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Six Basic PCB Design Principles

Six Basic PCB Design Principles

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Printed circuit boards are vital parts of smart devices and several equipments as they provide current or electrical signals to run them. You need different elements to construct a PCB, such as:

  • Schematic design
  • Database login
  • Electronic component configuration
  • Design preparation
  • Wiring
  • Block division
  • Testing

If any issue happens during a process, you have to go back to the previous process to correct it. The layout of PCB components is a complex thin as it determines a board\s appearance and neatness. Moreover, it also affects the function of the end product or device. We will discuss below the six basic PCB design principles in terms of its components and other factors.

1-Components Layout and Clearance

You have to place the components evenly on the board, leaving some space on the edges. The components around the edge should be 3mm away from PCB edges. In general, designers leave 5 to 10 mm space around the edges.

The components should be only on a board’s one side. There should be a separate pad for each lead pin.

Don’t cross up and down the components’ layout and keep a certain distance between the nearby components on the board. However, this distance should not be too small as it can hinder PCB maintenance.

Components should be installed at a low height and its lead should not be more than 5mm away from the PCB, as it can affect its quality to bear vibration.

Printed Circuit Board components that reside on a pad’s both ends must be a bit larger than their axial dimensions. The pads should be located where the coordinate grid intersects. The central distance of the pad has to be more than the board thickness to have a neat layout.

According to IEC or International Electrotechnical Commission, the standard spacing of the coordinate grid should be 2.54mm, whereas the axillary spacing should be 1.27mm.

However, these standards practically impact a few processes, including automatic drilling, computer automated design, components welding, and automatic assembly. But, such a grid spacing is not restricted in the case of manual drilling.

2-Defined Solder Mask

Solder mask expansion should be well-defined as it can cause issues if you over-define or under-define it. Tombstoning may happen if you don’t define the solder mask properly. Like, one side cools down faster than another side, affecting the board. So, by following the right parameters, you won’t have to revise your design.

The solder mask opening should be larger than the pad. In general, it expands 4 mils or 0.1mm. However, both can also have the same size, depending on the Printed Circuit board Fabrication.

3- Via Type& Routing Width

You must use the right via for routing as it won’t work if its diameter or ratio is not precise. The current won’t pass correctly due to fused vias. So, via styles should be considered while routing the entire PCB.

The routs should have enough width to carry the current that your device requires. You must have an impedance-controlled routing that needs various impedance profiles. You have to apply these profiles to routing widths to ensure a functional layout. Don’t have routing at an acute angle even if the signals have a low speed as acute angle hinders manufacturing. Like, an acute angle can increase the corrosion, leading to an open circuit.

Whereas it is vital to avoid the acute angle in the case of high-frequency circuits because it fully changes the track width at the corners and results in poor signals and discontinued impedance.

Six Basic PCB Design Principles
Six Basic PCB Design Principles

4-Components Installation

Different PC Board components are installed either vertically or horizontally. The horizontal components are parallel to the surface of the circuit board. Whereas in vertical installation, components are perpendicular to the PCB surface.

Vertical components allow you to have more quantity on a board’s surface. It is ideal for hearing aids, semiconductor radios, portable instruments, or devices that need a dense placement of components. For vertical installation, components have to be lightweight. Don’t install heavy components in a vertical direction as it can affect a PCB’s mechanical strength. Moreover, it causes vibration, and components can collapse, making a circuit less reliable.

On the other hand, the horizontal installation provides mechanical stability, and the circuit board also looks neat. It also helps lay down the printed wires because it enhances the elements’ span.

You can use any installation method, depending on your needs but make sure to arrange components evenly and the circuit should be anti-vibration.

5-Considering The PCB Layout Type

PCB layout has either a regular arrangement of components or is irregular. In an irregular format, the axis of the components are not aligned with each other, so it seems messy. However, it helps lay down the printed wires easily as there is no restriction of direction. Such a layout is ideal for high-frequency circuits and involves a vertical installation.

Whereas in a regular format, the component axis is aligned and either parallel or perpendicular to the sides of a PCB. It provides a neat board and makes certain processes easier, like PCB assembly, debugging, welding, maintenance, and production.

Moreover, a regular format is ideal for low-frequency circuits where the board has a few component types and its surface is loose. However, the number of components is high and such an arrangement also suits electronic instruments. But, due to the direction restrictions, such a PCB has a complex layout of wires, increasing the overall length of the wires.

6-Factors That Affect the PCB Layout

You also have to consider the factors that affect a PCB layout, like the direction of the signals, device position electromagnetic interference, thermal interference, mechanical strength, etc.

