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PCB Design, Planning, and Components Selection in Printed Circuit Boards

PCB Design, Planning, and Components Selection in Printed Circuit Boards

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Designing a printed circuit board or PCB can become challenging because there are many factors to consider, including environmental conditions the PCB will be exposed to and the desired electrical components that the PCB will use. The best design, planning, and component selection bring the best-printed circuit boards. All electronic products contain printed circuit boards so considering the above elements is essential that we will discuss these elements in this article.

Questions Regarding PCB Planning?

A few questions to keep in mind when designing and planning a PCB include:

  • How many layers do I want?
  • What thickness of copper foil/laminate do I want?
  • Do I want to use plated through holes or non-plated through holes?
  • Do I want my board to be double-sided, single-sided, or multilayer?
  • Are all of my components going to be surface mount or through-hole?
  • Are all of my connections going to be made using jumpers or solder pads?
  • Can I get away with using cheaper non-plated through holes instead of plated ones? Can I get away with not having a ground plane layer if all my signals are digital logic levels?
  • Does my design require low-noise analog filtering?
  • Will I need to isolate high-voltage circuitry from low-voltage circuitry, and high-speed circuitry from slow-speed circuitry?

You can start designing a PCB after getting answers to the above questions.

PCDesign: Basic Guidelines

Before you even begin to design your printed circuit board, make sure you understand some basics of PCB design. When designing a Printed Circuit Board several things should be considered. Keep in mind that most errors caused by circuit boards are usually associated with improper grounding and power distribution.
If you are trying to create a custom PCB or just update an existing board, it is important to consider whether it will be surface mounted or through-hole mounted.
Size: The size of your circuit board will also play a big role to see how much space you have for components. You can either choose to go with a larger board and have less room for components or vice versa.
Layers: The number of layers in your circuit board also plays an important role to see how many components you can fit into one area. There are three basic types of circuit boards, such as single-sided, double-sided, and multi-layer. Single-sided circuits only have traces on one side while double-sided circuits have traces on both sides of a sheet of material called laminate. Multi-layer circuits consist of multiple layers stacked together which increases current capacity.
It is important to know what type of circuit board you will need before starting any design work because it may require special tools or materials that aren’t available at home orin local electronics stores.

PCB Design, Planning, and Components Selection in Printed Circuit Boards
PCB Design, Planning, and Components Selection in Printed Circuit Boards

PCB Layout Techniques

While surface-mount technology dominates today’s electronics designs, you still may need to design or repair an older circuit that uses through-hole components. Whatever your reason is for dealing with through-hole components, there are several layout techniques you should be aware of to ensure reliable operation.
Many PCB layout problems stem from poor component placement rather than PCB material defects. By following these best practices when laying out a PC BOARD using through-hole components, you can help avoid these common mistakes If possible.

  • Place resistors before capacitors on each side of a power supply line. This way, if any capacitor fails, it will not causedamage to the resistors placed after it.
  • Place decoupling capacitors close to the chip they are used for decoupling. For example, if you have a microcontroller with two crystal oscillators, place one cap near each oscillator and connect them at opposite corners of their respective pads.
  • Placing both caps near only one oscillator would increase the parasitic inductance between those two connections, reducing efficiency.
  • Don’t place any other traces within 0.5mm of a signal trace running parallel to another signal trace on different layers. Signal traces running parallel are said to be coupled and can pick up noise from each other due to electromagnetic induction caused by nearby power or ground planes.
  • Try to keep traces spaced away from each other by 1mm or more if possible. If you must cross a signal trace over another signal trace, do so at right angles and use wide traces to reduce coupling.
  • When placing multiple closely-spaced power/ground pins on a single side of a DIP package, leave enough room between pins for solder mask relief cuts. Otherwise, you could end up with a solder mask bridging across adjacent pins when you remove your stencil during soldering operations.
  • Never put a hole in a signal trace and even small holes can cause shorts to the surrounding traces and components, especially if you don’t seal them off with liquid electrical tape or conformal coating. Similarly, don’t drill holes in the ground or power plane areas because those holes could become filled with solder during soldering operations.
  • Drill larger holes for mounting standoffs instead of smaller ones for mounting screws to save time and improve manufacturability.
  • Keep in mind that you may want to place components on a PCB around a standoff if you plan to solder wires or connectors directly to it. Always use solid core wire for power and ground traces. Stranded wire has too much resistance and tends to break easily under repeated flexing.
  • Keep track of your trace lengths to make sure none are longer than 2-3 times their widths. Longer traces can affect signal integrity and lead to intermittent failures in your final product.
  • When possible, use a ground plane layer to provide a return path for your power and ground traces. Power and ground planes also act as heat sinks, helping to dissipate heat from your components.
  • If you can’t use a separate ground plane layer for some reason, try to place as many of your signal traces on that layer as possible. That way, if one trace causes a problem with another trace or component, it won’t affect any other traces running on that layer.

