BS EN 13603-2013 pdf download.Copper and copper alloys Test methods for assessing protective tin coatings on drawn round copper wire for electrical purposes.
For the hydrochloric acid electrolyte. dilute 170 ml of hydrochlor acid (Nd), p = 1,18 g/ml, to 1 000 ml with deionised water.
NOTE The unalloyed tin coating dissolves anodically at an efficiency of nearty 100 %; for determination of the electrolyte efficiency, see 4.5.6.
WARNING — Hydrochloric acid causes burns and is irritating to the respiratory system. Avoid breathing the vapour and prevent contact with eyes and skin.
This electrolyte dissolves tin coatings at very low cell voltages at which there is no anodic attack on the substrates when they are exposed at the end of the test.
4.2.2 TIn, tin grade in accordance with EN 610.
4.3 Apparatus
Suitable instruments may be constructed from readily available components. Alternatively, a proprietary instrument may be used.
4.3.1 Direct reading instruments
Proprietary direct reading instruments are available for use with electrolytes recommended by the manufacturer.
The calculation of thickness of tin coating from current density is made electronically. The instrument shall have some means of indicating when the unalloyed tin coating has been fully removed.
4.3.2 Other instruments
Instruments other than proprietary direct reading instruments record the quantity of electricity, in coulombs, used in dissolving the unalloyed coating from the measuring area, usually in arbitrary units, from which the thickness can be calculated using factors or tables.
4.3.3 ElectrolytIc cell
The electrolytic cell Consists of a container for the electrolyte, a cathode and an anode, which is the test sample. If the container is made of metal, such as stainless steel, the container can serve as the cathode. If the container is made of insulating material, a separate cathode is required.
Also required are a device for supporting the appropriate length of the test sample and an agitation mechanism. Depending on the wire diameter, the test sample may be a straight length of wire or, if necessary to obtain sufficient surface area for smaller diameter wires, a holding device such as that shown schematically in Figure 1 is required. A magnetic stirrer or similar system shail be used to provide agitation.
4.5.3 Electrolysis (Dissolution of the unalloyed tin coating)
The electrolyte (4.2.1) and test piece shall be introduced into the cell so that a known area is exposed to the electrolyte. EffOrtS shall be made to ensure that no gas bubbles occur on the measuring area by use of the agitation mechanism. The electrical connections shall be made and the agitator operated. Electrolysis shall be continued until dissolution of the unalloyed tin coating is complete. as indicated by a sharp change in the anode potential or cell voltage, or by the operation of the automatic cut-out.
After completion of the test, the test piece shall be removed from the cell, rinsed with water and examined to ensure that complete removal of the unalloyed tin coating has occurred over the measuring area (see 4.5.4.9).
4.5.4 Factors affecting the measuring accuracy
4.5.4.1 Coating thickness
The optimum accuracy is achieved with coating thicknesses in the range 0,2 pm up to 50 pm.
4.5.4.2 Current variation
For instruments using the constant current and time measuring technique, current variation will cause errors. For instruments using a current-time integrator, too large a change in current can change the anode current efficiency or interfere with the end-point, causing an error.
4.5.4.3 Area variation
The accuracy of the thickness measurement will be no better than the accuracy to which the measuring area is known. Area variations due to electrolyte level (excessive agitation), can lead to measurement errors. In some cases it can be advantageous to measure the length after electrolysis is complete and re-calculate the area.
4.5.4.4 AgitatIon
Agitation (i.e. the rate of stirring) shall be sufficient to remove any gas bubbles formed during the test, which can adhere to the test piece or cathode. Excessive agitation shall be avoided to prevent interference with the length of test piece submerged.
4.5.4.5 Condition of the test piece surface
Oil, grease, paint, corrosion products, staining or other surface chemical treatments can interfere with the test.
4.5.4.6 Cleanliness of the cell.BS EN 13603-2013 pdf download.
BS EN 13603-2013 pdf download
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