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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

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Differences Between IC and a PC Board

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Before discussing the IC, you must know what PCB is. The PC Board or PCB has electronic components to help a device function. All digital and electronic devices have PCBs, like consumer products, smartphones, computers, laptops, tabs, etc. The purpose of the PCB is to eliminate assembly issues and have less wiring, enhancing automation and production.
The PCB has different types in terms of the number of layers. Like, it is either a single layer, double layer, four or six layers, or a multilayer circuit board. Now, we will discuss the difference between PCB and integrated circuits.

What Is IC Or Integrated Circuit Board?

The integration of chips makes an integrated circuit, like chips used in a CPU and motherboard are ICs or integrated circuits. Initially, IC was called an integrated block. You will see the IC soldered on a printed circuit board. In other words, a printed circuit board carries the integrated circuit.
The purpose of the integrated circuit or IC is to integrate an ordinary circuit into a chip. So, if the IC gets damaged, the chip won’t work. But, if the PCB gets damaged, you can replace the components.

Printed Circuit Board and Its Components

PCB has different types, however, today’s circuit board has specific components, such as:
Layout and Circuit: PCB circuit is a tool for conducting between different components. A copper surface becomes the base and power layer. Besides, it involves routing through drawing.
Dielectric Layer In The Board: it is also known as the substrate that contains insulation that lies between the layers and a circuit.
Through-Hole Via: vias are made for conducting and a through-hole via helps multiple layers conduct. The plug-in of a device is a large through-hole. There is also a non-through-hole that helps in surface mounting and fixes screws while PCB assembly.
Solder Mask: The copper surface is not always tinned. Epoxy resin is used to print the non-tinned area to separate the tinned copper to prevent a short circuit. Solder mask has different colors, including black, green, red blue, etc.
Silkscreen or Marking: Silkscreen is used to make legends or mark names and locations of different components. It helps maintain a PCB after assembly.
Finishing: the copper surface has to be tinned or it would get oxidized. The surface finish involves different processes, such as ENIG, HASL, immersion tin or silver, and OSP. You can use any method according to your needs as each finishing method has some pros and cons.

Features of Advanced PCB

High-Density PCB’s
PCB is becoming advanced due to new technology. You will see the HDI circuit boards in all small gadgets. Both installation and ICs are also improving with time.
More reliable
Now, PCB is more reliable than before because we have better testing tools. Moreover, its manufacturing and the end product are of high quality.
Up To Parameters
Each PCB material has certain mechanical, electrical, physical, and chemical properties. You will get a high-performing PCB if its design is according to the standards and design parameters.
Better PCB Production
PCB production has also increased with time due to better tools, design software, and advanced technology. Various standards ensure a high-quality device, such as automation, standardization, management, etc. You will see better equipment to test your PCB to have a high-quality end product.
PC Board Assembly
Assembly has also improved and helps you to have more production than the previous years. Similarly, you can develop complete equipment by assembling different components.
PCB Maintenance
PCB maintenance is also essential, especially, if the assembly gets issues. You can easily replace the damaged parts, restoring the system. Making lightweight, and mini or smart PCB is also easier than before. You can have a device with high-speed signals by maintaining your circuit board.

Features of Integrated Circuit

The integrated circuits were developed by Jack Kilby and Robert Noyce. The integrated circuit is very common in certain industries, such as military, civil electronics, television, communication, radio recorder, computer, etc. It provides the following benefits.

