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The failure mechanism of the electromigration in Ag-Pd bonding wires was investigated through stressing with a current density of 1.23 × 105 A/cm2 at temperatures of 150 °C to 300 °C. It was found that the grains of the wire materials grew rapidly during current stressing for 100 minutes at various temperatures. In contrast, the grain structure remained almost unchanged after storage at these temperatures for 100 minutes without current stressing. The mean-time-to-failure (MTF) for various current-stressed Ag-Pd alloy wires decreased with increases in Pd content. The activation energy for the electromigration of these wire materials was measured, and the results indicated that the main driving force was surface diffusion of Ag. [ABSTRACT FROM AUTHOR]

The materials characteristics of annealing-twinned Ag-alloy wires with various Au and Pd contents were evaluated in this paper. The results indicated that both Ag–8Au–3Pd and Ag–15Au–3Pd have higher strength and corrosion resistance than do pure Ag and binary Ag-Pd wires. On the other hand, the pure Ag, Ag–0.5Pd, Ag–3Pd, and Ag–4Pd wires possess the merits of lower material cost, higher electrical conductivity, and higher electromigration durability than do the ternary Ag-Au–Pd wires. However, the breaking load and elongation of pure Ag wire are inferior to those of Ag–0.5Pd, Ag–3Pd, and Ag–4Pd wires. In addition, the corrosion resistances of pure Ag and Ag–0.5Pd wires are far inferior to those of Ag–3Pd and Ag–4Pd wires. Based on these performances, the ternary Ag–8Au–3Pd wire is an ideal substitute for the traditional Au wire due to its high strength, corrosion resistance, and reliability, while the Ag–3Pd and Ag–4Pd are cost-friendly bonding wires for high-frequency integrated circuit devices. [ABSTRACT FROM PUBLISHER]

The mechanism of electromigration in Ag-alloy wires containing different amounts of Pd and Au has been studied. Thinning and thickening accompanying grain growth were observed in worn bonding wire after current stress. The mean time-to-failure of bonding wires stressed with different current densities is highly dependent on their electrical resistivity, and wire temperature increases during current stress, owing to the Joule effect. An indirect method is proposed for in situ assessment of the temperatures of these fine wires under current stress. A mode of failure of these bonding wires was deduced by kinetic analysis. This mode can be correlated with atomic diffusion in the wire. [ABSTRACT FROM AUTHOR]

Ag-4Pd binary alloy wire has been produced as an alternative to a previously developed Ag-8Au-3Pd ternary alloy wire to meet requirements for high electrical conductivity and low cost. The electrical resistivity of this Ag-4Pd bonding wire, manufactured with a conventional method, is 3.7 μΩ cm, close to the values of traditional 3N Au wire (3.5 μΩ cm) and Pd-coated Cu wire (1.8 μΩ cm). To further improve the performance of this bonding wire, a large amount of annealing twins were introduced in this Ag-4Pd alloy wire through an innovative concept of sequential drawing and multiple annealing processes. The resulting electrical resistivity of this annealing-twinned Ag-4Pd wire is 3.5 μΩ cm. In contrast to the apparent increase in grain size in the conventional Ag-4Pd wire under electrical stressing with a current density of 1.23 × 10 A/cm for various times, the grains in this annealing-twinned wire grow much more slowly. The breaking load and elongation of this annealing-twinned Ag-4Pd wire are also higher than those of conventional wire. Furthermore, annealing twins increase the durability to electromigration of this Ag-4Pd wire under electrical stressing with various current densities. [ABSTRACT FROM AUTHOR]

The durability against electromigration of an annealing twinned Ag-8Au-3Pd wire is about double that of the conventional grained wire under electrical current stressing of 1.23 × 10 A/cm. During electromigration, a particular morphology of surface reconstruction comprising a stepwise structure and hillocks can be observed in this annealing twinned wire. The stepwise structure, which has been correlated to longer electromigration life, is postulated to result from dislocation slips driven by electron wind collisions and thermal diffusion of metallic atoms. The simultaneous processes of primary and secondary slips in crossing directions cause hillocks to form at the intersections of both slips. The results also indicated that the electrical current could enhance the grain growth in both wires but had an insignificant effect on the formation of annealing twins. [ABSTRACT FROM AUTHOR]

