What is Multilayer PCB?

A multilayer PCB is defined as a PCB made of three or more layers of conductive copper foil. They look like layers of double-sided circuit boards, laminated and glued together, with multiple layers of insulation between them. The entire structure is arranged so that two layers are placed on the surface side of the PCB to connect to the environment. All electrical connections between layers are made through holes such as electroplated through holes, blind holes and buried holes. This method can then be applied to generate highly complex PCBS of different sizes.

Why are multilayer PCBS so widely used

Multilayer PCBS came into being in response to the ever-changing changes in the electronics industry. Over time, the functions of electronic devices have become increasingly complex, requiring more complex PCBS. Unfortunately, PCBS are limited by issues such as noise, stray capacitance, and crosstalk, so certain design constraints need to be followed. These design considerations made it difficult to obtain satisfactory performance from single-sided or even double-sided PCBS – hence the birth of multi-layer PCBS.

Encapsulating the power of double-layer PCBS into this format is only a fraction of the size, and multi-layer PCBS are becoming increasingly popular in electronics. They come in a variety of sizes and thicknesses to meet the needs of their extended applications, with variations ranging from 4 to 12 layers. The number of layers is usually even because odd layers can cause problems in the circuit, such as warping, and are not cost-effective to produce. Most applications require four to eight layers, but applications such as mobile devices and smartphones tend to use around 12 layers, while some specialist PCB manufacturers have the capacity to produce close to 100 layers. However, multi-layer PCBS with multiple layers are rare because they are extremely cost effective.

Why are multilayer PCBS so widely used

While multilayer PCBS tend to be more expensive and labor-intensive to produce, they are becoming an important part of modern technology. This is mainly due to the many benefits they offer, especially when compared with single – and double-decker varieties.

Benefits of multilayer PCBS

From a technical point of view, multi-layer PCBS have several advantages in design. These advantages of multilayer PCB include:

• Small size: One of the most prominent and acclaimed benefits of using multi-layer printed circuit boards is their size. Due to their layered design, multilayer PCBS are themselves smaller than other PCBS with similar functionality. This has brought huge benefits to modern electronics as the current trend is towards smaller, more compact but more powerful gadgets such as smartphones, laptops, tablets and wearables.

• Lightweight construction: Smaller PCBS are used for lighter weight, especially since multiple connectors required for interconnecting single – and double-layer PCBS are eliminated in favor of multi-layer designs. Again, this plays into the hands of modern electronics, which tend to be more mobile.

• High quality: These types of PCBS tend to be better than single-layer and double-layer PCBS due to the amount of work and planning that must be done when fabricating multi-layer PCBS. As a result, they are also more reliable.

• Improved durability: Multi-layer PCBS tend to last longer due to their nature. These multilayer PCBS must not only bear their own weight, but also be able to handle the heat and pressure used to glue them together. In addition to these factors, multilayer PCBS use multiple layers of insulation between circuit layers, combining them with prepreg adhesives and protective materials.

• Increased flexibility: While this does not apply to all multilayer PCB components, some do use flexible construction techniques, resulting in flexible multilayer PCBS. This may be ideal for applications where slight bending and bending can occur on a semi-regular basis. Again, this does not apply to all multilayer PCBS, and the more layers you add to a flexible PCB, the less flexible the PCB becomes.

• More powerful: Multilayer PCBS are extremely high-density components that combine multiple layers into a SINGLE PCB. These close distances make the boards more connected, and their inherent electrical properties allow them to achieve greater capacity and speed despite being smaller.

• Single connection point: Multi-layer PCBS are designed to be used as a single unit rather than in series with other PCB components. As a result, they have a single connection point, rather than the multiple connections required to use multiple single-layer PCBS. This turns out to be beneficial in electronic product design as well, since they only need to include a single connection point in the final product. This is especially useful for small electronics and gadgets designed to minimize size and weight.

These advantages make multilayer PCBS useful in a variety of applications, especially mobile devices and high-function electronics. In turn, as many industries move to mobile solutions, multi-layer PCBS are finding a place in a growing number of industry-specific applications.

