What is Printed Circuit Board and How Does it Work?

What is Printed Circuit Board (PCB)?

PCB or printed circuit board electrically connects and mechanically supports the electronic or electrical components using pads, conductive tracks, and the other features which are to be etched from a single or more layer of copper laminated on or between the sheet layers of a non-conductive substrate.

The components are usually soldered on the PCB to fasten it mechanically and connect electrically to it. The alternatives to the printed circuit board comprise point-to-point construction and wire wrap. Both these were once popular but are now rarely used.

These circuit boards need additional design effort for laying out the circuit with assembly and manufacturing being automated. The electronic computer-aided design software is known for doing much of the layout work. Mass-producing circuits with PCBs are faster and cheaper as compared to the various wiring methods.

These components are wired and mounted in a single operation. A huge number of printed circuit boards are used to be fabricated at the same time as the layout has to be done once only. These boards are manually created in small quantities with a number of reduced benefits.

The initially printed circuit boards used through-hole technology and mounted electronic components by leads which were inserted via holes on one side of the board. Additionally, these were soldered on the copper traces on the other side. These boards may be single-sided consisting of an unplated component side or a compact double-sided board with components soldered on both sides.

The horizontal installation of through-hole parts with two axial leads like resistors, diodes, and capacitors is put to action by bending the leads 90 degrees in the same direction. A part is inserted in the board where often the bending leads are situated on the backside of the boards in opposite direction to improve the mechanical strength of the parts.

The leads are soldered and trimmed off at the ends. These leads may either be soldered manually or with the help of wave soldering machines. Through-hole manufacture adds to the board cost as it needs numerous holes which are to be drilled accurately. It further limits the routing area present for the signal traces on the layer just below the top layer on multi-layer boards. The holes are required to be passed via these layers to the opposite side.

Types of PCB

Printed circuit boards are single-sided with one copper layer, double-sided with two copper layers present on both the sides of single substrate layer and multilayer which comprises an inner and outer layer of copper and alternating with layers of substrate. Let’s read in detail about the types of PCBs.

Single-Sided PCB

Single-sided printed circuit board are the basic type of circuit boards which consist of one layer of base material or substrate. The layer is generally covered with a thin copper metallic layer which is a good electricity conductor.

These types of circuit boards have a solder mask for shielding which is applied above the copper layer in addition to the silkscreen coat. These boards are used for the production of volume and have a low cost. Also, these boards may be used for simple circuits such as sensors, power sensors, electronic toys, and relays.

Double-Sided PCB

Both sides of the substrate of double-sided PCBs feature metal conductive layers. The holes present in the circuit board allow metal part attachment of one side to the other. These boards connect circuits to either side with the assistance of either of the two mounting schemes.

These schemes are surface mount technology and through-hole technology. The through-hole technology includes inserting of lead components via pre-drilled holes on the circuit board. These are soldered on the opposite sides to the pads.

The surface mount technology involves electrical components which are to be straight-away placed on the circuit board surface. There are ample benefits of using a double-sided printed circuit board.

Surface mounting has the capability of attaching more circuits to the board as compared to through-hole mounting. The printed circuit boards are used in a wide range of applications such as power monitoring, mobile phone system, amplifiers, test equipment, and others.

Multi-layer PCB

These types of boards consist of more than two copper layers such as 4L, 6L, 8L, etc. This type of PCB expands the technology which is used in various double-sized PCBs. There are many layers of a substrate board and the insulating materials are known for separating the layers in a multi-layer PCB.

The multi-layer printed circuit board is known for providing high component density. This is because the circuit traces present on the inner layers would otherwise consume the surface space present between the components.

There has been a significant rise in the popularity of multilayer PCBs with more than two in addition to more than four, the copper planes were concurrent with the adoption of surface mount technology. The multilayer PCBs make analysis, repair, and field modification of circuits impractical and highly difficult.

Rigid PCBs

These are referred to as the types of printed circuit boards which have base material that is fabricated from a solid material and cannot be bent. The advantages of this type of board are that these boards are compact which makes sure that the variety creation of complex circuitry around it.

The rigid printed circuit boards offer simple repair and maintenance as all of the components are marked clearly. Additionally, the signal paths are also organized well.

Flexible PCBs

These boards are constructed by using flexible base material. These are present in single-sided, double-sided, and multilayer formats. They help successfully reduce the complexity of device assembly.

Although it has many advantages, some of them are as follows. The printed circuit boards help in saving space to a large extent and reducing the overall board weight. These further help in decreasing the board size making it ideal for different applications which need high signal trace density. These are designed keeping in mind the working conditions where density and temperature are a major concern.

