Top 10 Applications for PCBs

Printed circuit boards, or PCBs, are key components of electronic components. Most people use them every day without even thinking about it, and they are critical to a wide variety of industries. There are a massive number of applications for PCBs, but we’ll cover 10 of the most common printed circuit board uses.

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What Is A Printed Circuit Board Used For?

PCBs are boards that connect electronic components. They’re an integral part of the electronics we use in our everyday lives across a wide range of industries. They are made of a non-conductive material and have lines, pads and other features etched from copper sheets that electrically connect the electronic components within a product. Components such as capacitors and resistors are also soldered onto some PCBs.

Today, the use of PCBs in electronics is widespread and there are various types of PCBs. They can be single-sided, double-sided or multilayer. They can be rigid, flexible or contain both rigid and flexible parts.

Types of Assembly Processes

There are two main methods used for PCB applications — thru-hole and surface mount.
1. Thru-Hole Mounting
In the thru-hole mounting process, the assembler places component leads into holes drilled into a bare PCB. This technology was the original one used for PCBs.

Thru-hole technology creates a stronger connection than surface mount technology does, so it’s used for applications that require high reliability. This is because the leads run all the way through the board, as opposed to being attached with solder as in surface mounting. Thru-hole technology is also useful for testing and prototyping applications that require manual adjustments of components.
2. Surface Mounting
In the surface mounting process, components are mounted directly to the PCB surface using solder. This method was developed in the s and became popular starting in the s. Today, it is the most commonly used component mounting method. Surface mount boards use small components called vias, rather than thru-hole components, to connect the various layers of the PCB.

Using surface mounting allows the assembler to attach components to both sides of the board. Surface mounted components can also be smaller, enabling more parts to fit on a single board. This reduces costs and has allowed electronic devices to get smaller and smaller over the years. Surface mounting can also be completed faster and is a less involved process than thru-hole mounting is, further reducing costs.

What Are Common Uses for PCBs?

Because so many different sectors use PCBs, you can find them almost everywhere in everything from small consumer devices to huge pieces of machinery. Where are printed circuit boards used? Here are 10 of the most common PCB applications by industry.

1. Medical Devices

The healthcare sector is using growing numbers of PCBs as technologies advance, revealing new capabilities. PCBs play a role in devices used for diagnostics, monitoring, treatment and more.

Special attention must be paid to ensuring reliability when producing medical PCBs because proper functioning can be critical to patient health. In many cases, PCBs must also meet strict standards for sanitation, especially those used for implants. Boards used for implants and many other applications, such as emergency room monitors, must also be relatively small. Because of this, many medical PCBs are high-density interconnect, or HDI.

PCBs are used for medical devices such as:

• Medical imaging systems: CT, CAT and ultrasonic scanners often use PCBs, as do the computers that compile and analyze these images.
• Monitors: Heart rate, blood pressure, blood glucose monitors and more depend on electronic components to obtain accurate readings.
• Infusion pumps: Infusion pumps, such as insulin and patient-controlled analgesia pumps, deliver precise amounts of a fluid to a patient. PCBs help ensure these products function reliably and accurately.
• Internal devices: Pacemakers and other devices that are used internally require small PCBs to function.

The medical sector is continually coming up with more uses for electronics. As technology improves and smaller, denser, more reliable boards become possible, PCBs will play an increasingly important role in healthcare.

2. LEDs

Light-emitting diodes, or LEDs, are an increasingly popular lighting technology used for residential and commercial lighting and across numerous industries including the automotive, medical and computer technology sectors. LEDs are favored for their energy efficiency, long life and compactness.

One role that PCBs play in LED applications is the transfer of heat away from the bulb. High temperatures decrease the average life of LEDs. Because of this, PCBs used for LEDs are typically made with aluminum, which can transfer heat better than other metals. This eliminates the need for an additional heat sink to a design and means it can be more compact.

You can find LED PCBs in:

• Residential lighting: LED lighting, including smart bulbs, help homeowners light their property more efficiently.
• Storefront lighting: Businesses can use LEDs for signage and to light their stores.
• Automotive displays: Dashboard indicators, headlights, brake lights and more may use LED PCBs.
• Computer displays: LED PCBs power many indicators and displays on laptop and desktop computers.
• Medical lighting: LEDs provide bright light and give off little heat, making them ideal for medical applications, especially those related to surgery and emergency medicine.

