The Pros and Cons of Multilayer PCBs

Smaller and lighter printed circuit boards (PCBs) are becoming increasingly popular within the PCB industry. The old, rigid, and thick PCBs that many are used to are becoming increasingly obsolete with regard to current applications. The electronic devices that so many people rely on every day are becoming smaller and lighter. Smartphones, laptops, and many more devices are being built with portability in mind, and PCB manufacturers must respond to this trend in order to survive.

Thankfully, PCB designers are beginning to meet these new demands with multilayer PCBs. Multilayer boards can pack the same amount of power into a PCB that’s half the size of the original or traditional double-sided printed circuit boards. Multilayer PCBs are popping up more and more within the electronic devices that people use every day.

Many PCB manufacturers are currently deciding whether or not to incorporate multilayer PCB capabilities into their PCB manufacturing process. By doing so, although implementing such technology can be both costly and time-consuming, a manufacture will undoubtedly become positioned on the cutting edge of this industry. But before you make the decision, there are several things that are useful to know about multilayer PCBs.

How Multilayer PCBs Are Manufactured

Take a normal PCB, and simply fold it in half. You now have, essentially, the framework behind a multilayer PCB. Of course, the process is much more complicated than that. The most advanced multilayer PCBs are the same size as conventional PCBs, even when “folded.” They can even be made out of flexible materials, resulting in a truly ground breaking product. To design a multilayer PCB, special attention is required during the manufacturing process.

To design a multilayer PCB, special attention is required during the manufacturing process. The layers of the PCB must be intricately arranged so that they fit perfectly with one another; no air can be left in between the layers. Next, layers of prepreg and other special adhesives must be added to the entire surface of the PCB in order to ensure isolation of the internal layers of circuitry. Finally, a special lamination process using heat and pressure will bond the layers together into a single solid PCB.

How Multilayered PCBs Are Designed

Obviously, designing a multilayer PCB is no easy task. Designers must be specially trained regarding the intricacies of this technology. Frequently, trial and error is the best way to find the perfect design, although there are two basic things to remember when designing a multilayer PCB.

First, special attention must be undertaken for aligning through-holes from layer to layer. Due to the fact that through-holes may be designed to connect only specific layers (as in blind or buried vias), or connect all layers from top to bottom, alignment accuracy is critical. Second, multilayer PCBs are more susceptible to heat and pressure than conventional PCBs. If components are not properly aligned, some layers could twist or bow, which could potentially harm the other layers as well.

Advantages of Utilizing Multilayer PCBs

There are numerous advantages to utilizing multilayer PCBs in your design. The most obvious of which is the size of the PCB. Because of their design, multilayer PCBs are inherently smaller than traditional PCBs.

Additionally, multilayer PCBs generally provide better quality than normal PCBs. Their cost is higher, however, because more design work, financial investment, and time go into their development and manufacturing. Because they have to be able to withstand their own weight and handle the heat and pressure used to bond them together, PCBs must be covered with layers prepreg and other protective materials, increasing both their cost and their durability.

Finally, multilayer PCBs are each designed to become one single unit. This means that they are easier to mount in a final product and usually have only one main connection point, neither of which is true with regard to separate, single layer PCBs. This makes multilayer PCBs invaluable for small electronics.

Disadvantages of Utilizing Multilayer PCBs

Perhaps not surprisingly, multilayer PCBs aren’t fit for all electronics and have some significant drawbacks. First, there is their cost. Multilayer PCBs cost more at every stage, from design through manufacturing and depaneling. Unless smaller size is absolutely necessary, there may be cheaper alternatives available.

Additionally, multilayer PCBs are the result of new technology, so the equipment required to produce them is still relatively expensive. Furthermore, producing multilayer PCBs takes much longer than a traditional single or double layer PCB, which also adds to the cost of the final product.

Finally, if problems arise during the manufacturing process, fixing multilayer PCBs is exponentially more difficult than fixing a traditional PCB because any possible flaws may be buried in internal layers. Consequently, small flaws in the manufacturing process that are normally fixable could render a multilayer PCB useless. In combination with the increased cost of production, this can create a potentially high cost for reworking.

Are Multilayer PCBs Right for You?

Multilayer PCBs are still a growing application in the PCB industry and many of their drawbacks are a result of this fact. If you’re debating on whether or not to implement multilayer PCBs into your manufacturing process, you need to properly weigh the pros and cons.

While they may be perfect for high-end electronics, the present level of demand isn’t nearly as high as it’s expected to be in the future. Therefore, it may take some time for the specialized manufacturing equipment to pay for itself. However, by building your multilayer capability now, you can be better ready for the increased demand when the use of multilayer PCBs inevitably becomes more widespread.


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