Insulation Integrity
Polymer breakdown describes the chemical or physical alteration of organic materials within a multilayer board, which reduces the electrical resistance between conductive layers. Dielectric degradation happens when moisture ingress, thermal cycling, or ionic contamination creates conductive paths through the insulating base material. This phenomenon sets the limit for the operational lifetime of high-voltage circuit designs by lowering the breakdown voltage threshold below the intended safety margin.
Failure Mechanism
Elevated heat levels accelerate the movement of particles through the substrate, causing permanent structural changes in the molecular chains of the resin. Once the material reaches a transition point, the resin loses its ability to block current across gaps between copper features. Internal voids created during the lamination process act as focal points where electric field stress exceeds the capacity of the insulation.
These areas heat rapidly under voltage, producing carbon tracks that complete a short circuit between planes. High humidity exacerbates the process as water molecules absorb into the porous sections of the laminate.
Testing Parameter
Automated high-potential leakage measurements detect early stages of material breakdown by applying stress significantly higher than operating conditions. Technicians monitor current flow for minute fluctuations that signal internal microscopic pathways formed within the substrate. Boards pass this inspection only when current leakage stays under a predefined microampere threshold across the entire duration of the electrical dwell period.
A stable reading confirms that the insulation remains free from conductive contamination or internal lattice ruptures.
