Electrodeposited tin properties & their effect on component finish reliability

Electrodeposited pure tin finishes on electronic components are a leading contender to replace the industry standard tin-lead. Since the electrodeposited finish directly influences the critical reliability characteristics of the component itself, the nature of the Pb-free component finish must be well characterized and understood. Only through a thorough examination of the attributes of the electroplated tin deposit can critical decisions be made regarding component finish reliability. This paper investigates the properties of electrodeposited tin that may have an effect on component reliability, namely, grain structure (size and shape), oxide formation, tin whisker formation, and solderability. Data is presented from laboratory and production settings, with the objective being to enable manufacturers to draw their own conclusions regarding previously established perceptions and misconceptions about electrodeposited tin properties.