Characterization of mechanical testing on lead free solder on electronic application

Abstract

Soldering is a well-known metallurgical joining method that uses the solder in which two or more metal items are joined together by melting and flowing a filler metal solder into the joint. It is widely used in the electronic applications. In parallel with the need of lead free solder, the usage of Pb is eliminated and addition of compositions such as Zn, Al, Cu and Ag has been introduced in the Sn-based solder. This is in order to produce better solder alloy for the electronic packaging. Also additions of rare earth (RE) elements are such as Bi, Sb, In, Co, Mn and etc are introduced to produce the solder alloy. In this paper, the mechanical properties of the Sn-9Zn/Cu alloy and Sn-4Zn-6Bi/Cu alloy which is tested based on the shear test and tensile test. Sn-9Zn alloy has been found out to be the better substitute of the Pb-based alloy due to its melting point of 198°C which is important for the assembly of electronic packaging. Zn is also a composition which is of low cost and this helps to overcome the high spending of any electronic company. The Sn-4Zn-6Bi alloy has been found to have better mechanical properties than Sn-9Zn alloy. The addition of Bi has decreased the melting point to 189°C. Besides that, the addition of Bi enhances the shear strength of the solder joint as well as possessing a better mechanical characteristic. This shows the Sn-4Zn-6Bi can be a better choice of a leads free solder. Test was conducted using lap shear test with three different crosshead speed using both the alloys after reflowed temperature of 230°C, 250°C and 270°C. All this measure is taken in to serious consideration and importance for producing the better lead free solder.