Interesting Facts about Multilayer PCBs

Interesting Facts about Multilayer PCBs

The development and implementation of multilayered PCBs is driven by necessity and increasing demand for miniature devices. Although PCBs have been used since decades in electronic devices; most of them were single or double layered with drawbacks such as noise and capacitance. Also, with the increasingly complex and miniature devices being designed and in demand nowadays, PCBs have also become smaller and layered to be fitted in any size and shape. Hence, multilayered PCBs were developed. Normally you can find four to 10 layered PCBs in many electronic gadgets such as smartphones. But the number of layers can go up to even 100 in certain complex devices and advanced circuits; however, this is not a very common feature. This post discusses some of the factors one should consider when deciding on the number of layers of PCBs and the benefits of multilayered PCBs.

What is a Multilayer PCB?

Single layer PCBs are still used in simple devices. This comprises only a single layer of conductive material. Two-layer and three-layer PCBs are just as common. While these PCBs obviously have two and three layers, they also offer a better surface area much larger than that of a single-layer PCB. However, a multilayer PCB has to have at least three layers of conductor material. These materials can range from ceramic, glass, and aluminum to Teflon and FR4, usually with a copper foil. A multi-layer PCB manufacturer usually has a combination of single-sided and double-sided rigid PCBs. They are made of alternately arranged layers of prepreg and core materials. These are laminated air tight under high pressure and temperature. A melted and cured adhesive or a thin coating of it surrounds these layers for protection against the external environment and probable damages.

There is not much difference between prepreg and core materials except that core is cured, while prepreg materials are malleable and can be easily formed into sheets. When these materials are exposed to high temperatures, they melt and thus the layers are fused. They solidify once cooled.

Here is a representation of a multilayer PCB:

Copper foil
Prepreg materials
Copper foil
Core materials
Copper foil
Prepreg materials
Copper foil

Factors to Consider When Choosing the Number of PCB Layers

Here are some factors which may help you decide on the number of layers depending upon the complexity and size of the device:
  • Most commonly used are 4-, 8-, 6-, and 12-layer PCBs. These are used in computers, smartphones, industrial control systems, medical devices, GPS systems, and more.
  • If you are looking for high processing speed and need to fit the PCBs in a slim pocket-size device, consider going for at least 4 layers or 6-layer PCB depending on the circuitry required.
  • You can choose a single layer PCB if you are an enthusiast or a student and want to make a circuit at home.
  • Usually, six to eight layers are suitable for personal computers.
  • 10 to 12 layers are generally suitable for industrial systems.
  • Consider the size and scale of circuit boards and the electromagnetic compatibility required when considering the structure of the PCB.
  • Determine the type and density of wiring, sensitive signals, and the type of power supply.
  • Finalize this before going ahead with the stack up as it will help you decide the position of the circuit of each layer.

Benefits of Multi-layere PCBs

There are many benefits of using multilayered PCBs for specific applications. Here are some of them:

  • These PCBs are small, compact, and lightweight, a feature which modern electronics devices demand.
  • They are durable and insulated with protective materials in between each circuit layer.
  • These PCBs are powerful and are suited for high-density assemblies, which are well connected with good electrical properties.
  • They are designed to function as a single unit, and hence can be work with a single connection point.
  • They have better impedance control features.
  • They offer increased flexibility in case of most devices.

Applications of Multi-layer PCBs

As mentioned, multilayer PCBs are especially useful for small and high-end devices. They find applications in the following areas:

  • Computers
  • Cell phone towers
  • GPS systems
  • Satellite systems
  • Fire alarm systems
  • Wearable devices
  • Handheld electronic devices
  • Industrial monitoring and control systems
  • X-ray systems
  • Heart monitoring systems

Are you looking for end-to-end PCB solutions for your applications? In case you manufacture electronic or electromechanical devices, you would require multi-layer PCB manufacturer . Ensure you approach reliable multi-layer PCB manufacturers for the same. Twisted Traces is a well-known manufacturer and assembler of various types of PCBs, which are RoHS compliant. They have a market presence of over 30 years.

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