Real-time contact angle's measurement of molten solder balls in laboratory conditions

Purpose The purpose of this paper is to show a possibility to measure a change of a contact angle during the melting in real-time and to reveal significant factors of a wettability. Influence of the flux with combination of plasma on copper surface was investigated in experiment as well. Design/methodology/approach Laboratory equipment consists of heating and optical part that was developed and tested for real-time contact angle's measurements. Solder balls based on Sn96.5/Ag3/Cu0.5 and Sn63Pb37 spread out on a copper substrate during a melting process. The wettability of pure copper surface was compared with copper surface treated with flux or combination plasma-flux. The contact angle and spreading rate of a melted solder balls observed by the charged-coupled device camera were analyzed in real-time and measured using the JavaScript. Findings Laboratory equipment allows for analysis of contact angle and spreading rate in real-time during the melting process. The contact angle decreases more noticeable after applying the plasma-flux treatment in contrast to no flux or flux treatment only. Using the plasma treatment before application of the flux improves the wettability and the effectivity of the flux activity on the copper surface during the melting process. Originality/value The interpretation of the results of such a comprehensive measurement leads to a better understanding of the mutual relation between flux and combination plasma-flux of the wetting during the melting process. The simple, cheap, fast and accurate laboratory equipment, which consists of the heating and the optical part, allows for the wettability evaluation of the melting process in real-time.