Tag Archives: PCB Design

Best Printed Circuit Board Routing Practices

Auto routing is an incredible tool for PCB design. It can save time and money, as well as reduce the risk of errors in the design. But, after completing the auto-routing process, you must remember that some manual routing is still necessary to ensure the best performance and reliability for your circuit board. In this article, we will explore the best practices for Printed Circuit Board routing after auto routing goes the distance. We will see what kind of manual routing is necessary, how to go about it, and why it’s important.

Assess the Quality of Your Auto-Router’s Work

Before you begin the process of editing or manually routing your design, you must assess the quality of the work completed by your auto-router. If your design has a lot of violations or errors, then it’s likely that manual routing is going to be necessary. To assess the quality of your auto-routed design, start by checking for errors. Make sure you properly connected all the tracks and that there are no shorts or open circuits.

Also, check the placement of the routes to ensure that they have the right width and direction. You must make sure that there are no sharp corners in the traces, as these can create stress points and reduce the reliability of your circuit. After completing this assessment, you’ll have a better idea of how much manual routing you need to complete your design.

Edit Your Design to Clean Up the Auto-Router’s Mistakes

When you auto-route your PC Board, it is important to review and clean up the results before sending it off for manufacturing. This is especially true if the auto-routing process got off center, leaving you with an excessively long or inefficient route. Before doing any manual routing, take some time to examine the auto-router’s work and make any necessary corrections.

First, check for violations of routing rules like clearance, width, and length rules. Make sure that the auto-router didn’t miss any components or create any neglected sections of traces. Then, look for any vias that you can replace with direct routing or traces that are easy to shorten to increase efficiency. You should also visually inspect the entire board layout to ensure everything looks reasonable and follows good design principles.

After editing your design to fix any errors, it is time to move on to the manual routing process. Be sure to take your time and double-check all your work before sending it off to a manufacturer. This extra effort can save you time and money down the road.

Manually Route Any Difficult or Important Signals

Manually routing signals is always the best way to ensure that you’re PCB will function correctly. Even though auto-routing can help complete most of the work, it’s important to manually route certain signals to achieve a high-quality design. This includes difficult or important signals such as the clock or power signals which require special attention.

When manually routing a signal, you must make sure that there is enough spacing between the tracks to ensure that the signals won’t be interfered with by any other nearby signals. Moreover, if you are routing high-frequency signals, you should ensure that the impedance of the track is correct for those frequencies.

Make sure that the routing of the signal is in the most direct manner possible. This minimizes the amount of noise picked up by the signal and helps reduce crosstalk between other traces on the board. Routing the high-speed signals manually also helps minimize trace inductance, which can cause ringing on the signals and increase noise levels.

By taking the time to manually route certain signals, you can ensure that your design will be reliable and high quality. Moreover, you can use techniques such as differential pairs and impedance matching to further enhance the performance of these sensory signals. You may want to consider setting aside some extra budget when designing your PCB with manual routing. As the process can be more costly than auto-routing.

Moreover, before going into production, you must double-check that all the signal routes are correct. Using software tools such as DRC (Design Rule Checking) can help identify any errors to fix them before the board goes into production. Doing this will help ensure that your final product is of the highest quality and able to meet your performance requirements.

 Check Your Work For Errors Before Sending It To Fabrication

Making sure your design is free of errors before sending it to fabrication is essential for the success of your PCB. During the auto-routing process, small errors can occur and the manufacturer would reject your design. To avoid this, you should double-check your design for any errors before sending it to the manufacturer.

To check for errors, you should use a combination of inspection tools, such as visual inspections and electronic rule-checking (ERC) software. Visual inspections involve examining the traces and components on the board. Whereas the ERC software checks your design against a set of rules defined by the manufacturer.

Inspecting your board manually can help you identify issues with the routing that an auto-router could not detect. For example, if two traces cross without via, you should add one to prevent shorts and crosstalk. If you notice any errors, such as incorrect trace widths or spacing, make sure to adjust them accordingly before sending your design to the manufacturer.

Also, ensure that your design meets the manufacturer’s requirements before sending it out for fabrication. The design should be compliant with their minimum trace widths, spacing, drill sizes, and more. If the design is not compatible with manufacturing parameters, it can result in costly delays and rejections, which could easily have been avoided.

 How to find that PCB design is according to the manufacturer’s requirements

You can do it by checking the size of your design. Make sure that all components fit within the PCB dimensions and have the right placement. Then, make sure that any traces or vias are wide enough for your manufacturer’s specifications. In the case of auto-routing, you must check for any clearance issues between traces. This can help you spot any potential problems before sending your board off for fabrication.

You should also review the data sheets to make sure that no noise or interference could affect the operation of your board.

