the parts in a PCB work hand in hand with each other, so without a proper understanding of the laws, you cannot assemble them to correspond with each other.

Another law that can be applied in the making a PCB is Kirchhoff’s law, especially when the application is straightforward. Although often, when designing a PCB, we tend to overlook Kirchhoff’s law, more specifically regarding current densities. PCBs can only hold a specific amount of current before they heat up. Note that excessive heat often results in broken traces.

The copper’s thickness and width will determine the capacity of current the PCB trace can carry. Kirchhoff’s law dictates that the total sum of current going through a node should equal zero, meaning that the PCB trace carrying the combined current should have a large enough width to prevent the build-up of heat.

13 Various Types of PCBs

As mentioned earlier, there are various types of PCBs. The constant evolution of PCBs is what has made this possible. Technological advancements have also made it easy for different types of PCBs to be made. There are various types of PCBs, and they all function differently. Each rigid-PCB has specific properties that make it suitable and the best choice to perform a specific task. That is why we are at liberty to have a personalized PCB to cater to a particular need or be used in a specific application we may have.

Certain PCBs are best suited for low-performance devices, meaning they are easier and cheaper to manufacture. On the other hand, we also have PCBs meant for high-performance devices, which are more expensive to produce. Some of the different PCBs include single-sided PCBs, multi-layered PBCs, double-sided PCBs, rigid PCBs, and aluminum-backed PCBs.

14 Space Travel

PCBs are used in different applications, and perhaps the most fascinating of all is space travel. They are an essential part of space travel. Note that prototype PCBs and mass-produced PCBs are both lightweight and need very minimal electricity. They are the best option in close quarters for complex electronics, which is what a spacecraft needs. PCBs helped get the astronauts of Apollo 11 to the moon and back safely, making them an intrinsic part of NASA’s space program.

It is also worth noting that the aerospace industry comprises both challenging and high-temperature environments. Therefore, a rigid-PCB is essential in this industry. Rigid PCBs can be made using high-temperature laminates and aluminum and copper substrates. Some aerospace applications include controlling lower instrumentation systems, temperature sensors, power converters, airplane cockpit instrumentation, and auxiliary power units.

This is why it is also vital for engineers to know how the different laws affect PCBs’ overall design and functionality. It is also worth noting that while a rigid PCB can be used in different applications, the overall design may differ based on the function it is expected to perform in the application. For instance, a PCB used in aerospace has a significant difference from one used in medical applications.

15 Gramophones Had PCBs

In the early and mid-1900s, PCBs were already around. These PCBs were used in some tube radios and gramophones. It is worth mentioning that the PCBs used during that period do not look like the PCBs we are currently producing. However, it is those PCBs that have led to the PCBs we currently have. The current ones are more advanced, much smaller in size, and will probably get even smaller, easy to repair, and are more efficient. Without the initial PCB, you probably would not be reading this article from your phone, laptop, desktop, or tablet.

Summary

There are multiple other fascinating facts about PCBs worth noting, but we found the above listed more vital to mention. You had probably never thought about the multiple components working together to ensure that your smartwatch is fully functional or that different printed circuit boards are used in the different applications based on the speed and efficiency of a device.

It is easier to order a personalized circuit board when you are well aware of how they function because then you can easily state the specifications you would like your PCB to have. Remember that despite the various technological advancements we see now, most of them are not new. They are simply improvements and advancements of an old invention. The smartphone you are using now has a very long and significant history that dates back in time. Other than rigid PCBs, various other PCBs cover the entire spectrum. Whatever you are looking for and whatever application you need a PCB for, you are covered from the superficial one layer to multiple-layer circuit boards.

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