Bell metal metal used is a high-tin alloy of copper and tin with approximately a 4:1 ratio of copper to tin (78% copper, 22% tin). This is a much higher tin component than that used in statuary bronze. A range of percentages of tin content can vary from 20 to 26%, depending on the founder who has arrived empirically at their own alloy ratio. It has been found that increasing the tin content increases the decay time of the bell strike, thus making the bell more sonorous. Taking into consideration overall properties, such as tensile strength, hardness, wear resistance, cast quality, sound,
Tin-silver-copper (95%+) tin. For example, the common "SAC305" solder is 3.0% silver and 0.5% copper. Cheaper alternatives with less silver are used in some applications, such as SAC105 and SAC0307 (0.3% silver, 0.7% copper), at the expense of a somewhat higher melting point. SAC alloys are the main choice for lead-free surface-mount technology (SMT) assembly in the electronics industry. SMT is a process where components of circuit assemblies are mounted directly onto the surface of a printed circuit board and soldered in place. SMT has largely replaced “through-hole technology” where components are fitted with wire leads into holes in the circuit