Design and Manufacturing Guidelines for 6-Layer Printed Circuit Boards

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The 6 -layer PCB (printed circuit board) is a printed circuit board with a multi -layer conductive layer. Its basic structures include the internal and external copper foil layers and the intermediate isolation layer. Among them, the first and 6th layers are the signal layer. Signal. This design allows more functions and higher performance in a limited space.

6-layer PCB application

The 6 -layer PCB (printed circuit board) plays a key role in modern electronic manufacturing, and its application is wide and diverse. The following are the main application areas of the 6 -layer circuit board:

1. In the field of communication equipment, the application of 6 layers of PCB is very common. For example, communication devices such as mobile phones and routers need to use this type of PCB. Due to the large amount of data processing of communication equipment and high requirements for circuit boards, the 6 -layer PCB can provide higher data transmission rate and lower signal interference, thereby ensuring the normal operation of the equipment.

2. In the field of industrial control equipment, the 6 -layer PCB also plays an important role. Industrial control equipment usually requires a large amount of data and complex control tasks, which have high requirements for the stability and reliability of the circuit board. The high stability and high reliability of the 6 -layer PCB can ensure the stable operation of the industrial control equipment, thereby improving production efficiency.

3. In the field of medical instruments, 6 -layer PCB is also widely used. For example, the ECG monitor and ultrasonic diagnostic instrument in medical equipment need to use this type of PCB. Because medical instruments have high requirements for data accuracy and stability, the 6 -layer PCB can provide high -precision signal transmission and stable working environment, thereby improving the work efficiency and diagnosis accuracy of medical equipment.

4.6 layers of PCB also have a wide range of application prospects in data centers and high -speed communication. Its high -density design can achieve smaller size and higher integration, saving space and cost for electronic products. At the same time, due to the characteristics of its high signal transmission rate and low signal loss, the 6 -layer PCB can meet the needs of high -speed communication and data centers.

Benefits of Using 6 Layer Printed Circuit Board

The six-layer printed circuit board incorporated within the multilayer board offers unmatched benefits. These exceptional advantages and specific characteristics of the six-layer printed circuit board are delineated in more detail hereinafter.

Firstly, a diminished size and surface area. The inclusion of additional layers provides ample room for diminishing the footprint of the printed circuit board. Consequently, one defining characteristic of the six-layer circuit board lies in its ability to minimize the overall area occupied by the end product while facilitating more intricate functionalities. This stands as one of the key motivators behind the utilization of six-layer printed circuit boards on an increasing scale currently. Reflecting the escalating demands for the portability of electronic gadgets, these attributes align flawlessly with prevailing market trends.

Secondly, superior electrical performance. With the escalating complexity of products, semiconductor DC, AC, rectification currents, diverse frequencies, and powers, encompassing high-grade ICs, elevated voltages, ADC conversion rates, precision, and so forth, the electrical performance benchmarks of components utilized for printed circuit boards invariably rise. This enhanced electrical reliability of six-layer printed circuit boards renders the interaction among components more reliable, offering a distinct edge over single- and double-layer printed circuit boards.

Thirdly, enhanced durability. Comparative to single-sided and double-layer printed circuit boards, six-layer printed circuit boards incorporate multiple insulation layers, thus enhancing PCB robustness for optimized prevention of PCB shorts, thereby prolonging PCB lifespan and product longevity.

Fourthly, superior connectivity, reduced weight. In contrast to conventional single-sided printed circuit boards and double-sided printed circuit boards, the elaborate circuitry of the six-layer printed circuit board simplifies component connections, thereby minimizing the usage of interconnection components and subsequently, reducing the total weight of the PCBA assembled product. As such, this represents a compact, yet lightweight solution ideal for portable electronics.

Lastly, the intricate stacking arrangement delivers a more robust structure and effectiveness. Design considerations related to stacking arrangements play a pivotal role in PCBs. Six-layer PCBs exhibit a more intricate stacking array compared to single-sided PCBs and double-layer PCBs. However, this increasingly complex configuration also enhances PCB application potential, ensuring quality and stability guarantees.

Which material does the 6 -layer PCB use?