Rigid-Flex-PCB

These types of PCBs are a combination of flexible and rigid circuit boards. They consist of multiple layers of flexible circuits which are attached to numerous rigid boards. These are built with precision and used in different military and medical applications. These boards help in saving 60% of weight and space.

High-Frequency PCB

This type of printed circuit board is used in the frequency range of 500 MHz – 2GHz. Additionally, these are also used in different types of frequency critical applications such as microwave PCBs, communication systems, and microstrip PCBs.

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Aluminium Backed PCBs

These ones are used in high-power applications, the reason being that the aluminum construction assists in heat dissipation. PCBs backed by aluminum are known for offering high-level rigidity and low-level thermal expansion. These qualities make these PCBs ideal for applications with high mechanical tolerance. These are PCBs are also used for power supplies and LEDs.

Parts of PCB

A basic printed circuit board comprises a flat insulated material sheet and a layer of copper foil which is laminated to the substrate. Let’s read about the parts of PCB in detail. The copper is divided by the chemical etching into different conducting lines which are known as circuit traces or tracks, vias to pass connections between layers of copper, pads for connections, and features like solid conductive areas for various purposes including electromagnetic shielding.

The tracks fixed in place function as wires and are often insulated from each other via air and the board substrate material. It has been noticed that the printed circuit board may have a presence of coating which protects the copper from getting corroded. The chances of solder shorts between undesired electrical contact or traces are reduced with stray bare wires.

A PCB has multiple copper layers, let’s read about these in detail. A two-layer PCB board comprises of copper on both sides while a multi-layer board sandwiches additional copper layers between layers of insulating material. The conductors present on various layers are connected with each other with vias.

After two-layer PCBs, the next step consists of a four-layer printed circuit board. The two layers are mostly dedicated as ground planes and power supply while the other two boards are used for the purpose of signaling wiring between the components.

It has been observed that the “through-hole” components are mounted by wire leads that pass via board and get soldered to traces on its other side. The “surface-mount” components are often attached to copper traces by leads on the same of the PCB. A board might use both methods for mounting the components.

Printed circuit boards comprise of through-hole mounted components which are highly uncommon. Surface mounting is generally used for diodes, IC chips, resistors, transistors, and capacitors. Through-hole mounting may also be used for large components like connectors and electrolytic capacitors.

The pattern which is to be etched in each of the copper layers of a printed circuit board is generally known as the “artwork”. This etching is mostly done by utilizing the photoresist which is coated on PCB after which it is exposed to light which is projected in the pattern of the artwork.

Operations of Digital Multimeter

Test equipment offering several electronic measurement tasks in a single tool may be termed as a digital multimeter. Commonly, it is also known by names such as Ohm meter, Volt Ohm meter, and Voltmeter.

The basic measurements performed by a digital multimeter comprise of measurement of volts, ohms, and volts. They are also for performing additional measurements by using logic and digital technology. This includes frequency, continuity, temperature, capacitance, etc.

The new integrated circuits of the digital multimeter are faster, efficient, and work with high accuracy compared to the analog multimeter. In the case of additional features, it is close to reading but not accurate.

A multimeter is considered good which has continuity and is packed with smart features including the ability to troubleshoot, graph, and log data. A multimeter is a useful device that is simple in nature. It consists of three parts as selection knob, ports, and display screen.

The function of PCB Components

PCB components are made up of various complex electrical elements which comprise capacitors, transistors, diodes, resistors, and fuses. Each part must perform well so that the printed circuit board performs properly.

Resistor

One of the components of PCB is a resistor which is a small electronic device with two terminals transmitting electric current for producing voltage. For testing these, an ohmmeter is used. A resistor is required to be isolated such that the results produced are indicative of the it.

Circuit Board Capacitor

The circuit board capacitors are the electronic devices that are used for storing energy as an electrostatic field. These are composed of an insulating material that is placed between two conductive plates. The flow of direct current can be blocked in PCBs while the flow of indirect current is turned on.

Diode

A diode is an electrical device that is used for transmitting current in one direction and comprises a semi-conductive material between two terminals. While the current is enabled in one direction, diodes are known for blocking the current in opposite direction. However, the behavior of a diode can be manipulated.

Advantage of PCB

A printed circuit board forms a crucial part of modern electronic equipment. It consists of a large number of active and passive components connected with traces from one side to the other on the board.

A printed circuit board has a huge number of electronic components that are interconnected through copper tracks which makes these less bulky. Mostly, the components are small in size and it’s tough to connect these together by using wires in the absence of any aid of printed circuit boards.

