Tag Archives: PC Board

Significance of Copper Coating in PCB Design

Significance of Copper Coating in PCB Design

PC Board, PC Board fabrication, PCB Design, PCB Fabrication, Printed Circuit Board, , ,

Printed circuit boards have a certain unused area, which is coated with copper known as copper coating or filling. There are several benefits of copper coating and one of them is to minimize the impedance of ground wire, as well as enhance the anti-interference and power supply, and minimize the voltage droppings.
The copper coating also helps prevent the deformation of a PCB during soldering. However, you have to manage copper coating properly to avoid certain issues that we will discuss here and find ways to resolve.

PCB has wirings distributed capacitance regarding high frequencies. The designer knows that when the length is higher than 1/20 of the corresponding wavelength of the noise frequency, it will cause the antenna effect causing the noise emission through wiring. Poor grounding of copper results in noise, so the ground line should have a hole with a pitch that is lower than λ/20 to have a good grounding on a multi-layered Printed Circuit Board.

The grid has traces in multiple directions and the trace width comes up with a corresponding electrical length to help a PCB operate. If the operating frequency is low, the gridline becomes less effective. But, the electrical length compatible with a PCB’s operating frequency causes bad effects and the PCB stops working transmitting the signals somewhere else.

High-frequency PCB resists a multi-purpose grid having high-interference requirements. On the other hand, the low-frequency PCB comes up with a wide current circuit and the designers use it for copper plating.
The grid should be compatible with the PC design, otherwise, the signals get scattered interfering with the entire system. The high-frequency PCB should have a high multi-purpose grid, and low-frequency PCB involves copper laying.

There are two methods of copper coating known as grid copper and large-area coating. In a large-area copper coating, bubbles develop due to wave soldering. In large-area coating, some slots are opened and the foaming of the copper foil is alleviated. Whereas the grid coating provides shielding to reduce heat dissipation, and it also provides electromagnetic shielding.

  • Sometimes the PCB has several grounds, including GND, AGND, and SGND. The main surface of a circuit board becomes a reference to use copper plating, or as a digital or analog ground. However, copper pouring does not need to be separated. Moreover, the designer has to increase the thickness of the power connections, such as 3.3V and 5.0V which helps make different deformed surfaces having different shapes.
  • When it is about different grounds single-point connection, the process involves a connection through magnetic beads or 0-ohm resistors.
  • You also have to take care of copper coating in areas adjacent to the crystal oscillator, which is a source of high-frequency emission. The basic technique is to shield a copper coating of the crystal oscillator and ground it separately.
  • There is another issue of a dead zone, also known as the Island. However, you can reduce it by defining a hole.
  • PCB ground should have equal treatment while wiring. You can’t depend on copper coating by adding a hole to remove a pin’s connection, as it would affect the signals badly.
  • The PCB design should not have sharp angles, such as 180 degrees, because they cause a transmitting effect in terms of electromagnetism.
  • The multi-layered PCB’s middle layer has open wiring that should not have copper as it is harder to manage and keep it grounded.
  • You should also properly ground the metal reinforcement and a metal heat sink.
  • You should also properly ground the metal block that causes heat dissipation regarding a three-terminal regulator. The isolation belt of the crystal oscillator should also be grounded properly.

So, you can make a copper coating significant by managing the grounding issues. Such management can reduce the signal path’s backflow issue and also reduce electromagnetic interference.

Many unused surfaces in a PCB are coated with copper known as copper coating or filling. There are several benefits of copper coating and one of them is to minimize the impedance of ground wire, as well as enhance the anti-interference and power supply, and minimize the voltage droppings.

The copper coating also helps prevent the deformation of a PCB during soldering. However, you have to manage copper coating properly to avoid certain issues that we will discuss here and find ways to resolve. PCB has wirings distributed capacitance regarding high frequencies. The designer knows that when the length is higher than 1/20 of the corresponding wavelength of the noise frequency, it will cause the antenna effect causing the noise emission through wiring. Poor grounding of copper results in noise, so the ground line should have a hole with a pitch that is lower than λ/20 to have a good grounding on a multi-layered PCB.

Moreover, the grid has traces in multiple directions and the trace width comes up with a corresponding electrical length to help a PCB operate. If the operating frequency is low, the gridline becomes less effective. But, the electrical length compatible with a PCB’s operating frequency causes bad effects and the PCB stops working transmitting the signals somewhere else.