LEDs are becoming increasingly common in a variety of applications, meaning PCBs will likely continue to play a more prominent role in lighting.

3. Consumer Electronics

Smartphones, computers and the many other consumer products that people use daily require PCBs to function. As we add electronics to more of our products, PCBs become a bigger part of our daily lives.
Manufacturers are producing smaller and smaller smartphones and laptops that still have many advanced capabilities, which require small PCBs with a high volume of connections. PCBs used for consumer electronics also need to be relatively low-cost to keep the price of the final product low. Manufacturers also want reliable boards, because they need their products to function as expected to stay in business.

A huge range of consumer products use PCBs including:

• Communications devices: Smartphones, tablets, smartwatches, radios and other communications products require PCBs to function.
• Computers: Computers for both personal and business feature PCBs.
  Entertainment systems: Entertainment-related products such as televisions, stereos and video game consoles all rely on PCBs.
• Home appliances: Many home appliances also have electronic components and PCBs including refrigerators, microwaves and coffee makers.

The use of PCBs in consumer products is certainly not slowing down. The proportion of Americans who own a smartphone is now 77 percent and growing. M

any devices that weren’t electronic before are now also gaining advanced electronic functionality and becoming part of the Internet of Things (IoT).

4. Industrial Equipment

Printed circuit board uses in the industrial sector vary widely. Electronic components power much of the equipment in manufacturing and distribution centers as well as other types of industrial facilities.
The PCBs used in the industrial sector often need to be especially high-powered and be durable enough to withstand the harsh conditions that exist in industrial facilities. PCBs may need to be resistant to rough handling, vibrating machinery, extreme temperatures or harsh chemicals. To meet this need for durability, industrial PCBs may be made with durable metals or thermal-resistant materials and be thicker than other kinds of PCBs. Industrial PCB assembly services may include thru-hole technology to increase durability.

Some of the industrial applications for PCBs include:

• Manufacturing equipment: PCB-based electronics power electric drills and presses used in manufacturing.
• Power equipment: The components that power many types of industrial equipment use PCBs. This power equipment includes DC-to-AC power inverters, solar power cogeneration equipment and more.
• Measuring equipment: PCBs often power equipment that measures and controls pressure, temperature and other factors.

As robotics, industrial IoT tech and other types of advanced technology become more common, new uses for PCBs are arising in the industrial sector.

5. Automotive Components

Automotive manufacturers are using growing numbers of electronic components in their vehicles. In earlier times, PCBs were only used for things like windshield wipers and headlight switches, but today they enable many advanced features that make driving safer and easier.

Depending on what part of the car a PCB is used for, it may need to be able to withstand extreme temperatures or vibrations. It’s also critical that they perform reliably if involved in a safety feature of the car. Because of these challenges, manufacturers may use high-temperature laminates, aluminum or copper substrates, or thru-hole mounted components. They also use flex-rigid PCBs because of their ability to withstand vibrations.

Today, you can find PCBs in automotive components such as:

• Entertainment and navigation systems: Stereos and systems that integrate navigation and entertainment rely on PCBs.
• Control systems: Many systems that control the basic functions of the car rely on electronics powered by PCBs. These include engine management systems and fuel regulators.
• Sensors: As cars become more advanced, manufacturers are incorporating more and more sensors. These sensors can monitor blind spots and warn drivers of nearby objects. PCBs are also necessary for the systems that enable cars to automatically parallel park.

These sensors are part of what enable cars to be self-driving. Fully autonomous vehicles are expected to become common in the future which is why a large number of printed circuit boards are used.

6. Aerospace Components

The electronics used in aerospace applications have similar requirements to those used in the automotive sector, but aerospace PCBs may be exposed to even harsher conditions. PCBs may be used in a variety of aerospace equipment including planes, space shuttles, satellites and radio communications systems.

Aerospace PCB manufacturing requires using materials that can withstand high amounts of vibration, extreme temperatures and other harsh conditions. Some aerospace PCBs even need to be able to perform in outer space and must be extremely durable. Boards made with lightweight materials such as aluminum are also beneficial for use in aerospace. Anodized aluminum may be used to increase resistance to oxidation.

