IEC 60093: Test Methods for Volume Resistivity of Solid Insulating Materials

Below 10⁶ Ω·m, Your Insulation Is Dead: The IEC 60093 Threshold

IEC 60093 specifies volume resistivity testing for solid insulating materials. One number — ρ_v (Ω·m) — determines whether a material can still function as an insulator.

Three-electrode system principle: Measuring electrode, guard electrode (eliminates surface leakage current), and HV electrode. The guard electrode separates volume current from surface current — in high-humidity environments, surface leakage can exceed volume current by orders of magnitude. Without a guard electrode, the measured “volume resistivity” is completely wrong.

Judgment threshold: Materials with ρ_v below 10⁶ Ω·m are generally considered to have lost insulating capability. For FR-4 PCB substrate, normal values are 10¹²–10¹⁴ Ω·m. If FR-4 absorbs moisture and ρ_v drops below 10⁸ Ω·m, the laminate is severely compromised — risking CAF (Conductive Anodic Filament) failure under high voltage.

TN Lab — One resistance value defines a material insulating lifeline.