  • Generally, the direction of the signal flow is from left to right of which left is the input and right is the output. It is also from top to bottom of which the top is the input and the bottom is the output. Connectors which are in direct connection to the input and output should be close to the input and output connectors. Integrated circuits or transistors should be the core components. Whereas other components should be located according to their electrodes’ location. You should also consider the size, a number of pins, shape, and polarity of components.
  • You should adopt certain ways to prevent electromagnetic interference that occurs due to different external factors, like spatial electromagnetic ways, poor wiring, poor installation of components, etc. You can avoid these issues during the layout design. But, interference will happen if the PCB design is not right
  • You should shield the components that interfere with each other. High-frequency components should have small wiring. Similarly, the components of weak and strong currents should be separated. Wires with high potential should be at a great distance to avoid 50Hz interference. Likewise, the metal components should not be adjacent or they should be well-insulated to avoid a short circuit.
  • While designing a PCB, you must know which components are temperature sensitive and which are heat components. The heating components like resistors should be located near the shell or near vent holes to dissipate heat. Don’t place many heating components near each other. Also, use fans or radiators to prevent the rise in temperature beyond its limit.
  • Whereas the temperature-sensitive components should be away from the heat source. In general, integrated circuits, transistors, electrolytic capacitors, and thermal components are temperature sensitive. These components get affected due to the rise in temperature, especially in a circuit’s long-term operation.
  • The board should also be mechanically strong and its center of gravity should be stable. Don’t install heavy or heating components directly on the board, instead, they should be under the chassis to have a stable board. If the board size is above 200mm it will cause mechanical stress, so it should be strengthened with a mechanical frame.

Finally, many PCB design software uses the power layer to have a fast design process. You can connect more wires to ensure the current has a minimum impedance or voltage drop down, thus giving enough ground return paths.

FAQs

1.How To Layout A Printed Circuit Board?
You have to follow certain steps to create a PCB layout. Such as making the schematic drawings, developing a blank PCB layout, creating a PCB stack-up, schematic capture, defining design principles, defining DFM, linking to PCB, placement of components, inserting drill holes, and the route traces.

2.Is It Hard To Design A PCB?
It is not hard to design your PCB if the electrical schematic is right. Besides, following the design parameters also makes the design process easy.

3.Why Is My PCB Green?
The color of the solder mask determines the PCB color. So, if the solder mask is green, you say that PCB is green. The solder mask shields a copper circuit to avoid shorts circuit or soldering issues.

4.What Is The Purpose Of Following PCB Design Rules?
PCB design rules or principles help you to develop a system to automate the testing of design requirements. You get an interface between the physical and logical sides to create a circuit board. So, you can automate the DFM tests by following the rules to ensure that you can build a PCB.
Would like to know more about Design Principles or PC Board assembly? Write us at sales@pnconline.com

Printed Circuit Board Copper Thickness Vs Current

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The right function of PCB depends on the copper thickness, trace width, and weight. Printed circuit boards have traces made of copper, and we also call them conductors. Copper traces have a specific thickness, width, length, and weight that affect the flow of current.

PCB has copper layers for the flow of electric current. The wrong copper thickness can affect the PCB assembly process. But, if you understand the relationship between copper thickness and signal transmission, as well as the cost of PCB fabrication, it would help you choose the right copper weight or thickness for PCB design.

So, you must know what is copper thickness or weight and why is it important. You should also know the heavy copper’s application, and PCB construction cost.

Sometimes you can’t change the trace width due to certain spacing requirements or PCB density. But, you can change the copper thickness to have maximum current flow. You have to consider signal integrity while designing a PCB. The signal integrity and current loss rely on the amount of impedance that happens on copper traces.

Printed circuit boards with heavy copper are used in high-power electronic devices which are vulnerable to tough environments. Thick traces ensure durability and can carry more current without increasing the trace width or length. However, lighter copper traces are also used to have a certain trace impedance without having a highly small trace width or length.

You must understand the relationship between the current flow and copper thickness while designing your PCB. So, you have to know the copper trace fabrication, in this case, and its effect on signal integrity.

PC Board Fabrication

PCB fabrication involves different steps, including etching which is done on the inner layers and the top surface of the board. You need a laminate sheet finished in copper. In etching, you have to remove additional copper from traces and several other parts of the PCB, like pads and angular rings. Fabricators use an ammonia-based liquid to complete the process of etching.

Generally, the copper sheet thickness is 1oz, like 0.5 oz. on each side of the sheet. You can etch it down to decrease the thickness or can increase the thickness by plating it up to have the desired sheet.