Some uses for PCBs in the aerospace sector include:

• Power supplies: PCBs are a key component in the equipment that powers a variety of aircraft, control tower, satellite and other systems.
• Monitoring equipment: Pilots use various kinds of monitoring equipment, including accelerometers and pressure sensors, to monitor the function of the aircraft. These monitors often use PCBs.
• Communication equipment: Communication with ground control is a vital part of ensuring safe air travel. These critical systems rely on PCBs.

7. Maritime Applications

All sorts of marine vessels and systems rely on PCBs to function. This includes small vessels, large cargo ships, submarines, communications systems and navigation equipment.

PCBs used for maritime applications must also be able to withstand harsh conditions. Manufacturers of maritime PCBs emphasize reliability as it’s essential for the safety of the crew and passengers that electronic equipment works correctly.

• Navigation systems:Many maritime vessels rely on PCBs for their navigation systems. You can find PCBs in GPS and radar systems as well as other equipment.
• Communications systems: The radio systems that crews use to communicate with ports and other ships require PCBs.
• Control systems: Many of the control systems in maritime vessels, including engine management systems, power distribution systems and autopilot systems, use PCBs. These autopilot systems may help with boat stabilization, maneuvering, minimizing heading error and managing rudder activity.

8. Safety and Security Equipment

Many aspects of security systems, whether for homes, businesses or government buildings, rely on PCBs. They play a role in our safety and security more often than many people realize.

The ideal type of PCB depends on its specific application, but all PCBs used for safety and security applications need to be reliable because these products must operate as expected at all times to be effective. Some security devices may be used outdoors and should use PCBs that can withstand outdoor environments.

Some safety and security devices that use PCBs include:

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• Security cameras: Security cameras, whether used indoors or outdoors, rely on PCBs, as does equipment used to monitor security footage.
• Smoke detectors: Smoke detectors as well as other similar devices, such as carbon monoxide detectors, need reliable PCBs to function.
• Electronic door locks: Modern electronic door locks also incorporate PCBs.
  Motion sensors and burglar alarms: Security sensors that detect motion rely on PCBs as well.

PCBs play an essential role in many different types of security equipment, especially as more of these types of products are gaining the ability to connect to the Internet.

9. Telecommunications Equipment

PCBs are a critical part of the telecommunications industry. They’re necessary for consumer devices such as smartphones but also for the infrastructure that enables those devices to work.

The telecom sector uses a wide variety of types of PCBs because of the many different types of equipment used in the industry. Some equipment is kept in stable indoor environments, while some infrastructure must withstand outdoor environments that include storms and extreme temperatures.

Telecom equipment such as the following requires PCBs:

• Telecom towers: Cell towers receive and transmit signals from cell phones and require PCBs that can withstand outdoor environments.
• Office communications equipment: Much of the communication equipment you might find in an office requires PCBs, including switching systems, modems, routers and Voice over Internet Protocol (VoIP) devices.
• LED displays and indicators: Telecom equipment often includes LED displays and indicators, which utilize PCBs.

The telecom industry is constantly evolving, and so are the PCBs the sector uses. As we generate and transfer more data, powerful PCBs will become even more important for communications.

10. Military and Defense Applications

The military uses PCBs for a wide range of applications, including communications equipment, computers, vehicles, firearms and more.

PCBs used for military applications must be exceptionally reliable and durable. They may be exposed to extreme conditions, and they could play a role in national security. The military uses materials such as high-temperature laminates, aluminum and copper because of their ability to withstand harsh conditions such as high temperatures. Anodized aluminum may be used because of its resistance to oxidation. Some military printed circuit board applications may also benefit from the enhanced reliability of thru-hole technology.

Some military and defense uses of PCBs include:

• Communications equipment: Radio communication systems and other critical communications require PCBs to function.
• Control systems: PCBs are at the center of the control systems for various types of equipment including radar jamming systems, missile detection systems and more.
• Instrumentation: PCBs enable indicators that members of the military use to monitor threats, conduct military operations and operate equipment.

The military is often at the cutting edge of technology, so some of the most advanced uses of PCBs are for military and defense applications. The uses of PCBs in the military vary widely.

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Digital PCB technology has come a long way in the field of Electronics, as innovations and developments fulfil the demands for faster, smaller and cheaper electronics devices and gadgets. Digital PCBs consist of several microprocessors and other electronic circuitry which have the capability to manage thousands of operations each second. When compared to analog circuit boards, digital PCBs come with a number of improvements, the major ones being better impedance matching and improved insertion loss control of transmission lines. 