Why are multilayer PCBS so widely used

Disadvantages of multilayer PCBS

Multi-layer PCB has many advantages and is suitable for various advanced technologies. However, these types of PCBS are not suitable for all applications. In fact, several disadvantages may outweigh the advantages of multilayer PCBS, especially for electronics with lower cost and complexity. These disadvantages include:

• Higher cost: Multi-layer PCBS are much more expensive than single-and double-layer PCBS at every stage of the manufacturing process. They are difficult to design and take a lot of time to solve any potential problems. They also require highly complex manufacturing processes to produce, which requires a lot of time and labor for assemblers. In addition, due to the nature of these PCBS, any errors made during manufacturing or assembly are extremely difficult to rework, resulting in additional labor costs or scrap charges. On top of that, the equipment used to produce multilayer PCBS is very expensive because it is still a relatively new technology. For all these reasons, unless small size is an absolute necessity for an application, a cheaper alternative may be a better choice.

• Complex production: Multi-layer PCBS are more difficult to produce than other PCB types, requiring more design time and careful manufacturing techniques. That’s because even small flaws in PCB design or manufacturing can make it ineffective.

• Limited availability: One of the biggest problems with multi-layer PCBS is the machines needed to produce them. Not all PCB manufacturers have the wherewithal or necessity for such a machine, so not all PCB manufacturers carry it. This limits the number of PCB manufacturers that can be used to produce multi-layer PCBS for customers. Therefore, it is advisable to inquire carefully about the PCB manufacturer’s capabilities in multi-layer PCBS before deciding on a PCB manufacturer as a contract manufacturer.

• Technical designer required: As mentioned earlier, multi-layer PCBS require a lot of design beforehand. Without previous experience, this can be problematic. Multilayer boards require interconnections between layers, but must simultaneously reduce crosstalk and impedance problems.A single problem in the design can result in a board that does not work properly.

• Production time: As complexity increases, so do manufacturing requirements. This plays a key role in the turnover of multi-layer PCBS – each board takes a lot of time to produce, resulting in more labor costs. In addition, it can lead to a longer time interval between placing an order and receiving the product, which can be problematic in some cases.

However, these problems have not disappeared from the utility of multi-layer PCBS. While they tend to cost more than single-layer PCBS, multi-layer PCBS have many advantages over this type of printed circuit board.

Advantages of multi-layer PCBS over single-layer alternatives

The advantages of multi-layer PCBS over single-layer alternatives become even more obvious. Some of the key improvements that multilayer PCBS provide include:

• Higher assembly density: While the density of single-layer PCBS is limited by their surface area, multi-layer PCBS multiply their density by layering. Despite the PCB’s smaller size, the increase in density enables greater functionality, increasing capacity and speed.

• Smaller size: Overall, multi-layer PCBS are smaller than single-layer PCBS. While single-layer PCBS must increase the surface area of the circuit by increasing the size, multi-layer PCBS increase the surface area by adding layers, thereby reducing the overall size. This allows higher-capacity multilayer PCBS to be used in smaller devices, whereas higher-capacity single-layer PCBS must be installed in larger products.

• Lighter weight: Component integration in multi-layer PCBS means less need for connectors and other components, providing a lightweight solution for complex electrical applications. Multi-layer PCBS can accomplish the same amount of work as multiple single-layer PCBS, but with a smaller size, fewer connected components, and reduced weight. This is an essential consideration for small electronic devices where weight is a concern.

• Enhanced design features: Overall, multi-layer PCBS can outperform average single-layer PCBS. By combining more controlled impedance characteristics, higher EMI shielding and overall improved design quality, multi-layer PCBS can achieve more, despite being smaller and lighter.

Why are multilayer PCBS so widely used

So, what do these factors mean when deciding on multilayer and single-layer structures? Essentially, if you want to produce small, lightweight and complex equipment where quality is critical, multi-layer PCBS may be your best choice. However, if size and weight are not major factors in product design, single – or double-layer PCB designs may be more cost-effective.