GB/T 37568-2019Tin-plated copper and copper alloy strip (English PDF)

3.1 Tin plating strip

The strip that uses electrochemical principal or physical means to attach a tin metal layer with uniform thickness on the surface of copper and copper alloy strip.

3.2 Reflow electro-tinning strips; RFSn

After the matt tin plating treatment, the copper and copper alloy strips are subjected to the reflow surface treatment to form a tin plating strip with tin-layer of a glassy and smooth surface.

3.3 Hot-dip tinning strips; HDSn

The tin plating strip that make the copper and copper alloy strip to smelt tin through dipping method; and plate the tin layer with the same thickness on both sides of the copper and copper alloy strip.

5.2 Appearance dimension and its allowable deviation

5.2.1 The tests on the base metal and appearance dimension of tin plating strip shall be carried out as per the provisions of GB/T 26303.3.

5.2.2 The thickness measurement of tin plating layer shall be carried out as per the Appendix B.

5.3 Mechanical properties

The tensile test of base metal of tin plating strip shall be carried out as per the provisions of GB/T 34505-2017; the specimen number shall be P4 in Table 3 of GB/T 34505-2017. The Vickers hardness test shall be carried out as per the provisions of GB/T 4340.1.

5.4 Electrical properties

The electrical property test of base metal of tin plating strip shall be carried out as per the provisions of GB/T 351 or GB/T 32791; while the arbitration test shall be carried out as per the provisions of GB/T 351.

5.5 Weldability

The weldability test of the tin plating strip shall be carried out as per the provisions of Appendix A.

5.6 Adhesion

The coating adhesion test of the tin plating strip shall be carried out as per the provisions of GB/T 9286 or as per the method agreed between the supplier and the purchaser.

5.7 Oxidation resistance

The oxidation resistance test of the tin plating strip shall be carried out as per the provisions of GB/T 6461.

5.8 Surface quality

6.5 Judgment of inspection results

6.5.1 The value of the inspection result shall be rounded off as per the provisions of GB/T 8170; and shall be judged by the rounding-off value comparison method.

6.5.2 When the chemical composition of the baes metal of the tin plating strip is unqualified, then such batch of strip shall be judged to be unqualified.

6.5.3 When the base metal, appearance size and its allowable deviation of tin plating strip is unqualified, then such roll of strips shall be judged to be unqualified.

6.5.4 When the mechanical property and electrical property inspection results of the base metal of tin plating strip are unqualified, then take double quantities of specimens from such batch of strips (including that roll of strips that are unqualified in the original inspection) for reinspection; if all the reinspection results are qualified, then the whole batch shall be judged to be qualified. If there is still unqualified item in the reinspection, then such batch of strips shall be judged to be unqualified.

6.5.5 When the weldability, adhesion, and oxidation resistance inspection results of tin plating strip are unqualified, then take double quantities of specimens from such batch of strips (including that roll of strips that are unqualified in the original inspection) for reinspection; if all the reinspection results are qualified, then the whole batch shall be judged to be qualified. If there is still unqualified item in the reinspection, then such batch of strips shall be judged to be unqualified; or supplier inspect roll by roll, only the qualified can be delivered.

6.5.6 When the surface quality of the tin plating strips is unqualified, then such roll of strips shall be judged to be unqualified. […]

A.1 Scope

This Appendix specifies the test method for weldability of tin-plated copper and copper alloy strip.

This Appendix is applicable to the test for weldability of tin-plated copper and copper alloy strip.

A.2 Method overview

The specimen is dipped vertically into the soldering batch at the speed of 3mm/s; stand for 5s; then take it out at the same speed.

Visually compare with the standard sample of the tin plating strip to assess whether the weldability is qualified.

A.3 Specimen

At least take 3 blocks of specimens with size of 10mmx40mm before tin plating. The specimen can't be touched by hand directly during the sampling and sample-preparation processes; the surface of the specimen shall be free of any contamination or corrosive residue.

The strips of outer layer of roll or the initially 200mm of the outer end of the cartridge is not suitable for weldability test. If the reinspection is carried out, the first lap of the strip roll shall be removed.

A.4 Test device

The test device includes the fixed soldering bath and the device capable of dipping the specimen at a predetermined speed and stroke for a predetermined period of time, then taking out.

The quantity of soldering material is at least 0.5kg; the depth of the soldering bath at least reaches 40mm.

B.4 Test device

The test device is X-ray fluorescence coating thickness measuring instrument; and passes the metrological verification.

A.5 Test parameters and procedures

B.5 Test procedures

According to the operating procedures of X-ray fluorescence coating thickness measurement instrument, measure the thickness through selecting the points.

The number of measuring points shall be selected according to the size of the sample; however, at least 5 points are measured on each side; the measuring point shall be representative; point-selecting can refer to Figures B.1 and B.2.

B.1 Scope

This Appendix specifies the coating thickness measurement of tin-plated copper and copper alloy strip.

This Appendix is applicable to use X-ray method to measure the coating thickness of tin-plated copper and copper alloy strip.

B.2 Method overview

The coating thickness shall be measured by the X-ray fluorescence coating thickness measuring instrument; at least 5 measuring points are measured on each side; finally calculate the arithmetic mean value of the coating thickness.

B.3 Specimen

The specimen is taken to be 200mm long as per the width of the strip. The specimen can't be touched by hand directly during the sampling and sample-preparation processes; the surface of the specimen shall be free of any contamination or corrosive residue. […]