Components Selection for Printed Circuit Boards

Deciding what components to choose when designing printed circuit boards is an important process that affects your final product. These electronic components come in many shapes and sizes, with different specifications for power consumption, weight, and other factors.

Knowing how to choose your components efficiently can prevent expensive mistakes down the line. This guide will help you understand how to select components for your PCB design effectively.

A printed circuit board contains conductive tracks made from metal foil and a conducting adhesive, typically etched into a thin layer of non-conductive material such as fiberglass or epoxy resin. Components are then placed on these tracks at specific points called pads, which are connected by copper traces forming circuits.
The PCB is usually used to connect electronic components like resistors, capacitors, transistors, and diodes with each other to form an electrical circuit. The most common materials used for PCBs are FR4 (fiberglass) and G10 (FR4 glass laminate). Other materials include CEM-1 (glass epoxy), Rogers 4003 (aluminum), Rogers 4350 (aluminum), and PTFE-based laminates.

The Purpose of Design

When designing printed circuit boards, many factors need to be considered and you can split them into two categories, such as functional requirements and design constraints.
The functional requirements describe what your printed circuit board needs to do, while design constraints determine how it will be designed. For example, if you want your product to have a battery life of more than five hours you need to consider things like battery size and power consumption when designing your product.
Functional Requirements
Four main functional requirements must be met when designing printed circuit boards, such as performance, reliability, serviceability, and cost.
Performance refers to how well your product performs its intended task.
Reliability means that your product should work correctly all of the time without fail.
Serviceability means that it should be easy to repair any problems with your product once they occur.
Cost refers to whether or not you can produce your final product for a reasonable price.
These requirements may change depending on who your target market is. If you are targeting high-end consumers, reliability and serviceability might take priority over cost. On the other hand, if you are targeting low-income customers in developing countries, affordability might take priority over everything else.

Connectors for Printed Circuit Boards

Solderless connectors are used to connect different electronic components on a printed circuit board. They’re available in two categories, such as through-hole and surface mount.
These connectors can also be classified by their location on a PCB, such as an edge-mounted or through-hole mounted. The primary difference between these two is the size.

Edge-mounted connectors are smaller than through-hole ones because they don’t have as much copper around them. This makes them better suited for smart devices having less space, such as cell phones and laptops. Whereas the through-hole mounted connectors are larger and easier to work with but require more space on a PCB.

Would like to know more about design, planning, and components selection in PCB or pcb assembly services? Write us at sales@pnconline.com

PCB Design

DFM Issues in PCB Design

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You need a well-designed PCB for the effective functioning of the device, and you can have it by focusing on the DFM or Design for Manufacturing. Different requirements are there in terms of PCB design, management, and fabrication that you have to follow. At the same time, you should consider the timeline to have a circuit board within your budget.

PCB and DFM Issues

Having well-executed CAD tools is easy, but these tools cause certain DFM issues which need lots of effort to solve. Sometimes a PCB is correct in terms of electrical requirements, but it is hard to manufacture because you don’t focus on the design layout. The layout issues stay hidden, making it hard for you to assemble a PCB, besides the testing also becomes difficult.
However, you can overcome the DFM problems if you understand the entire process of manufacturing. Now, we will discuss a few DFM issues, including tolerances, acid traps, SMD issues like open vias and uneven connections, a wrong opening of the solder mask, and the violation of standards.
Once you know these problems, it becomes easier for you to resolve them and have an easy fabrication that involves less time to review the design. So, let’s discuss the DFM issues one by one and find their solutions to have the best device.

Connection Issues On The SMD Pads

The connections on the SMD pads often become uneven as components are so small and hard to handle. These connections should be even to avoid the tombstoning while soldering reflow. Likewise, this rule also applies to the BGA pads for precise soldering. In other words, you should place a compatible pad according to the footprints of the components, so the size of the pad matters a lot. Generally, the pad sizes are standard for common components.
The designer can easily check the pad sizes without exporting the Gerber files, like through a 3D, as the manufacturer won’t do this for you. Manufacturers only see the Gerber files to compare the sizes of the components’ in the BOQ.
You also need testing after PCB fabrication to make sure that the connection is even and it involves deep inspection like an X-ray. So, the designer should inspect the footprints to see if they are according to the lead size of the component.

