Soldering iron

Safety Application Guide for Multilayer Ceramic Chip Capacitors

Mounting

Soldering conditions

Soldering iron

The soldering conditions shall be within the limits in the catalogs or product specifications.

When soldering capacitors beyond limits of the conditions stated in the catalogs or product specifications,
cracks in the capacitor may occur due to thermal stress. Cracks may cause the deterioration of insulation
resistance, reliability, and bending strength of the capacitor.
When using a lead-free solder which has a high liquid phase temperature (over 200 ℃), take account of cracks compared to using Sn-Pb eutectic solder. Particularly, partial heating and rapid heating/cooling to a capacitor significantly increases the risk of cracking.
The tip of soldering iron should not touch directly to the termination electrodes of a capacitor.

Set soldering condition in order to reduce thermal stress to the capacitor prior to soldering.

(1) Preheating
When the temperature difference between the tip of solder iron and the capacitor or the printed wiring board is large, a crack may occur due to the thermal stress in capacitor. The crack may cause the deterioration of insulation resistance, reliability, and bending strength.
Preheat the capacitor and the printed wiring board to 150 ℃ or more. Maintain the capacitor and the printed wiring board at the preheating temperature during hand soldering.
Avoid rapid heating/cooling and partial heating. Define the time to reaching to the preheating temperature as the preheating time.
(2) Manual soldering conditions (Recommended condition of soldering iron)
Although using a high temperature soldering iron makes soldering work efficient, the large temperature difference between the tip of the soldering iron and the capacitor induces thermal stress which may cause cracks in the capacitor resulting in a deterioration of bending strength of the capacitor.
Set a proper time for soldering of which tip temperature should be under 350 ℃. In case of long time for soldering, solder leaching of the termination electrode may occur.
(3) Caution after soldering
Avoid rapid cooling of capacitors and substrates after soldering, including reworks. Natural cooling is recommended.

Keep solder fillet size within the appropriate range.

When the amount of solder is too little, the poor and unbalanced solder fillets may cause the insufficient connection or the capacitor may fall off the printed wiring board.
When the amount of solder is too much, a crack may be caused due to the mechanical and/or thermal stress.

Safety Application Guide for Multilayer Ceramic Chip Capacitors All Lists