Various types of heat treatment

Heat treatment related to plating technologies include [1] baking treatment for the purpose of preventing hydrogen brittleness by plating, [2] reflow (remelting) treatment for the purpose of preventing whisker occurrence, and [3] heat treatment to enhance the hardness and wear resistance of plating films. It is advantageous to improve the reliability of plating films and make them more functional.

Type of plating Features (characteristic value)
Baking treatment - Heat treatment conditions to remove hydrogen brittleness (in the case of zinc plating/high-tensile steel materials)
Tensile strength (kgf/mm2) Heat treatment temperature × time
105 – 145 190 – 220°C × 8hr or more
145 – 180 190 – 220°C × 18hr or more
More than 180 190 – 220°C × 24hr or more

- Heat treatment to improve adhesion properties (in the case of electroless nickel-phosphorus plating)
Iron-based materials 210 ± 10°C × 1 - 1.5 hr
Copper-based materials 190 ± 10°C × 1 - 1.5 hr
Aluminum-based materials 130 ± 10°C × 1- 1.5 hr
Reflow (remelting) treatment - Melting at a temperature somewhat higher than the melting point (232°C) to reliably remove internal stress for the purpose of preventing whisker occurrence in tin-based plating films.
Heat treatment Heat treatment is performed after plating to enhance the hardness and wear resistance of plating films (mainly amorphous plating).
Heat treatment temperature (°C) held for 1 hour Hardness (Hv)
Ni-8wt%P Ni-12wt%P
Without heat treatment 540 580
200 550 650
300 780 810
400 900 970

Adoption examples

Various types of heat treatment

Reflow treatment of tin plating