BS EN 13603 pdf free download
BS EN 13603:2021 pdf free download.Copper and copper alloys – Test methods for assessing protective tin coatings on drawn round copper wire for electrical purposes.
4 Thickness of the unalloyed tin coating
4.1 General
This document refers to two different methods to measure the thickness of the tin coating layers on copper wires, the first one is based on the electrolytic dissolution of the tin layer. The second one is based on the direct measure of the tin layer on the wires by means of the reflection of an X-ray beam on its surface.
4.2 Principle of the method based on the electrolytic dissolution of the tin coating
4.2.1 General
Anodic dissolution of a well-defined area of the unalloyed coating using a suitable electrolyte, followed by detection of the virtually complete dissolution of the unalloyed coating by a rapid change in cell voltage. Calculation of the unalloyed coating thickness from the quantity of electricity (in coulombs) used, which can in turn be calculated from:
a) the time interval between the start of the test and the first rapid change of cell voltage, if it is conducted at constant current density; or
b) the integrated quantity of electricity used in dissolving the unalloyed coating.
4.2.2 Reagents and materials
4.2.2.1 Electrolyte, either a hydrochloric acid electrolyte or an electrolyte recommended by the instrument manufacturer.
For the hydrochloric acid electrolyte, dilute 170 ml of hydrochloric 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 nearly 100 %; for determination of the electrolyte efficiency, see 4.2.5.6.
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.
4.2.2.2 Tin, tin grade in accordance with EN 610.
4.2.3 Apparatus
Suitable instruments may be constructed from readily available components. Alternatively, a proprietary instrument may be used.
4.2.3.1 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.
4.2.3.2 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.
4.2.3.3 Electrolytic cell
The electrolytic cell consists ofa container for the electrolyte, a cathode and an anode, which is the test piece. lithe 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 piece and an agitation mechanism. Depending on the wire diameter, the test piece may he 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 shall be used to provide agitation.BS EN 13603 pdf download.
