Advantages and disadvantages of multilayer printed circuit boards

multilayer printed circuit boards

Printed circuit boards (PCBs) are the core of most electronics today, determining basic functions through combinations of components and wiring mechanisms. Most PCBs of the past were relatively simple and limited by manufacturing techniques, while today’s PCBs are much more complex. From advanced flexible options to odd-shaped varieties, PCBs are much more varied in nowadays’ world of electronics. Of particular popularity, however, are multilayered PCBs.

Read on to learn more about multilayer PCBs, their advantages and disadvantages in the world of modern electronics.

What Is a Multilayer PCB?

The definition of multilayer PCB is a PCB that is made with three or more conductive copper foil layers. These appear as several layers of double-sided circuit boards, laminated and glued together with layers of heat-protective insulation between them. The entire construction is arranged so that two layers are placed on the surface sides of the PCB to connect to the environment. All electrical connections between the layers are achieved with vias such as plating through holes, blind and buried vias. Application of this method then leads to the generation of highly complex PCBs of varying sizes.

Advantages of Multilayer PCBs

Most PCB manufacturers are finding the demand for multilayer boards increasing by leaps and bounds. This growing demand is fed by the need for smaller, lighter boards for use in electrical devices, military equipment, healthcare miniaturization, and an expanding market for smart devices incorporated in home automation systems.

Smartphones and computers are perfect applications for multilayer PCBs with their need for compactness and light weight, yet sophisticated functionality.

From a technical standpoint, there are numerous advantages to the use of multilayer designs, over and above saving space and weight:

1. By incorporating multiple layers in a single PCB, boards can increase functionality.

2. Manufacturing processes for multilayer boards result in high-quality, reliable end products.

3. Multilayer boards by their innate electrical properties provide high capacity and high speed in a smaller footprint.

4. Higher density of assembly

5. Connectors required for multiple separate PCBs are reduced or eliminated, simplifying construction and further reducing weight.

6. Multilayer PCBs can be manufactured in both rigid and flexible construction. Be advised though, that the more layers incorporated in a flex PCB, the less flexible it becomes.

Advantages and disadvantages of multilayer printed circuit boards

Disadvantages of Multilayer PCBs

Every technology has pros and cons, and multilayer PCBs are not immune from negative attributes:

1. Cost – one of the primary negatives in designing and implementing multilayer PCBs is the cost. As specialized processes are involved in the manufacturing of these boards, there is a considerable investment required for fabricators to offer these services. This makes the cost of multilayer boards higher than a traditional single or double-sided board.

2. Service availability – not all PCB manufacturers have made the commitment to manufacturing these complex boards, limiting the resource options available to PCB designers.

3. Compactness of multilayer boards generates design concerns for such issues as crosstalk and impedance problems.

4. With increased functionality comes the need for more extensive testing of a single PCB. Manufacturing cycles may also be longer, due to the very complexity of the manufacturing process.

5. Repairing a multilayer PCB can be extremely difficult, and may even be unfeasible or impossible. This makes failure of a multilayer board costly, since it may need to be totally replaced.

6. Interconnection between layers is critical for board function, making design and fabrication of microvias and overall density critical.

Overall, multi-layer circuit boards are often better quality than regular PCBs, as more designing, planning, and investment is put into the development of these types of boards. Although the cost can be higher, it more than makes up for the price in terms of functionality and performance. These boards are generally designed to be one single unit which makes mounting the board onto the final product much easier.