How To Make MultiLayer PCB?
Multilayer PCB is PCBs with an unlimited number of conducting layers separated by insulating layers. Multilayers are usually made up on the inside of double-sided boards. while the outer layers consist of single-sided boards. Prepregs are laminates with no conducting layer which are also used as insulators. Heat and pressure are used to bond each layer to form a multilayer board. 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 plated through holes, blind and buried vias.
A single or double layer PCB cannot be classified as a multilayer PCB. However, any PCB with the number of layers greater than two is considered as a multilayer PCB (4, 6, 8,…-layer PCB). There are various reasons that make PCB Designers move to a multilayer PCB. The major reason could be thought of as, to improve the ease of routing capability and most importantly, to improve the electromagnetic compatibility.
It stack-up must be made in such a way that, the complete board shall meet the electrical signal and power needs and also meet the mechanical strength requirements. Most professional PCB designs are able to exhibit around 15dB fewer emissions.
When making a multilayer PCB, you must plan about the configuration of your PCB stack-up. Wrong PCB configuration may give rise to undesired electromagnetic interference and poor signal integrity. Below are some of the important things to consider about signal when making a multilayer PCB design.
- Consider the type of signals to be routed e.g. different signal frequencies
- Consider the signal rise and fall
- Sufficient return for the signal loop
Likely signal delay caused by permittivity - Possible cross-connection and overlap