The sheets are done rough during fabrication to bond them to the dielectric material. However, the roughness can also affect the signal integrity in the case of high-frequency boards. The frequency above 100MHz can result in trace resistance that opposes the flow of current.

In the case of plated vias, you should add traces after drilling the holes and it often involves the process of electrodeposition. For example, the PC Board manufacturer places the circuit board in an electrolytic solution having copper ions. Then, he applies a direct current to create a potential around the hole, distributing the ions in the entire via, which is also known as filling. Such a distribution helps you to find the quality of the signal flow that occurs along traces. So, it is very useful to understand PCB fabrication to have a functional design.

Relationship Between Copper Thickness And Signal Flow

In general, fabricators buy copper sheets with specific weight and thickness as they want fixed numbers. But, engineers say that the copper parameters are changeable after having a set trace width and length to enhance the signal flow or integrity.

The current carrying capacity of a PCB is determined by a specific standard known as IPC-2152. It shows the trace parameters, including the thickness and weight of the copper, and trace length and width. These parameters are interconnected, depending on a material’s thermal and electrical properties.

Role of the PCB Copper Thickness to Enhance the Current

Engineers use some calculations and equations during PCB design as discussed below. These calculations are 99% correct in many PCB designs, so let’s understand them.

1-Finding the Signal Power, P (W) and Voltage, or V (Volts)
You must know these quantities from PCB operation design.
2- Finding Trace Impedance, R (Ω).
You have to set it and you can manage it during the fabrication of the PCB.
3-Finding The Maximum Flow Of Current For The Trace I (A).
You can find the current by using the below equations.
I = V2/R or I = P/V or I = √ (P/R)

4- Finding an Increased Temperature T (°C).

You must know the increased temperatures, or you can evaluate it from the PCB operation design.

5- Finding the Cross-Sectional Area of the Trace A (Mils2).

It involves constants of curve fitting, such as k, b, and c that approximate the
IPC-2152 curve. This curve links the area to its current carrying ability.

K for internal layers= = 0.024, b = 0.44, c = 0.725
K for external layers== 0.048, b = 0.44, c = 0.725

A = (I/ (k ×Tb)) 1/c

6- Finding Trace Width or W, Mils

You should also set the trace width as required.

7- Finding PCB Copper Thickness? (Mils).

= A / w

You can use the PCB design software to set the thickness of copper, or you can use values of the copper weight, as most contract manufacturers use it. Such parameters are proportional to each other. Here is how to find the copper weight.

Copper weight (oz.) = (copper thickness (mils) / 1.37
According to the thumb rule, the weight of one square foot of copper is one ounce. If you follow the right equations, you can create a well-designed PC Board even for the first time.
What Is Heavy Copper And Why Do You Need It?
If the copper weight is over 4oz, you can consider it heavy because a standard weight or thickness ranges from 1 to 3oz. You can use heavy copper to have

  • More current carrying capacity
  • High capacity to bear thermal stresses and have good thermal management.
  • Better heat dissipation
  • Great mechanical strength to have large through-hole components and heavy connectors.
  • Power converters and planar transformers

Sometimes the PCB fabricators use 1 oz. copper for internal layers and 4 oz. for external layers of a multi-layer PCB. Certain issues can be controlled by using the same copper thickness in stack-ups of opposing layers, as it can eliminate the PCB bending due to heat generated during its function.

Like, if you have a PCB with 8 layers, you can group the opposing layers as 1 & 8, 2 & 7, 3 & 6, 4 & 5. That means layers 1 and 8 should have a similar thickness or weight, and the same goes for layers 2 and 7 and other groups.

FAQs
What Is Copper Thickness And Weight In Printed Circuit Boards?

Copper is used in a PCB having a thickness of 1 oz., however, some engineers measure it in ounces. The thickness of copper determines the copper weight. Like, when the weight of copper covers one square foot of sheet, it makes copper thickness. Hence, 1 oz. of copper covering 1 square foot will result in 1.37 mils or 0.0348 mm foil thickness.
Why You Have To Consider the Copper Weight In PCB?

You can determine the current carrying ability of a PCB with the help of the thickness of its copper traces or copper layer. For PCBs with well-controlled impedance, the trace width helps determine the essential copper thickness. Besides, some other factors are also essential, such as a circuit board’s weight, compatibility of PCB components, and the type of connectors on a PCB.

Does Copper Weight Affect The Cost Of PCB Construction?

A printed circuit board with heavy copper involves expensive manufacturing, besides, it needs more time to make it. In other words, thicker copper is always more costly than standard copper. The manufacturing time of heavy copper is also high that also increases the total cost of PCB manufacturing.

