Fundamentals of Printed Circuit Board

Fundamentals of Printed Circuit Board 

We live in a world driven by technology and use them in nearly every aspect of our daily lives. We tend to depend on smart electronic devices to make our lives easier, organised and better connected. Needless to say, all these electronic devices are designed over a Printed Circuit Board (PCB). PCB Design Services is a product design process involving high-level engineering tools for board design.

PCB Design is the point in a design stage at which all the design decisions made earlier come together and where unforeseen problems related to performance, power distribution analysis, signal integrity, thermal analysis and noise mismatching make themselves known and have to be resolved.

What is a PCB or printed circuit board?

Printed Circuit Board is a critical component in electronics that enables and integrates all the electronic circuits/components of a design. These boards are used in various electronic products – from Smartphones, Smart Tabs, Reader, Camera Devices, Access Controller, Infotainment Systems to Medical devices, Industrial equipment, Automotive Electronics, Radars, Defense, Military and Aerospace equipment and all other computing systems.

Printed circuit boards were initially developed during World War II for military applications. Over the years, this technology was adopted by electronic manufacturers enabling them to offer cost-effective, compact, and power-efficient solutions.

The printed circuit board is made up of a thin layer of conducting material, usually copper films printed over a non-conducting layer known as substrate. These substrates are made up of special materials which do not conduct electricity. The most commonly used substrates are Resins, Fiberglass, Epoxy Glass, Metal Board, Flame retardant (UL94-V0, UL94-V1) and Polyimides.

Fundamentally PCBs are single layer, double layer, and multi-layer. The layer classification of Printed Circuit Boards is based on the number of conductive layers present in the PCB. The below figure shows the cross-section of various types of PCBs.

Typically, there are two different methods for mounting components on a Printed Circuit Board – through-hole and surface-mount. In the through-hole method, the components consist of thin leads that are pressed through tiny holes in the board on one side and soldered on the other side. The through-hole method is mostly used because of the mechanical stability it provides to the components. In the surface-mount method, the terminals of every component are soldered to the same surface of the Printed Circuit Board directly. Mostly surface-mounted components are small and have a tiny set of solderable pins or Ball Grid Array (BGA) on the component.

PCB Material Classifications

A PCB is broadly classified into three different categories:

1.   Rigid PCB

2.   Flex PCB

3.   Rigid-Flex PCB

Let’s have a look at these categories in detail:

1. Rigid PCB

Rigid PCB, as the name suggests, is a solid, inflexible PCB which cannot be twisted or folded to fit into a specific mechanical enclosure. The Rigid PCB which is also known as the Standard PCB is made up of resin and glass along with copper foils which are generally known as Laminates. These laminates come with specific thicknesses to form a standard double-sided PCB, i.e., 0.4mm, 0.6mm, 0.8mm, 1.2mm, 1.6mm, 2.4mm, etc. Multiple sheets of these laminates are used along with pre-preg to form a multi-layer design.

Rigid PCBs are the cheapest PCBs. These are also known as the traditional PCBs and are more widely used in various electronic products. The best example of a rigid PCB is the computer motherboard. Some of the solid PCBs that we see in our daily lives are washing machine, refrigerator, telephones, and calculators.

A simple construction of the double-sided PCB and multi-layer PCB are shown below:

Benefits of Rigid Printed Circuit Boards:

o   Cost-Effective solution

o   Rugged and reliable

o   High-density circuits

2. Flex PCB

As the name suggests, the Flex PCB is a flexible PCB that can either be folded or twisted to form a specific shape. The flexible nature of these PCBs helps in accommodating a complex PCB in a smaller form factor thereby reducing the product size. The clutters within a given frame, replacing a wires/cables with a simple flex PCB. The substrate in the Flex PCBs is made up of thin insulating polymer films or polyimides similar to the Rigid PCBs. The key objective of Flex PCBs is to improve the bend and make the product compact and flexible with a lesser layer count. The thickness of the copper foils and the polyimides are made thinner to achieve the flexibility of the product. . “The thinner the copper foil, much reliable is the Flex PCBs.” A Stiffener/Backer is attached to the Flex PCBs to prevent plate buckling and support for components.

