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Agilent AN 1305-4 Effective Electrolytic Capacitors Testing Application Note Agilent 4263B LCR Meter Introduction (4) When a shorted device is measured, Agilent 4263B LCR Meter Solution With increased requirements for size the internal circuit of a conventional (1) Accurate Low Impedance Measurement reduction and higher reliability design, LCR meter is latched up, and it needs The 4263B LCR Meter employs a it is becoming necessary to evaluate a long recovery time. 4-terminal pair configuration and an electrolytic capacitors employed in advanced low noise design so that it electronic equipment. Production vol- (5) Some inexpensive LCR meters do makes accurate measurements up to ume has been increasing for circuit not range up to 100 kHz, and the 1 F. For example, when 10 mF is meas- applications. Manufacturing and QA equivalent series resistance of the ured at 120 Hz, the 4263B's accuracy, now have to improve their testing of electrolytic capacitors need to be 0.57% can be achieved. Also, the meas- electrolytic capacitors. Here are the evaluated at 100 kHz. urement cable can be extended up to solutions offered by the Agilent 4 m while maintaining the measurement 4263B LCR Meter to meet these meas- (6) Most LCR meters cannot detect accuracy. urement requirements. whether or not the contact between the fixture's electrodes and the device's (2) High System Throughput electrode is good, thus decreasing the The measurement speed of the 4263B Current Problems in Electrolytic reliability of a measurement. LCR Meter at 100 Hz/120 Hz is 25 ms Capacitor Evaluation (Meas.Time: SHORT). Figure 1 shows When making electrolytic capacitor (7) There are no test fixtures for the you the fluctuation of the 22 mF measurements using conventional terminals (for example, big screw Aluminum Electrolytic Capacitor LCR meters, there are quite a few electrodes) of the big electrolytic Measurement by SHORT mode, and shortcomings. capacitors. 120 Hz of the 4263B. (1) Impedance value of the electrolytic capacitors is usually so low that an accurate measurement is hard to achieve. Some LCR meters cannot measure above 20 mF due to a limited measurement range. (2) Electrolytic capacitors are cur- rently tested at 100 Hz or 120 Hz. The measurement speed at those frequen- cies is quite slow, and higher through- put cannot be achieved by automatic measurement systems. (3) When a