As you know that high-frequency PCB resists a multi-purpose grid having high-interference requirements. On the other hand, the low-frequency PCB comes up with a wide current circuit and the designers use it for copper plating. The grid should be compatible with the PC design, otherwise, the signals get scattered interfering with the entire system. The high-frequency PC Board should have a high multi-purpose grid, and low-frequency PCB involves copper laying.
There are two methods of copper coating known as grid copper and large-area coating. In a large-area copper coating, bubbles develop due to wave soldering. In large-area coating, some slots are opened and the foaming of the copper foil is alleviated. Whereas the grid coating provides shielding to reduce heat dissipation, and it also provides electromagnetic shielding.

Significance of Copper Coating in PCB Design
Copper Coating in PCB Design

Also, PCB has several grounds, including GND, AGND, and SGND. The main surface of a circuit board becomes a reference to use copper plating, or as a digital or analog ground. However, copper pouring does not need to be separated. Moreover, the designer has to increase the thickness of the power connections, such as 3.3V and 5.0V which helps make different deformed surfaces having different shapes. When it is about different grounds single-point connection, the process involves a connection through magnetic beads or 0-ohm resistors.
Similarly, you must take care of copper coating in areas adjacent to the crystal oscillator, which is a source of high-frequency emission. The basic technique is to shield a copper coating of the crystal oscillator and ground it separately. There is another issue of a dead zone, also known as the Island. However, you can reduce it by defining a hole.

Moreover, the PCB ground should have equal treatment while wiring. You can’t depend on copper coating by adding a hole to remove a pin’s connection, as it would affect the signals badly. The PCB design should not have sharp angles, such as 180 degrees, because they cause a transmitting effect in terms of electromagnetism.
The multi-layered PCB’s middle layer has open wiring that should not have copper as it is harder to manage and keep it grounded. You should also properly ground the metal reinforcement and a metal heat sink. You should also properly ground the metal block that causes heat dissipation regarding a three-terminal regulator. The isolation belt of the crystal oscillator should also be grounded properly.

You can make PCB more effective by applying copper plating the right way. The design of the PCB matters a lot in this case because you need the right tools. Lots of software are there that designers use according to their requirements. You can also get customized PCBs through online platforms by giving your requirements.

At the same time, you need to follow specific design rules, and the fabrication should also be of high quality. Both designer and manufacturer should be experienced to provide the best PCB with correct copper coatings.

Wrap Up

PCB has wirings distributed capacitance regarding high frequencies. The designer knows that when the length is higher than 1/20 of the corresponding wavelength of the noise frequency, it will cause the antenna effect causing the noise emission through wiring. Poor grounding of copper results in noise, so the ground line should have a hole with a pitch that is lower than λ/20 to have a good grounding on a multi-layered PCB. The grid has traces in multiple directions and the trace width comes up with a corresponding electrical length to help a PCB operate. If the operating frequency is low, the gridline becomes less effective. But, the electrical length compatible with a PCB’s operating frequency causes bad effects and the PCB stops working transmitting the signals somewhere else.

High-frequency PCB resists a multi-purpose grid having high-interference requirements. On the other hand, the low-frequency PCB comes up with a wide current circuit and the designers use it for copper plating. The grid should be compatible with the PC design, otherwise, the signals get scattered interfering with the entire system. The high-frequency PCB should have a high multi-purpose grid, and low-frequency PCB involves copper laying.

Would like to know more about the Copper coating in PC design or pcb fabrication? Write us at sales@pnconline.com

High-Frequency PC Board

High-Frequency PC Board Applications, Specifications, and Challenges

circuit board manufacturer, PC Board, pcb assembly services, Printed Circuit Board, printed circuit board manufacturers, prototype pcb manufacturer, , , , ,

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

PC Board

Basic PC Board Rules for Successful IoT Design

PC Board, pc board assembly, pcb assembly, pcb assembly usa, PCB Design, , , ,

The world is becoming smart each day due to IoT, or the Internet of Things. Your life becomes easier when you connect every device to the internet or Wi-Fi. These days there are many smart homes and products which will stay there in the future. The IoT design is a specific area of electronics design that has boosted the PCB industry.
However, the development of a revolutionary design is not so simple even though the IoT devices are smart and seem simple, it is not so. You need a well-designed PCB for such a device. The PCB should have specific components to meet the needs of the smart world.
The IoT design involves rigid-flex circuits with certain challenges and physical interfaces which are not there in ordinary PCBs. You need certain tools for a smart PCB, like PADS, Xpedition, and other such simulation tools.
Now, smart devices are managed through remote apps, however, it is just a little part of the IoT. The technology is working in big industries like agriculture, transport, biomedical, and consumer electronics. It involves wireless technologies, such as Wi-Fi, Bluetooth, and cellular networks. So all such devices need well-designed hardware in the form of PCBs.