Ideally, Flex PCBs are a great choice for designing PCBs of high speed and controlled impedance. These PCBs are widely used in aerospace, military, mobile communications, computers, digital cameras and more.

Benefits of Flex PCBs:

o   Allows bending and folding to fit into an arbitrary shape

o   The thin and lightweight enables a substantial reduction in packaging size

o   Flexibility makes it easier for installation and service

o   Effectively reduce the volume of the product

o   Suitable for miniaturized and high-reliability electronic products.

3. Rigid-Flex PCBs

Rigid-flex PCBs are circuit boards that use a combination of both Rigid and Flexible board technologies in a given design. Typically, Rigid-Flex boards consist of multiple layers of Rigid and Flex on a PCB, that are interconnected within a 3D Space. This combination enables efficient space utilization as the flex part of the circuit can be bent or twisted to achieve the desired shape of the mechanical design.

Similar to the Rigid PCBs, standard FR4 layers merged along with polyimide layers, usually in the centre, are used to form a Rigid-Flex PCB. Rigid-Flex PCBs are most commonly found in devices were space/weight are major concerns, such as smartphones, digital cameras, USB, CT Scanners, Pacemakers, and automobiles.

Benefits of Rigid-flex PCBs:

o   Rigid-Flex PCBs enable design freedom, space minimization, weight reduction, that will eventually reduce the packaging requirements significantly

o   Integrates both rigid and flexible circuits to minimize interconnects

o   Dynamic and flexible and fits into smaller spaces

o   Suitable for high-density, miniaturized and high-reliability electronic products

o   Flex circuits eliminate wire routing errors

BACK SIDE CONTROLLER BOARD PCB

FRONT SIDE CONTROLLER BOARD PCB

So, there you have it. The basics of PCB and it’s classification.

Ref:-

1. Mistral Solutions Pvt. Ltd

2. https://www.tempoautomation.com/blog/

3. https://jayconsystems.com/circuit-board-design/

Increase of BMS cables sale

Increase of BMS cables sale

The global IBMS market is highly fragmented with the presence of several global and local vendors. Global vendors mostly operate as original equipment manufacturers (OEMs), catering to the requirements of the end-user through distributors/dealers or system integrators. Technical knowledge and ability to customize based on end-user requirement by vendors will hold the key to a strong foothold in the market.

Building management system cables also commonly known as BMS cables, intelligent building cables or automation cables are used to automate all of the systems in place within a building or home. Research suggesting the BMS market will reach $19.25 million by 2023; it’s even more of an opportunity for electrical contractors to capitalize.

The global IBMS market will continue to grow at a healthy pace throughout the forecast period. Apart from energy and cost savings, other important drivers are the degree of flexibility provided by open IBMS solutions, the high degree of productivity it provides, and a higher return on investment along with enhanced security. These factors are attractive to many businesses, thus driving the market growth.

An advance Building Management System can control the safety in homes and offices, monitoring doors and windows for alarm systems and detect floods and fires. Equipment and installations are designed for the control, monitoring and optimization of various functions and services provided in a building that includes: heating, ventilation, air-conditioning, lighting, security systems and the operation of electric / electronic applications. 

A shielded cable that is not grounded does not work effectively. Any disruptions in the path can raise the impedance and lower the shielding effectiveness. Firstly make sure you have a cable with sufficient shielding for the application's needs. In moderately noisy environments, a foil alone may provide adequate protection. screened cable (plural screened cables) Wire for the transmission of electricity or electronic signals, protected by an enclosing web of earthed wire mesh to avoid electromagnetic interference from (or to) other signals. Grounding: a point in contact with the ground, a common return in an electric circuit and a arbitrary point of zero voltage potential. It also provides personal safety and protects the equipment. Control the voltages developed on the ground when the earth-phase short circuit returns through a near or distant source. Provide a stable voltage reference to signals and circuits. Minimize Electromagnetic Emission (EMI) effects.

