Trace Quantification
Low resistance quantification provides a window into the structural integrity of metallic bonds. Micro-ohmic measurement identifies the quality of via plating and the consistency of heavy copper traces by measuring resistance values below one thousandth of an ohm.
Integrity Detection
Minor variations in the cross sectional area of a conductor result in measurable changes during the test. When micro-ohmic measurement is applied to a daisy chain of vias, it reveals the presence of thin plating or corner cracking that would survive a standard continuity check. The sensitivity of the equipment allows for the monitoring of resistance changes during thermal cycling or vibration testing.
This data helps engineers predict the fatigue life of the interconnections before a catastrophic failure occurs.
Thermal Compensation
Temperature fluctuations exert a strong influence on the resistivity of copper and must be compensated for during the analysis. A micro-ohmic measurement taken at room temperature will differ from one taken at operational heat levels, so reference tables are used to normalize the results. The effectiveness of the test is limited by the surface finish of the pads, as oxidation or contamination can increase the contact resistance.
Proper probe pressure and tip geometry are vital to piercing these layers without damaging the board surface.