  • Lightweight structure
  • Less lead
  • Small volume
  • Solder joint
  • More reliability
  • Longer lifespan
  • High performance
  • Mass production
  • Low cost

IC is a microelectronic component or device in a PCB. IC technology involves the manufacturing of chips, design technology, processing technology, testing, packaging, design innovation, and mass production.
The integrated circuit is a key part of advanced electronic sand it is the heart of many circuits. You will see at least one chip or IC in every electronic device. IC is a combination of various electronic components, including capacitors, resistors, transistors, etc. These components together make a small chip and are linked to having a common goal. There are different types of ICs, such as

  • Single-circuit logic gates
  • Voltage regulators
  • Open amps
  • Motor controllers
  • 555 timers
  • Microprocessors
  • Microcontrollers
  • FPGAs
  • Many others

There is a complex process of making layers of copper, semiconductor wafers, and several other materials. These materials interconnect to make resistors, transistors, and other parts of a circuit.
Not only IC is too small, but it has very thin copper layers and semiconductor wafers. The layers have very delicate connections. Similarly, The IC die is a very small circuit that is too tiny to connect or solder, so you have to package the die that converts the delicate die into a black chip that you often see.
You can enhance the working life of equipment by using the IC to assemble different electronic tools. It helps you to increase the assembly density many times compared to transistors.
These days, you would see silicon ICs involving semiconductors. So, IC is a device that integrates capacitors, resistors, semiconductors, and other elements that make a circuit perform certain tasks. The device connects wires between these components on the silicon wafer through oxidation, diffusion, aluminum evaporation, epitaxy, and photolithography, and then it is welded in a casing or shell.

Differences Between IC and a PCBoard
Differences Between IC and a PCBoard

What Is IC Package?

IC package helps convert a die into a device to have a connection. Die’s outer connection has a small gold wire to a pad on the package that helps to connect it. The pad or pin is silver and it is an extruded terminal on the IC that continues to connect to a circuit’s outer parts. There are different types of IC packages having different dimensions, installation methods, and a number of pins.
Understanding Pin Numbering and Polarity Marking
You should know that every IC is polarized and each pin is different in its function and location. So, the package must show each pin’s nature and function. Mostly the ICs have DOT or Notch to differentiate the first pin. Like, sometimes only one pin is the first or sometimes both are.
Package Mounting
The mounting of a package on a PCB also varies, it can be SMT or surface mount, SMD, or a through-hole mounting. The through-hole package is often large and easy to manage, and it is created to get stuck through a board’s one side and soldering the other side.
The surface mount package has different sizes, small or minuscule. These packages are created to be soldered to the PCB surface and sit on one side. The SMD package has pins either perpendicular to the chip or extruded out the side, or set in a matrix on a chip’s lower part. Such ICs are hard to assemble with hands and need special tools for this purpose.
Dual In-Line Package or DIP
DIP is an ordinary through-hole IC package having two parallel lines of pins that extend perpendicularly from a black, and rectangular plastic casing.
SMT, SMD, or Surface Mount Package
There are many types of SMT packages and in the case of ICs, you must have a custom PCB having compatible copper patterns to be soldered. You need special automated tools to solder the SMD package.
SOP or Small Outline Package
The SOIC package is the SMT cousin of the DIP as this is what you see when you bend all the pins outward on a DIP, reducing the size. The SOP package is very easy to solder with hands. The spacing between the pins should be 1.27mm or 0.05”.
The shrink small-outline package or SSOP is a small type of SOIC package. Likewise, there are TSOP or thin-small outline packages and TSSOP or thin-shrink small-outline packages.
It is easy to understand the difference between IC and PCB if you know all their features as described above.

Final Thoughts

The integrated circuit is a key part of advanced electronics and it is the heart of many circuits. You will see at least one chip or IC in every electronic device. IC is a combination of various electronic components, including capacitors, resistors, transistors, etc.
The purpose of the integrated circuit or IC is to integrate an ordinary circuit into a chip. So, if the IC gets damaged, the chip won’t work. But, if the PCB gets damaged, you can replace the components. However, PCB and IC work together to help an electronic device function.
Would like to know more about the ICs, PCBs or pcb assembly? Email us at sales@pnconline.com

Advantages of A HDI Printed Circuit Board and Its Applications

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Unlike a traditional PCB, HDI has high-density circuitry. It consists of different types of vias, including buried, blind, and micro-vias. Some other features of this PCB include:

  • Surface to surface through vias
  • HDI construction involves layer pairs
  • Passive layers without electrical connection
  • Minimum two layers having through vias

HDI PCBs are ideal for smart devices or electronics having less weight. You must hire an experienced manufacturer to have an HDI printed circuit board because it has very narrow tolerances. So, only experts can handle such a PCB, as a little defect can lead to serious issues.