Impact of IoT on the PCB Design and Construction

You have to follow certain rules while designing an IoT-based PCB. It involves a precise evaluation and focusing on the power management, sensors, and the wireless connection, and the Printed Circuit Board should be compatible with all these factors. The design of such printed circuit boards is not like the conventional boards.

Which Aspects Influence the IoT PCB

You have to consider the size, layout, signal strength, security, power, and thermal management while designing a smart PCB. Let’s look at all these factors individually.

1: PCB Size

As IoT devices are small, they need tiny components for signal transmission. Manufacturers use MEMS technology to develop modern sensors because they are economical, reliable, and help develop a small layout. Such a board should have well-integrated components, precise placement of the processor and MCU, and the Wi-Fi interface. Besides, the analog areas should be separate from the digital areas.

2: Layout Design

In the case of IoT, the printed circuit board should have multiple layers to enable traces’ routing. Such a PCB has stringent constraints when it comes to EMC or electromagnetic compatibility.
Moreover, high-density components need high-density interconnections or HDI to help reduce the pads’ size and increase the number of vias or holes.

3: Signals Integrity

The PCB should have high-end sensors for precise signals, free from the coupling. The signals should not interfere with the wireless signals and power lines. They should work well in all kinds of operating conditions.

4: PCB Materials

Smart technology and IoT have resulted in innovative materials for developing PCBs, including flexible boards. A flexible PCB is designed after considering the material’s mechanical structure and position of the electric components. You can place many components on a flexible PCB, so it is also suitable for wearable devices.
A flexible PCB has simple wiring than a rigid PCB and it stays strong during mechanical stresses, which are often hard to ignore.

5: Power Management

You have to consider the battery life of the IoT devices, and the power management helps you to enhance the battery function. You must have a well-integrated circuit in terms of power. The circuit should have functional blocks within the power cost or budget.
The designer of the PCB design PCB design should estimate the power consumption in a device’s multiple operating conditions. You must know that the wireless transceivers sometimes come up with absorption peaks while the transition from an Off state to an On state. Besides, considering the power consumption during a battery’s deep sleep mode is also essential because it helps determine the battery function.

6: Security System

Though the internet world has unlimited benefits, you become vulnerable to lots of threats. The IoT involves a shared network, so you cannot escape from attacks without good security. The water, gas, and electricity meters also become unsafe due to IoT devices. Similarly, the electro-medical device is also at risk as it has highly sensitive data.
Security software is not sufficient in this case, so the designer has to consider it while developing any hardware. However, the cryptographic engines provide high-end security through encrypted algorithms, including DESM, AES, as well as SHA.

7: Thermal Management

An IoT device is very small and runs with a battery, and it has a slot-free cover, so it needs proper thermal management. The designer should take care of the hot spots while designing a PCB. These hot areas happen when their temperature gets over 150 °C, but it can be managed through traces geometry, like the width and height ratios. You must provide copper plating to thermal vias and should add the copper planes for thermal management.
The IoT PCB has a limited area, so the designer has to provide the grounding area carefully for proper RF connectivity and heat dissipation. Sometimes the designer focuses on the simulation of the thermal air and provides it through both 2D and 3D models. Whereas, the tools like ECAD and MCAD help in this case.

Some Other Design Considerations

As IoT devices involve wireless connections, they should be certified in terms of RF components. These certificates have different names depending on the country as FCC works in the United States, and Canada has IC. Whereas CE is used in Europe, moreover, some additional certificates are also required, including WEEE and PTCRB, which ensure the standard emission of the radiations.
The certification process becomes easier if you use a pre-certified RF module because you can use it in the device directly, and you don’t have to pay for an expensive certification.
Due to smart solutions, more design tools are emerging for designing the IoT PCB that involves the AMS or analog signals, circuit analysis, simulation, and some models.
The strength of the connections is validated through simulation, so it is essential to consider. Well-designed software can simulate a circuit’s schematic by taking care of various design parameters, like time and frequency domain, operating point, sensitivity, worst conditions, and the Monte Carlo analysis.
The designer also has to consider the size, battery life, charging time, and power usage in the case of wearable devices.