A Wrong Solder Mask Opening

The term solder mask or solder aperture is an opening that helps the solder stay intact on the SMD pads while soldering, be it the wave or hand soldering. A solder ball develops on the pad while soldering which can collapse if it’s too large, moving around at high temperatures. Designers leave a small opening in the solder mask to keep the solder ball intact while soldering, even if the ball is too large. This technique also works in the BGA where a solder dam develops when the mask hinders the pad from circuit board’s via.
You can eliminate this issue by creating the footprints of the components having a proper solder mask opening which often crosses the pad edges about 4 to 5 mils. When the solder aperture is very large, it is not able to block the flow of a solder ball while wave soldering.

Open Via Issues In The SMD Pad

The designer should not give via-in-pad in the PCB. When you place a through-hole via very near to the soldering area, it causes the solder to move through a circuit board’s back. When via is attached to the internal layer’s large plane, it will cause the heat dissipation into that plane. So, it results in tombstoning during pcb assembly.
Though the via-in-pad has a great role in the HDI PCB having BGAs with a fine pitch, it should be avoided in smart circuit boards. You should insert plated-over vias for small boards to avoid the heat dissipation that occurs during soldering and also makes via the connection for thermal relief.

PCB Design
DFM Issues in PCB Design

Understanding the Acid Traps

Printed circuit boards consist of various copper images. Engineers remove extra copper from the laminate with the help of chemicals that sometimes get trapped in a PCB with narrow corners, and this is called an acid trap. This process results in rough copper, damaging the PCB.

There is a way to avoid the acid traps by using low-viscosity chemicals. Acid traps also happen when the routing is done at 90 degrees, so beware of the solution that a PCB manufacturer uses, in this case, to see if it is causing acid traps. The best practice is to route the traces at 45 degrees to avoid the acid traps.

Design Tolerances

PCB design depends on precise parameters and tolerances and you have to maintain them. If you don’t use specific design requirements, the routing tools will create any tolerance. You should keep traces at some distance from other traces, from pads, and from the copper pours. The clearances help in etching and leave a space for manufacturing clearances.
These tolerances are also essential in high voltage layouts. According to the IPC 2221 standards, the difference between conductive elements determines the minimum clearance between the conductor and a trace. The purpose is to avoid the unintended ESD or, conductive filamentation in the case of adjacent conductors, and electrochemical corrosion.

IPC Standards and Their Violation

There are unlimited IPC standards that you have to follow for a reliable PCB. Such standards are regarding tolerances, the annular ring size of the via as per aspect ratio, teardrops on vias and pads, land patterns, sizes of micro vias, trace width as per current, and high temperatures.
Some manufacturers check the Gerber files and testing rules to see if you have violated any standards. Generally, the IPC standards are not mandatory, unlike high-end industries, but following them makes a Printed Circuit Board more reliable.

Accessing The DFM Issues Through PCB Design Software

The above DFM issues are the common ones in PCB manufacturing, but there are several other issues. If you manage all the design rules, you and your manufacturer would end up with a reliable PCB. You need the right software to create a rules-based PCB, avoiding the DFM issues.

Frequently Asked Questions

What Is DFM In A PCB?
DFM is Design for Manufacturing which means you have to have a special layout design for a PCB to be manufactured correctly. You will have to face many issues if there is no DFM.
How to Check the DFM Issues?
There are certain PCB testing tools to check the data set, finding issues that can delay the manufacturing. Many online platforms also offer DFM testing tools.
What is SMD in a PCB Design?
SMD stands for Surface Mount Device, and SMD components are parts being soldered to the PCB by using the surface mount technique. There are several types of SMD components having different forms.
What is BGA in a PCB Design?
BGA means a ball grid array, and it’s a surface mount technique for integrated circuits. It helps mount devices permanently, like in microprocessors.
What are PCB Tolerances?
PCB design depends on precise parameters and tolerances, and you have to maintain them. If you don’t use the specific design requirements, the routing tools will create any tolerance. You should keep traces at some distance from other traces, from pads, and from the copper pours. The clearances help in etching and leave a space for manufacturing clearances.
What Are IPC Standards in PCB?
There are unlimited IPC standards that you have to follow for a reliable PCB. Such standards are regarding tolerances, the annular ring size of the via as per aspect ratio, teardrops on vias and pads, land patterns, sizes of micro vias, trace width as per current, and high temperatures.

Final Thoughts

Having well-executed CAD tools is easy, but these tools cause certain DFM issues which need lots of effort to solve. Sometimes a PCB is correct in terms of electrical requirements, but it is hard to manufacture because you don’t focus on the design layout. The layout issues stay hidden, making it hard for you to assemble a PCB, besides the testing also becomes difficult.
However, you can overcome the DFM problems if you understand the entire process of manufacturing. Now, we will discuss a few DFM issues, including tolerances, acid traps, SMD issues like open vias and uneven connections, a wrong opening of the solder mask, and the violation of standards.
There are several DFM issues, and if you manage all the design rules, you and your manufacturer would end up with a reliable PCB. You need the right software to create a rules-based PCB, avoiding the DFM issues.
Contact us at sales@pnconline.com to know more about DFM issues or pcb assembly services.