Source - ak.picdn.net

It is very important for digital PCBs to be carefully designed and engineered in order to eliminate problems like impedance discontinuities in transmission lines, improper plating of the through-hole interconnections, and other signal-integrity-related issues. Digital PCBs have a number of features that give them an upper hand during the functioning of an electronic circuit. Some of these features are:

• High layer count
• Tight dimensional tolerances 
• Stub elimination
• High packaging density
• Complex stack-up structure, and more

Difference between Analog and Digital PCBs

There are various similarities and differences when it comes to analog and digital routing in PCBs in terms of bypass capacitors, power supply, ground design, voltage errors, electromagnetic interference (EMI), etc caused by PCB board routing.  

Fig 1:-Analog and Digital signals

Source- Proto-Electronics

Analog circuits consist of a combination of Op-Amps, resistors, capacitors, and other electronic components used on a PCB. These combinations of various components forming an analog circuit can vary in different manners. The main two applications of analog circuits are:

1. Filtering signals: In the case of a continuous signal, a continuous analog filter is needed to remove all the unrequired frequencies from the circuit. As compared to a digital filter, analog filtering applications are much easier and more economical.

2. Sensors: Converting adaptable real-world data into information that is recognizable by an embedded system or a computer is done with the help of sensors. If data is not available, sensors create an analog signal and convert it into digital signals. These systems have low amplitude and need signal conditioning in order to increase the quality of the signal to better utilize the full range of an ADC, unlike high voltage systems.

On the other hand, digital circuits consist of a combination of logical and sequential components by making use of logic gates that work on digital signals. When compared to analog circuits, digital signals operate on the logic of 0’s and 1’s to represent data in a digital form on a single IC.

Criteria for selection of PCB materials for Digital circuits

There are certain factors that should be taken into consideration while selecting materials for digital PCBs. Some of them include 

1. Dimensional tolerance stability: The digital PCB must-have materials that will provide flawless mechanical stability while going through different temperature stability, vibrations, shocks, and electrical surges.
   
2. Superior thermal management: The materials must have the capacity to provide excellent heat transfer and heat dissipation, and must ensure the layers do not decompose, delaminate or start to peel away at higher frequencies
   
3. Enhanced signal performance: During the functioning of the circuit, the signal performance should be constant throughout the PCB with minimal signal losses even during frequency variations. Designers must make sure that the selected materials have a low dielectric loss factor (Df) to ensure that losses do not take place.
   
4. Tight impedance control: Digital PCBs will require tight control of impedance routing as they will have to maintain a stable dielectric constant (Dk) during high-speed operations.
   
5. Moisture and chemical resistance: Materials that have a low absorption rate of moisture and chemicals must be selected so that there will be minimal variations in the desired electrical performance in the PCB.

Digital PCB materials

The foundation or the base of a PCB antenna consists of a substrate and a laminate, which also determines the performance of the PCB. Qualities such as function, longevity, and cost efficiency should be kept as a priority while designing a PCB, hence selecting the proper type of PCB material is critical. The material that one considers while designing a PCB can have a short-term or long-term effect on the performance. The pricing of a PCB material is directly proportional to the performance of the PCB. When the high performance of a PCB is not essential, a material named lightweight polyester can be considered as it comes with a low cost and good versatility

While selecting the materials, the temperature is a parameter that must be considered. The heat resistance should be higher than the heat produced as due to surplus heat a circuit may fail. Tg (glass transition temperature) is when PCB loses its rigidity and ability to perform well. Tg should match the assembly process being used, as a Tg with a minimum of 170° C is recommended for lead-free assembly. For a high-performance PCB, Tg should be higher than 170°C whereas a standard PCB has a Tg of 130°C. The advantage of having a high Tg is that there is a great ability to resist chemicals and moisture.

Materials generally used in PCB substrates range from FR-1 and G-10 to PTFE. Laminates are formulated from CTE, PTFE, CEM, and various other compounds.

• FR-4: FR stands for “flame retardant” and it is widely used in standard boards. It comes with two Tg points, the first is 135°C and the second is 150°C-210°C which is applicable for high-density uses.
  
• G-10: It is a high-pressure fiberglass laminate. G-10 and FR-4 are used as an insulator for electrical and electronic application.
  
