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Full Introduction of Printed Circuit Board

Printed circuit boards have been existing for a long time. These boards are useful in several applications. In the manufacturing of electronics, PCBs play a significant role. The use of printed circuit boards is common in most industries today. In this article, we will discuss all you need to know about PCBs.

Printed Circuit Board- What is it?

A printed circuit board is the foundation of most electronic devices. This board is the framework where you mount all components of an electronic device. It is sometimes regarded as the skeleton of a device.

A PCB provides electrical and mechanical support to devices. This board used tracks, conductive pathways, and signal traces to provide this support. With this board, you can mount and connect resistors, capacitors, and diodes. Engineers can also mount semiconductors and radio devices via a PCB. This board is the backbone of most devices.

Even the smallest device uses PCB. You will find PCB in electronic and electrical components like radios or beepers. PCBs feature electrical and mechanical properties.  They serve as a support piece for surface-mounted components. Materials such as fiberglass, copper, or epoxy material are used for PCB manufacturing.

There are different types of PCBs. Single-layer PCBs are ideal for simple electronic devices. Multi-layer PCBs are suitable for complex hardware.  PCB is also referred to as a printed wiring board. This board creates a pathway for current flow.  While some PCBs are flexible, some are rigid. A flexible printed circuit board enables the circuits to fold and bend into shape.

PCBs offer a lasting solution to the problems of traditional wired circuits. Due to their weight, they are ideal for use in today’s devices. The low cost of production and reliability of this board makes it a better option.  These circuit boards have continued to gain popularity in the electronics world.

Types of PCBs Based on Layers

pcb board Circuit Board

PCB boards are available in different types. The application you use them for determines the type you get. For most complex devices, multi-layer PCBs are suitable. Most simple applications need single-layer PCBs.

Multilayer PCB

A multi-layer PCB is a circuit board that features over two copper layers. Multilayer PCBs can be four layers, six layers, or twelve layers. These boards are ideal for complex applications. There are different layers of insulating materials and substrate boards.

These materials separate the layers in this type of PCB. Multi-layer PCBs are compact-sized and provide space and weight. Multi-layer PCBs are commonly used due to their flexibility. These circuit boards are very useful in high-speed circuits. They give more space for conductor power and pattern.

The substrate material between these boards offers protection. This prevents the components from any form of burning. The extra layers in multilayer boards prevent electromagnetic interference.

Single-layer PCB

A single-layer circuit board features a layer of a substrate. The substrate of a PCB is also the base material. A Single-layer PCB is also known as a single sided PCB. This is because a layer of conducting material coats one side of this board. PCB manufacturers use copper to cover the layer of this PCB. Copper is ideal for this use since it is a good conductor of electricity.

Copper creates a great conductive path for this type of PCB. Engineers place a solder mask on the top of the copper layer. This helps to offer protection. There is a silkscreen coating on the solder mask’s top. This silkscreen coating marks the elements on the circuit board.

Double-sided PCB

Here, there are two layers of substrate and copper material between the copper layers. A double-sided PCB is ideal in applications like vending machines, LEDs, amplifiers, and more.  Two different types of technology connect the components on these boards.  This technology includes Surface Mount and Through Hole.

The through-hole technology inserts lead components via the pre-drilled holes on the board. The surface mount technology places electrical components directly on the circuit board’s surface.

Types of PCBs Based on Base Material

Flexible PCB

A flexible circuit board is one that uses a flexible base material. These boards can be available in different layers. They can be single or double layers. You can bend or fold this type of PCB. Flexible PCB involve many components and circuits. Polyamide, conductive polyester film, or polyether ether ketone are used for this PCB.

Rigid PCBThis type of PCB uses solid material for its manufacturing. This prevents the circuit board from twisting. You can’t bend a rigid PCB because the material is solid. Rigid boards create various complex circuitry around them. The base material of a rigid PCB board is a firm substrate. This substrate offers the board strength and rigidity. A rigid PCB has multiple layers. The multiple layers are solder mask, silkscreen, copper, and substrate.

It is important you know that a rigid board can come in different layers. It could be a double layer, single layer, or multi-layer. This depends on the intended application. However, you cannot modify this type of PCB once you fabricate them.

Rigid circuit boards are ideal in applications like control towers, GPS equipment, and CAT scans. These boards have low electronic noise and are cost-effective. They can also withstand vibrations. A computer motherboard is a good example of this board.

Rigid-flex PCB

A rigid-flex board combines the properties of a rigid and flexible board. This combination provides both strength and flexibility. Most applications make use of these boards because of their properties. The flexible part of this board is ideal for interconnections between rigid circuit boards. Rigid-flex board designs are complex because they are produced in 3D.

Rigid-flex PCBs are lightweight and strong. These boards are ideal in applications like consumer electronics, medical, and aerospace.

Materials Used in The Production of a PCB

Different materials make up a printed circuit board. The dielectric substrate is the major component of a PCB. It could either be flexible or rigid.

