Silver plating joints

In a draw-out MCC all current-carrying components should be periodically checked for their silver-plating, proper contact area, spring pressure and tightness of joints (this procedure can follow the manufacturer s maintenance schedule) or at least during the six-monthly or yearly maintenance check ups of the busbars and the busbar joints as noted above. The contacts or their springs may be replaced when the contacts are worn out or... 

Bus conductor with plain connection joints Bus conductor with silver plated or welded contact surfaces... 

Fig. 3.22. Arrangement of the leads inside the conductivity cell shown in Fig. 3.23. Cu copper wire, Sd soldered joint, W tungsten wire, SW spot-weld, Pt platinum wire, S soda glass sleeve, SS silver-soldered joint, P borosilicate glass arm fused to the cell, PtP platinum plate electrodes held together with lead glass beads L.

At the end of April, 1800, Sir Joseph Banks showed the first part of Volta s letter to Carlisle, who by 30 April had constructed a pile from 17 silver half-crowns, a like number of pieces of zinc, and pasteboard discs soaked in salt water, arranged in the order silver, zinc, card, silver. . . card, silver, zinc. A gold-leaf condensing electroscope showed that the silver end was negative and the zinc end positive (see p. 14). To ensure better contact, Carlisle put a drop of water on the upper plate and noticed evolution of gas, which Nicholson thought smelt of hydrogen. Nicholson proposed an experiment which they made on 2 May. A joint paper was published by Nicholson in July. ... 

Other surface finish-delated defects Immersion silver (Imm-Ag) sometimes exhibits hn-ear arrays of microvoids at the intermetalhc interface which detracts from solder joint strength. Electroless nickel/immersion gold (ENIG) sometimes results in brittle fracture if the plating chemistries are not maintained properly. 

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