Assessment of XRF technique as a method to measure percent ag in SnAg solders for flip chip applications

Pb-free SnAg solder has become the industry standard for fabricating flip chip interconnects utilizing C4 (controlled collapse chip connection) technology. One area of interest for manufacturability of Pb-free solders is the ability to control and measure the %Ag composition and its variation from wafer to wafer, chip to chip, and C4 to C4.