Effect of Alloying Elements on the Radio Noise Characteristics of Silver Based Alloy Contacts

Ag-Cu, Ag-Au and Ag-Pd alloys have been used as the contacts of the relays for low current below several amperes. In breaking these contacts, an arc discharge appears and then the radio-interference-field due to the arc disturbs the operation of LSI near the contacts. Thus, these contacts are operated at the closed circuit current 0.5% 7A, source voltage dc.50 V, resistive load and in air, and then the radio -interference-field are measured. From the measured results, we find that alloying silver with Cu, i.e. Ag-Cu alloy, is useful for the stabilizing of arc and resulting in the decrement(suppress) of radio noise in our measured frequency range from 1 to 200MHz. Therefore, besides of the contact properties such as a contact-resistance, a weld-proof and an errosion, it is necessary to clarify the properties relating to the radio noise of the above Ag-alloy contacts, especially the effects of alloy-elements (Cu, Au and Pd) on the radio-noise-characteristics. Thus we operated (broke) Ag, Au, Pd, Ag-Cu, Ag-Au and Ag-Pd contacts at the closed circuit current of 0.5% 7A, the power source of dc.50volts, resistive load and in air, and then measured various properties of the radio noise caused by the contact breaking arcs. As the results, we find that the alloying silver with Cu, i.e. Ag-Cu alloy, acts to stabilize the arc, so that the radio noise due to the arc decreases (suppression).