24 layer pcb

24 Layer PCB – Stackup, Fabrication Challenges, and Advantages

Multilayer boards have continued to be a game-changer in the electronics industry. Since the advent of this PCB, more complex and compact electronics have been designed. The majority of today’s electronic devices incorporate multilayer PCBs. In this article, we will be discussing a 24 layer PCB.

What is a 24 Layer PCB?

A 24 layer PCB is an advanced type of multilayer board with 24 copper layers. This PCB comprises signal layers, ground plans, and power planes. Also, this PCB consists of silkscreen, soldermask, and more.  A 24 layer PCB is about 5mm thick. Due to the higher number of layers in it, it provides dimensional stability.

The manufacturer effectively arranges the ground layers and signal layers. This helps to ensure the PCB is compatible with HDI applications. These applications are high-density interconnects. The materials used in a 24 layer PCB ensure a low dielectric constant. Also, the dielectric materials used in this advanced multilayer board are thin. Therefore, this helps to create a tight coupling between layers.

Materials used for 24 Layer PCB

The 24 layer PCB comprises different materials in its fabrication. It features materials like copper foils, FR4, CEM3, and epoxy resins. In this PCB, the manufacturer presses and bonds copper foil and fiberglass resin materials. FR4 is a PCB material that provides enough rigidity in electronic products. It offers adequate glass transition temperature.

Also, this material offers excellent resistance to moisture. This implies that PCBs that incorporate FR4 can withstand high temperatures. Also, this material allows proper dielectric strength.

Silkscreen, FR4, and solder mask are the base materials for 24 layer PCBs. High transition glass temperature is an important feature of 24 layer PCBs.

Other materials used for 24 layer PCB fabrication include copper foil and prepregs. A 24 layer PCB can feature different copper thicknesses. The copper thickness and number of layers help it to conduct high current loads.

 

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What is a 24 Layer PCB Stackup?

A 24 layer PCB stackup is the arrangement of layers on the circuit board. In multilayer PCBs, there are several ways of arranging copper layers on a board. Manufacturers consider some important factors before arranging a multilayer stackup.

In a 24 layer stackup, there are routing layers, ground planes, and power planes. The routing layers can be the top, middle, or bottom layers. The ground planes and power planes are very crucial in this stackup.

The routing layers create interconnections between the components. Manufacturers can place a routing layer on the bottom, top, or middle layers. This depends on the application requirements of the board. Signal routing is a crucial part of multilayer boards. The stackup configuration of a 24 layer PCB determines its functionality. A well-arranged stackup will ensure signal routing in PCBs.

24 Layer PCB Manufacturing

The manufacturing of 24 layer PCB involves certain processes. Since this PCB features more than ten layers of conductive material, its fabrication is complex. Manufacturers laminate layers of core and prepreg under high pressure and temperature.

In this process, manufacturers ensure that air isn’t trapped between the PCB layers. They also ensure the adhesive holding the layers melts properly. A 24 layer PCB incorporates a wide range of materials. Core and prepreg are similar materials. However, prepreg is more malleable than core. This is because it isn’t completely cured.

When manufacturers apply high temperatures to the stackup, the prepreg will melt. Then the layers join together. After it cools off, the result is a solid 24 layer board. Manufacturers apply soldermasks to multilayer boards. The function of the solder mask is to prevent traces from shorting.

The inner layers of the multilayer boards comprise core material of glass fiber and epoxy resin. The prepreg laminates the layers together.  Manufacturers stack the inner layers together to ensure layer alignment.

The manufacturing process of a 24 layer PCB is outlined below:

  • Inner layer imaging and etching
  • Lamination of inner layers
  • Drilling the board
  • Outer layer imaging
  • Plating and etching
  • Outer layer etching and stripping
  • Solder masking
  • Screen printing
  • Testing

Advantages of 24 Layer PCB

This PCB helps to enhance the functionality of electronic devices. A 24 layer board features great advantages needed for your projects. Some of these advantages are:

Compact design

A 24 layer PCB supports compact designs. This PCB features ground and signal layers placed on one another. This board is ideal for smaller devices like laptops, mobile phones. Electronic devices are becoming smaller in size, yet complex. A 24 layer PCB is ideal for complex and miniature devices.

Ideal for varying temperature

A 24 layer PCB can work under varying temperatures. This PCB is specifically designed to function in different temperatures. A 24 layer board is ideal for use in high-performance and high-end applications.

High current conduction

Another important benefit of this PCB is the ability to carry high current loads. This PCB features different copper thicknesses. It can tolerate high electrical forces.

High functionality

A 24 layer PCB is very functional. Due to this, it is widely used in high-density interconnect and high-power projects. Also, this PCB enhances efficiency in high-speed projects.

 

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Fabrication Challenges of a 24 Layer PCB

There are certain problems commonly associated with the fabrication of a 24 layer board. This PCB comprises thinner dielectric layers and thicker layers. Therefore, there are some problems faced by manufacturers during fabrication. Some of these problems are:

Drilling

This is a problem manufacturers deal with during the fabrication process. Boards with a higher number of layers are more difficult to drill.

Layer alignment

It is important to ensure layer alignment in multilayer PCBs. However, this can be very challenging. The alignment tolerance of the external layer is less than that of the internal layers.

Layer coupling and pressing

Pressing difficulties increase as the inner layers of a PCB increase. This makes layer coupling quite challenging. It is advisable manufacturers consider thermal resistance. The arrangement of layers on a 24 layer PCB requires special attention.

Conclusion

Multilayer boards support thousands of components. Also, this board features tens of thousands of vias and tracks on them. A 24 layer PCB is a reliable solution that enhances the quality of high-end applications.

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