Apparatus and Method for Screening Electrolytic Capacitors

Abstract

A method for screening electrolytic capacitors places a capacitor in series with a resistor, applying a test voltage and following the charge curve for the capacitor. A high voltage drop across the capacitor indicates high reliability and a low voltage drop is used to reject the piece. The leakage current is not adversely affected during the test.

1 - 11 . (canceled) 
     
     
         12 . An apparatus for screening capacitors to remove unreliable parts from a large population comprising:
 at least one test capacitor attachment for attaching a test capacitor during a test;   a series resistor in series with said test capacitor;   a first power supply providing a first voltage across said test capacitor and said series resistor;   a voltage detector capable of measuring voltage across said series resistor; and   a second power supply providing a second voltage through a diode across said series resistor.   
     
     
         13 . The apparatus for screening capacitors of  claim 12  wherein said series resistor has a resistance of at least 0.1 Mohm to no more than 10 Mohm; 
     
     
         14 . The apparatus for screening capacitors of  claim 12  further comprising a timer for determining a test time after which said first power supply and said second power supply cease providing voltage to said test capacitor. 
     
     
         15 . The apparatus for screening capacitors of  claim 14  wherein said test time is at least 0.5 min to no more than 5 min. 
     
     
         16 . The apparatus for screening capacitors of  claim 12  wherein series combination of said test capacitor and said series resistor receives at least an average break down voltage. 
     
     
         17 . The apparatus for screening capacitors of  claim 16  wherein combination of said test capacitor and said series resistor receives no more than 1.5 times said average breakdown voltage. 
     
     
         18 . The apparatus for screening capacitors of  claim 12  further comprising a fuse.