12 Layer PCB Stack-up Thickness Standards and Applications

 

Introduction

Printed Circuit Boards (PCBs) are the backbone of many contemporary electrical appliances we rely on daily. Complex printed circuit board (PCB) designs were created to meet the increasing demands of modern technology for smaller and more powerful electronic devices. These days, 12 Layer printed circuit boards are a standard feature of the sophisticated electrical circuits in today’s automobiles. Creating an integrated circuit board out of many layers is part of the design process for 12 Layer PCBs. This layer stack-up approach is desirable in today’s automotive applications since it allows designers to create efficient and compact designs. When designing electronic circuits for vehicles, 12 Layer PCBs can save you money while yet giving high-end features and durability.

Moreover, they’re exceptional since they can endure harsh environments and extreme temperatures. Polyimide, an organic substance with excellent heat-resistant qualities, is used primarily in their construction to withstand challenging conditions. Because of this, the PCB will continue to work correctly even when subjected to extreme temperatures.

12 Layer PCB
12 Layer PCB

 

 The best PCB makers frequently use gold as the surface finishing material for 12 Layer PCBs because of its excellent resistance to unfavorable environmental conditions. In some cases, heat sinks ensure the PCB continues functioning properly even when temperatures rise. As automobile technology improves, 12 Layer PCB stack-ups have become popular among PCB designers. They provide a stable basis for advanced automotive electrical circuits, allowing quick and efficient connections to withstand harsh environments, such as high temperatures.

These custom-printed circuit boards (PCBs) have several uses in the automobile industry. They are used in everything from navigation systems to transmission control units to electronic ignition assembly systems.

 

Key Components Used in 12 Layer PCB Stack-up

More complicated and efficient electronic designs have been possible because of the advent of the 12 Layer PCB stack-up, which has dramatically altered modern electronics. These complex printed circuit boards (PCBs) function on three main components: copper, prepreg, and substrate.

Copper

12 Layer printed circuit board (PCB) stack-ups often employ copper as their principal conductor. The high electrical conductivity of this material makes it perfect for transferring power and data throughout the board. The copper layer thickness is a significant factor in the overall performance of the PCB. High-power applications benefit from thicker copper layers because of their lower resistance and higher current-carrying capability. On the other hand, high-frequency circuits benefit from thinner copper layers, which reduce signal loss and impedance.

Prepreg 

Pre-impregnated (Prepreg) fiberglass is an essential insulating material. It is made out of a resin adhesive-impregnated fiberglass weave. Prepreg sheets are bonded together by resin during the PCB manufacturing process, which involves heating and pressing the sheets between two layers of copper. The PCB’s mechanical strength and electrical properties are directly affected by the prepreg material chosen. Dielectric characteristics, which influence signal speed and impedance regulation, differ between prepregs.

 Layer's Components
Layer’s Components

Substrate

The substrate material is the PCB stack’s foundation, providing structural support and electrical insulation for the whole 12 Layer PCB. Because of its high electrical conductivity and low dielectric constant, FR-4 (Flame Retardant 4) is frequently utilized as the substrate material. The FR-4 glass-reinforced epoxy laminate used for PCB substrates is extremely sturdy and reliable. This substrate material provides a firm base for the copper traces and components, keeping them in place despite mechanical disturbances.

Copper, prepreg, and substrate all work together to provide a sturdy and dependable 12 Layer PCB stack-up. The PCB’s fast data transfer rates, thermal stability, and impeccable signal integrity are all thanks to the components and how they were chosen and laid up.

 

12 Layer PCB Stack-Up

This complicated stack-up resembles a sandwich-like construction made up of three primary materials: substrate, prepreg and copper. The conducting copper layers are meticulously stacked in the stack-up, separated by prepreg layers. This stack is then baked and pressed at high temperatures to securely bond the layers, resulting in a robust and functioning PCB construction.

A PCB’s entire stack-up influences critical characteristics such as thickness, weight, and size. Manufacturers may develop 12 Layer PCBs that fulfill the unique needs of diverse electronic applications by carefully organizing the layers and selecting acceptable materials. It is a vital part of making multi-layer PCBs to measure precise material thickness. This stack-up approach is critical for economically constructing circuits on a single board with numerous layers.

