Hey Guys! Hope you are doing great. We always enjoy when you come back to our site for useful information so you can excel and grow in your relevant field. Today, I am going to reveal the details on the Introduction to PCB. It is a printed circuit board that uses pads, tracks and lines incorporated on a single board to electrically connect the electronics components. I’ll discuss main features of PCB and what makes it very useful in latest technology? Let’s hop on the board and dive in the details of PCB.
Introduction to PCB
- PCB is a acronym of Printed Circuit Board that helps in connecting the electronics components with pads, tracks and lines incorporated on a laminated copper sheet.
- It is considered as an insulating material which can be developed using epoxy on which copper layer is laminated.
- PCB design has been evolved in an amazing way and revitalized the latest technology. You can have a look at top 10 PCB design software.
- Before the inception of PCB, professional used laborious method of point to point wiring to connect the electronics components. This method was costly and lead to a most complicated design.
- In order to get rid of end to end wiring and make the circuit design hassle free, first PCB was developed by Australian Engineer Paul Eisler.
- With the passage of time demands of electronics became prevalent, this made professionals think they should come up with an ideal solution that made the electronics cheap and incorporated in a lesser space.
- This was the start of PCB that revolutionized the electronics industry with lots of innovation and productive ideas.
- Mostly, PCBs are composed of composite material, composite epoxy and fiber glass.
- These are the most common components used in electronics devices that makes the circuit design sophisticated and compact.
- PCBs come in different layers and multiple designs. PCBs used in simple electronics are composed of single layer. Most compact and advanced hardware like graphics card and motherboard are composed of multi layers PCBs.
- PCBs are not associated with computers only, they are widely used in advanced electronics including digital cameras, cell phones, TV, scanners and automatic control systems.
- There are also online PCB design services available you can work with. You can have a look at Top online PCB design services.
Through Hole Technology
- Earlier PCBs were made using through hole technology where electronic components were mounted with leads inserted through hole and were soldered on the other side of the board.
- Based on requirements, boards can be single sided or more advanced double sided with components placed on both side of the boards.
- Through hole parts can be installed horizontally with two leads that are bend at 90 degree. Insert the parts in the board, solder the leads and trim off the ends.
Surface Mount Technology
- Surface mount technology was came into play in 1960s and became commonly used in 1990s.
- Instead of using wire leads to pass through the hole, components came with small end caps that were soldered into the PCB surface.
- Components placement on both sides of the PCB was the common choice than through hole technology, providing a much larger circuit density with relative smaller PCB assembly.
- Surface mount components are 10 times smaller than through hole components, making them an ideal choice for most of the applications.
- Surface mounted devices have a leg over through hole devices because of low cost and compact design.
Composition of PCB
- Simple PCB is composed of different layers that are joined together with the help of heat and adhesive, giving the board a compact shape into a single object. Let’s discuss each layer one by one.
- The base material, also known as substrate, is composed of fiber glass.
- The FR4 is the most common fiber glass used today. It is like a solid core that provides rigidity and thickness to the PCB board.
- Some PCB boards are composed of phenolics and epoxies which are not as durable as FR4 but they are less expensive and come with unique bad smell.
- Low end consumer electronics mostly use these types of substrates.
- Phenolics come with low decomposition temperature which allows these substrate to erupt and delaminate if solder is placed on board for longer duration of time.
- Nature of substrate material defines whether board will be Flexible PCB or Rigid PCB.
- Beside substrate there exists a thin layer of copper foil.
- Heat and adhesive is used to laminate the copper foil on the board.
- Commonly, both sides of substrate are laminated with copper specially in double sided PCB, except cheap electronics where only one side of the board is laminated with copper.
- Board come with number of layers ranging from one layer to 16 layers or more.
- The copper thickness varies from board to board and can be defined in ounces per square foot.
- The one ounce per square foot is suitable for most of the PCB, but applications where we require more power come with 2 or 3 ounce per square foot.
- Each inch per square encompasses 35 micrometer of thickness.
- Above copper layer foil, there lies a solder mask layer.
- This layer is applied on the copper layer to insulate the copper layer in order to avoid conduction in case direct contact happens with some metal or conductive material.