IoT PCB Development

You must focus on the pcb fabrication process and assembly before making it. As a smart device has less space, a flexible PCB works for it because you can bend it as you want without affecting the device.
Besides, the manufacturing tools and equipment should be strong enough to bear vibrations and shocks. Other than a flexible PCB, the designer can use the SiP technology for the simple manufacturing of the IoT PCB. The SiP or System-In Packages help to use a complex analog, RF, and a digital system through a single chip. However, the chip works just like a traditional chip.
The IoT device should have a consistent network connection like the 24/7 operation works in the industrial applications having a 100 % uptime.
Likewise, it is essential for a PCB to have constant power to work consistently. The battery life of the portable devices should be extended for high efficiency.
Whether it’s the PCB design or some other stage of the IoT device development, the verification of the manufacturability of the product is essential. The DFT or Design for Test tool works in this case and helps to find any defect in the PCB before using it.
Likewise, the DFMA analysis helps to detect any issues while PCB designing, and you can resolve them before producing the PCB.
Similarly, you have to consider the security of the IoT devices to avoid any counterfeiting of a PCB that often happens in metrology applications. Manufacturers are now developing advanced technologies to create the IoT PCB. Like, they use the coded IDs for every PCB layer, so it is hard to replicate it.
So, you can create a well-designed and well-assembled IoT PCB by considering important factors.

Final Thoughts

The IoT design involves rigid-flex circuits with certain challenges and physical interfaces which are not there in ordinary PCBs. Smart devices are managed through remote apps, however, it is just a little part of the IoT. The technology is working in big industries like agriculture, transport, biomedical, and consumer electronics.
IoT involves wireless technologies, such as Wi-Fi, Bluetooth, and cellular networks. So all such devices need well-designed hardware in the form of PCBs. You need a well-designed PCB for such a device. The PCB should have specific components to meet the needs of the smart world.
You have to follow certain factors while designing an IoT-based PCB. It involves a precise evaluation and focusing on the power management, sensors, and the wireless connection, and the PCB should be compatible with all these factors.
Would like to know more about PCB design rules or PC Board assembly? Email us at sales@pnconline.com

What is Back Drilling in PC Board Manufacturing

What is Back Drilling in PC Board Manufacturing?

Circuit board fabrication, PC Board, pc board assembly, PC Board fabrication, pcb assembly, PCB Design, PCB Fabrication, printed circuit assembly, Printed Circuit Board, , , ,

Back Drilling is a way to remove the copper barrel’s stub from the through-hole. A stub is an unused part of the plated-through holes as it does not perform any function on the circuit, so it’s not needed.

For example, while producing a 12-layer PCB you have to make a hole to connect the first to 10th layers. In general, via holes are drilled and then copper plating happens which connects the first layer to the 12 layers, whereas you only have to connect the first layer to the tenth layer.

The part from the 11 to 12 layer is useless as there is no electrical connection, so it is only a pillar. This extra length of via affects the signal passage, making the communication weak. So, that extra pillar or stub has to be removed from the back through another drilling.

Moreover, back drilling is also known as CDD, controlled depth drilling and you can use it in any Printed Circuit Board having weak signals.

Why Do You Need To Remove the Stub

The stub is not just a waste, but it affects high-speed signals by distorting them. When these signals pass through a copper barrel having a long stub, it results in a high distortion. Thick or multi-layered PCBs and back panels are more vulnerable to weak signals due to stubs.

Printed circuit boards of high-frequency should have blind and buried vias, as well as back drilling. Besides, you don’t have to consider the layout design in the back drilling. On the other hand, you have to consider the aspect ratio in blind vias.

When the Circuit board fabrication is over, the fabricators redrill the holes to remove the stubs. This process involves a large drill compared to other holes. In other words, you have to back drill the holes to a controlled or limited depth, like it should not reach the last layer including via.

However, the back drilling is not a clean process like other drilling methods, as the copper gets electrolyzed in this case. Besides, the drill point is sharp in this case, so the fabricator leaves a small point. Moreover, the b-value or the remaining stub length should be from 50 um to 150 um.

What Are The Benefits Of Back Drilling Or CDD?

Back drilling has many benefits as described below;
• It involves fewer bit errors
• It reduces the deterministic jitter
• It provides more data rates
• You get more channel bandwidth through back drilling
• The enhanced independence matching helps reduce the signal attenuation
• It helps reduce the resonance mode’s excitation or noise
• It does not involve the consideration of any aspect ratio
• It reduces a stub’s EMI radiation
• Back drilling reduces the thickness of local plates
• It enhances the signals, making them powerful
• It eliminates the need for blind holes
• It enhances a PCB’s production process

Back Drilling Principles

During the drill bit drilling, the tip of the drill connects with the substrate board’s copper layer. This process produces a low-level current to evaluate the PCB’s surface height, drilling with an appropriate depth. So, drilling stops after the set depth.

Applications of Back Drilling

You can use the PCBs with back drilling for different industries, including aerospace, computers with large servers, medical equipment, communication, and military.
In the case of military or aerospace, only the manufacturers having a background with these industries are eligible to provide the back drilling in PCBs. This means the ordinary PC Board companies can’t get such projects.