High-Frequency PC Board

High-Frequency PC Board Applications, Specifications, and Challenges

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Some electronic products need special signals for which you have to make a high-frequency PC Board. Such a circuit board can provide 500 MHz to 2 GHz frequency that is ideal for microwaves, a radio frequency, and certain mobile applications that involve high-speed designs.

Several electronic components and switches are complex and need to transfer signals at a fast speed which is provided by high-frequency PCBs. Such boards need special materials because ordinary materials can affect signal transmission due to a poor Er value. Designers have to consider certain factors while designing the high-frequency Printed Circuit Board that we will discuss below.

Understanding a High-Frequency PCB

PCB involves connections of different components through conductive paths to run a specific electronic item. Designers use copper to develop a conductive path in a PCB. Circuit boards also help in signal transmission in the case of Wi-Fi and other satellite systems. In other words, you need a high-frequency circuit board to connect multiple objects through signals.

High-Frequency PC Board
High-Frequency PC Board Applications, Specifications, and Challenges

Which Factors Affect The High-Frequency PCB?

The design of a high-frequency PCB is not that easy because certain factors influence it and you have to consider them. Such boards have complex fabrication due to high-frequency laminates. Besides, the circuit board has to manage different applications’ thermal heat transfer.
You can’t use any material for high-frequency PCBs because it influences signal transmission that can be fast or slow, depending on the material. Moreover, the change in a material’s Er value also affects a PCB’s impedance.
Similarly, the dielectric material also plays a role in the design of high-frequency boards. Manufacturers use different dielectric materials as mentioned below:
1. Roger’s
2. Teflon
3. FR4.
The Roger’s is not expensive, and its DF and DK values are also less than other materials. Besides, it is ideal for prototyping manufacturing and applications. Moreover, there is a minimum chance of signal loss due to this material.
Whereas Teflon is used due to its high frequency that is up to 5 GHz that enhances the speed of signals between different parts and objects.
On the other hand, the FR4 is ideal for RF applications that need a frequency from 1GHz to 10 GHz. But, the electric products having FR4 have certain drawbacks due to their limitations.
The best material for high-frequency PCBs is Teflon due to factors like water absorption, DK, and DF. Teflon is more expensive than other materials, but it is ideal for products that need more than 10 GHz frequency of signals.
What Are The Standard Specifications Of a High-Frequency PCB?
You have to consider certain materials to have a high-frequency board as mentioned above. Moreover, the change in a material’s Er value also affects a PCB’s impedance. PCBs are available in different frequencies and have certain specifications that we will discuss below.
PCB Size: It should be at least 6 mm x 6 mm, and can go up to 457 mm x 610 mm.
PCB Thickness: It ranges from 4 mm to 5 mm.
Type of Material. Generally, it should be RO4003C, Ro3003, RT5880, and Ro3010
Weight of Copper: It ranges from 0.5 oz. to 2 oz.
PP: It includes Domestic-25FR, Domestic-6700, and Roger’s 4450F.
Min Spacing: It should be at least 3 mils.
Solder Mask Colors: Some common colors, in this case, are yellow, red, white, green, and blue.
Sides of Solder Mask. They are according to the design files.
Silkscreen Colors and Size: The colors are mostly white, black, and yellow, whereas the sides are according to the files.
Impedance Clearance: It is either plus 10% or minus 10%, depending on the design.
High-Frequency PCB Finish: It can be immersion tin, gold, silver, or electroless nickel. All these finishes should be RoHS certified.
Annular Ring: It should be min 4 mil.
Diameter of Drilling Hole: It is a minimum of 6 mils.

All the above species are standard and may change according to the board design. Besides, most circuit boards are customized and designed according to your needs. It is hard to recognize the best high-frequency circuit board, however, the material and specifications can help you in this case. You can also get professional help from a qualified PCB designer and/or a circuit board manufacturer.

Top Tips To Develop The Best High-Frequency PCB

As you know high-frequency PCBs have a high density and integration than other PCBs, they need a thoughtful design and fabrication. Such boards are more scientific than traditional circuit boards, and we have some tips to help you create a reliable PCB.

1. The pins that exist between various layers of a high-frequency PCB should have minimal leads as an alternate. Besides, the lead between different pins should be small.
2. When it comes to high-frequency devices, there should not be more bends between their pins.
3. Make sure that loops don’t develop while wiring.
4. The impedance of signals should be compatible.
5. The power pins of an integrated PCB should have a high-speed decoupling.

Meeting the Challenges of A High-Frequency PCB

No matter how well-designed is your high-frequency circuit board, you have to face some challenges during its fabrication and assembly. Let’s discuss some common issues in this case.