What Is Etching In PCB?

In etching, you have to remove additional copper from traces and several other parts of the PCB, like pads and angular rings. Fabricators use an ammonia-based liquid to complete the process of etching.

How To Determine The Current Capacity Of A Printed Circuit Board?

The current carrying capacity of a PCB is determined by a specific standard known as IPC-2152. It shows the trace parameters, including the thickness and weight of the copper, and trace length and width. These parameters are interconnected, depending on a material’s thermal and electrical properties.

Final Thoughts

PCB involves different materials, including copper that have certain parameters, including thickness and weight. The copper thickness has a direct link to the current flow and the signal integrity, so its knowledge is essential for PCB designers, engineers, and fabricators. PCBs with heavy copper help create more reliable devices with increased current flow and better performance.

However, many smart devices have thin copper layers, depending on their requirements. You can develop a flawless circuit board by considering copper weight, thickness, as well as trace width and length, and several other features as described above. Besides, you must hire a good fabricator in this case.

Would like to know more about PCB Copper thickness and current or PC Board assembly? Email us at sales@pnconline.com

PCB Design Guidelines For Reduced Electromagnetic Interference

PCB Design Guidelines For Reduced Electromagnetic Interference

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Printed circuits should be well designed and well-built to help devices work accurately. These circuits should have good materials to minimize certain issues, including the high EMI or electromagnetic interface. On the other hand, poor design can cause weak signals and high radiation, disabling the device. Here, we will discuss all essentials of EMI and how to reduce it.
Electromagnetic interference or EMI is defined as any disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation. The effects of EMI can range from a simple degradation of signal quality to complete equipment failure. In order to avoid these negative effects, it is important to design your Printed Circuit Board with EMI in mind.
Reduced electromagnetic interference (EMI) on your circuit board ensures that your electronic devices and products don’t interfere with nearby electronics and may even improve the overall performance of your products. We will share some key tips that you can follow to help reduce the EMI generated by your circuit boards and improve the performance of your final products.

PCB Design Guidelines For Reduced Electromagnetic Interference
PCB Design Guidelines For Reduced Electromagnetic Interference

Optimizing the EMI PCB Design

Electromagnetic interference has many reasons,and you have to reduce it through the filter.You can create the EMI filters using a single component or a network of many components having dedicated circuits to reduce different mode noises. Now, we will discuss the EMI filter design and its standard types.
After deciding on the basic EMI design, you will have to optimize it through a circuit board’s specifications. Like, if the purpose of the EMI filter design is to drive other PCBs, you must add more filter elements to have smoothing, isolation, and limits of electrical parameters. The limitof meeting the board’s needs depends on the PCB design capabilities and the available analysis methods.

How PCB EMI Happens

You will see electromagnetic frequencies everywhere all around you, such as appliances, or electronic products having current. EMI falls into different categories when it comes to PCB.

  • High-power devices cause EMI, like amplifiers, antennas, processors, FPGAs transmitters, etc.
  • Moreover, the change of components can also cause interference affecting g the device.
  • EMI often occurs along traces and at connector points. Unnecessary coupling occurs between the ground planes and signal paths because of lost capacitance.
  • EMI also happens due to external sources, like when the board is near a source that emits radiation. This external source can be a device, equipment, or some other circuit board.

It is very hard to eliminate all types of EMI sources, but following certaindesign rules can help in this case. You can minimize the disturbing noises through different techniques that we will describe in this article.
What Are EMI Design Guidelines?
Like every PCBoard, there are certain design parameters to follow while designing a suitable EMI filter design. You have to adopt a certain perspective in this case, as described below.
PCB Design Perspective 2-Dimensional
First of all, you have to make marks for component placementwhich you can do through a design software library, or you can upload a file taking it from other sources. It also involves spacing, routing of traces, and design clearances. But, you will have to consider a few things to do so, such as:

  1. Make sure that component libraries and pads are compatible.
  2. There should be a maximum distance between the adjacent elements, such as traces, pads, and annular rings, as it will reduce the EMI.
  3. Designers should consider the types ofsignals for component partitioning.
  4. Make sure that the trace size or width is according to the required current capacities.
  5. The impedance compatibility should be addressed in terms ofexcellent power transfer and differential routing.
  6. Make sure to provide thedepenalization according to the terms and conditions of the board clearance.
  7. Devices with high radiation should be shielded.
  8. Silkscreen should be used wisely to enhance PCB assembly through reference points and component polarities.

Various Techniques To Minimize EMI

Design should involve minimum EMI, and you can achieve it by adopting different techniques.

