Color changed as a consequence of Wave Soldering on fuse-clip from Littelfuse

If you are concerned about the discoloration of the fuse-clip 01220083Z from Littelfuse Inc. after putting it through the process of wave soldering, the information from Littelfuse given below should hopefully reassure you.

This discoloration should be considered purely a cosmetic discrepancy and there is no detrimental effect on electrical performance.

Wave soldering is one of the methods used by Littelfuse Inc. to solder its through-hole-technology fuse clips. For wave soldering, the recommended maximum temperature of the solder should be 245 ± 5°C. When using lead-free solder, the maximum solder temperature can reach a maximum of 260°C. Ensure that the allowable maximum temperature is not exceeded for the solder that will be used. The standard wave soldering process includes the preheat ramp-up temperature phase, the peak temperature, soldering phase, and the cooling ramp-down phase. By keeping the solder temperature within the maximum recommended temperature and keeping the fuse clip in the solder wave for no longer than the recommended duration, the wave soldering process will avoid causing cosmetic changes to the fuse clip surface. Tin- and silver-plated fuse clips can exhibit discoloration after soldering. Tin-plated fuse clips can exhibit a yellow discoloration.

Tin has a melting temperature of 231.89ºC. Exceeding this temperature or exceeding the recommended duration time in the solder wave will cause yellowing of the surface. Subjecting the fuse clips to extreme conditions can cause an “orange peel” effect. Silver-plated fuse clips can exhibit a yellow/black discoloration after soldering. Also, silver reacts easily with sulfur in the environment, and the silver-plated surface will turn yellow over time. This is a natural phenomenon, but the chemical reaction will not affect the form, fit, or function of the fuse clip.

As an alternative to wave soldering fuse clips, they can be manually hand soldered. Littelfuse recommends a maximum soldering iron temperature of 350 ± 5°C. Solder should be applied for no longer than 5 seconds. The fuse clip can be hand soldered no more than three times.

The following image shows the discoloration of the fuse clip:


It is normal to have a slight color change on the base area when the temperature rises up to 245-250°C. The discoloration seen in the above image shows iridescence which indicates overheating. It is suggested that the wave soldering peak temperature should not rise above 245°C.

Applicable Part Numbers
DK Part # Mfr Part #
F3782-ND 01220083Z
F4184-ND 01220087Z
F4190-ND 01220090Z