- Most common used solder-mask comes in green color, however it is also available in red color.
- Above soldermask layer, there exists a silkscreen layer that allows the user to add symbols and number for better understanding of the board.
- Silkscreen labels provide the clear indication of function of each pin and component soldered in the board.
- Silkscreen mostly comes in white color but there are also other color available including red, grey, black yellow.
- Common practice is using silkscreen in one color as combination of different colors of silkscreen makes it difficult for the user to read the board properly.
Types of PCB Boards
- PCBs can be divided into different types depending on the nature and number of layers used in the boards. Let’s discuss one by one.
Single Sided PCB Boards
- Single sided PCB boards came into play at 1950 and became an ideal choice for many applications since then.
- In single sided PCB boards, copper tracks are found on the one side of the PCB board.
- Pins of different components are inserted from one side of the board to the other side that comes with copper tracks and lines.
- These pins are then soldered on the copper side in order to provide the conducting path to the components.
- These types of PCBs are commonly used in many electronic devices including printers, coffee machines, basic electronics circuits and calculators.
- I have posted a tutorial Interfacing of Arduino with 2 Relay Board, in that tutorial 2 Relay Board’s PCB is Single Sided PCB and is shown below:
Double Sided PCB Boards
- Double sided PCB boards are served as a basic component for advanced technology applications.
- In these boards, copper tracks are applied on both sides of the boards.
- In order to provide link between two points on the both side of the boards, holes are created on the boards and then laminated with the copper layer.
- The components on these boards are electrically connected using two techniques i.e through hole or surface mount technology.
- Using through hole technology, leads also known as wires are inserted in the hole and then each lead is connected to the right component and build a smooth conducting path throughout the board surface.
- Wires don’t behave as connectors in surface mount technology, instead whole board provides a wiring surface where small leads are directly connected to the board.
- Different functions can be accomplished at a much faster rate with less space using surface mount technology which helps in minimizing the cost and makes the whole project light weight.
- Double sided PCB boards are widely used in many applications including amplifiers, vending machines, LED lightening, HVAC systems and general power supplies.
- Here’s an image of Double Sided PCB Board:
Multi-layer PCB Boards
- Multilayer PCB boards are composed of number of double layered PCBs.
- These boards are then glued together with pieces of insulation in order to avoid excessive heat that can damage the components.
- Multi layer PCBs come in different forms ranging from four layers to 16 layers or more.
- The thickest multi layer PCB ever developed by professionals was 50 layers thick.
- These boards are more complex than double layered PCBs, help in initializing faster operations than standard PCB boards and are very similar to microchip composition.
- Multi layer boards are used in wide range of applications including satellite system, weather equipment, x ray equipment, data storage, GPS technology and many more.
- I have discussed types of PCBs based on number of layers, however, there are other types too like Aluminum PCB and High Frequency PCB, but they are used for more robust applications where heat dissipation is required.
- 1: PCBs are widely used in industrial machinery for many useful applications. Thick copper PCBs are a great replacement of thin copper PCBs in many situations. Thick copper PCBs are suitable for many applications including motor controllers, industrial load testers and high current battery chargers. There are many software to make PCB design, however, if you are involved in embedded system you may like designing PCB in Proteus Ares.
- 2: Latest technology used in most of the electronics uses less power than their prior editions, making it economical and widely used in medical field. Most of the advanced medical equipments use high density PCBs that provide compact and smallest design possible. Small size and light weight of PCB beautifully replaces the old traditional equipments and becomes an ideal choice for medical field. These devices are useful for a range of applications from small component like pacemaker to large complex machine like X-Ray machines and CAT scanner.
- 3: Aluminum backed PCBs are widely used in LED based lighting systems which encompass low power consumption and high level of efficiency. These PCBs are capable of transferring heat from one point to another and are considered as a step ahead from standard PCBs. These PCBs are the back bone of basic lighting solutions and LED applications.
- 4: Automotive and aerospace industries are widely surrounded by vibration environment, this is where flexible PCBs come into play. These PCBs can withstand high vibrations and severe environments due to their flexible and compact design. They can house in tight spaces like instrument gauge and instrument panel. Being a light weight makes it an ideal choice for making manufacturing parts of transportation industries.
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