Stack-Up Layers Arrangement

This complicated 12 Layers stack-up is methodically organized by layering the conducting and insulating layers of the printed circuit board to permit the complicated integration of electronic components. This critical step is carried out by expert engineers who take into account every circuit component to produce a highly functional and reliable board.

Internal Signal Layers 

The internal signal layers are at the heart of the 12 Layer PCB. These layers are principally in charge of supporting the intricate routing of traces, which are required for signal transmission between various components and areas of the circuit. The suitable layout of these internal signal layers guarantees little signal interference, and signals propagate efficiently across the board.

Power and Ground Planes

The power and ground planes are interspersed throughout the internal signal levels. These layers are critical components of a reliable and efficient power distribution system. The power planes provide electrical power to the components, while the ground planes serve as a point of reference for the electrical signals. The 12 Layer PCB delivers decreased noise and improved signal integrity by carefully positioning these power and ground planes.

Prepreg Layers

These layers, also called bonding layers, are used to connect the copper layers. These layers are made of resin-treated glass and act as insulators between neighboring copper layers. The prepreg layers ensure the necessary space between conductive lines, preventing electrical interference or short circuits.

Outer Signal Layers

The outer signal layers are the 12 Layer PCB’s outermost layers. These layers have a high density of surface-mounted components and connections. Designers may optimize the use of available board space by adequately arranging the components on these outer signal layers, allowing for greater functionality in tiny electronic systems.

Number of Layers

A typical 12 Layers PCB must include a minimum of 12 Layers of conductive copper to trace signals, six prepreg layers, and five core layers. The designers carefully select the number of Power layers and Ground layers throughout the design stage. The board’s isolation and electromagnetic compatibility (EMC) requirements determine the number of planes. EMC refers to the board’s capacity to work successfully in the presence of electromagnetic interference, preserving the circuit’s overall integrity and stability.

The main goal of creating a 12 Layer stack-up is to create a perfect environment for routing high-speed, high-frequency, and mixed signals. As electronic devices improve and require higher data transfer rates, this stack-up structure becomes increasingly important in maintaining signal integrity and minimizing signal interference.

 

Layers Thickness Standard

Meeting strict standards for monitoring heights and material thickness is essential during the 12 Layer stack-up phase of producing multi-layer Printed Circuit Boards (PCBs). Typically, a 12 Layer PCB will be 1.6 mm thick., and this is where the design starts to take shape. While this is the standard thickness for these PCBs, it is not a hard and fast rule. To meet the requirements of various circuits, there may be a need for a range of thicknesses. For example, the mechanical strength or isolation between layers of a PCB may benefit from using thicker materials.

Prepreg is the principal material used for the layout of 12 Layer PCBs. Composite material Prepreg is made from resin-treated glass. Its adaptability allows it to serve as bonding layers, cover gaps in foils, and provide a central core for outer layers. Copper foils of varying weights, often beginning at 0.5 ounces or more, are used while creating the outer layer of the PCB to ensure maximum performance.

It has been seen that a 1.6mm thick board is optimal for efficiently producing 12 Layer PCB boards throughout the manufacturing process. Interestingly, boards with as many as 16 layers are built on a foundation of the same thickness. The increasing prevalence of HDI boards reflects the dynamic nature of the electronic device market. The 12 Layer stack-up is an impressive feat in PCB technology, which always evolves to meet the growing need for smaller, higher-performing devices.

Let’s look at two alternative stack-up choices using materials of typical thicknesses to help you comprehend the conventional 12 Layer PCB stack-up. These defined thicknesses guarantee uniformity and dependability throughout the PCB manufacturing process.

12 Layer Stack-up 1.6mm 1 Oz PCB

In a multi-layer PCB, it is a complex and extremely efficient arrangement of layers. There are a total of 12 Layers within this stack, and they all work together to ensure that signals travel without interruption. The signal tracks are routed efficiently thanks to the layering structure, which consists of three Ground planes, Power planes, and six Signal layers.

The signal layers are positioned next to the plane layers, which is a notable aspect of this stack. Crosstalk is sometimes a concern in high-density PCB designs. However, this layout greatly enhances isolation between the signal layers. Signal quality and dependability can be enhanced by reducing crosstalk, which reduces the possibility of signal interference.

