The specific applications listed above represent only a fraction of multilayer PCBs applied throughout the industry. But why are they used so widely?  PCB factory china tells you the reasons.

Much of the favoritism toward multilayer PCBs lies in industry trends. With electronics progressing ever toward miniaturization yet multi-functional options, the internal components of those electronics must follow the same trend. While single and double-sided PCBs have proven limited in their ability to balance size and functionality, multilayer PCBs provide a comprehensive solution.

While there are several drawbacks to using multilayer PCBs over single and double-layer options, such as increased costs, design times and production inputs, these costs are becoming more accepted in today's world. Functionality is largely favored over cost, and people are willing to pay more for high capacity electronics. Additionally, as the technology becomes increasingly mainstream, production techniques and machinery will eventually become less expensive, especially as new techniques arrive in the industry.