Consider Scaling

A professional fabricator knows that the thickness of internal layers decreases during the lamination of a multi-layered PCB made if FR4. So, the manufacturer should evaluate the percentage of such a loss. This helps printed circuit boards manufacturers get the right dimensions after the lamination process is over.
Besides, the laminate material is not hard like FR4, so it reacts differently. You should know the behavior of each material. Besides, you should scale each thickness separately or it will affect the registration from drill to pad and layer to layer. The fabricator should know all the statistics in this regard.

Preparing Different Layers

A board with several layers is complex, as you have to prepare each layer to have a strong bond, especially in the case of Teflon. Soft material can get deformed during the aggressive preparation of a surface. Such a deformation results in wrong registration, turning a PCB into a scrap.
Replacing the Teflon becomes expensive and causes delays in fabrication. So, you must prepare the surfaces carefully to avoid such challenges.

Preparation of Holes

You need to prepare the hole before plating. Like, it should be free from debris or epoxy attached to its walls. A smooth surface helps have a well intact copper plating. However, ceramic or Teflon involves a different kind of hole preparation.
This process involves a lot of care like you should consider various parameters of the drill machine to avoid the smearing of the substrate. After drilling, the hole is treated through plasma that involves gases. Poor preparation of the hole before copper plating might result in poor signal transmission. Hence, a PCB should have clean holes to perform better.

Considering the CTE Rate

The designer also has to consider the CTE or coefficient of thermal expansion of different materials. Different materials have different expansion rates, besides this expansion can occur in any direction like x, y, or z, depending on the heat. You can have well-finished holes if the CTE is less.
The factor of CTE can cause issues during a hybrid PCB of several layers when you join the high-frequency materials with FR4. So, the CTE of the materials should be compatible, or different layers or materials will expand differently, creating an issue.
Other than layers, vias also have to face this issue. Hence, the plugging material of the vias should be compatible with other materials.

Compatibility

Some FR laminates are similar to the RF materials in terms of behavior, and you should understand it. For example, the ceramic impregnated boards are hard when you drill through the drill bits. The hit counts should be less, besides, the RPM and spindle settings should be customized.
Sometimes the holes have fingers, which are hard to remove, so the adjustment of drilling parameters is essential to reduce fiber.
So, you can meet all the above challenges if you design and fabricate a PCB carefully by approaching a prototype pcb manufacturer to verify your design.

Importance of a High-Frequency PCB

A high-frequency PCB is widely used in different industries, such as military, interchanges, gadgets, vehicles, PC, instrumentation, clinical, and other such fields. These circuit boards are more in demand than before, and 15% of circuit boards in the market come up with high frequency.

Final Words

Sometimes the electronic components and switches are complex and need to transfer signals at a fast speed which is provided by high-frequency PCBs. Such boards need special materials because ordinary materials can affect signal transmission due to a poor Er value.
You can’t use any material for high-frequency PCBs because it influences signal transmission that can be fast or slow, depending on the material. Moreover, the change in a material’s Er value also affects a PCB’s impedance. PCBs are available in different frequencies and have certain specifications.
Would like to know more about high-frequency PCB applications or pcb assembly services? Email us at: sales@pnconline.com

What is High TG In PC Board Fabrication?

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The making of PCB involves different steps, technologies, and terms, and TG is one such term that refers to the Glass Transition Temperature. High TG PCB is the board made at a high temperature. We will discuss this topic in detail, including the TG value, features, applications, materials, parameters, and much more.

What is High TG PCB?

If a PCB’s temperature goes beyond a set TG value, its condition will change. Like, the solid board will turn rubbery, affecting a PCB’s function. Depending on where you use a PCB, the temperature of the application should be at least 10 to 20C less than the PCB temperature.

Understanding TG Value

TG means Glass Transition Temperature like there is a certain limit of this temperature for PCB and that specific temperature is the TG value. TG value helps in understanding the PCB material, and you can find which temperature is required for its service.

Secondly, it helps you to find the condition of the PCB material, like if it’s solid, flexible, or solid-flex.

High TG PCB and Its Features

You have to choose a high TG Printed Circuit Board for your application carefully, because it involves multiple features, including thermal, electrical, mechanical, and chemical features.

Thermal Features: they include the TG or Glass Transition Temperature, thermal conductivity, thermal temperature’s coefficient, and decomposition temperature. TG is the temperature at which the state of the PCB material changes. But, when the board cools down, it gets back to its initial condition.

Electrical Features: they include the surface resistance, electrical power, volume relativity, and the dielectric constant and loss tangent.