1.6mm 12 Layer Stack-up 
1.6mm 12 Layer Stack-up

 

In addition, there are neighboring ground and power planes at the tenth and eleventh levels (L10 and L11) of the stack-up. This setup is recommended for routing analog signals because it provides more isolation at the 12th layer (L12). An accurate and high-fidelity signal is sent since analog transmissions are not impacted by noise or interference because of the better isolation offered by the surrounding ground and power planes.

Moreover, this stack-up copper weight of 1 ounce (1 Oz) ensures sufficient conductivity and thermal performance. Copper is an excellent conductor for electrical signals and helps dissipate heat effectively, ensuring that the PCB remains within safe operating temperatures even under demanding conditions.

The 1.6 mm thickness of the stacked component provides a good compromise between robustness and compactness. Modern electrical devices benefit from this thickness since it allows for lightweight and compact designs without risking durability or reliability.

12 Layer Stack-up 2.0 mm 1 Oz PCB

This stack-up is a state-of-the-art arrangement with several advantages for cutting-edge electrical designs. Advantages to the printed circuit board’s overall performance and usefulness are realized by placing the Ground and Power planes close to each signal layer in this stack-up.

2.0 mm 12 Layer Stack-up
2.0 mm 12 Layer Stack-up

 

The decrease in voltage loss is a major benefit of this stack configuration. Electrical current has reduced resistance as it goes through the circuit board thanks to the placement of Ground and Power planes next to each signal layer. A constant and stable power supply is essential for the proper functioning of many devices and systems, and the minimized voltage drop ensures this.

Additionally, this stack-up layout aids in creating shorter current return pathways. A printed circuit board (PCB) needs a current return channel whenever electricity is being transmitted or received. Return pathways are optimized and minimized thanks to the Ground and Power planes’ proximity to the signal layers, which results in better signal integrity and less electromagnetic interference.

 

Advantages and Disadvantages 

Advantages 

With its intricate design and multiple layers12 Layer, PCB offers several advantages that cater to the demands of complex electronic devices. 

High Density

12 Layer PCBs can fit many components in a small space. This PCB type lets designers miniaturize electrical equipment without compromising functionality.

Better Signal Quality

High-speed electronic systems need signal integrity to transmit data without deterioration or interference. The 12 Layer PCB stack-up controls impedance and signal crosstalk, improving signal integrity and performance.

Better Power Distribution

12 Layer PCBs’ stack-up power and ground planes increase power distribution. This stabilizes power delivery to components, reducing voltage fluctuations and improving circuit efficiency.

EMI/RFI Mitigation

The multi-layer structure of a 12 Layer PCB reduces EMI and RFI. Separate ground planes and regulated signal routes reduce noise and improve electrical gadget functioning.

Multi-functional Capabilities

Complex electrical equipment generally needs several functions. 12 Layer PCBs enable multi-functional electronic systems by integrating circuits and subsystems.

Disadvantages 

While 12 Layer PCBs offer numerous advantages, there are some limitations and considerations that designers and manufacturers must keep in mind:

Cost

Complex 12 Layer PCBs cost extra to build. Specialized prepreg and heavier copper weights increase board costs.

Design Complexity

A 12 Layer PCB requires a complex design. PCB designers must assess signal paths, power planes, and ground planes to improve functioning.

Fabrication Challenges

They are more challenging to build than simpler boards. As layers increase, manufacturing and registration errors become more essential and may decrease output rates.

Compromised Signal Integrity

12 Layer PCBs improve signal integrity, but maintaining signal traces and managing impedance becomes more important as frequencies rise. To minimize signal degradation and timing issues, high-frequency designs must be meticulous.

Component Availability

Layers reduce component space, restricting design component options.

Troubleshooting

Internal signal traces complicate post-manufacturing changes.

 

Factors Affecting the Cost of 12 Layer PCB Stack-up

Quality of Materials and Size of Boards: 

Materials for specialized PCBs are expensive. Larger boards cost more because they take more time and materials to make.

The thickness of the Copper Layer:

 PCBs with a lot of power need bigger signal lines to keep the heat down. The budget could be affected by making the 12 conducting layers thicker.

Temperature Resistance

For high-temperature PCBs, the glass transition temperature has to be raised by changing the plastic, which makes the cost go up.

Holes

The price depends on how many and how big holes are needed for the design. Electroplating needs more holes and material that conducts electricity.

Specifications

Fabrication needs specialized equipment and skilled labor, which also increases the price.

