When the capacitors are used exceeding the limits given in the catalogs or product specifications, cracks may occur in the capacitors and the reliability may deteriorate, especially the rapid temperature changes and partial heating during soldering may cause cracks. The temperature profile should be in accordance with the catalogs or product specifications.
Generally recommended temperature conditions for flow soldering is as follows:
When the capacitors are soldered under long duration or high temperature, the dissolution of electrode (leaching), deterioration of adhesion (shear strength) and capacitance decrease may occur.
Excess solder generates high contraction stress. The capacitor may also be exposed to thermal and/or mechanical stress resulting in cracks or breaks. Insufficient solder results in deficient capacitor adherence to the printed wiring board, which may cause capacitor detachment or deficient electric connection and reliability deterioration of the circuit may occurs.
Typical amount of solder are shown as follows.
Flow soldering shall not be applied to the capacitor designed for reflow soldering only.
Cracks due to thermal stress or dissolution of electrodes (leaching) may occur and may result in deterioration of adhesion (shear strength) or decrease in capacitance.
Some large size and small size capacitors are unsuitable for flow soldering.
Consult us for details.