A review on effect of minor alloying elements on thermal cycling and drop impact reliability of low‐Ag Sn‐Ag‐Cu solder joints

Abstract

Purpose -The purpose of this paper is to discuss the reliability of board level Sn-Ag-Cu (SAC) solder joints in terms of both thermal cycling and drop impact loading conditions, and further modification of the characteristics of low Ag-content SAC solder joints using minor alloying elements to withstand both thermal cycle and drop impact loads. Design/methodology/approach -The thermal cycling and drop impact reliability of different Ag-content SAC bulk solder will be discussed from the viewpoints of mechanical and micro-structural properties. Findings -The best SAC composition for drop performance is not necessarily the best composition for optimum thermal cycling reliability. The content level of silver in SAC solder alloys can be an advantage or a disadvantage depending on the application, package and reliability requirements. The low Ag-content SAC alloys with different minor alloying elements such as Mn, Ce, Bi, Ni and Ti display good performance in terms of both thermal cycling and drop impact loading conditions. Originality/value -The paper details the mechanical and micro-structural properties requirements to design a robust bulk SAC solder joint. These properties provide design and manufacturing engineers with the necessary information when deciding on a solder alloy for their specific application.

Microstructure and morphology of the soldering interface of Sn–2.0Ag–1.5Zn low Ag content lead-free solder ball and different substrates

“…Wang et al [ 17 , 18 ] studied the Sn–Ag–Cu Ternary Metal Coating Solder, they found that with the increase of Ag content, the elongation will decrease obviously, and the alloy strength will increase. This is because the number of Ag 3 Sn particles will increase during the aging process, causing cracks to form along the particle interface [ 19 ] found poor thermal cycling performance and impact resistance of low silver content Sn–Ag–Cu solders. After adding Cu components to Sn–Ag–Cu solder, the comprehensive properties of all aspects have been greatly improved, but the wettability has decreased significantly high, which is quite different from Sn–Pb solder [ [20] , [21] , [22] ].…”

Analysis of Microstructure and Mechanical Properties of Bismuth-Doped SAC305 Lead-Free Solder Alloy at High Temperature

“…These stresses are induced in solder joints due to the different coefficients of thermal expansion of electronic components and circuit board on which solder joint is made [5]. Solder joints are also responsible for keeping the electronic components intact, which means they must possess excellent mechanical and thermo-mechanical properties to support the components [6].…”