Chemical Features: the chemical properties of a high TG PCB include the moisture absorption and the methylene chloride resistance of the PCB material. The TG PCB should be able to resist moisture if it’s near water.
Mechanical Features: the mechanical features are also important to know regarding the TG PCB. They include the flexural and peel strength, and the young’s module.

Suitable Materials for High TG PCB

A PCB has two materials, including laminate and substrate. The substrate includes epoxy resin, glass, or paper weave. The substrate should be compatible with the TG. Some common substrates that we use for a high TG PCB are;

  • CEM-1, 2, 3,4, and CEM-5
  • G-10 and 11, FR-1 to FR-6
  • Aluminum
  • Knapton
  • Pyralux

The last three materials are flexible.

The laminates should also be compatible with your TG PCB in terms of strength and temperature. Some common laminates are:

  • FR-1, and FR-4
  • CEM-1, CCEM-3
  • Teflon

Criteria for High TG PCBs

Printed circuit boards with a high TG value are based on certain criteria as described below:

  • The selection of a PCB, depending on the components like it can be single or double-sided PCB or embedded.
  • The stack-up PCB with a single layer or several layers
  • The design of such boards can be based on a module or it can be custom
  • The strength of the board also matters, like it should be robust either electrically or mechanically
  • PCB’s bendability also helps to classify the TG PCB, like if it’s hard, flexible, or hard-flexible
  • The electrical strength also helps classify the TG PC Board

Generally, manufacturers use bendability and strength to classify a TG PCB‘s physical properties.

Where Can You Use The High TG PCBs?

You can use the high TG circuit boards in intense conditions, as the environments with high-vibration devices. They are also suitable for applications with shocks, chemical components, and high temperatures. Like, missiles and car parts often come up with chemicals. So, the suitable industries for high TG PCBs include aerospace, telecommunications, military and defense force, automobile, and down-hole drilling.

What to Consider While Designing a Rigid PCB?

You must hire a professional PCB manufacturer for the right design, manufacturing, and assembly of these boards. The engineer must know the kind of environment that suits a TG PCB to function precisely. Below are a few examples to help you understand it.

Commercial Use

Many telecommunication companies use the best materials for mobile devices to enable them to bear high shocks. Like, the phone should not get damaged easily when you drop it.

Auto Industry

PCB has to be safe under a car’s hood as it’s mostly vibrating, so a shock or crash might happen. Hence, a rigid PCB is the best solution in this case.

Aerospace Industry

The flying machinery always needs the high TG PCB because there is intense vibration, like in the jet engine, as there are thousands and millions of micro-vibrations in one minute. So, equipment related to aerospace should be able to tolerate extreme temperatures, like from -45°C to 85°C.

Other Applications

These boards are also ideal for solar power equipment, such as power inverters and cogeneration equipment. As these boards resist temperature, they work well in many industries. Like, one of its applications involves Lead technology, like the medical, computer, and telecommunication industries.

The TG PCB is also used in broadcasting, like booster stations. Besides, the fire detectors and burglar alarms also need such boards.

Use of High TG Flex PCB

It is clear from the name that a flex PCB can adapt any design or shape to get compatible with certain products. Like, they can tolerate intense environments better than rigid PCBs. You can use the high TG flex PCB in defense and military, aerospace, medical equipment, consumer electronics, auto, wireless networks, as well as industrial equipment.

What To Consider While Designing a Flex PCB?

You must hire a professional PCB manufacturer for the right design, manufacturing, and assembly of flex PCB. The engineer must know the kind of environment that suits a TG PCB to function precisely. You should see if:

  • You need a flex PCB for an ordinary environment or an extreme environment like an explosion. Whereas the cell phone has a normal environment.
  • The environment should be free from any moisture before installing a high TG circuit board.
The Design Process

The design of a high TG PCB involves different steps, such as

  • Using the right software, like CAD, Eagle, Altium Designer, etc.
  • You must know the power requirements to suit different components on the PCB. You should also consider a specific plan for noise reduction caused by a TG PCB.
  • Preparation of the stack-up plans documents as it is essential for making the best TG PCB.
  • The floor layout for a PCB with proper sections, including components. Like you can place them together or separately.
  • TG PCB should be complete in terms of a power plane and ground details. These details ensure proper routing for signals.
  • The board should be compatible with patterns in terms of sizes. All components should be well-placed to help a PCB function the right way.
  • It is important to design routs for high-frequency signals, as the route should be clear for a flawless signal transfer. This step involves vias, as they help in proper signals. You need the reverse via and signal via in this case.
  • You must follow the 3W-rule to increase the traces’ distance which helps to reduce the coupling effect.
  • Another rule to reduce the coupling effect is the 20 H rule.
  • In the end, check the routing guidelines to see if you are doing everything the right way.
Specs and Design Parameters

The fabrication of a high TG PC Board Fabrication involves certain parameters and specs, depending on the application. Some standard parameters are described below.

