Printed Circuits| the latest advancement in electronics
A ‘Brain’ has an important role to play in the functioning of human body. Exactly like a Brain the printed circuits are probably the most important part in an electronic device. It provides support to the system by sending electricity to various parts of the device. Secondly, it acts as a shed to the wires that are mounted on the surface. It also takes care of the components that are connected to the socket.
Material and Layers:
They are commonly casted out of epoxy (composite form), fiberglass or any other composite material. Generally printed circuit boards are comprised of single layer for simple electronic devices. However, the complex hardware like motherboards or graphic cards is composed of multiple layers that may cross over 10 layers in some cases.
As we all might think that printed circuits are so complicated and can be used in computers and hi-tech electronics only. Well this is not entirely true. Is it used in computers? Yes, but it is also used in simple electronic devices ranging from small toys to radios and cameras. It is used mostly in digital electronics but is also used in other fields such as automotive sector, medical field etc. PCBs are of many types and hence, these ‘many types’ are used in different fields such as-
• Automotive-science and space-science: As we all know the nature of the work that is being done in these two industries. We can easily reach at a conclusion which is, the use of complex PCBs. Not only complex but the printed circuit board should be flexible also. Flexibility of the PCB makes it durable during extreme conditions and places as well. For example, in an automotive vehicle as well as rocket there are places where circuits are involved but these places vibrate as well. So, in those cases the flexible PCB always turns out to be the best.
• Industrial application: Printed circuits are usually used in big plants that require hi-tech electronic activity while they function. Instead of thin copper PCB thick ones are used. These circuit boards are required for battery charges that flow high volumes of current, motor controllers and load testers.
• Lights: The LEDs that are used nowadays due to their low power consumption and high efficiency. The aluminum based Printed circuit boards are used to make such LEDs. The feature of this Al based PCB is that it validates heat transfer at high levels as compared to standard PCB. These PCBs can be used both high and simple luminous solutions.
• Medical science: To test new technologies in medical science we require efficient devices. The use of electronic devices that are complex and consume low amounts of power has made it easier to experiment. PCBs can be found in devices that are small to the devices that are complex such as they are present in pacemakers as well as in complex devices like CT- SCAN Machinery.
The Printed circuits boards are of several types based on the particular way in which they were manufactured. The most common classification of PCB is:
Based on the layers:
• Single layer PCBs
• Double layer PCBs
• Multi-layer PCBs
Based on rigidity:
• Rigid PCBs
• Flexible PCBs
• Flex-rigid PCBs
Based on the amount of transmission (current and signals):
• High Frequency PCBs
• Aluminum-Backed PCBs
Based on number of layers-
Single Layer PCBs:
• These PCBs have only one single layer of base material.
• One-sided metal coating for it to be electrically conductible.
• Most common coating is done of copper due to its good conductivity.
• A protective solder mask followed by the marks of the circuit-plan.
• These are easy to design and manufacture.
• Used in simple electronic items
Double Layer PCBs:
• They have a double-sided printed base.
• Thin copper coating on both sides makes it conductible.
• These boards have Holes in them to allow the circuits on each side to connect with each other.
• Two ways in which these circuits are connected. The first includes connection through holes the other one includes the connection via a surface-mount.
• In surface-mounting method the board itself acts as a wired base.
• Consumes less space.
• Lighter than single-layer thick PCB.
• Uses- Industrial fields, HVAC systems, vehicle dashboards and vending machines
Multi Layer PCBs:
• Consists of more than two layers of double sided PCBs.
• These multi-layers are glued and insulated to avoid melting caused by high temperatures.
• Come in different thickness i.e. more the layers are, thicker will be the PCB.
• Used for accomplishing complex tasks of the electrical/ electronic industry.
• Uses- Data storage unit, GPS, satellites etc.
Based on Rigidity:
• Made of solid material that prevents it from swirling.
• A motherboard in a CPU is made of a Rigid PCB.
• These are the PCB, manufactured at the largest scale.
• They are of single as well as multilayer.
• Made of flexible materials such as plastic.
• They are manufactured in single, double and multi layer types.
• The cost of fabrication is high as compared to the rigid PCBs.
• They are lighter than the rigid PCBs.
• They are highly useful at places where the working part produces vibrations.
• They are shock-proof, they don’t corrode and they are waterproof- a sense of durability!
• A sandwich of rigid and flexible PCBs.
• It has many benefits over using an only rigid or flexible PCB.
• These boards have a less number of parts as the wiring of two can be merged into one (flexible and rigid).
• Streamlined design
• Reduced board size as compared to any of the former types.
• Less weight
• Applications: Cell-phones, pace-makers, digital cameras and automobile.
Based on the amount of transmission (current and signals)-
• Designed to transmit signals beyond one gigahertz of frequency.
• Teflon, PPO (polyphenylene oxide) resin and FR4-grade glass reinforced epoxy laminate.
• Teflon-made high-frequency PCBs are the most expensive ones due to the cost of Teflon.
• While choosing a good high-frequency PCB one must know:
• Dielectric loss
• Thermal expansion
• Water absorption
• Made of aluminum or copper underlying boards.
• Designed to have a low thermal resistance.
• Advantages over fiberglass PCBs-
1. Low cost
2. Environment friendly
4. Heat dissipation