By taking the time to ensure your design is compliant with the manufacturer’s requirements, you can help ensure a successful Circuit board fabrication process and save yourself from potentially costly delays down the line.

After confirming compliance, consider running some simulations to test your board’s performance under various conditions. This will allow you to see if there are any areas with crosstalk or power integrity issues. Moreover, if your board has high-speed signals on it, you may want to simulate its performance at various temperatures or levels of humidity.

Some Other Rules To Follow

You have to follow certain rules while making PCB layout as it will bring good results. So, let’s explore it further.

  • The traces should have as much direct and short routing, as you can do without affecting the design.
  • Try to route similar signals together, as the routing of RF and RF signals should be together. Similarly, two digital signals should also have the same route.
  • Try to route vias as simply as possible, such as BGAs, ball grid arrays, or some other types of vias.
  • Make sure to work according to the DFM guidelines to have perfect manufacturing.
  • In the case of high-power signals, you consider impedance and choose high-quality material while routing traces or determining the length.

    Design Principles

The design standards of printed circuit boards keep on changing due to changing technologies. But, you can’t compromise on safety and quality in this regard. The design of the PCB involves certain principles that you have to follow to have an effective product. Let’s look at those principles.

  • The grid spacing should be precise
  • The traces should be direct and shortest possible.
  • You should be careful about power distribution
  • Try not to have multiple grids
  • The placement of the components should be wise as it will make design and PCB inspection easy.
  • Make use of silkscreens in the best way to have more benefits.
  • Always try to follow the DRC (design rule check)
  • Try to avoid auto routers and go for manual work as much as possible if the budget allows you.

Wrap Up

When you auto-route the PCB, it is important to review and clean up the results before sending it off for manufacturing. This is especially true if the auto-routing process got off center, leaving you with an excessively long or inefficient route. Before doing any manual routing, take some time to examine the auto-router’s work and make any necessary corrections.

By taking the time to manually route certain signals, you can ensure that your PCB design will be reliable and high quality. Moreover, you can use techniques such as differential pairs and impedance matching to further enhance the performance of these signals.

Would like to know more about the PCB routing practices or PC Board assembly after auto routing? Email us at sales@pnconline.com

ET Testing for Printed Circuit board Fabrication

As technology advances, so does the complexity of multilayer printed circuit boards. To ensure that these boards are functioning correctly, it is essential to conduct effective electrical testing during the manufacturing process. Here, we will discuss the importance of electrical testing in multilayer PCB manufacturing. We will also overview the different types of electrical tests which are applicable, and explain how to ensure that the practice of these tests is effective.

By following the right guidelines, you can ensure that your multilayer PCBs are manufactured according to the highest standards of quality and reliability. So, testing allows manufacturers to ensure the quality of their products and that they meet the customer’s requirements.

The Importance of Electrical Testing

The electrical testing of multilayer printed circuit boards is a critical step in the manufacturing process. It ensures that the components on the board are functioning properly and that the board can support the expected load and environment. Proper electrical testing helps identify any defects or performance issues in the PCB before it goes into use.

Electrical testing is an essential part of ensuring the quality and reliability of a PC Board. It is also a crucial factor in meeting safety and regulatory standards, as it helps to detect any potential problems that could lead to product failure or safety issues

Remember, that electrical testing does not replace physical inspection. However, it is still an important tool for identifying hidden defects that would be difficult to detect by a visual inspection.

In other words, electrical testing is an essential step for a PCB Manufacturer as it helps to ensure the safety, reliability, and performance of the product.

The Different Types of Electrical Tests

When it comes to electrical testing in multilayer PCB manufacturing, you would see several different types of tests. These tests can range from basic electrical parameters such as voltage, current, and resistance, to more complex tests such as signal integrity and thermal imaging. Let’s take a look at some of the most common electrical tests for PCBs.

  • A visual inspection
  • Electrical continuity
  • Solder joint integrity
  • In-circuit test
  • Flying probe test
  • Boundary scan test
  • Continuity test
  • Insulation resistance test
  • Open circuit voltage test
  • Functional test.

Visual inspection is an initial step in electrical testing that involves a visual examination of the PCBs to detect any defects in the components. Electrical continuity tests check to make sure that the connections between the components are intact and the power is flowing properly through the board. The tool for this test is often an ohmmeter.

The solder joint integrity tests ensure that all the solder connections are properly soldered and functioning correctly.

The in-circuit test checks for any short circuits, broken connections, or other defects in the circuit design.

The flying probe test verifies that all the pins are connected properly.

The boundary scan test checks for any problems in the data path signals.

