Everything You Need to Know About 4-Layer and 6-Layer PCB

Introduction

Another vital factor one should consider before they produce their boards is the layer count. In this case, we will tackle the 4-Layer and 6-Layer PCBs, the most frequently used board in the industry because of their many capabilities and advantages.

Introduction to 4-Layer vs. 6-Layer PCB

Introduction to 4-Layer vs. 6-Layer PCB

In contrast to a 6-Layer PCB, which contains six layers of conductive material, a 4-Layer PCB has four. A dielectric substance is a barrier between these layers, while vias link the conducting layers.

The number of layers on the board determines a PCB’s performance, price, and dependability. Depending on the project’s needs and intended complexity, one should choose between a 4-Layer and 6-Layer PCB.

Consequently, we’d like to dig deep into this article and the concept of each layered board to evaluate whether they are suitable for one’s desired purpose and application. We will touch on its stack-up configurations, benefits, applications, and factors to decide whether a 4-Layer PCB is better than a 6-Layer PCB or vice versa.

What is a 4-Layer PCB?

As was previously said, a 4-layer PCB is a particular kind of circuit board that includes four layers of conductive material isolated by layers of insulating medium. The layers are interconnected by vias; small holes drilled through the board allow electrical signals to pass from one layer to another.

Typically, the top and bottom copper layers of a four-layer PCB are utilized for power and signal transmission. The two inner layers, which serve as the ground and power planes, are likewise constructed of copper. The power and ground planes give the data on the top and bottom layers a steady reference signal, which lessens noise and enhances signal quality.

Designing 4-Layer PCB

In situations with an intermediate degree of complexity, such as consumer electronics, industrial controls, and medical equipment, 4-layer PCBs are frequently utilized. They outperform 2-Layer PCBs regarding efficiency and noise suppression while being more affordable for several situations.

Different Stack-Ups of a 4-Layer PCB

Essentially, there are two (2) fundamental stack-ups a 4-Layer PCB can have. We will thoroughly dissect them in this section.

1st Stack-Up

  • Layer 1: Signal
  • Layer 2: Ground/Power
  • Layer 3: Power/Ground
  • Layer 4: Signal

Typically, the first stack-up option for a PCB is chosen when many chips are present on the board. This configuration is preferred as it provides better signal integrity performance. Nevertheless, as the wiring and other board specifics mainly determine electromagnetic interference (EMI) performance, there might be better options. It is significant to notice that the structure is positioned on the signal layer’s connecting layer, which has the maximum signal density.

Furthermore, radiation can be suppressed and absorbed more effectively at this location. Also, expanding the board area is advised to adhere to the 20H rule, which specifies that signal traces should be spaced apart by at least 20 times their height to reduce resonance and disturbance.

2nd Stack-Up

  • Layer 1: Ground
  • Layer 2: Signal/Power
  • Layer 3: Power/Signal
  • Layer 4: Ground

The second method for building a 4-layer PCB is frequently utilized when sufficient room surrounds the chip, and the chip density is modest. The central layers of the PCB are labeled as signal and power lines in this format, while the outside layers are used as ground lines.

A broad wire is used to transport the power supply on the signal line to reduce the susceptibility of the power supply current and the signal microstrip channel. The fact that this architecture has the worst EMI efficiency out of all 4-layer PCB layouts should be noticed. Nonetheless, it could be a viable solution for situations where chip concentration is low and the area is not an issue.

Benefits of 4-Layer PCB

As many people know, 4-Layer PCB is an advanced option for a 2-Layer PCB with increased capabilities. Therefore, it has a lot more to offer than the 2-Layer PCB. Some of the benefits of utilizing a 4-Layer PCB are discussed below.

  • Increased Density: With four layers of copper, a 4-Layer PCB can support more components and complex circuit designs than a 2-Layer PCB.
  • Improved Signal Integrity: By using dedicated power and ground planes in a 4-Layer PCB reduces noise and crosstalk, resulting in better signal integrity and less interference.
  • Thermal Dissipation: The additional copper layers in a 4-Layer PCB can help dissipate heat more efficiently, which is essential for high-power applications.
  • EMI/RFI Shielding: The internal ground plane in a 4-Layer PCB can provide a natural shield against electromagnetic and radio-frequency interference.
  • Reduced Size and Weight: By using a 4-Layer PCB can reduce the size and weight of a device compared to a 2-Layer PCB, which can be crucial in portable or handheld devices.

