Quality discrimination method for screening inspection of capacitors manufactured

摘要

A capacitor quality discrimination scheme capable of permitting accurate and reliable determination of whether or not a capacitor under inspection is acceptable in quality. To this end, a method for discriminating the quality of a capacitor based on the charge characteristic upon application of a DC voltage thereto includes determining a standardized selection value charge characteristic of the dielectric polarization component of the capacitor, and then quadratically approximating one of (i) the ratio of the capacitor's actual measured current value m(t) and its calculated current value j(t) as obtainable from the standardized selection value charge characteristic, (ii) the difference between m(t) and j(t), (iii) the difference between logarithmic values of m(t) and j(t), and (iv) a ratio of respective logarithmic values of m(t) and j(t). If the secondary coefficient of quadratic curve approximation formula is positive in polarity then the capacitor determined to be a defective product; otherwise, the capacitor is determined to be good.