The materials used in the 6 -layer PCB (printed circuit board) mainly include conductive materials, insulation materials and substrate materials. The following is a detailed introduction to the main materials used in 6 layers of PCB:

1. conductive material:
▶ Copper foil: The outer copper foil layer is a layer of metal foil on the surface of the PCB board. It will be processed into the required line pattern for connecting each component. The inner copper foil layer is located between the inner signal layer and is also used for the connection and transmission of the circuit.
▶ Gold plating, silver plating, etc.: Under certain specific needs, in order to improve the performance of electrical conductivity or prevent oxidation, metals such as gold -plated and silver plating may be used as conductive materials.

2. Insulation material:
▶ Prepreg: This is a thin piece of insulation material, which is used for adhesion materials and insulation materials for the inner conductive graphics of the multi -layer printing board. During the layer pressure, the semi -curing epoxy resin is squeezed away to form a reliable insulator.
▶ Polymidamine (PI), Polytesterafluoroethylene (PTFE), etc.: These high -performance insulation materials are also often used in 6 layers of PCB to improve insulation and high temperature resistance.

3. substrate material:
▶ FR-4: This is a glass fiber-covered copper plate with good insulation performance and mechanical strength. It is a substrate material commonly used in 6 layers of PCB. FR-4 contains flame retardants, so it is also called FR (flame retardant) layer.
▶ Other FR layer boards: In addition to the FR-4, there are FR-2 (paper-based phenolic resin layer plates), FR-6 (polyester resin glass fiber layer plate), etc. FR layer boards can also be used for 6-layer PCB manufacturing , But they may be different in certain performance or processing.

What Makes up a 6 Layer PCB Stackup?

A 6 layer PCB stackup comprises different layers. The ground plane, power plane, and signal layers make up a 6 layer PCB stackup. Each of these layers has its functions. However, it is important to understand how these layers play a significant role in the functionality of this stackup.

Ground plane
The ground plane functions as a return path for current from various components on the circuit. It is a layer of copper foil that connects to the ground point of the circuit. This separate layer is so large that it covers the whole board. The ground plane allows the PCB manufacturer to ground components easily.

Power plane
This is a plane of copper that connects to a power supply. The power plane provides a supply of voltage to the circuit board. This layer is often seen in multilayer stackups since these stackups use an even number of layers. A power plane reduces the operating temperature of a board as it can handle more current.

Signal layers
These layers include the bottom layer, top layer, and inner layer. All these layers have electrical connections.

▶Bottom signal layer: This layer is primarily for soldering and wiring. For a multilayer board, manufacturers can place components.
▶Top signal layer: It is also referred to as thecomponent layer. This layer is used to arrange copper or wires.
▶Inner signal layer: This layer is connected to power and ground planes. It has electrical connections and consists of an entire piece of the copper film. The inner signal layer can only be seen in multilayer boards.

6 -layer PCB stack design rules

The rules of the 6 -layer PCB stack design are mainly based on the performance requirements of the circuit board, signal integrity, the layout of the power supply and the formation, and the shielding effect. The following are some key stack design rules:

1. The tight coupling between the formation and the signal layer: the distance between the formation and the power layer should be as small as possible, and the thickness of the medium should be as small as possible to increase the capacitance between the power layer and the power efficiency.

2. Isolation between the signal layer: Try not to be adjacent directly between the two signal layers to prevent signal stringing and ensure that the performance of the circuit is stable.

3. Use the internal electrical layer to block: For the multi -layer circuit board, the signal layer should be adjacent to a internal electric layer (formation or power layer) as much as possible. The role of effectively avoids the skewers between the signal layer.

4. The layout of the high -speed signal layer: The high -speed signal layer should generally be between the two internal electrical layers. Small interference to other signal layers.

5. Symmetry of layered structure: During the design process, the symmetry of layering structure needs to be considered, which helps ensure the stability and reliability of the circuit board.

6. Use multiple ground electrical layers: This can effectively reduce ground impedance and improve the performance of the circuit board.

7. The use of even layers: It is generally recommended to use the even layer of PCB to avoid the odd number layer, because the strange number layer circuit board is easy to bend.

Factors To Consider In The Design Of 6-Layer PCB Stack-Up

Several factors need to be considered while designing the 6-layered PCB stack-up:

Signal Integrity Considerations
The electrical signal transmission through PCB is the result of signal integrity. Thus, trace lengths are planned carefully to prevent signal delays and distortions. On the other hand, impedance matching involves designing traces and terminations to match the characteristic impedance of the transmission lines, minimizing signal reflections. Additionally, minimizing crosstalk between adjacent traces is essential to avoid interference and ensure signal integrity. The design can maintain the desired signal quality and prevent data errors or signal degradation by addressing these factors.

