Voltage Boundary
Electrical testing of high-voltage circuit boards establishes the minimum stress levels at which localized electrical breakdowns occur in insulating voids or gaps. This crucial parameter, defined as partial discharge inception voltage, marks the transition from stable insulation to active micro-discharges within the dielectric material. It is measured by gradually increasing the applied alternating current voltage while monitoring the board with high-frequency sensors or ultrasonic detectors.
Testing ensures that the operating voltage of the assembly remains well below this threshold to prevent gradual material degradation.
Dielectric Quality
Microscopic voids and delamination between board layers lower the threshold of ionisation within the laminate. A low partial discharge inception voltage indicates the presence of air pockets or moisture trapped during the lamination process. These air pockets ionize under lower voltage stress than the surrounding epoxy resin, initiating localized discharges that erode the organic polymer.
Tracking and carbonization eventually follow, creating a conductive path that leads to short circuits.
Screening Protocol
High-reliability applications, such as automotive or aerospace electronics, mandate the verification of this threshold during final board inspection. Measuring the partial discharge inception voltage ensures that assemblies can withstand transient overvoltages without suffering internal dielectric damage. This qualification process confirms the structural integrity of the resin-impregnated glass-fibre layers.