An innovative Ag-8Au-3Pd bonding wire with a high twin density has been produced. The grain size of this annealing-twinned wire changes moderately during electrical stressing, unlike that of the conventional grained wire, which increases drastically and even leads to a bamboo structure. In addition, the durability against electromigration of the annealing-twinned Ag-8Au-3Pd alloy wire is higher than that of the conventional grained wire. This higher durability can be ascribed to the surface reconstruction of a stepwise morphology and slow grain growth resulting from the abundance of annealing twins in this wire. [ABSTRACT FROM AUTHOR]

Abstract: It has previously been established that Sn-9Zn-0.5Ce alloy possesses mechanical properties superior to those of undoped Sn-9Zn alloy, and is free of the problem of rapid whisker growth. However, no detailed studies have been conducted on the electromigration behavior of Sn-9Zn-0.5Ce alloy. In this research, Sn-9Zn and Sn-9Zn-0.5Ce solder joints with Au/Ni(P)/Cu and Ag/Cu pads were stressed under a current density of 3.1×104 A/cm2 at room temperature for various periods of time. Due to finer grain sizes, the electromigration effects were more severe in Sn-9Zn-0.5Ce solder joints than in Sn-9Zn solder joints when joint temperature was around 80°C. In addition, both solder joints (Sn-9Zn and Sn-9Zn-0.5Ce) with Au/Ni(P)/Cu pads possess longer current-stressing lifetimes than those with Ag/Cu pads because Ni is more resistant than Cu to migration driven by electron flow. [Copyright &y& Elsevier]

Ag-alloy bonding wire has excellent physical properties and is widely applied in microelectronics, but growing concerns about circuit failure induced by electromigration (EM) have raised doubts about this material. One point of frequent debate is the diffusion mechanism. This study provides a novel perspective by investigating the evolution of the microstructure via electron backscatter diffraction (EBSD) to settle the controversy over the diffusion mechanism of Ag-alloy bonding wire during EM. Particular focuses are the propensity for grain growth, the effects of the coincidence site lattice (CSL) on the grain boundary network, the texture transition, and the influence of thermal energy during EM. A stage-like transition in the dominant diffusion mechanism in different stages of EM is proposed and substantiated from the viewpoint of microstructure evolution. • Microstructure evolution of the Ag-4 Pd bonding wire during electromigration. • Effect of coincidence site lattice and thermal effect on grain boundary migration during EM is discussed. • Failure mechanism of the Ag-4 Pd bonding wire during EM is elucidated. • Stage-like diffusion path transition was substantiated through the texture study. [ABSTRACT FROM AUTHOR]

Abstract: It has previously been established that adding 0.2wt.% Zn into a Sn–3Ag–0.5Cu–0.5Ce alloy improves the mechanical properties and eliminates the problem of rapid whisker growth. However, no detailed studies have been conducted on electromigration behavior of Sn–3Ag–0.5Cu–0.5Ce–0.2Zn alloy. The electromigration damage in solder joints of Sn–3Ag–0.5Cu and Sn–3Ag–0.5Cu–0.5Ce–0.2Zn with Ag/Cu pads and Au/Ni(P)/Cu pads was studied after current stressing at room temperature with an average current density of 3.1×104 A/cm2. With additions of 0.5wt.% Ce and 0.2wt.% Zn, the electromigration processes of Sn–Ag–Cu solder joints were accelerated due to refinement of the solder matrix when joint temperature was around 80°C. Since Ni is more resistant than Cu to diffusion driven by electron flow, solder joints of both alloys (Sn–3Ag–0.5Cu and Sn–3Ag–0.5Cu–0.5Ce–0.2Zn) with Au/Ni(P)/Cu pads possess longer current-stressing lifetimes than those with Ag/Cu pads. [Copyright &y& Elsevier]