During the Reed Switch glass sealing process, Oxides are formed on the leads outside the glass seal area, which need to be removed. This is done using an electro-cleaning and etching process which dissolves the Oxides and also polishes the surface of the leads as a preparation for the Tin plating.
After this a total wash in demineralised water is done to leach out any impurities and chemicals from the previous process. The Reed Switches are then loaded in to jigs and taken for Lead-out plating with pure Tin. This whole process is RoHS compliant and Lead (Pb) free. The reed switches undergo lead-out Tin plating in fixtures which are lowered into the baths.
After Tin plating, the reed switch leads are inspected for patches or non-uniform coloring, solder-ability, weld-ability and uniformity of Tin plating thickness. For special purpose Reed Switches, the leads are plated with Gold. Normally, the plating thickness of Tin is around 20-30 microns.
Tin plating of reed switch leads provides excellent solder-ability and also prevents the corrosion of the underlying Nickel-Iron alloy wire. If welding of reed switch leads is required, during non-standard lead formations, Tin plating is done after this to ensure that the minor oxidation formed during welding is also cleaned and polished first.
Tin plating also offers a long shelf life of at least one year, when stored in a humidity controlled store. But if this period is extended the leads may need to be stripped and re-plated with Tin. This process depends on the environment as well as the geographical location of the Reed Switches being stored.
After this stage, the Reed Switches are taken for Buzzing as it stabilises the contact and also matures the alignment of the blades for lower contact resistance measurements and better durability in the field.
