19-20 October 2006, Trnava, Slovak Republic 430 CO-MAT-TECH 2006 TRNAVA, 19 - 20 October 2006 THERMAL AND MATERIAL PROPERTIES OF LEAD-FREE SOLDERS Janka CHRIAŠTEĽOVÁ 1 , Milan OŽVOLD 1 , Matej JERGEL 2 1 Department of Materials Engineering, Faculty of Materials Science and Technology, Slovak University of Technology, Pavlínska 16, 917 24 Trnava, Slovak Republic, babulaj@pobox.sk, milan.ozvold@stuba.sk 2 Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11 Bratislava, Slovak Republic, 1 INTRODUCTION Intensive studies on the development of lead-free solder alloys have been carried out, due to environmental and health concerns about products that contain lead. Lead-free solders have been required to substitute the traditional Pb-Sn solder alloys as the major interconnecting materials in electronic packaging process. At present several lead-free solder alloys such as Sn–Ag, Sn-Cu and Sn–Zn alloys have showed potential for replacing traditional Sn–Pb solder. One of the important requirements for the electronics solders is their processing temperature, which is required to be as low as the Sn–Pb eutectic alloy [1]. In this paper the material properties of several Pb-free Sn-based alloy systems have been studied. Differential Scanning Calorimentry (DSC) was used to determine the thermal properties of solders, as in our previous contribution [2]. For the study of the phase analysis X-ray diffraction methods were used. For experiment the eutectic or near eutectic solders with the following compositions: Sn96.5Ag3.5, Sn91Zn9, Sn99.3Cu0.7, Sn95Cu4Ag1, Sn95.8Ag3.5Cu0.7 have been chosen (all composition are given in weight percentages). In particular, Sn-Zn eutectic alloy has been much expected as a candidate for Pb-free solder material, because Zn is available with low cost and the melting temperature of the alloy (199°C) is close to that of Sn-Pb eutectic solder, compared with other Sn-based eutectic alloys (e.g., Sn-Cu:227°C, Sn-Ag:221°C, Sn-Cu-Ag: 221°C), which allows us to use the current reflow process and apparatus. The Sn-Cu-Ag solders are also important because they are generally recognised as the first choice for lead-free solder. Ternary alloy of the eutectic composition Sn95.8 Ag3.5Cu0.7 was reported to have the eutectic temperature 221°C, which is lower melting temperature than those of Sn-Ag and Sn-Cu systems.