A typical PCB is known for offering a platform that facilitates the compressed and efficient arrangement of electronic components. Its compactness permits the creation of complicated and big electronic circuits in little form factors. This reduces the space in devices.

It is simple and easy to check and make any replacement of the failed components whenever required. The polarities of the electronic components on finely designed PCBs are clearly labeled on the board.

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This in turn makes the installation process and the repair process convenient. A PCB is known for taking much less time in comparison to the conventional circuit board in assembling a circuit. Yet another of its features is that all its components remain fixed to the board which is done by the solder flux.

There are hardly any loose connections or short circuits found in a PCB as the connections are created through copper tracks. Also, PCBs are known for creating fewer electronic noises. The components are organized in such a way that the electric current is less between them. Mass production of PCBs may be done at a low cost. All these factors make the performance of the circuit reliable. There were the advantages of PCB.

Disadvantage of PCB

Some of the disadvantages of PCB are as follows. They are not suitable for the users who conduct heavy current as such current tends to heat up the thin copper wires causing problems. Also, there is a large risk of overheating during the process of soldering.

PCB vs. PCBA

A PCB is a printed circuit board while a PCBA expands to the printed circuit board assembly. A PCB is a board that electronically connects the electric components by using conductive pads, traces, and other features which are etched from copper foil which are laminated on a non-conductive substrate.

A PCBA is the board after all the parts and components have been installed and soldered on the PCB. It can now accomplish the electronic function for which it has been designed. It is the process of passing on the PCB through PTH (plated through-hole) and SMT (surface mounted technology) processes.

PCB is a circuit board while PCBA is the circuit board plug-in assembly. While one is a finished board, the other one is a bare board. A printed circuit board is made up of epoxy glass resin material and has been divided into 4, 6, and 8 layers according to the number of signal layers.

In these layers, the common ones are 4 and 6 layers, and chip components are attached to the PCB.

PCBA can be understood as a circuit board that is in a finished form and can be made after the process on the circuit board is finished. A PCB bare board passed through the SMT patch which is further passed via the process of the DIP plug-in is referred to as PCBA.

Applications of PCB

A printed circuit board or a PCB plays a crucial role in the current times because technology has become vital in our daily lives. This circuit board forms a foundation that may be used in every electronic device. Let’s read about the areas where these are applied.

One of the uses of PCB takes place in the consumer electronics that are used by people around the globe. Whether it is a computer, mobile phone, coffee maker, microwave, or any other home appliance, all these have a circuit board within them.

The printed circuit board highly benefits the industrial sector including the business which comprises manufacturing facilities and production lines. These facilitate automation that helps the business in saving costs and reducing manmade errors. A PCB is usually designed to withstand the high-power application and industrial sector demands.

These boards significantly contribute to the medical sectors not only in the production of appliances but also in diagnostic, monitoring, and treatment devices. The Application of PCB in the medical sector is growing at a high speed due to the usage of technology.

In modern times, the automotive industry produces vehicles that are known for featuring a huge range of advanced electrical parts that provide functionality. In comparison to the past, these days uses of PCB have increased in various sector.

Why is PCB used?

PCB or printed circuit board is considered important in various electronic gadgets which are used for different purposes. These uses include domestic as well as industrial ones across sectors. The design services of PCB are being used for designing electronic circuits.

In addition to the electrical connection, it is known for giving mechanical support to the components which are vital. The printed circuit board designs may be created both manually as well as automatically.  The manual layouts are being created with the assistance of CAD drafting, and the automatic router which helps in producing the designs automatically.

PCBs are the core components that are present in almost all electronic gadgets. These gadgets may be computers, cell phones, or even laptops. There has been an increase in the demand for printed circuit boards which is why the number of PCB services has also increased.

PCB is known for holding all the electronic components which are considered necessary for an electronic device to function. The fabricators are used to etch the metal with acid so that electrical pathways are created among different components which assemblers mount on the board.

Many advantages are brought to the electronic industry by the printed circuit board or PCB. These advantages include compact design, easy way of repairing and testing, low assembly errors, low noise and interference, short circuit avoidance, and improved reliability and repeatability.

It possesses the ability to mount all the components on a PCB leading to a compact design. The designer may experiment with the placement of these components on the printed circuit board along with the interconnections. This may happen until the optimum layout is reached which offers the minimum size that is possible.

It has been advised that the manufacturers must use specific designs to make PCBs which states that the PCBs in the production lot is similar. In comparison to the manually wired assembly, it is difficult to predict which component is going to detach itself.

A PCB is considered as most reliable when it comes to holding the components securely. This is why it is used across various sectors for different purposes.