What are the benefits of an HDI circuit board?

There are many advantages of the HDI printed circuit board, provided it is according to the design parameters. Your product can perform better with the HDI technology. Let’s study its benefits one by one.

It Needs Less Space

HDI circuit boards don’t take much space, so the overall weight of the final product is also less. You can have more components on a board’s both sides, getting a functional, small, and lighter device.

Better Electrical Function

You get an enhanced electrical performance through HDI because of a little distance between the components and more transistors. Such features involve less power consumption, resulting in better signals. The signal transmission becomes fast due to a smaller size, besides, there are lesser crossing delays and signal losses.

More Cost-Effective

Since an HDI PC Board is smaller than traditional boards, it needs fewer raw materials, hence its cost is also less. Instead of having multiple PCBs in one product, a single HDI PCB is enough for better performance through small size and minimum material.

Quick Production

The production time is also faster than the conventional boards. Your product gets ready for selling if its construction involves an HDI printed circuit board having minimum materials. It is easy to place the components on HDI boards, moreover, better electrical performance is there to reduce the troubleshooting and testing time.

More Reliable

The micro vias in the HDI PCB come up with small aspect ratios and involve high-quality manufacturing, making the board reliable. A reliable PCB is always cost-effective, so the end product is also reliable and satisfactory

What To Consider While Designing An HDI PCB

You have to consider certain factors and parameters while designing the HDI circuit board. The production of such a board is different from others that we will discuss below.

Lamination Process

High-density PC Board Fabrication involves sequential laminations where you have to combine the PCB layers or cores with copper and pre-set layers. It involves heat and pressure according to the type of the circuit board. Once the lamination is over, you need to drill vias several times, unlike a traditional PCB. So, such a sequential lamination process helps manufacturers have flawless drilling without any breaking or shifting.

Understanding The Via-In-Pad

The construction of the high-density PCB involves the via-in-pad process to help you to make vias on a flat surface of your PCB. You have to plate vias, filling them in different ways, capping them, and then plating over them. The process of via-in-pad consists of 10 to 12 steps, and it needs skilled workers and special tools. There are many benefits of using the via-in-pad for HDI boards, including reduced space, simple thermal management, and less time to bypass the capacitors, in the case of high-frequency layout designs.

Considering Via Fills

You should also consider the type of via fill as it has to be compatible with the PCB requirements and its application. Some common filling materials, in this case, include electrochemical plating, copper, silver, and conductive and non-conductive epoxy of which non-conductive epoxy is highly used. Moreover, via fill should be flushed with the flat surface of the PCB and should also be fully soldered.

The via fill helps develop the blind, buried, and drilled vias in the case of both standard and micro vias. Then comes via plating to hide it under the SMT surface. It involves several drill cycles at balanced depths to have precise drilling. Such well-controlled drilling needs special tools and more time.

Layout Options

You will see the HDI circuit boards having different layout designs, including

  • 1-n-1 PCB
  • 2-n-2 PCB

A 1-n-1 PCB is the simplest HDI circuit board as it is a single construction of multiple layers of high density. These layers are interconnected, and such a board needs sequential lamination on both sides of the core. Whereas the 2-n-2 PCB consists of two layers of high density to help you to stack micro vias around the layers. The micro vias have copper filling in the case of complex layout designs.

The HDI structure can reach high levels of X-n-X even though its complexity and cost limit the construction. There is also the any-layer HDI with a very dense layout where conductors can interconnect easily through laser micro vias. You will see such designs in CPU and GPU chips, like in many mobile devices and smartphones

Laser Drilling

When it comes to the any-layer HDI, you will have to apply the laser drills to create micro vias. In this process, the drill emits a laser of 20 microbe diameter which can easily cut the glass or metal, providing small and clean vias. You can also use the uniform glass to make very small holes, as such a glass type has a low dielectric constant.