• PFTE (Polytetrafluoroethylene): PFTE can be a good choice in high-frequency, microwave, and high power boards as it comes with a Tg of  160°C and 280°C.
  
• CEM-1, CEM-2, and CEM-3: They work well in high-density applications. The Tg offered by CEM-1, CEM-2, and CEM-3 is 122°C,125°C, and 125°C respectively 
  
• Polymide- As a substrate it offers a Tg of 250°C or more for high power circuits. For flexible circuits, polyimide substrates should be preferred since FR-4 substrates are rigid. Polyamide substrates are slightly costlier than FR-4 substrates but offer high resistance to temperatures.

Rules for designing digital PCBs

Most PCB design systems have the capability to transfer rules between the schematic and the layout. It permits the schematic to drive design rules instead of waiting to input all the constraints on the layout side, this is a huge advantage for designers. This level of organization offers designers the capability to form rules for specific net and component placing which are essential for circuit designing. Net or net class allows to group like nets together and assign a rule set to them. As the net rules are already present in the design database, so the designer need not rely on written instructions. For ensuring that the circuit board is designed precisely, here are some rules that need to be followed:-

1. Default values- The design tool in the software will start off with default values which usually arise due to the leftovers from previous designs or system defaults. The designer should confirm these values before they start to ensure they aren’t routing with incorrect trace widths or placing the components too close. To avoid such problems, these default values can be reset through the settings. Also, it should be ensured that the spacing for default values is set as per the required schematic of the circuit to prevent inconveniences caused by prior settings.

2. Classes - Although most of the rules can be configured for individual nets or components, this process can be time-consuming if there are hundreds of objects to work with that require unique rules and constraints. Some of the design tools provide a system for installing classes of nets and components to make it easier to configure rules and constraints. 

Fig 2:- Installing classes

Source- Circuitstudio

For example, the unique trace widths and the spacing requirements can be configured for a particular value of nets, a designer can create a set of rules for one power class and add those to nets.

3. High-speed design rules: When it comes to high-speed digital circuit designing, specific trace lengths can be set up as well as length matching can be done to nearby connecting traces which helps in improving the stability of data lines. In order to route the traces together at set differences, differential pairs can be set up at distances by creating unique trace topologies for specific net characteristics. For impedance-controlled routing, trace widths can be set automatically, and via sizes can be assigned to net classes.

Fig 3:- Trace designing

Source - Pcbdesignworld

4. Choosing the right PCB board spacing: Selecting the right spacing between the components used in the circuit and the spacing between the PCB lines helps in improving the desired electric output and also saves cost and rework. An ideal via aspect ratio of 6:1 ensures fabrication of the board wherever required which aids in trouble-free drilling. 

Fig 4:- PCB spacing 

Source- Optimumdesign

Also, during the design process, components and circuit schematics must be properly represented in any CAD software which allows designers to view accurate simulations before mass production.

5. Protection against electrostatic discharge: Digital PCBs are highly vulnerable to electrostatic discharge which may occur due to failure caused during the operation of solid-state components like integrated circuits (ICs), batteries, etc. If not taken seriously, circuits could malfunction or even explode. PCB designers must make use of ESD protectors like metal-oxide varistors, transient-voltage-suppression diodes, polymer-based suppressors, etc to avoid issues caused by electrostatic discharge.

Conclusion

While designing digital PCBs, utmost care must be taken throughout the designing process to ensure the circuit, as well as the PCB, so that the system performs at its maximum potential. There are various factors to consider when it comes to selecting the right material for the digital PCB. The materials must have dimensional stability, high thermal management control, moisture and chemical resistance, etc for the signal to pass through the PCB smoothly and without any disruptions. FR4 is one of the best-suited materials when it comes to designing digital PCBs due to its high dielectric strength and superior signal integrity.

Before going into mass production, it is important for designers to simulate the electronic components and their functioning on the PCB to get the appropriate outputs. For high-speed digital circuits, designing trace lengths is essential as it improves signal stability for better transmission of signals. Spacing of components must be done in the right manner by keeping the right proximity to avoid signal interference. A via aspect ratio of 6:1 can be done for efficient fabrication and drilling on the board which helps in flexibility during the wiring and soldering process. The best possible practice to avoid electrostatic discharge and its effect on PCBs is to make use of various protectors like metal-oxide varistors, transient-voltage-suppression diodes, polymer-based suppressors, etc.

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