Low Cycle Fatigue Properties of Ni added Low Silver Content Sn-Ag-Cu Flip Chip Interconnects

Abstract

The straddle fatigue test has been performed to study the fatigue properties of Sn-1.2 mass%Ag-0.5 mass%Cu-0.05 mass%Ni for flip chip interconnections. The low cycle fatigue resistance of the alloy is equivalent to that of Sn-3 mass%Ag-0.5 mass%Cu alloy, even though the fatigue endurance of Sn-1 mass%Ag-0.5 mass%Cu alloy was poorer than that of the 3 mass%Ag alloy. The alloy has fine microstructure and Ag 3 Sn intermetallic compound makes a network structure together with fine (Cu,Ni) 6 Sn 5 compound. The microstructure resulted in high cyclic strain hardening exponents, which leaded to good low cycle fatigue endurance of the alloy.

Thermal Fatigue Properties of Sn-1.2Ag-0.5Cu-<i>x</i>Ni Flip Chip Interconnects

“…Recently, thermal 7) and isothermal fatigue properties 8) of Sn-1.2Ag-0.5Cu solder joints are improved by a small amount of nickel addition (0.05 mass%Ni) into the solder, and thermal fatigue life of Sn-1.2Ag-0.5Cu-0.05Ni solder joint is shown as long as that of Sn-3Ag-0.5Cu. 7) These properties strongly correlate to microstructure of the solder, and good thermal fatigue properties of Sn-1.2Ag-0.5Cu-0.05Ni are due to both fine Sn grains in an initial solder joints and suppression of Sn-grain-coarsening after thermal fatigue test.…”

Reliability of Solder Joint with Sn&ndash;Ag&ndash;Cu&ndash;Ni&ndash;Ge Lead-Free Alloy under Heat Exposure Conditions

“…1,2) Among lead-free solders, ternary Sn-Ag-Cu solders [3][4][5][6][7][8][9][10][11] are expected to be the substitute of a Sn-Pb eutectic solder, and have become wide spread in the manufacture of many electronic devices. However, the advanced lead-free solder, which has higher reliability than ternary Sn-Ag-Cu solders, is required to be used for various industry machines.…”

Deformation Fracture Characteristics of Microelectronic Sn-3.0Ag-0.5Cu-<I>x</I>Ni Solders

“…Figure 7 shows a comparison of the tensile fracture subsurface of specimens with varying Ni content, and the fracture characteristics show that the -Sn phase possessed a tensile plastic deformation flow after tensile testing, thus the -Sn phase was the main deformation mechanism. According to relevant reports [8][9][10][11][12][13][14][15][16] and comparing Fig. 3 with Fig.…”

“…[1][2][3] Under drop tests and pull tests, many reports have shown that the fracture resistance of Sn based solders can be enhanced by a very small addition of Ni, RE etc. [4][5][6][7][8] Also, related studies 4,5,[9][10][11][12][13] have revealed that Ni addition (>3000 ppm) has a significant influence on the microstructure, creep, shear strength, fatigue properties and the characteristics of intermetallic compounds (IMC) in the interface. However, the studies emphasized the interfacial effect between solders and substrate; the relationship between the bulk solder and microsegregation has not been examined.…”

“…So, understanding the deformation resistance of the bulk solders is an important subject. Many studies have discussed the characteristics of the (CuNi) x Sn y IMCs layer in Ni/Au pad and OSP pad, 4,5,[9][10][11][12][13] however, the addition effect of Ni ( 3000 ppm) in the bulk microstructure and the relevant fracture properties have still not been examined. Owing to the effect of Ni addition being closely related to the solder microstructural characteristics and the solder joint reliability, this study uses Sn-3.0Ag-0.5Cu-xNi solders not only to analyze the characteristics of (CuNi) x Sn y compounds, but also investigate the deformation fracture mechanism under tensile testing and vibration testing.…”