The continuity test measures the resistance of a circuit by sending a small electric current through it. If the resistance is too high or too low, then it indicates an issue with the circuit. Engineers conduct this test to make sure that all the traces, components, and vias on a Printed Circuit Board are properly connected.

The insulation resistance test checks for any potential problems with insulation between the conductive paths on the board. It does this by measuring the amount of resistance between different parts of a circuit. If the resistance is too high, then it could indicate a problem with the insulation on the board

The open-circuit voltage test checks for any potential problems with short circuits and opens on a board. It does this by measuring the amount of voltage between two points on a circuit. If the voltage is too high or too low, then it could indicate a problem with the circuitry on the board.

The functional test checks that the board is functioning properly by sending various signals through it and verifying that they are working correctly. This test can also be used to verify that all components on the board are connected and functioning properly.

Overall, these different types of tests help ensure that the multilayer PCBs meet the desired performance specifications and will function properly. Testing is essential to detect any issues before they become major problems down the line.

Remember that each type of test has its unique purpose, so you must conduct them all to gain the full scope of results. After each type of test has been conducted, the results should then be compared against the customer’s requirements and expectations. If any discrepancies are found, further investigation should be conducted to determine the root cause of the issue.

Once all tests have been completed, engineers should take corrective actions if necessary.  They should thoroughly document any changes and provided them to the customer for full transparency over the production process.

It is also essential to have periodic re-testing throughout the product’s life to make sure that performance remains consistent over time. By taking all of these steps, manufacturers can ensure that their products meet customer standards and provide a reliable operation over time.

Factors to Consider When Conducting Electrical Testing

Electrical testing is a critical part of multilayer PCB manufacturing and one of the most important steps to ensure that the finished product will perform correctly. When performing electrical testing, you must consider several key factors, such as:

1: You must consider the expected environment and the use case of the PCB. You may require different tests, depending on the intended application. For example, if the PCB application is for a high-temperature environment, it should be tested for high-temperature performance.

2: You should consider the capabilities of your testing equipment. Different tests may require different types of equipment. If you don’t have the right type of equipment, it’s important to acquire the necessary testing tools to ensure accurate results.

3: You must also consider the layout and connections of the PCB. When conducting tests, it’s important to make sure that all the components are connected properly and that no loose connections or other issues exist.

4: While performing the electrical tests, you must consider the desired level of accuracy and precision. The more precise and accurate the test results, the better you can ensure that the PCB will perform correctly in a particular application.

Tips for Conducting Effective Electrical Testing

Start with The Basics: Before conducting the electrical testing, you must start with the basics. Make sure your multilayer PCB design is sound and that all the components are correctly placed. This is critical for ensuring accurate results.

Check For Short-Circuits: Short circuits can be disastrous for multilayer PCBs, so you must check for them during electrical testing. Look for any evidence of heat damage or discoloration on the board, as these are signs that short-circuit may be present.

Use An Oscilloscope: Using an oscilloscope is a great way to detect any issues with your multilayer PCB design. This tool can show you the exact path of electrical current and pinpoint any problems in the board’s circuitry.

Inspect The Components: During electrical testing, you should also inspect each component on the board to ensure a secure and precise connection. Look for signs of physical damage, such as bent pins or broken solder joints.

Test Each Layer Separately: When performing electrical testing, you must test each layer of the PCB separately. This will help you to identify any problems on a specific layer, rather than having to go through the entire board again.

Look for Potential Issues: Finally, keep an eye out for any potential issues that could arise during testing. Be aware of any changes in the voltage or current that could indicate a problem with your design.

By following these tips, you can ensure that you are conducting effective electrical testing in multilayer PCB manufacturing and get accurate results every time.

Final Thoughts

Electrical testing is an important part of the multilayer printed circuit board manufacturing process. When it comes to electrical testing of multilayer PCB, several different tests should be conducted to ensure that the board is functioning properly. These tests involve different tools and equipment. Depending on the nature of the PCB application and the type of the test. When performing electrical testing, you must consider several key factors as described above.

In the above section, we discussed the basics of electrical testing in multilayer PCB manufacturing, including the types of tests to use, how to set up an effective testing process, and tips for successful testing. Now, you should have a better understanding of how to conduct effective electrical testing in multilayer PCB manufacturing. By performing various types of electrical tests on your multilayer PCBs, you can ensure that they are functioning properly and are ready for assembly and use.

Would like to know more about the Electrical Testing or pcb assembly? Email us at sales@pnconline.com

smt-assembly

SMT Assembly and Thru-Hole/Chip Functionality

Printed circuit boards are parts of various electronic devices, home appliances, and vehicles. The function of these green chips depends on their material and assembly technology. Each step of PCB assembly is important and needs careful processing considering essential features.
Two methods are popular in PCBA, including, MT and THT. Let’s study them in detail.