How to Proceed With Back Drilling

The back drilling or CDD process involves a few steps, such as:
• It involves the PCB with tooling holes through drilling
• Copper plating of holes before sealing of the dry film
• Developing graphics on the external surface when the plating process is over
• After graphics, making plating with patterns and providing the sealing of the dry film of positioning holes. However, the sealing is done before the pattern process.
• The tooling hole’s s drilling and vias’ back drill
• Cleaning of vias from the residual that occurs during a back drilling of holes.
• The back drilling of the left via is done from the top surface, whereas the back drilling of the right via occurs from both sides.

PCB Features for Back Drill

The PCB with back drilling consists of certain features, such as:
• Only a rigid PCB can go through back drilling
• PCBs with 8 to 50 layers can have a back drill
• Its thickness is 2.5 mm or more than that
• The aspect ratio of the PCB is also large
• There is less trace in the external surface, like in a square array with press-fit holes.
• PCB dimensions are larger than the boards without back drilling
• The depth clearance for a back drill has to be +/- 0.05mm
• The thickness of the insulation should be at least 0.17mm
• Generally, the back drill hole is larger than other vias, like more than 0.2 mm
So, the PCB drilling involves various stages and back drilling is the second stage that removes the unused plating of vias. It involves a specific depth and the side of copper.
The secondary drilling has to be precise, and that depends on the expansion and contraction of the board, drilling technique, tool accuracy, and certain other factors.

Precautions to Follow While PCB Drilling

Whether it’s back drilling or some other, you need high-quality tools to bring the best results.
• Drills often wear while making holes in the thick boards, especially, small drills and they can affect the surface finishing, as well as the size of the hole. It also increases the drilling force, so your tool must have no wear.
• A worn-out drill needs more force to operate, besides, its temperature also increases, and eventually, the chemical and physical reaction of the drill wear also increases, causing a poor drill.
• You can reduce the drill wear by keeping the aspect ratios low, however, this is not in the case of back drilling.
• Also, take care of the chip load that depends on the drill diameter. Often drills with a small diameter break faster than the drill have a large diameter.
• You should hire professional services for your PCB design, execution, and assembly.

A Technique to Calculate the Drill Diameter

You can do it through the below formula,
Size of the back drill = size of the via or pad hole + 2 x design rule of an oversize back drill

Frequently Asked Questions

What Is The Main Purpose Of Back Drilling?

The basic function of the PCB back drilling is to remove a part of the through-hole that does not transmit the current. If you don’t remove a long hole, it will affect the high-frequency signal transition, causing reflection or distortion.

What Is A Stub In PCB Fabrication?

The stub is an unused part of plated-through holes, as it does not perform any function on the circuit, so it’s a waste. It will affect the signals if you don’t remove the stub.

What Are Plated-Through Holes?

The PTH or plated-through holes connect multiple layers of copper in a PCB to provide an electrical connection to the components.

What Is CDD In PCB?

CDD stands for controlled drilling depth or back drilling that removes stubs or wasted copper parts from the PCB holes.

What Are Other Factors Affecting The Integrity Of The Signals?

Not only stubs, but some other factors also affect the transmission of the electric signals in PCB components. Like, PCB material, connector type, chip package, vias, transmission lines, etc.

Why PCB Should Have Drilling?

The printed circuit boards have become more advanced and their demand has also increased that needs high quality. PCB involves through-hole drilling to create a transition path for the electric signals in various circuits.

Final Thoughts on Back Drilling In PCB

PCB drilling process has different stages and back drilling is the second stage that removes the unused copper plating. It involves a specific depth and the side of copper. It has to be precise, and that depends on the expansion and contraction of the board, drilling technique, tool accuracy, and certain other factors. Printed circuit boards of a high-frequency should have blind and buried vias, as well as back drilling.

The stud or extra length of via affects the signal passage, making the communication weak. So, that stub has to be removed from the back through another drilling. The back drilling is not a clean process like other drilling methods, as the copper gets electrolyzed in this case.

PCBs with back drilling is used in different industries, including communication, computers, military, aerospace, etc. you may have to go through some challenges while back drilling, but by following some precautions you can overcome them.

Interested to know more about Back Drilling or Printed Circuit Board assembly? Just email us at sales@pnconline.com

PC Board Fabrication, V-Scoring-Purpose and Benefits

PC Board Fabrication, V-Scoring-Purpose and Benefits

PC Board, pc board assembly, pcb assembly, pcb assembly services, pcb assembly usa, pcb board assembly, SMT assembly, , , ,

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