A study of the magnetic dipole moment behavior for a distribution of copper snowballs

Power Loss or the attenuation of signals is a prevalent problem in high-speed circuits, especially at high frequencies. It is the signal integrity Engineer's goal to design a system that will reduce the fatal effects of signal attenuation and thus assure system integrity over a range of frequencies.;In the PCB manufacturing industry, the under-side (bottom surface) of copper foils used as traces or ground layers is typically roughened to provide better adhesion to a dielectric substrate or laminate like FR4.;According to Oak Mitsui engineers in Camden, South Carolina one of the primary copper foil manufacturers for high speed circuits, copper foils typically have to pass a peel test to determine the foil's bonding strength to the dielectric because it plays an important role in the durability of the board. Copper "snowballs" are typically added to create roughness on the underside of the foils; they are thus called anchor nodules because it is harder to peel copper foil away from the adjacent dielectric material if the nodules are present.;Unfortunately, anchor nodules have been shown to jeopardize the integrity of an electromagnetic signal travelling along such traces, as anchor modules contribute to signal attenuation and dispersion.;It is quite intuitive to say that larger anchor modules will greatly influence high surface roughness loss.;As electromagnetic fields that represent signals travel down a trace, the fields scatter from and penetrate into the anchor modules, inducing electric and magnetic dipole moments on the snowballs and causing power to be lost from the signal. It is the focus of this thesis is to study magnetic dipole moments induced in anchor modules or 'snowballs' to better understand how they scatter or absorb as they pass over a distribution of snowball sizes.