Reducing The EMI Through A Ground Plane

The first barrier against EMI is the ground plane, as PCB needs a floating surface to function effectively. Printed circuit boards have a ground plane to give a reference line of 0 volts and take it to the power supply terminal for a circuit’s return path.

The circuit board becomes an antenna when there is noise due to ripples. A circuit board’s copper foil or the ground planeoccupies the maximum cross-sectional area of the circuit board. So, you can reduce the EMI or electromagnetic interference by effectively using the ground plane.

Reducing EMI Through Trace Layout

The conductive paths on the circuit boards are known as traces. Flowing electrons occur in traces due to an active circuit and are a little away from developing a radiating antenna.There are certain guidelines to follow regarding trace layouts, such as:

  • There should not be bends with sharp angles. Instead,round right angles are suitable to reduce reflections that occur due to an increase in capacitance in the corner areas lying at 45 degrees.
  • High-speed traces should be away from the low-strength signals. You can take an example of a clock that has high-speed signals. Whereas analog and digital signals should also be separate from each other.
  • The return paths should not be long, instead, make them short.
  • The differential traces should be close enough to enhance coupling. This techniquebrings influenced noises into a less problematic mode.
  • There should be a wise usage of vias as they help you take benefit of a circuit board’s multiple layers while routing.Designers should know that thereflections happen due to a change in impedance.
  • Different traces should not have vias. However, in case you need so, then you can have an oval anti-pad which two vias share, reducing the parasitic capacitance.

SomeWays of Reducing EMI from Components

  • Try to choose low-power consumption components.
  • You can use USB circuits within an enclosure, like PCB guards or Faraday cages. They can also eliminate the EMI from the circuitboard’s surroundings.
  • Use heat dissipation methods to avoid the EMI. Proper heat sinks and vias help in this case.
  • All the above techniques and guidelines can help you reduce EMI. But, the design, function, and PCB performance goals determine the EMI reduction technique you should choose.

Some Other Ways

Place decoupling capacitors close to the power pins of your ICs. These provide more capacitance closer to the source, reducing both conducted and radiated EMI.
Make sure you are soldering all components with enough solder so that there is no exposed metal at any point on the circuit board.
If possible, position sensitive analog circuits such as amplifiers or comparators away from digital circuits such as processors or microcontrollers.
Shielding (copper foil) can be used in conjunction with shielding paint to improve RF performance further. Shielding paint is usually made of copper powder mixed into an acrylic binder. The copper reacts chemically with air, so shielding paint should not be used in damp environments where there may be high humidity or condensation levels. In most cases, paints will have a shelf life of up to five years if stored in a dry place without exposure to sunlight.

EMI Optimized Circuit Board through PSpice

There is a simulation tool known as PSpice which can help you to analyze the electrical parameters of a PCB design. However, it should be done before submitting your design for construction.
Ithelps evaluate heat dissipation and distribution methods, different simulations, anda circuit’s behavior in different conditions.
You can use the PSpice Advanced Analysis tool for this purpose. You can optimize a PCB for minimizing EMI by following the design guidelines and using advanced methods.

FAQs

What is EMI in PCB?
Electromagnetic interference or EMI is defined as any disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation.
How To Reduce EMI?
You can reduce PCB EMI through traces, a ground plane, PSpice, and some other methods.
What Are the Reasons For EMI?
High-power devices cause EMI, like amplifiers, antennas, processors, FPGAs transmitters, etc. The change of components can also cause interference affecting the device.

Wrap Up

Electromagnetic interference (EMI) from power lines and high-voltage devices can damage circuitry, which can lead to failures in equipment and even safety issues. This article focuses on PCB design guidelines that will help you prevent EMI on your PCBs by making them less susceptible to outside interference, particularly during the power-up sequence.
By applying the guidelines described in this article, your designs will have lower susceptibility to radiated emissions, conducted emissions, and common-mode currents, making them less vulnerable to damage from outside sources of EMI.
Would like to know more about design guidelines for reduced EMI or printed circuit board assembly? Email us at sales@pnconline.com

Printed Circuit Board FR4 Material

Printed Circuit Board FR4 Material

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FR4 is a blend of fiberglass and epoxy resin, and manufacturers also call it a composite material. It resists flame and is highly used for PCBs as a substrate or base layer. FR4 circuit boards are now used instead of G10 boards due to their properties.

FR is also a great electrical insulator because it is completely water-resistant which means it does not absorb a little drop of water. Such qualities mechanically make it very strong and it maintains its qualities in all kinds of weather, including humid, hot, and dry weather.

