Aluminum Electrolytic Capacitors (Radial lead Type)

(5) Ripple current

Do not apply ripple currents exceeding the rated value.

Make sure that rated ripple currents superimposed on low DC bias voltages do not cause reverse voltage

conditions. Even if the current is below the rated ripple current, using the capacitor for longer than the rated

lifetime will cause ESR increase and internal generation of heat, which may eventually lead to vent open,

bulging of case/rubber, electrolyte leak, short circuit, explosion, or ignition in the worst case.

1.4 Connections in series or parallel

(1) Capacitors connected in parallel

Because the impedance of the capacitor and PCB’s wiring are very close, various impedance values may cause

unbalanced ripple current loads among parallel capacitors. Combine the same part number and wire them

carefully to minimize the potential risk of an excessive ripple current concentrating to one capacitor of the smallest

impedance.

(2) Capacitors connected in series

Voltage being applied to each capacitor must be smaller than the rated voltage. Unbalanced voltages to the series

capacitors may exceed the rated voltage. Voltage-divider resistors considering leakage currents could prevent the

over-voltage to the series capacitors. Conductive polymer hybrid aluminum electrolytic capacitors are not allowed

to be connected in series.

1.5 Capacitor mounting considerations

(1) For double sided circuit boards, avoid wiring patterns passing between the mounted capacitor and the circuit

board. When a radial lead type capacitor is dipped into a solder bath, an excess solder may deposit under the

capacitor by capillary action, causing short circuit between anode and cathode terminals. Also, lead holes must

be placed with special care for radial lead type capacitors because laminate on capacitor’s surface may become

damaged during flow process.

(2) The pitch between circuit board holes should match the lead wire pitch of the radial lead type capacitors within

the specified tolerances. Unmatched pitch may cause an excessive stress on lead wires during the insertion

process and result in short/open circuit, increased leakage current, or electrolyte leak.

(3) Clearance for case mounted pressure relief

Capacitors with case mounted pressure relief require sufficient clearance to allow for proper pressure relief

operation. The minimum clearance are dependent on capacitor diameters as follows.

(Ø 10 mm to Ø 16 mm: 2 mm minimum, Ø 18 mm: 3 mm minimum)

(4) Wiring near the pressure relief

Avoid locating high voltage or high current wiring or circuit board paths above the pressure relief. Flammable,

high temperature gas that exceeds 100 ℃ may be released which could dissolve the wire insulation and ignite.

(5) Circuit board patterns under the capacitor

Avoid circuit board runs under the capacitor, as an electrical short can occur due to an electrolyte leakage.

(6) Resonant vibration after circuit board’s production may make a heavy load on the capacitor and cause rapid

change in characteristics and/or capacitor’s break.

1.6 Electrical isolation

Electrically isolate the capacitor’s case from cathode terminals, as well as circuit patterns.

1.7 Capacitor sleeve and coating

The vinyl sleeve or laminate coating is intended for marking and identification purposes and is not meant to

electrically insulate the capacitor.

The sleeve may split or crack if immersed into solvents such as toluene or xylene and then subsequently

exposed to high temperatures.

2. Capacitor handling techniques

2.1 Considerations before using

(1) Capacitors have a finite life. Do not reuse or recycle capacitors from used equipment.

(2) Transient recovery voltage may be generated in the capacitor due to dielectric absorption.

If required, this voltage can be discharged with a resistor with a value of about 1 kΩ.

(3) Capacitors stored for a long period of time may exhibit an increase in leakage current.

This can be corrected by gradually applying rated voltage in series with a resistor of approximately 1 kΩ.

(4) If capacitors are dropped, they can be damaged mechanically or electrically. Avoid using dropped

capacitors.

(5) Dented or crushed capacitors should not be used.

The seal integrity can be damaged and loss of electrolyte/ shortened life can result.

01-Oct-21