Through-Hole Technology (THT)

Traditional PCB has through whole technology, involving both automatic and manual processes. THT is PCB packaging technology that involves pins or leads, besides, you have to insert the chips in the PCB through holes, soldering from below. The technique gives it the name through-hole.
Through-hole technology was more in practice till 1980 and every PCB device had this technology. Then SMT emerged where chips are installed on the surface. However, some PCBs still need through-hole chips, like capacitors and resistors.
THT needs more drilling, however, the device with this technology has a durable bonding with the circuit board.
Let’s look at the important steps of THT.

Installation Of Components

Engineers place PCB components with their hands, however, it needs precision depending on the design.
PCB Inspection
PCB inspection is crucial because most devices need flawless PCBs to work well. Most of the through-hole process is manual, so you have to make sure that the assembly is without any mistakes.
Printed Circuit Board Soldering
Soldering of components is also important as you have to fix the components manually. This is the last part of assembly, and the manual work makes it more reliable than SMT.

Why Is THT Still In Use?

Though THT is an old PCBA technology, you still need it for certain reasons, such as:

  • Even a hobbyist can assemble a circuit board with THT by using a soldering iron. It involves less hassle because the holes are away from surface pads compared to SMT.
  • If you observe a hobbyist application of the THT circuit board, you will see the ICs with the 8 or 14-pin having centers up to 0.100”xp.300”. Sometimes even the DIP processors have such spacing between the holes that helps in manual soldering, making the PC Board assembly easier.
  • After assembly, the troubleshooting or revision reduces in THT because it does not involve bridges between the pins, be it single or multiple components.
  • THT has better professional assembly, especially when a project is at a prototype stage. You can apply the through holes in a prototype layout to assemble the board faster.
  • After evaluating the board function, you can swap in the SMT having the same value, revising the circuit board’s layout. The new layout has small footprints to be inspected before final production. Such techniques reduce the front cost of a project which can benefit a subcontractor.

Remember that small products demand more pricing from outside vendors as they prefer high-volume production for continuous machine work.

Benefits Of Through-Hole Technology

  • When it comes to PCB design revision, a through-hole technology doesn’t need to create an additional solder stencil. So, manufacturers can save a huge amount of money on a PCB design having 2 to 3 revisions before it is ready to use. Besides, you don’t have to arrange the equipment for the pick and place function.
  • The manual inspection of a small lot of printed circuit boards reduces the fixture expenses or any other cost regarding linked setups.
  • Soldering is also cheap in THT, such as the tin-lead solder. Besides the issue of HASL or hot air solder leveling does not occur in through-hole technology, unlike SMT where the HASL makes it hard to place the components having a precise pitch.
  • You can easily assess the mechanical faults, including twists, and warps, and can deal with them while redesigning without affecting the assembly as what happens in SMT. Issues like twist and warp are not as problematic in manual assembly as in SMT.
  • The hand assembly of a PCB helps fit hard components by changing the wrist angle. Whereas the automated assembly needs an extremely flat circuit board for proper functioning.
  • THT can help pinpoint mechanical faults before it gets hard to resolve them. Otherwise, the inspection becomes costly when it has to go into the hands of three persons, including you, the contract assembler, and the PCB Manufacturer.
  • The components for THT are easily accessible that keep the job going without interruption. Moreover, you don’t need a third-party assembly in the case of small production.
  • With THT, the project timeline is predictable and easy to manage with minimum issues without causing any production delays.
  • Even if you don’t want to prefer a through-hole assembly, you must consider it as a temporary solution at early stages like validation and development. So, it can benefit anyone, including a hobbyist, any established company, or a beginner in this industry.

Surface Mount Technology-Surface Mount Chip

Surface mount assembly and SMT is other popular PCB assembly technology. It is an advanced method involving automation. Besides, it is ideal for smart PCBs that today’s smart devices need.
As the name shows, PCB components are directly installed on its top surface, whereas the device having a surface mount technology is called SMD. You can say that traditional through-hole technology is being replaced by surface mount assembly.
However, through-hole technology is still in practice for big transformers or power semiconductors as their components are not compatible with SMT. Likewise, many other heavy electronic devices with heat sinks need through-hole PCBs.
Surface mount technology has more positive aspects than negative pros, so let’s discuss them in detail.

