Installing Capacitors
(1) Installing
a) Used capacitors are not reusable, except in the case that the capacitors are detached from a device for periodic inspection to measure their electrical characteristics.
b) If the capacitors have self charged, discharge in the capacitors through a resistor of approximately 1KΩ before use.
c) If capacitors are stored at a temperature of 35℃ or more and more than 75% RH, the leakage current may increase. In this case, they can be reformed by applying the rated voltage through a resistor of approximately 1KΩ.
d) Verify the rated capacitance and voltages of the capacitors when installing.
e) Verify the polarity of the capacitors.
f) Do not use the capacitors if they have been dropped on the floor.
g) Do not deform the cases of capacitors.
h) Verify that the lead spacing of the capacitor fits the hole spacing in the PC board before installing the capacitors. Some standard pre-formed leads are available.
i) For pin terminals or snap-in terminals, insert the terminals into PC board and press the capacitor downward until the bottom of the capacitor body reaches PC board surface.
j) Do not apply any mechanical force in excess of the limits prescribed in the catalogs or the product specifications of the capacitors.
Also, note the capacitors may be damaged by mechanical shocks caused by the vacuum/insertion head, component checker or centering operation of an automatic mounting or insertion machine.
(2) Soldering and Solderability
a) When soldering with a soldering iron
·Soldering conditions (temperature and time) should be within the limits prescribed in the catalogs or the product specifications.
·If the terminal spacing of a capacitor does not fit the terminal hole spacing of the PC board, reform the terminals in a manner to minimize a mechanical stress into the body of the capacitor.
·Remove the capacitors from the PC board, after the solder is completely melted, reworking by using a soldering iron minimizes the mechanical stress to the capacitor.
·Do not touch the capacitor body with the hot tip of the soldering iron.
b) Flow soldering
·Do not dip the body of a capacitor into the solder bath but only dip the terminals in. The soldering must be done on the reverse side of PC board.
·Soldering conditions (preheat, solder temperature and dipping time) should be within the limits prescribed in the catalogs or the product specifications.
·Do not apply flux to any part of capacitors other than their terminals.
·Make sure the capacitors do not come into contact with any other components while soldering.
c) Reflow soldering
·Soldering conditions (preheat, solder temperature and dipping time) should be within the limits prescribed in the catalogs or the product specifications.
·When setting the temperature infrared heaters, consider that the infrared absorption causes material to be discolored and chang in appearance.
·Do not solder capacitors more than once using reflow. If you need to twice, be sure to consult us.
·Make sure capacitors do not come into contact with copper traces.
d) Do not re-use surface mount capacitors which have already been soldered.
In addition, when installing a new capacitor onto the assembly board to rework, remove old residual flux from the surface of the PC board, and then use a soldering iron within the prescribed conditions.
(3) Handling after soldering
Do not apply any mechanical stress to the capacitor after soldering onto the PC board.
a) Do not lean or twist the body of the capacitor after soldering the capacitor onto the PC board.
b) Do not use the capacitors for lifting or carrying the assembly board.
c) Do not hit or poke the capacitor after soldering to PC board. When stacking the assembly board, be careful that other components do not touch the aluminum electrolytic capacitors.
d) Do not drop the assembly board.
(4) Cleaning PC board
a) Do not wash capacitors by using the following cleaning agents; Solvent-proof capacitors are only suitable for washing under the cleaning conditions prescribed in the catalogs or the product specifications. In particular, ultrasonic cleaning will accelerate damaging capacitors.
·Halogenated solvents; cause capacitors to fail due to corrosion.
·Alkali category solvents; corrode (dissolve) an aluminum case.
·Petroleum category solvents; cause the rubber seal material to deteriorate.
·Xylene solvents; cause the rubber seal material to deteriorate.
·Acetone solvents; erase the marking.
b) Verify the following points when washing capacitors.
·Monitor conductivity, Ph, specific gravity, and the water content of cleaning agents. Contamination adversely affects these characteristics.
·Be sure not to expose the capacitors under solvent rich conditions or keep capacitors inside a closed container.
In addition, please dry the solvent sufficiently on the PC board and the capacitor with an air knife (temperature should be less than the maximum rated category temperature of the capacitor) over 10 minutes.
Aluminum electrolytic capacitors can be characteristically and catastrophically damaged by halogen ions, particularly by chlorine ions, though the extent of the damage mainly depends upon the characteristics of the electrolyte and rubber seal material. When halogen ions come into contact with the capacitors, the foil corrodes when voltages applied. This corrsion causes extremely high leakage current which causes in line with venting and an open circuit.
Global environmental warnings (Greenhouse effects and other environmental destruction by depletion of the ozone layer), new types of cleaning agents have been developed and commercialized as substitutes for CFC-113, 1. 1. 2- trichloroethylene and 1, 1, 1-trichloroethylene. The following are recommended as cleaning conditions for some of new cleaning agents.
–Higher alcohol category cleaning agents Recommended cleaning agents:
Pine Alpha ST-100S (Arakawa Chemical)