Parameters for Leakage Model

The experiment deals with the measurement and interpretation of electric leakage between parallel tinned and non-tinned Cr/Cu lands on a ceramic substrate, covered with an epoxy overlay about 1mm thick. The lands are 0.254 cm wide and spaced 0.0127 cm, 0.0254 cm, and 0.038 cm, while the thickness of Cr, Cu,and Pb-10%Sn in the land structure are 100 nm, 800 nm, and 10 nm, respectively. Chromium is used for adhesion. 

The experiment is conducted under various stress conditions to develop leakage kinetics to verify the model and to make projections to field conditions as a function of temperature, relative humidity, voltage, electrode gap, geometry, diffusivity parameters, and time. 

Using these parameters, the leakage criterion i can be expressed as a function of t,  

To reach a fail criterion of 10 Q from an insulation resistance of 10 n, it will take 10 hrs. at 40°C/40%RH/1 OV. The leakage dependence on d is practically nil. This may be the result of the polymer thickness being considerably larger than the gaps. 

---