There are several kinds of multilayer PCBs that are used in different applications. Here are some common types:

Standard Multilayer PCB: This is the most basic type of multilayer PCB, typically consisting of four to eight layers. It is widely used in general electronic devices and applications where moderate complexity and density are required.

High-Density Interconnect (HDI) PCB: HDI PCBs are designed to provide higher component density and finer traces than standard multilayer PCBs. They often have microvias, which are very small diameter vias that allow for more interconnections in a smaller space. HDI PCBs are commonly used in smartphones, tablets, and other compact electronic devices.

Flex and Rigid-Flex PCB: These types of multilayer PCBs combine flexible and rigid sections into a single board. Flex PCBs use flexible materials like polyimide, while rigid-flex PCBs incorporate both flexible and rigid sections. They are used in applications where the PCB needs to bend or conform to a specific shape, such as in wearable devices, medical equipment, and aerospace systems.

Sequential Lamination PCB: In sequential lamination PCBs, the layers are laminated together in separate groups, allowing for a higher number of layers. This technique is used when a large number of layers, such as 10 or more, are required for complex designs.

Metal Core PCB: Metal Core PCBs have a layer of metal, usually aluminum or copper, as the core layer. The metal core provides better heat dissipation, making them suitable for applications that generate a significant amount of heat, such as high-power LED lighting, automotive lighting, and power electronics.

RF/Microwave PCB: RF (Radio Frequency) and microwave PCBs are designed specifically for high-frequency applications. They use specialized materials and manufacturing techniques to minimize signal loss, impedance mismatch, and electromagnetic interference. RF/Microwave PCBs are commonly used in wireless communication systems, radar systems, and satellite communications.