                   

Cost of High-Density PCBs

Various factors can affect the cost of an HDI PCB, making it high or low. Here, we will discuss certain things to help you have a budget-friendly circuit board.

1-Quantity and Type Of Vias

Whether you choose a through-hole or micro vias, it will affect the cost of the board. Likewise, the number of holes also influences the cost. Larger vias will cost you less than smaller vias, as smaller ones are hard to create with precision.

2-Layers And Stack Up Height

The number of layers also affects the PCB cost. Likewise, you have to consider the height of the stack up to determine your budget. According to engineers, the 2-n-2 high-density circuit board’s design is more complex than the 1-n-1, so it costs you more. Moreover, extra layers also increase the PCB cost, so design your board carefully with a suitable number of layers.

3-HDI PCB Materials

The material you choose for your PCB also determines its cost. Some common core or base materials, in this case, include metal, fiberglass, FR4, etc. Whereas the finishing materials can be ENIG, immersion tin, HASL, gold, immersion silver, and many others.  Most manufacturers use the ENIG as it is smooth and easy to solder. You also have to consider the application of the board while choosing its material.

4-Quantity Of Sequential Layers

The number or quantity of the sequential lamination also affects the cost. The number of holes and the number of layers help determine the number of sequential laminations needed for HDI. Though more lamination means high cost and construction time, it ensures a reliable product that performs faster.

5-Type Of Setup

The type of setup also affects the PCB cost, like it is either stacked or staggered.  You can fill the stacked vias with copper, but it is not so with staggered vias. Via filling means you need additional materials and more time to produce your product or device.

6-Size of the Pad

You can decrease the cost by considering the pad size in the early stages. The HDI PCB design will be cost-effective if you choose the pad size wisely.

7-Less Turnaround Time

If you need your HDI board urgently, it would also increase its overall cost. An urgent order is always costly, so plan your project to avoid urgent construction and have a cost-effective project.

8-PCB Manufacturer

The PCB supplier or manufacturer should have competitive prices, or it will become costly for you. The supplier should offer a high-quality product at an affordable cost. Poor quality can end up in multiple repairs in the future, so select your HDI supplier wisely.

Applications of HDI PCB

HDI printed circuit boards are getting popular these days because of smart devices. High-density boards are not only cost-effective but they ensure high performance and reliable products.

  • The HDI PCBs are used in multiple industries, including consumer electronics, such as smartwatches, smartphones, tablets, laptops, digital cameras, as well as many GPS devices. The high-density circuit boards are also essential for IoT devices that you need at homes, such as refrigerators and smart thermostats. All such devices have made HDI technology more in demand.
  • HDI PCBs are also used in communication equipment that runs smart devices, such as routers, semiconductors, switches, and modules. Where there are radio waves in a gadget, means it has an HDI PCB. You will also see such circuit boards in digital audio and video equipment. From personal to network devices, all digital products come up with HDI PCBs.
  • Another application of the HDI board is in the automotive industry. Likewise, you will see it in aerospace where devices and equipment have to be lightweight to perform better. The latest cars also come up with computerized equipment. Like, you will see cars with boards having 50 microprocessors to handle engines, diagnostics, and safety features.
  • Similarly, the onboard Wi-Fi, GPS, backup sensors, and review cameras also depend on HDI printed circuit boards. HDI technology is constantly growing with the advanced automotive industry.
  • These days, you will see advanced medical equipment and devices which also depend on HDI circuit boards. Such equipment is used for monitoring, scanning, x-ray, and lab tests. The high-density PCBs make medical devices more reliable, functional, and cost-effective. Doctors can get reliable test results for their patients with advanced equipment.

Hence, you can’t imagine advanced gadgets, devices, and equipment without HDI PCBs due to their smart components. Would like to know more about HDI PCBs or printed circuit board assembly? Email 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

PC Board, PCB Design, Printed Circuit Board, printed circuit board assembly, , ,

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