Pcb Copper balance: a critical parameter

The equilibrium of copper balance can be a critical parameter in mitigating the phenomenon of tombstoning. However, it’s crucial to acknowledge that copper equilibrium is merely one of the influencing factors. Interestingly, there are instances where the industry intentionally engineers scenarios with the most unfavorable copper equilibrium.

This assertion may seem a bit overstated and isn’t entirely accurate, as there’s no interest in deliberately inducing an imbalanced copper distribution. However, this is a typical situation encountered in Radio Frequency (RF) design, where the parasitic attributes of thermal reliefs begin to exert a detrimental effect at extremely high frequencies. In numerous high-frequency designs, passive components are utilized as constituents of filter, impedance matching, or termination networks that are positioned on one side of the RF line and on a solid ground plane on the other. The RF line often takes the form of a coplanar waveguide with a VIA fence, resulting in a thermal configuration that is most challenging for any passive device situated between the RF line and the ground region. Despite this, many such designs are produced in large quantities without a significant decrease in manufacturing yield due to tombstoning.

The geometry of the component footprint, the soldering profile, and even the soldering technique employed significantly influence the likelihood of tombstoning. By meticulously controlling these factors, it’s possible to achieve high-yield manufacturing even in scenarios with the most unfavorable thermal balance.

Copper balance is frequently singled out as the primary contributor to tombstoning, while other contributing factors are often overlooked. While copper balance undoubtedly plays a role in the phenomenon, it’s essential to consider all the variables concurrently.