Positive Aspects Of Surface-Mount Technology

SMT Involves Minimal Surface: The component area, volume, and size in an SMT are 70% less than the component area in through-hole technology. Even the component area can become 90% less than its volume in a traditional PCB having a through-hole technology. Likewise, the overall weight of the PCB reduces, as the components’ weight reduces by 70 to 90%.
It Enhances The Signal Speed: a PCB assembled with SMT has a fast signal transmission due to a short circuit. The assembly density in such technology can go up to 5.5~20 solder joints in one square centimeter, like when there is paste on both sides of the PCB. Similarly, a PCB with SMT has a high impact and vibration resistance that helps create high-speed electronic devices.
Excellent Frequency: In SMT, the board has either no lead or it is very small which reduces its parameters, decreasing the interference in terms of RF. It means that the PCB gets high-frequency signals, and the device having it works faster.
Minimum Packaging Cost: when it comes to an SMT packaging price, you will see it much lower than THT. Since surface-mount technology involves effective production tools, the usage of packaging material reduces thus cutting down its cost. However, the decrease in the cost does not affect the quality of an SMT circuit board.
You don’t have to bend or cut the component leads in the SMT boards which reduce the assembly time, making production faster than THT. So, the production cost also reduces by 50% as the manufacturing process of SMT is quite simple.

Additional Info

In SMT, the solder paste is applied with a stencil printer that helps finish a raw board better and faster than a traditional method. In other words, you get fineness in an automated assembly.
The installation of the components becomes easier, as solder paste makes everything clear due to printing. Each SMT process is well-inspected that helps have accuracy.
In SMT, the process of reflow soldering also makes a circuit board highly durable. In reflow soldering, the technician places the circuit board under high temperature to melt and reshape the paste, making it permanent. You can use both reflow soldering and automation or can switch from one to another, depending on your needs.
The important thing is to design and assemble a PC Board considering all the dos and don’ts and have a flawless end product.

Some Negative Aspects Of SMT Assembly

Surface-mount technology is not full of benefits, instead, it has some drawbacks, such as:

  • It has less power
  • It is vulnerable to damage
  • SMT requires high-quality soldering because poor soldering can lead to leakage, tombstoning, bridging, and several other risks.
  • It involves delicate installation, resulting in dropped components.
  • Its inspection is hard, especially, the visual test as it has multiple types of solder joints.
  • The equipment cost is high.
  • It involves well-trained technicians that increase the learning expenses.
  • It needs consistent updates of assembly equipment due to fast development.

Final Thoughts

Printed circuit boards involve different assembly techniques, including a through-hole technology, and a surface-mount technology. The component area, volume, and size in an SMT are 70% less than the component area in through-hole technology.
When it comes to PCB design revision, a through-hole technology doesn’t need to create an additional solder stencil. So, manufacturers can save a huge amount of money on a PCB design having 2 to 3 revisions before it is ready to use.
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PC Board Electrical Schematic and Its Functionality?

Whatever we create, including a PC Board,is a picture or an idea that we convert to paper in the form of a diagram. You can’t proceed with manufacturing without a proper PCB layout or schematic.

An electrical schematic is a conceptual plan or drawing that helps understand the physical aspect of a PCB in terms of assembly.
The basic purpose of electrical schematicsis to have design communication.It should help manufacturers clearly understand it.Besides, the schematic directs you to makea PCB layout.

Schematics involve specific elements which are essential to understand, such as:

  • REFDES or reference designates
  • Symbols representing the components
  • Outputs
  • Nets

To know schematics in detail, you have to understand the above elements.

REFDES or Reference Designators-Identifying Labels

Identifying labels or reference designators help understand components because they describeso much about them. If REFDS is precise, it helps a reader to identify the types of the components and symbols,depicting every component.
So, each electrical component or part has a standard symbol.However, onlyspecific schematics follow such standards.
In some cases, reference designators can fully describe the component type, like when there is a generic box with pins itrepresents a passive component.

At the same time, reference designators also connect to theBOM, and bill of materials. Every Printed Circuit Board component needs a part number that BOM shows. Besides, it also helps find the area or location where components should be installed.
The format of the reference designators consists of a code in the form of a letter that describes the component, and its type having a specific number.

Symbols Representing Components

The electrical schematic has specific symbols of the physical components of PCB assembly in terms of soldering. They also describe the circuit boards’ structures, such as test points and vias.

The symbols are specific shapes or they are diagrams to indicate the type of PCB components. There are symbols for all electrical components like capacitors, diodes, resistors, and transistors.

The symbol of each component consists of pins that help in creating the electrical connections. The pins of all schematic symbols have specific numbers,depicting the physical components.

Designers can assign either a single symbol or multiple symbols to represent a single component of a PCB. Whereas the components having several pins are assigned many symbols to create a readable electrical schematic.

When a component is having multiple symbols, each symbol representing the same component has a similar designator.

