Effect Of Iron Or Manganese On The Properties Of SAC0307 Solder

As the development of electronic packaging technology and the improvement of technical standards, the use of lead-free solder has become one of the manufacturing standards for new generations of electronic products. But in the industry, the widely used Sn-Ag-Cu solder, which is basically high silver contented, is relatively costly and have poor shock resistance. Although low-silver solder is a good solution to the above two problems, its thermomechanical aging property is poor and its intensity is not very good. In this paper, low-cost solder SAC0307 was used as the matrix, micron-sized Fe particles or Mn particles were added into the solder to improve the performance of low-silver solder, and the proportion of ingredients which is both good for the mechanical property and thermomechanical property was expected to be found.After Fe or Mn were added in SAC0307, the microstructure of SAC0307 solder has been significantly improved. With the increasing proportion of elements by mass, the types of IMC(intermetallic compound) near pads are not changed. However, their morphology become complicated. And as the further increase of addition, parts of the compounds which are formed at pads start to grow independently and irregularly toward the inside of the solder. The average thickness of the IMC interface becomes larger.After Fe or Mn is added, there is little change in the melting point and resistivity of SAC0307 solder. Although wetting time has changed, the maximum wetting force remains the same, and it is a little larger than SAC0307. This shows that the SAC0307 with Fe or Mn meets the requirements of current industrial production standards. Fe or Mn can form tiny IMC which is dispersed in the solder structure, resulting in dispersion strengthening mechanism and improving the homemade solder’s hardness. Addition of trace Fe and Mn helps improve the shear-resistance of solder joints. As the addition amount of Fe or Mn increases, the shear-resistance continues to increase. Combined fracture analysis with mechanical curves, it can be concluded that the fracture mechanism of solders is ductile fracture and the improvement of shear-resistance is related to the dispersion of IMC in joint.