How Many Layers Do You Need

Designers prefer the even number of layers while developing the high TG PCBs. But, the odd numbers of layers are also suitable in certain applications.

Dimensions of PCB

The PCB dimensions depend on its application. Like, you need a large circuit board for a broader application. Besides, there should be enough space on the board to place the electrical components.

Well-Finished

The high TG PCB should be well-finished, and the material depends on where you want to use this board. Like, some common materials are;
HASL, or hot air leveling – It is ideal as it is cheap and can be stored for longer.
OSP, or organic protective surface
Immersion silver – It gives a smooth surface, and it is cost-effective. It has many storage limitations
Immersion tin – It suits the SMT

Immersion gold – It can be stored for longer with a few limitations.

ENEPIG, nickel palladium – It can be stored longer, but it involves a complex process.

Solder mask – It protects the PCB from environmental elements.

Weight of copper – You must also consider the weight of copper like it includes both initial and finishing copper. Generally, the weight is 1 oz. to 1.5 oz. or 5 oz. It also depends on the layer and board thickness.

Assembled PCB thickness – The TG PCB thickness depends on its material and type. Like, if it’s flexible, hard, or a hard-flex board.

Distance between layers – The distance or spacing of electrical components and layers should be equal for high-frequency signals. As it reduces the coupling effect.

Via sizes – The drill aspect ratio and the hole size should also be appropriate. Generally, the PG PCB can have either plated-through or non-plated through holes, depending on the placement and layout design.

Board quality – The board should have a high-grade material to ensure an effective function during application. Besides, you must check the quality of the TG PCB to evaluate its performance in terms of specs. Like, you should test its lamination, vias, copper plating, solderability, finishing, components, and cleanliness.

Interested to know more about PCB TG or PCB Assembly? Email us at sales@pnconline.com

PC Board Fabrication, V-Scoring-Purpose and Benefits

PC Board Fabrication, V-Scoring-Purpose and Benefits

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PCB or a printed circuit board has different holes, cuts, and elements, and V-scoring is one of them. V-scoring pre separates the PCB and designers also call it V-groove because a groove resembling V is cut on the circuit board’s top and bottom. Generally, the depth of the groove is 1/3 of the board depth and there is a thin layer between two Vs for the board processing.

The boards with V-grooves are either end to end or side by side with adjacent edges. The groove helps break boards with a little force, and you can divide a single panel into several parts with the help of V cuts.

Purpose of V-Scoring

Manufacturers use V-scoring while combining an array’s circuit boards for an effective assembly. It makes the assembly process less hectic, and you can easily set apart the assembled PCBs.

V-scoring helps to reduce pressure during the placement of SMD components on the circuit board by an SMT machine, and while separating the assembled PCBs.

The PCB panel helps manufacturers to insert the components at a high speed, using one panel at a time, rather than one circuit board.

The panel boards are loaded with their parts through an automated machine that performs the pick-and-place function.

These uses motivate PCB engineers, manufacturers, and buyers to use the V-grooves.

Specifying V-Scoring

Engineers specify V-scoring according to the groove depth, or a distance between the two grooves or Vees through a cross-section. The residual material in this case is known as Web. Each measurement has to be equal, including 1/3rd on the top, bottom, as well as a 1/3 web in the center.

The practice of the 90 degrees or the 30 degrees scoring is also there in some cases. However, the 90 degrees scoring is easy to break compared to the 30 degrees scoring.
You can alter these measurements according to your needs, depending on the array size and the ease of separating the boards later on.

You have to use a 30-degree cutter for a score-line cutting with a certain depth. You can calculate the rest of the web based on the material thickness. However, the tolerance of +/- .002″ is essential in this case.

When to Use a Jump Score

Jump score is used in some conditions though it is not that common. In jump score, the score does not go from one end to another, instead, it ends before the circuit boards end. Like, the cutting blade stops before another end comes. The jump scoring provides a firm array while assembly.

Some V-Scoring Terms

There are certain terms to consider while making PCBs with V grooves, and we will discuss them one by one.
• PCB board has some borders or extra material that helps in making a panel, and they are called Rails or Waste Tabs. They enhance a panel’s mechanical strength, allowing an extra material or borders that help to clamp a panel while assembling.
• Another term used in V-scoring is Fiducials which are marks being etched on the borders or a PCB’s inner surface, like on upper and lower layers of copper. Fiducials help the SMT assembly to identify the position of the PCB and SMD components.
• The other important elements are tooling holes located on a PCB’s four corners. The manufacturers use these holes to align a PCB during drilling and routing. Like, the alignment that involves the SMT carriers, solder plate printing, and PCBs’ final assembly.