Overall, these factors collectively determine the price of a 12 Layer PCB, considering both standard and unique specifications.

 

Applications of 12 Layer PCB Stackup

12 Layer printed circuit boards find wide applications in various industries due to their versatility and advanced capabilities. Some key areas where these PCBs prove to be highly valuable include: 

Consumer Electronics 

They integrate complicated functions into compact and stylish consumer electronics, including smartphones, tablets, household appliances, and entertainment systems.

Computer Electronics

12 Layer PCBs power high-performance desktops, servers, and data centers. These PCBs enhance data transmission, signal interference, and heat control.

Telecoms 

12 Layer PCBs are essential to the telecoms industry’s need for quicker and more reliable communication networks. Routers, switches, base stations, and other important communications infrastructures run smoothly using these PCBs.

Medical technologies

12 Layer PCBs help produce medical imaging, patient monitoring, and life-saving technologies. Medical PCBs offer precision and dependability.

Aerospace and Military

12 Layer PCBs help build sturdy and efficient aerospace and military equipment. These rugged PCBs work well in avionics, satellite communication, and military electronics.

More and more sectors are looking for methods to use limited space better without compromising performance or durability. Because of its versatility, 12 Layer PCBs are essential in the creation of cutting-edge electronic solutions.

 

Fabrication Process 

The manufacturing process involves several crucial steps, ensuring a reliable and efficient final product.

Finalizing Stack-up design and layout

The designer determines the material thickness and arranges ground, signal layers, and Power planes to create stack-up. After this, the board layout is finalized.

Making Phototools

 Each layer of the PCB is converted into films called photo tools using a UV plotter, representing individual negatives.

Printing Inner Copper Layers

 Phototools are printed onto pre-coated copper laminates, and a UV-hardened photoresistive material is applied.

Copper Layers Etching

The soft copper is etched away, and then it’s washed away under high pressure.

Inspection of the board and drilling Holes

Internal layer inspection is crucial since changes are not possible after layer binding. Drilling vias and holes is done after inspection.

Binding all Layers

PCBs are made by stacking, pressing, and baking layers of molten prepregs to bond together cores and copper layers.

Vias and Holes Drilling

External hole drilling is performed after layer binding.

Inner Layers Electroplating

For conductivity, the final stack is electroplated to set conducting material on the walls of the drilled holes.

Preparing Outer Layer

The exact process is repeated for the outer and inner layers.

Applying Solder Mask

Non-conducting liquid resin (solder mask) prevents shorts among signal traces.

Silk Screening

Relevant information is printed on the PCB through silk screening.

Testing

The final 12 Layer PCB is tested against the actual layout file to ensure functionality.

 

Conclusion

In conclusion, the 12 layer Printed Circuit Board (PCB) stack-up has revolutionized modern electronics, providing a stable foundation for intricate electronic designs. These advanced PCBs offer numerous advantages, making them highly valuable in various industries. They enable high-density integration, better signal quality, improved power distribution, and reduced electromagnetic interference, among other benefits.

The fabrication process of 12 Layer PCBs involves several crucial steps, ensuring a reliable and efficient final product. The selection of materials, thickness, and arrangement of layers plays a crucial role in the performance of the PCB. Copper, prepreg, and substrate work together to create a sturdy and dependable PCB stack-up.

It is important to note that while 12 Layer PCBs offer significant advantages, they also come with certain challenges. Complex design, increased fabrication costs, and potential signal integrity issues at higher frequencies are some considerations for designers and manufacturers.

The versatility and advanced capabilities of 12 Layer PCBs make them invaluable in various applications, ranging from consumer electronics to aerospace and military equipment. As technology continues to advance, the demand for efficient, compact, and high-performance electronic solutions will only grow, making the 12 Layer PCB stack-up an essential component in meeting these demands.

To ensure the quality and reliability of 12 Layer PCBs, adherence to essential quality certifications, such as CE, UL, RoHS, ISO, and IATF, is crucial. These certifications guarantee safety, environmental compliance, and adherence to international quality management standards.               Overall, the 12 Layer PCB stack-up represents a significant advancement in modern electronics, providing a solid foundation for complex and high-performance electronic devices. As the world of electronics continues to evolve, the 12 Layer PCB will play a critical role in shaping the future of technology.

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