Gold and Gold Alloys
| DMC 200 (24 Karat Gold) is unsurpassed in resistance to oxidation and sulfidation. It will form a polymer but is much less likely to do so than the platinum materials. Gold is relatively soft and, because of a low melting point, is susceptible to erosion. For this reason, gold is limited to application less than one-half ampere. Typical applications for DMC 200 and the other gold alloys are the low level, high reliability situations in sensitive relays in sound circuits. Gold has worked well where contact forces are in the very low five to ten gram range.
To improve the hardness of gold, it is alloyed with silver, platinum and nickel. Increasing hardness generally leads to a corresponding decrease in conductivity. This is normally of little consequence in low level operations because contact problems in this area are surface related as opposed to bulk material relationships in the higher amperage range. DMC-41 (69% gold, 25% silver, 6% platinum) is a well known gold alloy, and is used widely in telephone relay applications. DMC-43 (72% gold, 26.2% silver, 1.8% nickel) retains enough gold to give good protection against sulfiding. DMC-44 (75% gold, 25% silver) and DMC-47 (50% gold, 50% silver) are gold silver alloys which show improved strength. DMC-337 (72.5% gold, 14% copper, 8.5% platinum, 4% silver, 1% zinc) is an alloy that can be age hardened to provide it with excellent spring properties, thus making it ideal for use in microstampings. This heat-treat process endows the alloy with high tensile strength, high hardeness and resistance to wear. If low contact surface resistance is to be retained, gold content should not be lower than 65% to 70%. DMC-47, with 50% gold, will not be so noble as the other alloys listed, but does offer a lower cost gold material that will perform better than other basically silver alloys. Properties of Gold and Gold Alloys
 *Heat-treated condition. |