FR-4

This is an epoxy laminate material reinforced with glass. FR-4 comprises a flame-resistant material and woven glass cloth. FR-4 is a common material engineers use for PCB production. FR simply means fire retardant. This material features great electrical and mechanical strength. FR-4 features a high tensile strength.

Most FR-4 materials feature bromine that helps to prevent flames. This material can withstand moisture. Due to this, it is ideal in some applications.

Teflon

This is another common material for the production of PCB. Teflon is a lightweight and strong material. This material is common in applications that require tight tolerances. Teflon doesn’t expand when you subject it to high temperatures. One great thing about this material is that it is flame resistant.

Due to the properties of this material, it is ideal for high-speed applications. Teflon features physical strength and offers temperature balance.

Metal

Metal is the commonest material for PCB production. Some examples are aluminum, iron, and copper are conductive layers in circuit boards. Most PCB boards are clad with copper.  Metal allows the use of SMT for joining components. This material also offers mechanical durability and strength.

There are different materials used for producing PCBs. These materials all have their pros and cons. It is very important you choose the material according to the PCB use. Environmental factors are important factors to consider. Choose materials that suit your application.

Where is PCB Used?

A printed circuit board is ideal for use in several applications. PCBs have several advantages. This makes it the right choice in most modern devices. Printed circuit boards are used in the industries below;

Military

PCBs are a core component of most military devices. These boards can withstand vibration, shock, and heavy impact. Due to this, they are the right choice for these devices. PCBs are suitable for the production of military vehicles and modern weapons.

Military technology now integrates computerized technology to meet high demands. In the military, most devices are subjected to high temperatures.  High-frequency PCBs are the best choice for the production of these devices.

Medical

The introduction of PCBs has contributed significantly to the medical system. PCBs are ideal for the production of medical electronics. These boards are present in MRI machines, computers, radiation equipment, and more. The small size of rigid-flex and flexible boards enables the production of more compact devices.

These boards are present in implantable devices, hearing aids, and any tiny cameras. When you want to reduce the size of complex devices, rigid-flex boards are ideal. With these boards, you don’t need connectors and flex cables. Connectors and flex cables take more space in complex devices. PCBs are now present even in the smallest devices.

Industrial system

Most heavy-power industrial machinery makes use of PCBs. You can’t underestimate the use of these boards in industrial electronics. The use of PCBs has increased automation, information, and efficiency. These boards are the best means of enhancing manufacturing.

Heavy copper PCBs are used in applications where one-ounce copper boards can’t fit in. Heavy copper boards are present in motor controllers, load testers, and more.

Aerospace

The aerospace sector is another sector that relies on the use of PCB.  This circuit board is present in devices like flight controls, flight management systems, and more. Smaller and more complex boards are ideal for use in aerospace electronics. Rigid-flex and flexible boards provide survivability and durability. These boards also get rid of connectors, making them suitable for high-vibration applications.

Aerospace devices require the use of boards that can resist extreme temperatures and vibrations. Boards that feature aluminum are also ideal for use in the aerospace sector. A printed circuit board is a core component in aerospace equipment.

Telecommunication

In the telecommunication sector, PCB plays an important role. This circuit board is ideal for use in consumer devices. This sector uses various types of PCBs since there are different types of equipment there. The telecommunication industry is advancing; hence, the use of PCB is growing.

Telecom equipment like phone switching systems, LED displays, modems, and more require PCBs. As more data is transferred, high-performance PCBs will become more useful for communications.

Consumer Electronics

This is another sector that uses printed circuit boards. Consumer products like computers and smartphones require the use of PCB. The demand for PCBs keeps increasing as we implement them in our devices. Smaller devices require small PCBs with high performance.

Radios, tablets, smartwatches, and smartphones, among other use PCBs. Computers also feature PCBs. These circuit boards are present in today’s home appliances.

Advantages of PCB

PCBs have several advantages. This is a major reason they are used in so many industries.

Low costs

The cost of producing a printed circuit board is very low. This makes it useful in most applications. When manufacturing electronic devices, cost is an important factor to consider. The mass production of PCB is affordable.

Saves time and energy

The use of PCB saves a lot of time. The traditional way of connecting components takes more time. The assembling of a PCB takes less time once you complete the design.

A compact solution

A circuit board features several elements and parts. These boards are very lightweight, making them the right choice for some applications. This is why some of today’s devices are smaller. PCBs have provided solutions to the production of most electronic devices.

No loose connections

This is one of the advantages of PCBs. When you use this board, you don’t have to worry about loose connections. For the traditional method of using actual wiser, a loose connection is a problem. Sometimes, the wires might have issues with connection. A loose connection is often difficult to locate. The use of a PCB board has provided a lasting solution to this problem.

Low electronic noise

Low electronic noise is one of the benefits of PCBs. These boards are reliable for use in any application due to this benefit. Designers ensure they organize the electrical components on a PCB to avoid low radiation.

PCB Manufacturing Process

PCB Plated Through Hole Manufacturing Processes
PCB Plated Through Hole Manufacturing Processes

The manufacturing of a printed circuit board depends on some factors. There are processes to follow to ensure smooth production. A PCB circuit board can be single-layer or multi-layer. Below are the steps to follow when producing a circuit board.

