Thermal Stability Characterization of the Au–Sn Bonding for High-Temperature Applications

Abstract

There is a need for electromechanical devices capable of operating in high-temperature environments (> 200°C) for a wide variety of applications. Today's wide-bandgap semiconductor-based power electronics have demonstrated a potential of operating above 400°C, however, they are still limited by packaging. Among the most promising alternatives is the Au-Sn eutectic solder, which has been widely used due to its excellent mechanical and thermal properties. However, the operating temperature of this metallurgical system is still limited to ∼250°C owing to its melting temperature of 280°C. Therefore, a high-temperature-resistant system is much needed, but without affecting the current processing temperature of ∼325°C, typically exhibited in most high-temperature Pb-free solders. In this paper, we present the development and characterization of a fluxless die-attach soldering process based on goldenriched solid-liquid interdiffusion (SLID). A low-melting-point material (eutectic Au-Sn) is deposited in the face of a substrate, whereas a high-melting-point material, gold in this instance, is deposited in its mating substrate. Deposition of all materials was performed using a jet vapor deposition (JVD) equipment where thicknesses are controlled to achieve specific compositions in the mixture. Sandwiched coupons are isothermally processed in a vacuum reflow furnace for different reflow times. Postprocessed samples confirm the interdiffusion mechanism as evidenced by the formation of sound joints that prove to be thermally stable up to ∼490°C after the completion of the SLID process. Differential scanning calorimetry demonstrate the progression of the SLID process by quantifying the remaining low-meltingpoint constituent as a function of time and temperature, this serving as an indicator of the completion of the soldering process. Mechanical testing reveals a joint with shear strength varying from 39 to 45.5 MPa, demonstrating to be stable even after 500 h of isothermal aging. Moreover, these investigations successfully demonstrate the use of the Au-Sn SLID system and the JVD technology as potential manufacturing processes and as a leadfree die-attach technology.Index Terms-Fluxless, hermetic packages, isothermal solidification, jet vapor deposition (JVD), lead-free, shear strength, SLID, solder, transient liquid phase (TLP) bonding.

A Review of SiC Power Module Packaging: Layout, Material System and Integration

“…Transient Liquid Phase Bonding (TLPB) realized by bonding of parent materials with pre-deposited low-melting metal layer, whereas Transient Liquid Phase Soldering (TLPS) involves usage of the printed standard soft solders as interlayer for intermetallic phase (IMP) formation [77], [86]- [89]. The diffusion solder have Ag/In [90], [91], Ag/Sn [92], Au/In [93], [94], Au/ Sn [95], [96], Cu/Sn [97], [98], and Ni/Sn [99]. Considered the cost and environment friendly, the Cu-Sn alloy solder has been a good candidate for high temperature applications.…”

Interfacial reaction and mechanical properties for Cu/Sn/Ag system low temperature transient liquid phase bonding

“…In general, LTTLP bonding process is often conducted at temperatures higher than melting point of the interlayer by a range of 15-120°C, and bonding time mainly depends on the thickness of the interlayer [9,[15][16][17][18][19]. Most of studies concentrated on microstructure evolution [9,21,23], interfacial reaction [12,13,21], kinetics of the IMCs growth [12,13], thermal reliability [24,25], and electrical or mechanical behaviors of the joints [9,11,23] for above systems applied in electronic packaging and interconnects.…”

Effect of Strain Rate and Temperature on Tensile Properties of Bi-Based Lead-Free Solder

“…Although many studies on lead-free high-melting point solder have been conducted, the optimum substitute materials for Pb-rich solder have not been developed. Now, lead-free high-melting point solder is not regulated by RoHS restriction yet, but such lead-free solder is expected to be developed [1][2][3][4][5] . Pb-(5-10 mass%)Sn solder, however, are still considered the material of choice for high temperature applications due to the inherent limitations of Pb-free solders, including wettability, reliability, and cost 6) .…”