Traditional single-sided Printed Circuit Boards (PCBs) cannot meet the needs of increasing assembly density requirements as they have reached a functional limit of available space. Double-sided printed PCBs are also subject to the same physical constraints.

Multilayer PCBs have been developed to address these space issues. Multilayer PCBs are used in a range of professional electronic products ranging from everyday computers to complex military equipment. Multilayer PCBs are especially useful in circuits designed for high speed use. They provide benefits in reduction of the risk of overloading based on weight or volume, and provide additional space for conductor patterns and power.

Multilayer PCBs are now widely used in a broad range of electronic devices. They have become a crucial part of electrical components as they offer many advantages. Some of these include flexibility, reliability, small size, high assembly density, the use of shielding layers for electronic and magnetic circuits. They provide a useful tool for high-speed transmission requirements. Once they have been produced and tested, they are relatively simple to handle and install.

In terms of configuration, multilayer PCBs are made up of two (or more) ‘traditional’ PCBs that are stacked together. They are connected with pre-defined mutual connections. A single multilayer PCB will have at least here conductive layers. These are the two ‘outside’ layers, and at least one layer that has been synthesized in the insulation board.

The development of multilayer PCBS generates problems that aren’t relevant to single- or double- sided PCBs. These included stray capacitance, crosstalk and noise. The design of multilayer PCBs must take these factors into account. Development processes include avoiding parallel routing and minimizing the length of the signal line. When multilayer PCBs are designed with an understanding of the risks of noise, capacitance and crosstalk, and manufactured using state-of-the art equipment, close-tolerance PCBs can be manufactured with a range of layers to meet various specifications. Some boards can be built with up to16 layers, while if required, the process can be used to design and manufacture boards with up to 28 layers, with a maximum thickness of 3.2mm. As the technology used to design and manufacture multilayer PCBs continues to improve, they will become commonplace in many fields of use.

The specifications for producing multilayer PCBs are no different to those of single layer. They can be produced on all recognized PCB industry surfaces, and can use high frequency base materials for applications up to 80 GHz.

Cost is a factor that needs to be considered when designing multilayer PCBs. The manufacturing process is more complex and the production runs are shorter. There is also a longer production cycle, and more issues associated with testing. Traditional testing methods using on single layer PCBs are significantly more challenging when testing multilayer PCBs. As a result, the cost of multilayer PCBs will be proportionally higher than the cost of traditional PCBs.