Termination issues, high performance

Although silver to palladium ratios of 3 1, 4 1, and 6 1 are commonly used in hybrid apphcations, thrifted versions utilizing Pd contents less than 5% have been shown to have good leach resistance in 62% Sn-36% Pb-2% Ag solders. Table 8.4 compares properties of various Ag Pd ratios. These materials meet the requirements of high-conductivity materials needed for circuits with higher speeds and densities. Similar performance can be met by small additions of platinum to silver (1 100). The leach resistance of a 1 % Pt addition is shown to be equivalent to a 10 percent Pd addition with minimum effect on conductivity. However, Ag migration such as dendritic growth and diffusion into resistors or capacitors when used as a termination material is stUl an issue with only minor Pd or E t additions. 

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