Vias on Multilayer Printed Circuit Board
Multilayer PCBs are designed to accommodate complex circuits. There are many techniques for designing complex circuits. However, complicated circuits are always accompanied by difficulties in connection between components. One useful technology to solve this problem is to add vias when designing PCB boards.
Three types of vias are used in the PCB design. A buried via, like its name, electrically connect internal layers of a PCB. The blind hole is electrically connected to any inner layer through the top or bottom but does not pass through all layers of the PCB.
In order to electrically connect the top and bottom layer through internal layers, another type of via are added to the PCB. These via are called plated through hole or bare hole. The holes will be plated to the desired location in the PCB and then metallized with copper. This electrically connects all PCB layers. This is not only one function of the plated through holes. Plated through-hole also serves as a connection for a component to a plane or signal plane. Furthermore, In addition, plated through holes reduce track and jumper strain and can convert dense circuitry in small PCBs. As a result, these bare holes ultimately eliminate defects in the PCB. Further, their addition to the PCB doesn’t effect PCB cost as they only need drill or laser which is relatively cheaper.
When designing and adding plated through holes, consider the following points:
a.Make sure that the pad of the plated through hole is large enough so that the hole is easy to plate copper. It should be greater than 5 mils.
b.Make sure the hole meets the requirements of the insulated PCB.
c.The dimensions for the electroplated holes are 3 mils and 1.5 mils per side.
EPCB hopes this article is useful for your next multilayer PCB design.