films had numerous nodules and whiskers growing from the surface see fig4 3500 u00d7 magnification after 12 000 hours of aging and fig5 300 u00d7 magnification after 12 000 hours of aging in contrast the germanium doped tin plated films had zero whiskers develop across the 1 mm 2 area evaluated over the same 6 month 12 month and 18 month evaluation periods see fig6 1000 u00d7 magnification after 12 000 hours of aging as shown in the example above various surfactants may be added to the electrolyte solution containing the germanium and tin preferred surfactants are non ionic surfactants that act as leveling agents to help obtain a substantially uniform coating when plating onto a substrate preferred surfactants include triton x 100 igepal ca 630 nonidet p 40 conco ni dowfax 9n igepal co makon neutronyx 600 series nonipol no plytergent b renex 600 series solar no sterox serfonic n t det n tergitol np triton n etc with triton x 100 being particularly preferred without being bound to a particular theory it is believed that the d l tartaric acid serves to complex the germanium ions and probably the tin ions in solution in theory two metals with different electromotive potentials cannot be practically plated at the same time this limitation is usually overcome by chemically complexing one or both metals which effectively brings their electromotive potentials closer together and allows them both to be plated deposited at the same time other complexing agents that may work for the tin and germanium system include without limitation citric acid succinic acid aspartic acid edta mannitol or any organic compound with carboxylic acid groups or other groups capable of complexing metal ions in solution etc the germanium doped tin coatings affected through the processes.