Flux selection

Safety Application Guide for Multilayer Ceramic Chip Capacitors
Soldering conditions
Flux selection

Flux can seriously affect the performance of capacitors. Confirm the following items to select the appropriate flux.

Amount of flux

Put the suitable minimum amount of flux uniformly on the printed wiring board when a capacitor is soldered.
Flux is applied in order to improve solderability. If the amount of flux is too much, solderability may deteriorate due to too much flux gas being generated during flow soldering.
Foaming method is recommended in order to limit the amount of flux.

Chlorine content

Strong acidic flux should not be used. Use flux that has a chlorine content of 0.1 wt % or less. Flux with excessive amounts of halogen compounds and/or strongly acidic additives for activation may lead to a large amount of residue after soldering, deterioration of surface insulation of capacitors and the corrosion of terminal electrodes or lead wires may occur.

Type of flux

When using water-soluble fluxes, clean thoroughly.
If rinsing is not sufficient, residues of water-soluble flux dissolve easily when exposed to moisture so in high humidity conditions, insulation resistance may deteriorate insulation resistance and reliability by residue that adheres to the capacitor surface.
When using water-soluble flux, confirm that capabilities of the cleaning method and cleaning machine are well maintained. Sufficient rinsing and drying are needed to avoid an ion migration in the gap between the printed circuit board and capacitor.

Sn-Zn type solder may cause negative effect to capacitor reliability. Please contact us in advance of using Sn-Zn type solder.

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