Properties of FR4

FR4 is an inflammable material, and it is UL94V-0 compliant which means it does not spread fire, instead, it stops fire the moment the material starts burning. It has bromine that resists fire and does not absorb water as described above.
Moreover,the glass transition temperature is very high ranging from 115 to 2000 degrees Celsius, depending on the type of the resin and manufacturing method.Mostly such PCBs FR4 lies between the two layers of copper laminates.

Types of FR4 Material

FR4 material has different types, such as:
Standard FR4: Its heat resistance goes up to 140-a50 degrees Celsius.
High CTI FR4: The index of this type of FR4 goes beyond 600V.
High TG FR4: It has a high-glass transition value, such as 180 degrees Celsius.
FR4 without copper: This type of FR4 is suitable for insulating plates, and it can support the circuit board.

How To Choose The FR4 Thickness

FR4 thickness should be decided carefully as it contributes a lot to the applications of different PCBs. You should consider the following things in this case:

  • Design and flexibility
  • FR4 thickness should be compatible with components
  • It should not take much space on a PCB
  • Focus on the type of desired connections

Advantages of FR4

FR4 is cheaper than other substrates of circuit boards which makes it a standard material to develop small circuit boards. But, it is not good for high-frequency circuits or where the parts are suitable for flexible circuit boards.
FR4 is often suitable for RF applications with a frequency from 1GHz to 10 GHz. However, electric products having an FR4 have some disadvantages due to certain limitations.
FR4 material is one of the most popular choices for printed circuit boards because it offers a high degree of strength and rigidity. This means that your PCBoard will be less likely to warp or bend over time, which can lead to reliability issues. As already mentioned, FR4 material has excellent thermal stability, meaning it can withstand high temperatures without breaking down. This makes it ideal for use in harsh environments or in applications where heat dissipation is a concern.
As FR4 material is one of the most affordable materials on the market, which makes it is a great option for businesses on a budget. In addition to being cost-effective, FR4 material is also easy to work with, which can save time and money during the manufacturing process. It can be machined in a variety of ways, including deep draw and laser cutting, so customers are not limited in their design options
FR4 material is a great choice for PCBs because it offers good electromagnetic shielding. This means that it can help protect your circuit from outside interference. Additionally, FR4 is flame retardant, which makes it a safer option for use in electronic devices. It’s also strong and durable, so you can trust that your PCB will last for years to come.
It’s important to note that there are many different grades of FR4 material with different properties, so make sure you know what you need before ordering.

Some things worth considering when choosing an FR4 grade include: whether the PCB needs to support weight, how sensitive the device will be to temperature changes, how strong it needs to be, and how much flexibility is required.

Understanding PCB and Its Materials

Printed circuit boards manufacturers involve many steps, including design and finishing, leading to a huge production. Printed Circuit Board designers and engineers should consider the material in terms of its properties and applications. They should have it in Gerber files before sending the PCB design for manufacturing. In other words, PCB material determines the end product. Various PCB materials include the FR4, Teflon, PTFE, etc.
PCB substrates are made of phenolic and proxies, whereas PTFE is more costly than all others. Different PCB materials are available in the market, and you should choose them according to your needs.

Types of PCB Materials

Mostly PCB has four layers which are made one by laminating through a heating process. Each layer hasa specific PCB function and needs a specific material. PCB designersshould have full knowledge of materials in terms of their properties which should be suitable for specific applications.The end product with PCB is a specific device that needs a specific material, so it is a crucial factor.
PCB is composed of different materials from the base to the top, including copper, substrate or base layer, copper, solder mask, and silkscreen.
The subsequent layer of PCB is copper which is placed and bonded over a base material with heat and adhesive. The thickness of the copper layer is used according to the PCB and its application. Like, you can make it in one or two layers, depending on your needs. Mostly, cheap devices or gadgets have PCBs with a single layer of copper.
Like FR4, copper used in the circuit boards has different types in terms of resin, such as PF resin, epoxy resin, and polyester resin.
On the other hand, the silkscreen layer helps make marks or letters for programmers to read on a printed circuit board. The layer below a silkscreen is a solder mask and don’t forget to read our special post on solder masks.You can choose PCB materials by yourself or through an expert.

What is the FR4 Trace?

