Wetting and spreading kinetics in Sn/Cu system: application to electronic packaging

O. Liashenko, F. Hodaj
Grenoble Institute of Technology,

Keywords: wetting, spreading, reactivity, interfaces, metal/metal systems


Interfacial interactions - wetting and reactivity between liquid tin or tin-based alloys and copper substrate are of great interest in microelectronic packaging industry. Despite the fact that numerous studies have been performed on this subject, the initial stage of wetting has not been investigated in details and the corresponding contact angles are not well defined. In this work the wetting and spreading kinetics of a tin drop on a copper surface, in the temperature range 250 to 800°С, are studied by using the transferred drop technique in a metallic furnace under high vacuum and a rapid camera. The spreading kinetics from the initial to the final contact angle strongly depends not only on the type of intermetallic layer formed on the Sn-side but also on the experimental temperature. In order to determine the different stages of the spreading kinetics (non reactive and reactive spreading regime), specific experiments on the bulk Cu6Sn5 and Cu3Sn intermetallic compounds as well as on the Cu oxide substrates are performed. Experimental results are analyzed in the framework of non-reactive and reactive wetting processes and in relation with the miniaturization trend in electronic packaging industry.