Designing

This is the first step to manufacturing a PCB board. It is important you draw out a plan before you start the fabrication. The PCB designer creates a blueprint for the circuit board. This design must meet all the application’s demands. PCB designers make use of software to achieve this aim.

Extended Gerber is a popular software for PCB design. This software functions as an output format. It is a great choice for PCB design. Extended Gerber keeps track of all the details the designer needs. These details include the number of solder masks and number of copper layers.

Design Printing

After the design is planned, one has to print it out. A plotted printer prints the PCB design. This printer generates film that indicates the layers and details of the board. Fabricators use two types of ink colors on the inner layer of the circuit board.

The black ink indicates the circuits and conductive copper traces. The clear ink marks out the non-conductive areas. The reverse is the case in the outer layers of the PCB design.

Creating the substrate

The circuit board will begin to form in this stage. The substrate starts forming by passing the materials via an oven. After this, the manufacturer pre-bonds the copper to both sides of the layer. The substrate is the insulating material that holds the components.

Inner layers printing

Designers print the design to a laminate. A photo-sensitive film covers the body of the laminate. This film is also known as a photoresist. It features photo-reactive chemicals that get hard after exposing them to ultraviolet rays. The film’s then fit well over the laminate panel. The board and the film get UV light. When light penetrates into the clear part of the film, the photoresist under the copper hardens. The black ink then prevents the light from getting to some areas.

After the board is ready, manufacturers use an alkaline solution to clean up the photoresist. Cleanliness is very important in PCB manufacturing. The laminate should be cleaned properly. No dust particle should settle on the laminate during this stage.

This process prepares to manufacture the actual PCB. PCB consists of a laminate board. Glass fiber and epoxy resin are used for the production of a laminate board.

Etching

Sometimes, the inner layers of the PCB have extra copper. It is important you remove extra copper before you continue with the fabrication. The etching process involves covering the copper on the PCB. The chemical etching gets rid of any unprotected copper. Heavy PCBs may utilize more copper, which means more copper will go through etching.

Layer alignment

Once you have cleaned the layers of the PCB, you have to align the layers. The holes on the board help to align both outer and inner layers. The technician puts the hole on an optical punch. This machine fixes a pin down via the holes.

Inspection

After the optical punch, you need to ensure there are no defects. Automated optical inspection is a very important aspect of PCB fabrication. This is because once you lace the layers together, you can’t correct any errors. The AOI machine is used to detect any defects. This machine compares the circuit board with the Extended Gerber design.

PCB layers lamination

The PCB layers lamination process involves two steps. These are the lay-up and laminating steps. The circuit board will begin to take shape when you fuse the layers. During the laminating process, metal clamps are used to hold the layers.

The laminating process involves putting a layer of prepreg on the alignment basin of the table. The technician places the substrate over the pre-coated resin. After this, a copper foil layer is placed. The last thing to apply here is the press plate.

Drilling and plating

An X-ray machine detects the drill spots. The technician drills registration holes to ensure that the PCB stack is secured. A computer-guided drill helps to drill these holes. After the drilling, the technician files off any extra copper at the edges.

The technician plates the PCB after drilling the panel.  The plating process involves using chemicals to join several layers of the circuit board together.

Solder mask and silk screening

Before applying the solder mask, you need to clean all the panels. The fabricator can remove excess solder masks with ultraviolet light. Silkscreening involves printing important information on the board’s surface. The information includes warning labels, company ID numbers, etc.

Surface finish and testing

The PCB finishing requires the fabricator to plate the board with conductive materials. PCB fabricators use materials like hard gold, immersion silver, and among others for finishing the PCB. The last step is testing the PCB. All circuit boards must undergo necessary tests to ensure proper functioning.

What are the Components of a PCB?

PCBs consist of several electrical components. Each of these components has its own functions. They all play a role in the smooth functioning of a device.  The PCB board will stop functioning if any of these components fail.

Transistors

This component controls or switches any electronic signal in a circuit board. There are different types of transistors. The bipolar transistor is the most common type.

Inductors

Inductors save energy in the magnetic field anytime current flows via them.  This component helps to block signals within the circuit board.

Resistors

This component plays a significant role in the functioning of a PCB. Resistors transmit electric current to generate a voltage. This component also discharges electric power as heat. It is available in various materials.

Sensors

Sensors detect any changes in the environment. This component produces an electrical signal that matches with the change it detects. It then sends this signal to other components in the printed circuit board. Sensors can convert air quality into electrical energy.

Transformers

A transformer helps in transmitting electrical energy from one circuit to another.

Diodes

A diode is a component of a PCB that enables the free flow of current in one direction. LED is a good example of a diode. Diode helps to stop current flow in the wrong direction.

Conclusion

A printed circuit board has contributed a lot to the manufacturing of electronic devices. This board comes in different types.  Circuit boards feature great electrical and mechanical features. Due to this, they are ideal for use in most applications. Most devices feature printed circuit boards.