Role of filled vias in power distribution on PCBs
A key function of a PCB is power distribution. This is done by a combination of copper areas known as planes and vias, which provide low-impedance paths for power transfer between components on the board. Vias are conductive pathways that route power from the source to each component, and they’re often filled with either copper or non-conductive epoxy. The type of via filling you choose has a significant impact on the quality of your PCB, as well as its cost. This is why we encourage you to understand the different types of via filling and their role in power distribution on your circuit board.
There are several reasons why you may want to have your via holes filled with a conductive material. For example, filled vias can reduce the likelihood of air or liquid entrapment in the via during the reflow soldering process. They also improve the integrity of a via hole and help ensure a high yield through assembly.
Conductive via filling involves multiple steps that can increase manufacturing time. These include activation, electroless copper deposition, a time-consuming electroplating process, and chemical mechanical polishing. In contrast, non-conductive via plugging processes are much simpler and can be completed in a shorter amount of time.
Another benefit of a filled via is that it can offer structural support for the copper pad (in the case of a via-in-pad design). This helps prevent excess solder from wicking away from the pad and down into the through hole during the Reflow Soldering stage of the PCB manufacturing process.
Can you explain the role of filled vias in power distribution on PCBs?
Finally, filled vias can improve the thermal conductivity of a through-hole. The copper in the filled via wicks heat away from hot components, which can lengthen a PCB’s lifespan and prevent defects caused by overheating.
The primary purpose of a buried via is to establish low-impedance connections between the different layers in the PCB. They can be filled with conductive epoxy, a conductive powder or paste, or they can even be electroplated.
Buried vias are typically created using sequential lamination, where a fabricator drills from one intermediate layer to the next. As a result, they’re not visible in a finished PCB. This makes them more difficult to fabricate than other types of interconnects.
A buried via’s most significant advantage is its ability to deliver power with little impedance between adjacent layers of the circuit board. However, it’s important to note that a buried via is not suitable for all applications. Whether you’ll require a buried via depends on the electrical and thermal requirements of your project. You should always consult with your circuit board manufacturer to determine if a buried via is appropriate for your design.
This process is called a mask plugged via (MPV) or a Non-conductive Fill Via and is a good choice for vias that will be placed near the edge of a BGA device where solder wicking could occur. The MPV can be filled with a variety of materials, but it is typically designed to prevent solder wicking from the IC pad and into the hole.