Overall, a 4-Layer PCB compromises performance, cost, and complexity, making it a desirable option for several situations.

Applications of 4-Layer PCB

In essence, countless industries prefer 4-Layer PCB in their devices due to its numerous capabilities and smaller footprint; some are listed below.

Applications of 4-Layer PCB

Power Supply with 4-Layer PCB

  • High-Speed Communication Systems: A 4-Layer PCB is ideal for high-speed communication systems because it provides a more efficient path for signal transmission. The additional layers allow for better shielding, minimizing interference and noise.
  • Power Supplies: A 4-Layer PCB is helpful for power supply applications because it allows for better power distribution and ground planes. This can reduce noise and improve the overall performance of the circuit.
  • Medical Devices: Since the equipment in this field requires high reliability, a 4-Layer PCB can provide the stability and durability needed for these applications. The additional layers offer more flexibility in design, allowing for more complex circuits to be implemented.
  • Aerospace and Defense: The aerospace and defense industries require high-performance electronic components that withstand extreme conditions. A 4-Layer PCB can provide the necessary reliability and ruggedness for these applications.
  • Consumer Electronics: A 4-Layer PCB is commonly used in daily electronics, including smartphones and tablets, where space is limited. The additional layers allow for a more compact design while providing the necessary functionality and reliability.

Overall, a 4-Layer PCB is ideal for applications requiring high-speed, high-reliability, and high-performance electronic components.

What is a 6-Layer PCB?

An electrical circuit board with six conducting and two insulating layers are a 6-Layer PCB. As opposed to a 2-Layer or 4-Layer PCB, it is a more sophisticated and complicated form of PCB and has several advantages.

In comparison to a 4-Layer PCB, the two extra layers provide:

  • Better signal integrity.
  • A more significant component density.
  • Enhanced EMI (Electromagnetic Interference) protection.

What is a 6-Layer PCB?

6-Layer PCB

The signal layers have a more reliable power source and return path thanks to the ground and power planes, improving performance and lowering interference.

A 6-Layer PCB is frequently used in devices like network switches, routers, and telecommunications equipment that need high-speed connectivity. Moreover, it is utilized in significant computational systems, medical equipment, and applications related to aerospace and military.

In comparison to simpler PCBs, a 6-Layer PCB offers greater signal integrity, better power distribution, and a more prominent component density, making it a more intricate and sophisticated circuit board. It is a standard option for complicated and powerful electronic systems.

Various Stack-Ups of a 6-Layer PCB

Similar to the 4-Layer PCB Stack-Up, the 6-Layer PCB has two (2) basic configurations for its stack-up. Each of this stack-up has its particular purposes and applications.

1st Stack-Up

  • Layer 1: Signal
  • Layer 2: Ground
  • Layer 3: Signal
  • Layer 4: Power
  • Layer 5: Ground
  • Layer 6: Signal

A PCB’s Stackup 1 places the signal layer adjacent to the ground layer, improving signal integrity. With this configuration, the two layers may efficiently absorb magnetic field lines, which lowers system noise. Each trace layer’s susceptibility is regulated by the pairing of the ground and power layers.

The returning path for each signal layer is enhanced with a comprehensive power and ground layer present, ensuring a steady power supply and lowering signal distortion. The general optimized architecture of Stackup 1 provides excellent signal clarity and efficient noise suppression, making it appropriate for high-speed communications networks.

2nd Stack-Up

  • Layer 1: Ground
  • Layer 2: Signal
  • Layer 3: Ground
  • Layer 4: Power
  • Layer 5: Signal
  • Layer 6: Ground

Stack-up 2 of a 6-Layer PCB configuration is suitable for cases where the device density is not very high. This stack has all the advantages of the previous accumulation, with the top and bottom layers featuring a relatively complete ground plane. This entire ground plane can be a better shielding layer, improving the system’s EMI (Electromagnetic Interference) performance.

