MAKE AND BREAK PROPERTIES OF ELECTRODEPOSITS.

Properties of thin precious metal electrodeposits used as contact materials on base metals under make and break conditions are described. The investigations were carried out with the aid of a model device which simulated conditions existing in relays. The electrodeposits tested were AuCo//0//. //3, AuPd//6 Cu//2 , Pd, PdNi//2 O, Rh, and Ag/Rh sandwich. For these electrodeposits contact resistance is discussed in dependence on the number of operations for different electric loads (28-550 mA dc, 12-60 V, ohmic). At voltages below 12 V and currents below 100 mA with a 5- mu m-thick Rh, Pd, PdNi//2 O, and a 10- mu m-thick AuPd//6 Cu//2 layer more than 10**7 operations are available with no R//c (max) value above 100 m OMEGA . At the same voltage, with 5- mu m AuCo//0 //. //3 , even at a current of 30 mA only 10**6 operations are possible. Below 12 V/100 mA doubling the thickness of the layer results in a doubling of the number of operations. For all electrodeposits it is noted that at higher voltages and currents the maximum number of operations decreases significantly, nearly independently of the layer thickness.