Power and Ground Plane Design
A PCB’s overall performance depends heavily on the design of the power and ground planes. Several advantages to power and ground plane distribution can be realized. Noise reduction is one of the benefits. The planes serve as a shield, shielding the circuitry from outside noise. Another crucial element is stable power distribution, which guarantees that each component receives a steady supply of clean power. This helps prevent voltage swings and potential issues. Moreover, careful attention must be given to the placement and routing of power and ground traces to minimize the loop area, which reduces electromagnetic interference and improves signal integrity. These considerations collectively contribute to the efficient and reliable operation of the PCB.

Impedance Control and Routing Guidelines
Impedance control and routing guidelines are essential for maintaining consistent signal characteristics and preventing signal degradation. These guidelines dictate trace widths, spacing, and layer stack-up to achieve desired impedance values. Adhering to these guidelines helps minimize reflections and signal distortion.

EMI/EMC Considerations
EMI/EMC considerations are crucial for minimizing electromagnetic interference and ensuring compliance with electromagnetic compatibility standards. Shielding techniques, proper grounding, and strategic component placement are key to reducing EMI/EMC issues and ensuring the PCB functions reliably in its intended environment.

Materials
Standard substrate materials or aluminum cores are used to make single-layer PCBs. However, for the multilayer stack-ups, it should be clear that the aluminum core PCBs are not available. This is because multilayer aluminum PCBs are challenging to manufacture.

Thermal Management Techniques
Thermal management techniques are vital to prevent overheating and ensure the longevity and reliability of the PCB. This involves incorporating heat sinks, thermal vias, and proper component placement to dissipate heat efficiently. Thermal simulations and calculations can help identify potential hotspots and guide the selection of suitable cooling strategies.

6 Layer PCB Fabrication

Edit the schematic diagram
The 6 layer PCB can feature two layers of the ground plane in the circuit board. This means that the manufacturer can separate the digital and analog grounds. Involve the signal’s minimum return path in EMI. Ensure you check for any errors after creating the schematic diagram.

Create a new PCB file
After the manufacturer has created a new PCB file, the schematic netlist can be imported into that file. The manufacturer then sets the layer structure and adds layers. The next thing is to add the power and ground layers. During a 6 layer PCB fabrication, you must couple the main ground layer and the power layer. This should be at a distance of 5 ml.

Layout
Layout is very important in the fabrication of a 6 layer PCB stackup. The primary principle of layout is to ensure good partition. Moreso, the partition of digital and analog devices can help to minimize interference. Digital signals generate large interference and a strong anti-interference.

You need to check out the components layout with various operating voltages. Ensure that devices having large voltage differences are far apart. In principle, the best configuration type features 3 power layers and 3 signal layers. The ground plane is the second and fifth layers. The third and fourth layers are power and inner signal layers.

Ground plane production
In a 6 layer PCB fabrication, there are two layers of ground. They are DGND and AGND. The DGND is placed on the fourth layer while the AGND is placed on the second layer. The manufacturer uses wires to lead out the pins of the ground and top components. Then you use the via hole to connect the pins to the corresponding network. Ensure you use a few pads during the connection process. This is because the pads will increase interference.

Power plane production
You need to divide the power layer. This is because the 6 layer PCB will not feature one working voltage value. Follow these procedures for segmentation during a 6 layer PCB fabrication;

●Figure out a voltage network
●Change to the inner power layer    
●Draw a closed graph using a line
●Use wires to lead out the pins of the ground and top layer
●Create connection to the inner power layer via the pad
●Design the next power network.


Routing
Ensure the ground layer and power layer are made well. After this, route the signal lines. Routing during a 6 layer PCB fabrication requires serious attention. The manufacturer should ensure that the vital high-speed signal line goes to the inner signal layer. The signal can also move on its ground layer.

For instance, if analog signals are mostly on the top layer, the second layer should be set to AGND. Furthermore, you need to adjust the component layout appropriately to enhance wiring. The routing method for the inner signal layer is wire-pad –inner electric layer.

DRC Inspection
This is an important step for a 6 layer PCB fabrication. DRC simply means design rule check. After the manufacturer has drawn the board, the inspection must take place. Carrying out a DRC helps to enhance the fabrication yields of a 6 layer PCB.