Dynamic Kelvin Resistance Screening Mechanics for High Density Circuit Boards
Dynamic four-wire Kelvin screening uses thermal current pulses and flexure to isolate latent microvia cracks that pass static continuity tests.
Voltage Drop Resolution
Measurement Precision
Smallest detectable change in electrical potential that a system can record determines the sensitivity of a continuity test. Higher voltage drop resolution allows for the identification of microscopic fractures in the conductive paths of a board. It is the primary factor in distinguishing between a healthy via and one that is beginning to fail.
Quantitative Scaling
Resolution is defined by the number of bits in the analog to digital converter and the full-scale range of the input. The voltage drop resolution determines whether a system can see the difference between a clean and a compromised joint. For a system checking milliohm resistances, the hardware must be able to resolve changes in the microvolt range.
This precision ensures that a ten percent shift in resistance is clearly visible above the noise floor. Without sufficient resolution, the data appears flat and hides the onset of mechanical fatigue.
System Performance
Achieving high levels of detail requires stable current sources and low-noise input stages. Validation involves verifying the voltage drop resolution against a known resistance standard. Equipment used for thermal shock testing must maintain this resolution while temperatures fluctuate.
If the resolution is too coarse, the test cannot provide a defensible account of the circuit’s long-term reliability.