FR4 thickness is often 1oz,2oz, or 3oz, and the copper layer can be populated according to the design. It is also tested against the UV rays before removing the chemical solution to have correct copper traces which connect different parts on the FR4 PCB.
FR4 PCB trace can have signal issuesdue to mismatcheddriver’s and receiver’s impedance. Such an incompatibility results in bumps on the layer that reflects signals at a receiver’s end, sending them back to the copper trace.
The signal reflection that occurs due to mismatched impedance can affect the signal integrity. So, as a thumb rule, you should be careful, especially if the edge rate is lower than 1/6 of the propagation gap or delay in the copper trace’s length.
In the case of copper trace, signals occur 1 inch in 6 ns. You must take care of measurements to manage the impedance, especially if the edge rate is 1ns, whereas the copper trace is larger than one inch.

Printed Circuit Board FR4 Material
Printed Circuit Board FR4 Material

How To Manage The FR4 Trace Impedance

  • You can use resistive matching to make the driver and receiver’s impedance compatible. Such a technique involves a resistor having a value according to the source impedance. The resistive is set parallel with the receiver or in a series, depending on the requirements.
  • Some other techniques also help in this case, minimizing the signal reflection. A long PCB trace causes high-signal reflection. So, you can also reduce the trace length in a circuit board to overcome the signal reflection.
  • A signal’s return path is also important in this case because impedance can happen anywhere, including the signal trace or returning path.
  • If PCB has high-frequency signals, you should route the traces on the plane of a returning path. But, don’t route signals on a split plane because it would result in a discontinued impedance.
  • You must use advanced PCB design or analysis techniques to get precise results. The tools should possess advanced simulation.

Wrap Up

FR4 material is the standard fiberglass laminate that you’ll find in all PCBs (printed circuit boards). It has many uses, and each one will likely have its own set of requirements for using FR4 material. You’ll need to keep your specifications in mind when looking at FR4-based materials, but this will give you a good idea of what kind of FR4 laminates are available on the market today.
The FR4 board can be easily cut with a knife or saw and drilled through using a drill press or electric drill. You can even shape it using files or sandpaper if you need to, which makes it versatile as well as economical. So if you’re looking for high-quality circuitry in your next project, take a good look at what this particular type of PCB has to offer before making any decisions.
Would like to know more about the FR4 material or PC Board assembly? Email us at sales@pnconline.com

PCB Design

Understanding the PCB Design for Half Adder

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Multiple circuits’ combination involves various logic gates to create a multiplexer, encoder, de-multiplexer, and decoder. Such circuits have certain qualities, such as the circuit’s output more depends on the levels which are present at the input terminal.
Such a circuit lacks memory, and the previous input can’t influence the current input. The combined circuits consist of inputs and outputs.
A half adder is an electronic circuit that adds two binary numbers. So, two single binary numbers act as adders in this case. It can return the carry and the output, and the representation in practice involves the XOR and AND logic gates. There are two inputs in a half adder circuit, including A and B, generating the Sum and Carry. So, the number of outputs is also two in this case, like S and C.

Types of Combinational Circuits

  • Half adder
  • Full adder
  • Encoder
  • Subtractor
  • Decoder
  • Multiplexer
  • De-multiplexer

Understanding The Half Adder

Half adder is a digital circuit in PCB that provides an addition to binary numbers. In a half adder, a number’s weight is based on the binary digits’ position. The binary numbers are only from 0 to 1 of which 1 acts as the largest number and 0 as a smaller digit.
The two inputs of the half adder generate two outputs, so it is the simplest electronic circuit in the PCB. The inputs A and B are the bits where addition is required, whereas the Sum and Carry are the outputs abbreviated as S and C.

Half Adder Explained

The half adder circuit has two gates, including XOR and AND, and both have the same inputs. However, each gate generates the output, like XOR generates the Sum and AND generates Carry.

Half Adder Facts

According to engineers’ calculations if both ‘A and B’ inputs are 0, then both outputs like S and C would be 0.
However, if any of the input is 1, then the S or sum will be 1, but the C or carry will be 0.
However, if both A and B inputs are 1, then the S or sum will be 0, and the C or carry will be 1.
The half adder in a PCB performs additions according to the inputs applied.

2-Bit Half Adder

You can have the following combinations, such as

0+0=0

0+1=1

1+0=1

1+1=10

In this equation, 1+1=10, but it should be 2-bit output if rewritten, such as

0+0=00

0+1=01

1+0=01

1+1=10

In this case, the normal output is the Sum, whereas you should consider Carry as a carry-out. It is easy to implement a 1-bit adder through an XOR gate.
If you want to add two 8-bit, you can do it through the full adder because the half adder is suitable for the addition of one binary digit.
For two-binary digits, you will have to reduce the truth table. But, for a three-binary digit adder, the process of addition through a half adder should be done twice. Likewise, a four-digit adder involves another repetition of the half adder addition.
The entire process shows that it is easy to implement, but it takes lots of time.