Shielding: The shield must be connected to the signal reference potential of what is being protected. When there are multiple segments keep them connected, ensuring the same reference potential. The shielding is only efficient when it establishes a low impedance path to the ground. A floating shielding does not protect against interference. The use of non-magnetic metals around conductors does not shield against magnetic fields.

The cabling of the industrial communication systems (Modbus RS485) is different in some ways from the cabling used for power cabling and the electrician may experience some difficulties if he is not an expert in Modbus communication networks. A Modbus RS485 connects a Master device to one or more Slave devices. Henceforth, we shall consider Slave devices to be measuring instruments with serial communication, even if the cabling is similar for all Modbus devices.

Cable Selection

You should consider the following:

·         How many conductors do you need?

A minimum of three conductors, but the shield may be used as the common conductor, so shielded two conductor cable may be used. If you do not use shielded cable, then at least three conductors are required. Some RS-485 devices do not use a common connection, but we recommend always connecting common for reliable performance and to avoid damage due to surges.

·         What wire gauge do you need?

·         For unterminated networks, the current will generally be less than 10 mA and any gauge should work; we recommend #24 AWG to 18 AWG.

·         For terminated networks, the current can be 60 mA or higher, so heavier gauge wire may be needed for very long runs.

·         We recommend #22 to #20 AWG for runs up to 1000 ft. (~300 m).

·         We recommend #20 to #16 AWG for runs up to 4000 ft.(~1200 m).

·         What should the cable impedance and capacitance be?

Cables suitable for use in an RS-485 network should have an impedance of between 100 and 130 ohms, a capacitance between conductors of less than 30 pF per foot (100 pF per meter), and a capacitance between conductors and shield less than 60 pF per foot (200 pF per meter).

·         Do you need shielding?

Because RS-485 is differential, it is less susceptible to interference, so shielding is not always necessary. However, we recommend shielding for long runs and if there is electrically noisy equipment nearby like variable speed drives. If you use shielded cable, connect the shield to earth ground at one end (generally the PC or RS-485 master).

·         Do you need twisted wires?

Yes, especially for non-shielded cable.

·         What voltage rating do you need?

We recommend wire or cable rated for the highest voltage present. So if you are monitoring a 120/208 Vac panel, you should use 300 V rated cable. If you are monitoring a 480Y/277 volt circuit, use 600 V rated cable. If you have the WattNode in a separate enclosure and there is no way the mains wires can contact the Modbus output cable, then you could safely use lower voltage rated cable, such as 150 V or lower. Long runs of 300 V or 600 V rated cable may be expensive, so it may be more economical to use lower voltage rated cable and use a protective jacket in the regions where the cable is in the vicinity of dangerous voltages.

·         Can you run the RS-485 network cable adjacent to or in the same conduit with mains wires?

We strongly recommend against this. There may be interference from the high voltages and currents present on the mains wires, and if there is any insulation fault, arcing, etc. on the mains wires, it could put dangerous voltages on the low-voltage RS-485 network cable.

Most modern buildings now incorporate some form of BMS, focusing primarily on energy efficiency and saving costs. Whether that’s through proximity sensor lighting, climate control, door entry or security, they all work to achieve the same goal.

Efficient lighting control in a BMS system is just one way of reducing energy and saving costs for building owners. Using BMS, lighting can be automatically adjusted, depending on natural light detected or amount of people in the building. These cables are available in Low Smoke Halogen Free (LSHF), meaning they give off minimal smoke and toxic fumes. This is ideal for installation in public buildings such as schools, hospitals or airports where evacuation may be difficult in the event of a fire.