Electrical Components-Resistors

PCB has many electrical components, including resistors. The U.S designers use a zigzag line to describe a resistor. Whereas its symbol is a rectangle according tointernational standards.On the other hand, the letter R in schematics isa representation of the resistor.

CapacitorSymbols and Letter

Capacitors have two types, includingpolarized capacitors and non-polarized, and both have different symbols. The curved line is a symbol of a negative terminal of a polarized capacitor. Whereas the plus sign denotes a positive terminal of a polarized capacitor.Whereas the letter C defines a capacitor in schematics with REFDES.

Inductor Symbol and REFDES Reference

Inductors are also important passive components of a PCB, and their construction involves a series of curves.Manufacturers use a coil of wire to make inductors. Whereas the letter L defines a capacitor in schematics with REFDES.

Diode Symbol and REFDES Reference

Some other PCB electrical components within the PCB design include diodes that permit the current to travel in just one direction. The diode has different types, including

  • Zener diodes
  • LEDs or light-emitting diodes
  • Schottky diodes

Zener diodesprevent the reverse flow of a current. However, the reverse flow can happen at a certain electrical power level.
There are also LEDs or light-emitting diodes which emit light when having a forward flow of a current.
The Schottky diode has simple features,but it switches quickly and the voltage drops in a lower forward direction.
Other than LED, the letter D or L defines a capacitor in schematics with REFDES.

Transistors Symbol and REFDES Reference

Transistors involve the flow of current at the primary terminal and they function like switches. The basic types of transistors include:
Bipolar Junction Transistors-BJTs: It is a current managing device that helps a current flow either into one base pin or out of it, changing to high currents passing through emitters and collectors.

Field-Effect Transistors-FETs: The FE transistor is another current-managing device that helps voltage turn on the current on the pin, via source pins and adrain. Various drawings indicate transistors and the letter Q and M define a resistor in schematics with REFDES and also represent the MOSFET. However, some designers use the letter T in the wrong way.
Variable Resistors’ Symbol andREFDES Reference

Variable resistors have two categories:

  • Potentiometers-three terminals
  • rheostats-two terminals

The function of the variable resistors is to customize resistance according to users. An arrow across the resistor represents the rheostats, whereas an arrow on the side of the resistor shows potentiometers.

There are also varistors or voltage-dependent resistors which resemble the variable resistors, but they are denoted by a line across them.The symbols of the resistors include R, VR, and RV, depending on the type of the resistor.

IntegratedCircuits, Symbol, and REFDES Reference

A single-package circuit developed with a semiconductor is an integrated circuit. You can also consider such circuits asamplifiers, processors, power regulators, and memory of a device. The shape of the integrated circuit is like a rectangle or a square that you can install on a PCB. It is a box with power inputs and outputs or pins and sometimes a board has many boxes.

The symbolof the integrated circuit in a schematic is the IC or the U.

Resonator, Crystals, and Oscillators, Symbol and REFDES Reference

PCB also has resonators, crystals, and oscillators, which give a consistent frequency output. These elements are different in terms of circuitry and characteristics but they have a commonfunction.

Some Other Symbols

There are also several other symbols to show interconnections on a schematic having labels to find their electrical nets.
Mostly there is no reference designator for non-component symbols, however, some have symbols like TP or test points, and X, and MH on REFDES.

Understanding Nets in Schematics

The wired connections on the printed circuit boards are what designers call nets. They are lines that connect symbol pins to the nets. You have to properly label the nets while making schematics to help manufacturers identify them. Specific symbols depict thenets to the same or different pages when you don’t draw them as connections, such as interpage and intrapage symbols.

Try not to overlap the nets to have good readability, however, you can’t ensure it every time. A dot or a circle on a schematic diagram shows two nets’ connection. If there is no DOT in a schematic, it means there is no connection between the nets. Whereas advanced drawings have wire hops to show that the nets don’t connect.

Outputs of Schematics-Netlists & BOM

The schematic diagram has two important outputs, including BOM, and netlists. The netlist is a file that designers use to understand routing and parts’ placement on a PCB. The format of thenetlists can vary in symbols. The name of the nets is presented in the netlist, showing thelocation of connectionsbetween the PCB parts. Netlist also has an output tool to give names to the nets which were without names.
Generally, there are several tables in a netlist, listing the PCB components and their names, net names, and some other essentials. Sometimes the netlists include additional information to help you understand the SPICE.

Bill of Materials-BOM

Bill of materials shows data in the form of a spreadsheet,matching the REFDES in schematicshaving a number and a physical component. Designers use different formats for BOM outputs, depending on the nature of schematics and your requirements in terms of output.
There can be many reference designators with independent partnumbers to help with manufacturing. Some detailed BOMs consist of specific part numbers of a company, quantities of components at different locations on a PCB, and the part numbers for different vendors. In other words, BOM has essential information to understand schematics and develop it through different steps, including SMT assembly.

