This section of JIS defines the conditions for significant surfaces of tin coatings electroplated on a metal substrate in order to improve solder wettability and anti-corrosion properties in electrical components.

(1) Grade and minimum plating thickness

The plating grades are classified into five categories as shown in [Table 1] based on the minimum plating thickness.

[Table 1] Grades and minimum plating thickness for electroplated coatings of tin

The base-coat plating will be determined and agreed between the parties concerned.

(2) Plating quality

Here are the assessment items for determining the quality of plating films.

1. Appearance

The plating type of either bright or matte plating will be determined and agreed between the parties concerned. However, note that the plating surface must be flat and free from burnt or swelling areas, lumps, pits, or exposure of substrates or base-coat plating.

2. Minimum plating thickness

This thickness must conform to [Table 1].

3. Corrosion resistance

This property can be measured by a salt spray test, etc.

4. Adhesiveness

This property can be measured by any of the following: tape test, bend test, or thermal-shock test.

5. Solder wettability

Perform a solder wettability test by immersing the test item into melted solder.

6. Stress relief before plating

If a stress relief of the steel substrate is required, determine the conditions between the parties concerned.

7. Heat treatment after plating

If a bright finish after plating or heat treatment is required for hydrogen embrittlement removal and whisker prevention, determine the conditions between the parties concerned.

(3) Plating name and symbol

Plating names are described by the symbols shown in this table.

In the next volume, we will learn about the plating bond test.