Process of V-Scoring

It involves two blades being beveled at 30o, or 45o, or 60o, and the blade resembles a wheel with several gears or knives that make V-grooves. Both top and bottom blades rotate while cutting. When the PCB assembly is over, an individual assembly of the board occurs by dividing the sub panels.

Rules To Follow In V-Scoring

Some fabricators think that the perfect size of the board is compatible with an 18”×24” sheet of CCL, but this is not so. Because the fabricator has to use some part of the sheet while processing. Both customer and manufacturer should discuss the kind of a PCB they require, besides, it should be the best.

Some Rules for Exceptional Circumstances

1. There should be zero space between two circuit boards
2. If you opt for V-scoring, your PCB’s size should be at least 75×75 mm, and it can go up to 450 x1250 mm. So, the scoring won’t be successful if the board size is not as per the rule.
3. Make sure the V-scoring path or line is straight, whether it’s continuous like end to end, or discontinuous like jump scoring.
4. For a perfect V-groove, the minimum thickness of the board should be 0.6mm.
5. You can choose the groove angles from 30o, 45o, or 60o.
6. The space between the PCB edges and parts should be a minimum of 6.35 mm
7. The minimum distance between the PC Board Fabrication outline and V-grooves’ line has to be 0.35mm.

Benefits of V-Scoring

• V-scoring helps to use a PCB surface effectively
• It helps reduce the manufacturing cost by fabricating many boards on one PCB.
• It helps to place more than one circuit through one assembly, helping in precise sub-assembly.
• V-scoring tools are cost-effective, portable, and require minimum maintenance.
• It helps save time as it allows you to separate different parts from a final assembly.

Drawbacks of V-Scoring

There are some restrictions of V-scoring like it is not suitable for PCBs with components placed near edges.
V-scoring can affect the PCB structure, reducing its strength due to the mishandling of a solder machine. However, fabricators apply jump scoring to maintain a PCB’s strength. You can read the above section to understand the jump scoring.
In the case of V grooves, you have to allow a 0.05 inches clearance between the grooves and components. The blade should not come between the components, especially for taller parts. Likewise, you should keep enough clearance for components located on the wide connection surface.

Difference Between PCB Scoring and PCB Panels With Tab-Routing

The PCB design determines if you should choose V-scoring or tab-routing. However we have a guideline for better selection, but you have to follow it.
1. The circuit board shape helps to select the right scoring. Like, V-scoring is suitable for rectangular or square PCBs, whereas the tab-routing goes well with an irregular shape.
2. You should choose a tab-routing if the components are hanging on the PCB edges. Besides, the tab-routing does not affect the edge quality. Whereas V-scoring makes edges rough.
3. V-scoring works faster than tab routing, besides, it is cost-effective than tab-routing in terms of labor.
4. At the same time, there is less wastage of material in V-Scoring compared to the tab-routing, which also reduces the total cost.
5. It also depends on the number of boards in an array and the number of PCBs in both directions, including the X and Y planes.

Frequently Asked Questions

What Is The Difference Between The PCB And PCBA?

The process is the same, but it involves two stages. Like, PCB is just a circuit board with components, whereas PCBA is an assembled board with necessary components, and it is ready for application.

What is Jump-Scoring and Its Use?

Jump scoring involves a cut that starts from one end of PCB but it stops before the other end, unlike V-scoring. Jump scoring strengthens a board for multiple processes.

What Is Tab-Routing In PCBs?

Tab routing helps you to process different circuit boards on one panel. It also helps you to isolate boards by breaking the tabs that exist between various boards.

What Is The PCB Penalization?

A process of connected small boards in a single array is called the PCB penalization. It helps fabricators to move the circuit boards while assembly.

What SMT Stands For In PCB?

SMT stands for Surface Mount Technology, and it’s a process of installing the electrical components on the PCB directly. Whereas the component installed through SMT is known as SMD or Surface Mount Device.

Final Thoughts on V-Scoring

PCB fabrication becomes economical by adopting cost-effective processes, including V-scoring. The boards with V-grooves are either end to end or side by side with adjacent edges. The groove helps break boards with a little force, and you can divide a single panel into several parts with the help of V cuts.

It involves less routing space, so you can add several rows in the PCB panel to be fabricated. It eliminates the wastage of the laminate, besides, V-grooves also save money and time by streamlining the PCB processing and manufacturing.

V-scoring helps to reduce pressure during the placement of SMD components on the circuit board by an SMT machine, and while separating the assembled PCBs.

V-scoring tools are cost-effective, portable, and require minimum maintenance. Moreover, it helps save time as it allows you to separate different parts from a final assembly.
But, V-scoring can affect the PCB structure, reducing its strength due to the mishandling of a solder machine.

Interested to know more about V-scoring or PCB assembly services, email us at sales@pnconline.com