Half-Adder IC

You can implement the half adder by using the high-speed CMOS digital and logic-based Printed Circuit Board.

Understanding Equation

It is easy to identify the equation of the half adder PCBs through two concepts, such as the Sum of Products, SOP, and the Products of sum, POS. The Boolean system of such PCBs helps find the relations between the inputs applied and the generated outputs.
Designers draw the K maps to find the equation and the maps are based on the facts. The k map has two equations, as it has two logic gates.

The K map for the Carry brings the below facts.
C=A.B
Whereas the K map for the Sum or XOR brings
S= A⊕ B

Applications of A Half-Adder PCB

The basic half adder has several applications, such:

  • It offers additions on the binary bits, and the logic unit and arithmetic lying in the computer need a half-adder circuit.
  • The half adder circuits when combined can produce full-adder circuits.
  • Such logic of half-adder circuits helps in designing calculators. So, the PCB in a calculator prefers a half-adder circuit.
  • The half-adder circuit also helps calculate tables and addresses.
  • Other than additions, the half-adder circuits can also handle different digital circuits’ applications. So, you can consider it a vital part of digital electronics.

Implementing The Half Adder Through An NOR Gate: NOR is a universal gate that helps implement a half adder.

Implementing The Half Adder Through NAND Gate

The NAND is also a universal gate that shows that you can design any type of PC Board through NAND gates. In this type, the carry output is produced through one NAND gate’s output being applied to the input which is another NAND gate. The second NAND gate is AND-gate generated output.

The Sum’s output equation can be produced through the output of the initial NAND, but with A and B inputs. In the end, the outputs generated by the NAND gates are again tried on the gate, producing the Sum’s output.
Hence, the standard adder in a digital PCB is easy to design through different logic gates. However, the addition of multiple bits is hard and it becomes a half-adder’s limitation.

Understanding A Full Adder PCB

The full-adder circuit includes three inputs, such as A, B, and C which add three numbers for input, generating the Carry and Sum. Whereas the number of the outputs is two. The main reason for half and full adders is the addition.
If Carry is produced through a previous addition, you can add it to another, unlike a half adder.

Difference Between A Half And Full Adder

A full adder involves two AND gates, two OR, and two EX-OR gates. Full adder is applicable in digital processors, and additions of several bits.
You have to combine two logic gates for PCB design with a half adder. But, a full adder consists of three gates.
Half adder is required in the electronic devices to calculate additions. But, the full adder is applied to the digital processors to add a long bit.
You can have a high output in full adders. Moreover, they involve a high speed and are very powerful in supplying voltage.
Full adder is also suitable for GPU, or Graphics Processing Unit.
How Are Half Adder And Full Adder Similar?
Half adder and full adder have one thing in common and that is the addition, as both are combinational circuits and don’t need a memory, like sequential circuits.

FAQs

What Is An Adder In PCB?

The digital circuits have different benefits, and if their main focus is to provide an additional, it is called Adder. It has two types, including the half adder and the full adder, depending on its inputs and output. However, the output is called Sum and Carry.
Adder is used in different kinds of processors other than just computers. They are constructed for several numerical elements, such as binary code decimal or excess-3.

Is There Any Limitation Of A Half Adder?

Yes, the half adder has some limitations. Like, it cannot add the carry bit produced from the previous or old bit. So, the half adders can’t perform additions in the case of multiple bits.

What Is A Full Adder In PCB?

A full adder includes three inputs, such as A, B, and C which add three numbers for input, generating the Carry and Sum. Whereas the number of the outputs is two.

Where To Use A Half-Adder Circuit?

PCB with a half adder is used in calculators and digital devices. It has a simple design and you can convert it to a half subtractor.

How Many Types Of Combinational Circuits Are There?

The types of combinational circuits include the half adder, full adder, encoder, subtractor, decoder, multiplexer, and de-multiplexer.

What Are The Uses Of A Half Adder?

A half adder offers additions on the binary bits, and the logic unit and arithmetic lying in the computer need a half-adder circuit. Moreover, half-adder circuits when combined can produce full-adder circuits. The logic in designing calculators. So, the PCB in a calculator prefers a half-adder circuit. The half-adder circuits can also handle different digital circuits’ applications.

Wrap Up

A half adder is an electronic circuit that adds two binary numbers. So, two single binary numbers act as adders in this case. It can return the carry and the output, and the representation in practice involves the XOR and AND logic gates. There are two inputs in a half adder circuit, including A and B, generating the Sum and Carry. So, the number of outputs is also two in this case, like S and C.
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