Electrical Properties of Microvias on PCBs

Properties of Microvias on PCBs

Vias are the tiny conductive pathways that establish electrical connections between different layers on PCBs. They help improve the electrical performance of a circuit by reducing parasitic capacitance and EMI, enabling a thinner construction with more layers or higher routing density. They also enable improved signal integrity and impedance control.

The use of microvias pcb increases the surface area on a PCB to accommodate more components without increasing the overall board size, making it possible to design smaller and lighter electronic devices that have greater processing power than their predecessors. This is particularly important as the evolution of electronic products continues to follow Moore’s law trajectories.

Typically, PCB manufacturers drill holes on the printed circuit boards to connect components and conductors from one layer of the PCB to another. These holes are called vias and come in a variety of shapes, sizes, and patterns for various purposes. A via can be blind, buried, or a combination of both and can be filled with epoxy resin, non-conductive material, or electroplated copper. The fill material is what distinguishes a microvia from a regular hole, as it replaces the air that would otherwise hinder the ability of the via to conduct heat and signals.

A microvia is a type of via that has a high aspect ratio, which refers to the narrowness of the hole in proportion to its diameter. This is an important feature when comparing a microvia to a regular via because the narrower and taller structure can reduce crosstalk and electromagnetic interference. In addition, a microvia can reduce the amount of copper needed to connect a track to a ground or power plane due to the smaller width and height.

Electrical Properties of Microvias on PCBs

While mechanical drilling is a common way to create vias, laser ablation is increasingly being used due to its speed and accuracy. The process uses a laser beam to cut through the dielectric materials on the PCB, creating small holes that are perfect for microvias. It is faster and more accurate than traditional methods, resulting in a higher quality of end product.

There are many types of microvias, but the most important characteristics are its size and placement. The size of a microvia can be determined by adding the widths of two annular ring and the required microvia fabrication allowance to the as-formed diameter of the via. It can then be compared with the target pad and capture pad diameters of the circuit to determine if it meets requirements.

In order for a via to be considered a microvia, it must have an aspect ratio lower than 10:1. A higher aspect ratio can cause problems with plating the hole because it is harder to plate a small area.

Once the vias have been drilled, they are filled with either epoxy or pure copper to allow for electrical connections. The epoxy or copper is used to connect the inner layers of the PCB to the outer layers, allowing you to place and attach components to the circuit board.

Leave a Reply

Your email address will not be published. Required fields are marked *