Unlike what happens in many energy distribution systems, the manner in which the devices are connected in parallel is important. The RS-485 system used for Modbus communication provides a main cable (Bus or backbone), to which all the devices have to be connected with branches (also known as stubs) that are as short as possible. The branches must be no longer than 1200 mtr.

Maximum distance and maximum number of devices. The main cable must be no longer than 700 m! This distance does not include the branches (which must nevertheless be short). The maximum number of devices that can be connected to a main cable is 32, including the Master.

In order to increase the extent of the Modbus network, repeaters can be used; and signal amplifying and regenerating devices provided with two communication ports that transfer to each what they receive from the other.

The cable shield must be earthed only in one point. Normally, this connection is made at one end of the main cable.

In order to avoid signal reflections, a 120 Ohm termination resistance must be fitted on each end of the main cable. The end resistance must be used only at the ends of the main cable. If the total length of the main cable is less than 50 m termination resistances can be avoided at the ends of the main cable.

Fire safety is another major reason why owners may consider installing a BMS system into their building. High performance fire survival cables provide an excellent solution for connecting BMS with fire systems. The data and coaxial ranges are designed to carry on functioning in the event of a fire and provide vital signals to voice alarm, CCTV and allow systems to be shut down in an orderly fashion. Meeting specific fire resistance requirements.

Site Surveys Planning for Your Customer

Site Surveys – Planning for Your Customer

Most of us have heard the old saying “Prior planning prevents poor performance” and nowhere is it more important than planning out a Video Surveillance System & Access Control System. Taking time upfront to make sure your survey is complete and accurate will save great amounts of time, money and energy for your installers, making both you and the customers bottom line better.

Making the sale and picking the right product are only parts of the puzzle. Camera placement, lens selection, mounting options and cable planning are all equally important to the success of a job. These elements will also help you gain the loyalty of your customer. If you’re a salesman, project manager or an estimator, at some point you’re going to have to put a project together and it will help if you know what to look for.

Of all the various parts of a CCTV system & Access Control System, the one thing the customer is going to notice above all else is a picture that doesn’t meet his expectations. He won’t care what kind of cable you used to get the picture in front of his eyes, nor will he worry about whether there’s a space in between each piece of equipment mounted in a rack. But he will know right away if he can’t see what he thought he was going to see or if what he can see is out of focus.

Picking camera and lens combinations are one of those areas that have become far easier over time. More sensitive cameras and varifocal lenses have taken most of the work out of the selection process. EM Lock installation has taken most of the work out of the selection process. It is still important however to have a good grasp of the concepts.

Focal length of a lens refers to two main things, the distance a lens can see clearly and the width of the scene a particular lens can see. Focal length is rated in millimeters. The lower the millimeter number, the wider the scene. As you go higher in millimeters, the lens becomes more telephoto and the scene width is greatly reduced. Taking the time to pick the right camera and lens combination will make for a smoother install and a happier customer and reduce the need for return visits.

One aspect of a site survey and system design that is frequently over looked is the environment itself. Not only conditions like temperature and weather extremes, but also physical aspects of the environment. I was recently out at a customer’s site looking at a parking lot through the view of his cameras. The customer told me the view was good now but in the spring when the trees bloom he cannot see anything. His system was installed in the winter when all the trees were bare. Please remember that trees grow. Those newly planted saplings will become towering oaks in a few years. Make sure they won’t impede your view now or ever.

Physical obstruction aren’t only limited to the great outdoors. Warehouses are notorious for large shelving and stacks of product. Shelves and products are subject to reconfiguration at any time. Make sure your camera placement is high enough so that it doesn’t get blocked by a stack of boxes.

It seems obvious to take things like that into consideration but I can tell you it doesn’t always happen that way. In times like we are experiencing today the need to get in and out of a project quickly becomes very important to the bottom line, but we can’t let it compromise the integrity of our system design.