It is essential to remember that the power layer should be placed close to the layer that is not the primary component side. The bottom plane will be more complete, providing better shielding and reducing EMI. Furthermore, stack-up 2 offers better EMI performance with this placement than the first scheme.

Overall, Stackup 2 is a suitable configuration for systems with lower device density, offering improved EMI performance and better shielding due to the complete ground plane. However, other stack-ups may be more appropriate for systems with high device density.

Applications of 6-Layer PCB

Since a 6-Layer PCB has a more complicated configuration and architecture, these boards are expected to be used in intricate devices in various industries. Some of the market that prefers a 6-Layer PCB is stated below.

Applications of 6-Layer PCB

Audio Amplifier with 6-Layer PCB

  • High-Speed Digital and RF Applications: Generally, 6-Layer PCBs are designed to handle high-frequency signals with minimal loss and noise. They are commonly used in networking equipment, servers, and communication systems.
  • Power Amplifiers: 6-Layer PCBs can handle high-power applications with ease. They are commonly used in audio amplifiers, power supplies, and motor control systems.
  • Microwave Devices: 6-Layer PCBs are used in microwave devices like radar systems, satellite communications, and wireless networks.
  • High-Voltage/High-Current Applications: 6-Layer PCBs are used in applications that require high voltage and current capacities, such as industrial equipment, power distribution systems, and electric vehicles.
  • Impedance-Controlled Transmission Lines: 6-Layer PCBs maintain a consistent impedance throughout the transmission line, which is essential in high-speed data transmission and RF applications.
  • EMI/RFI Shielding: 6-Layer PCBs are designed with specific layers for shielding against electromagnetic interference (EMI) and radio-frequency interference (RFI). They are used in medical equipment, aerospace, and defense electronics.

In conclusion, 6-layer PCBs are appropriate for various applications requiring high reliability, speed, and power. They are often employed in fields including aircraft, telecommunications, medicine, and automobile electronics.

How to Properly Select the Right PCB Layer for your Applications?

Selecting the suitable PCB Layer for your application depends on various factors, including the circuit type, operation frequency, and board size. One can use the following principles to select the ideal PCB Layer for a particular application.

  • Determine the Type of Circuit: The type of circuit you are designing will determine the number of layers needed. Simple courses can be created using a Single-Layer PCB, while more complex circuits require multiple layers.
  • Consider the Frequency of Operation: One will need a PCB with multiple layers if the circuit operates at high frequencies. This is because a Single-Layer PCB may have issues with signal integrity and electromagnetic interference (EMI) at high frequencies.
  • Determine the Board Size: A Single-Layer PCB may be sufficient if you are designing a small board. However, suppose you are planning a larger panel. In that case, you may need multiple layers to accommodate all the components and connections.
  • Consider the Cost: The number of layers in a PCB affects the cost of production. Generally, the more layers in a PCB, the higher the price. So, it’s essential to balance the need for more layers with the cost of production.
  • Consult with a PCB Manufacturer: PCB manufacturers have expertise in designing PCBs and can provide recommendations based on the specific requirements of your application.

Overall, selecting the suitable PCB Layer depends on the circuit type, operation frequency, board size, cost, and consultation with your manufacturer. Considering these factors will help you design a reliable and cost-effective PCB for your application.

Summary

In summary, 4-Layer and 6-Layer PCB has their unique strengths and weaknesses. If there are operations, purposes, and applications that a 4-Layer PCB can’t handle, a 6-Layer PCB may have the possibility to work it out. However, a 6-Layer PCB has the upper hand since it has additional layers that provide more routing flexibility, allowing for higher component density and enhanced transmission quality.

If you want to learn more about other PCB Layer Configurations, please get in touch with PCBMay. If you’re planning to manufacture a layered PCB, then we can perform it too. Given that we’ve been operating in the industry for over 15 years, we can provide you with a quality and efficiently performing board.

Please send us your quote or any inquiry. We are always delighted to attend to all of your concerns. Also, we will respond immediately within an hour or two since verification might be needed for your quote.

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