Final Thoughts

You must know that the electrical schematic is a drawing that helps understand the physical aspect of a PCB in terms of assembly. The main aim of electrical schematics is to have design communication and help manufacturers construct the PCB. It should help you clearly understand parts and assembly. All electrical components have standard symbols. But, only specific schematics follow such standards. Different software help make electrical schematics that you can explore online.
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What is Printed Circuit Board Copper Clad Laminate?

What is Printed Circuit Board Copper Clad Laminate?

Printed circuit boards come in different materials known as substrate, including copper-clad laminate or CCL. PCB substrates are either organic or inorganic, depending on their properties. The organic substrates come up in different materials known as the reinforced board, such as glass felt, fiberglass, fiber paper, fiber cloth, and so on.
PCB fabricators impregnate there in forcing materials with an adhesive called resin, making it dry, and then cover it with copper foil at high pressure and temperature. Such a substrate is CCL or copper-clad laminate that resides on either one or both sides of the board. So, CCL is either single-sided or double-sided.
Rigid PCB has a rigid CCL with a substrate, such as

  • Resin epoxy FR4
  • PTFE
  • Aluminum or copper
  • Ceramic

These materials help make different types of PCBs, including single, double, and multilayer PCBs.

CCL Standards

Engineers define the CCL standard specification with ASTM D1867 and develop their circuit boards according to these standards. To cover twelve grades of CCL, ASTM needs the laminates to meet certain factors for peel strength, like

  • High temperatures
  • Volume resistivity
  • Water absorption
  • Flammability ratings
  • Dissipation
  • Dielectric breakdown
  • Permittivity
  • Lengthwise and crosswise strength

The PCB Manufacturer should also check the CCL for twist, warp, or blistering. CCL manufacturers often follow the IPC-410IC as a standard. Moreover, they use IPC-IM650 to test the fabricated CCL.

CCL Materials

FF4 CCL: As discussed above FR4 is a popular material for copper-clad laminate. The material is resin epoxy, and it is ideal for rigid circuit boards. You will see it on both sides and only one side of the board. The material is a combination of epoxy resin and fiberglass cloth. Resin makes the board fire resistant that’s why we abbreviate it as FR or flame retardant. However, it has to pass through testing to see if it is according to the UL94V-0 standards.

Copper base: like aluminum CCL, copper core CCL has a copper plate, copper foil, and dielectric layer for bonding. PCB’s thermal dissipation and dielectric bonding determine the overall thermal conductivity.
PCB with copper substrate has three types, depending on its design, such as copper without PTH, COB, or chip-on-board copper circuit board which is without the thermal pad insulation.
Aluminum CCL: Copper-clad laminate also has aluminum as a base material combined with a dielectric layer and copper foil. These materials are bonded through hot pressing and very high temperatures. The dielectric bonding determines the thermal conductivity of the aluminum core laminate. However, both copper foil and dielectric have high conductivity, and manufacturers often use ceramic to fill the dielectric layer.

What Is RF, Radio Frequency CCL?

The RF CCL is also known as the Microwave PC Board CCL as the board has microwave frequencies. Such a circuit board has certain characteristics to consider, such as

  • DK, dielectric constant
  • DF, dissipation factor
  • CTE, coefficient of thermal expansion
  • TCDR thermal coefficient of dielectric constant
  • Thermal conductivity

It involves high-frequency materials of which PTFE is a common practice. It is a synthetic material having great dielectric properties at high frequencies which are also known as microwave frequencies. A few companies develop the high-frequency PCB CCL, including Isola, Rogers, Taconic, and Panasonic.

What is Prepreg in CCL?

Prepreg or pre-impregnated CCL is a kind of fiberglass that is impregnated with a bonding material such as resin. The resin is not hard, however, it is dry and gets sticky when heated. In other words, the fiberglass is made strong through an adhesive just like FR4.
Prepreg materials come up in different thicknesses that determine their quality, such as standard resin, SR, medium resin, MR, or, high resin, HR. The PC Board manufacturer use the resin thickness according to the type of PCB they require.

What is Printed Circuit Board Copper Clad Laminate?
Printed Circuit Board Copper Clad Laminate

CCL PCB Applications

PCB with copper clad laminate is ideal for:

  • Electronics PCBs
  • Radars
  • High-speed communication devices, like 4G,5G, and LTE
  • Automotive products, such as ADAS radar
  • Avionics Radar
  • Automobiles
  • Welded tanks
  • Offshore platform shearing
  • Steam condenses
  • Pressure vessels
  • Heat exchangers
  • Missile components
  • Hydraulic bushings

The above applications related to communications are essential to communicate faster, such as 4G helps you download anything within seconds. Whereas 5G is much faster, in this case, and you can see it by comparing it with the old and low-speed communication devices.

How To Identify The Best CCL PCB

A few parameters help you find if the copper-clad PCB is the best or not, such as size, neatness or appearance, chemical properties, performance according to the environment, as well as a physical performance.

PCB Design Parameters Including Size: The size of the CCL matters a lot in PCB design as it’s the base material. The quality of the end product also depends on the thickness of the core material. At the same time, you have to consider other parameters, including length, width, wattage, and diagonal deviation. Each design parameter should meet the necessary standards to have an ideal product that performs well.

CCL Appearance: several issues happen during Printed Circuit Board manufacturing that can affect the appearance of the copper foil. Such as dents, pinholes, scratches, resin points, bubbles, wrinkles, etc. These issues also slow down the PCB CCL performance.

Environmental Compatible: Copper-clad laminate PCB should be compatible with the environment. Like, it should resist water and corrosion or its production will get slow, resulting in serious issues.

Chemical Function: The chemical properties of copper-clad laminate are also vital and should be according to the standards in terms of flammability. The Z-CTE or, Z-axis coefficient of thermal expansion, Tag, chemical resistance, and dimensional stability has to be considered.

Physical Function: Copper-clad laminate has to meet certain physical requirements, including the PS or peel strength, bending strength, dimensional balance, heat resistance, as well as punching. It should resist thermal stress.

Electric Property: Copper-clad laminate should electrically perform high, as it’s very important. As described above, copper-clad laminate PCB should strictly meet certain requirements, such as DF, DK, insulation resistance, CTI or comparative tracking index electric strength, arc resistance, and volume resistance.

How Many Types Of Copper Clad Laminate Are There?

You can classify the copper-clad laminate according to different factors, such as size, thickness, mechanical material, structure, insulation material, types of reinforcement, resin type, and CCL performance.
Copper-clad laminate is either rigid or flexible of which rigid CCL is further divided, depending on its combination materials. It is either single or double-sided, besides there are also special rigid CCL PCBs with a high-flame resistance and other properties.
Flexible CCL: It includes,

  • Non-flame retardant polyester
  • Flame retardant polyester
  • Polyimides with and without flame retardant
  • Fiberglass cloth of small thickness

Benefits of Flexible Copper Clad Laminate

  • The FCCL has many benefits, such as
  • It has great flexing power
  • It is ECO friendly
  • It is free from halogen
  • Better heat resistance
  • Great adhesive properties
  • it is a blend of different copper clad thickness

Special copper-clad laminate has ceramic and it’s also called ceramic CCL. It has different materials, such as aluminum oxide, aluminium it ride, silicon carbide, boron nitride, and beryllium oxide.

FAQs

What is the manufacturing process of CCL?
Copper-clad laminate has complex manufacturing, including rolled copper foil that acts as a conductive material. PCB fabricators impregnate the reinforcing materials with an adhesive called resin, making it dry, and then cover it with copper foil at high pressure and temperature.

What Are The Uses Of CCL PCB?
Copper-clad laminate is fiberglass mixed with resin and glass and it is on either one or both sides of the glass fabric. Engineers use it to develop radios, mobile devices, televisions, computers, digital devices, and other multiple electronics.

What Is Copper Foil In CCL?
Copper foil in CCL is a cathodic electrolytic material that lies on the metal foil in a PCB. The material is easy to bond with the insulating layer to provide a protective covering. It is also easy to corrode to make a circuit protector.

What are CCL Standards?
Copper-clad laminate standard specifications are defined with ASTM D1867 and engineers develop their circuit boards according to these standards. To cover twelve grades of CCL, ASTM needs the laminates to meet certain factors for peel strength.
The fabricators should also check the CCL for twist, warp, or blistering. Copper-clad laminate manufacturers often follow the IPC-410IC as a standard. Moreover, they have to use IPC-IM650 to test the fabricated CCL.

Final Thoughts

PCB different materials known as substrate, including copper clad laminate or CCL. PCB substrates are either organic or inorganic, depending on their properties. The organic substrates come up in different materials known as reinforced boards, such as glass felt, fiberglass, fiber paper, fiber cloth, and so on.
PCB fabricators impregnate the reinforcing materials with an adhesive called resin, making it dry, and then cover it with copper foil at high pressure and temperature. Such a substrate is CCL or copper-clad laminate that resides on either one or both sides of the board.
Would like to know more about Copper Clad Laminate or prototype pcb manufacturer? Email us at sales@pnconline.com