High temperature lead-free solder for microelectronics

Abstract

A11 A1 A14 A21 Alloy Codes -1st Fail -2P 0.1% -2P Mean -3P Gamma A32 A62 A66 0.00 0.50 1.00 1.50 2.00 2.50 Relative LifeThis paper reports results of a four-year industrial consortium effort to develop leadfree solders for high-temperature applications (up to 160∞C). Work included preliminary evaluations of 32 tin-based alloys, a screening of the thermomechanical fatigue performance of 13 promising alloys, and a full manufacturability and fatigue testing of the seven most promising of those alloys, namely . Eight different components were used on the reliability test vehicle, and the alloys were compared through Weibull analysis. In addition, the same seven experimental alloys were tested with ball grid array packages cycled up to 100∞C or 125∞C. All the leadfree alloys performed well, but those containing bismuth showed especially outstanding performance. In general, the ternary and higher alloys performed as well or better than the industry standard tin-silver eutectic, suggesting that solders other than the tin-silver eutectic should be considered for high-reliability, high-temperature applications.

Creep Behavior of Bi-Containing Lead-Free Solder Alloys

“…10 SAC-Bi was the best or second-best performing alloy with respect to lifetime measured in thermal cycles for most tests and components. 7,8 Based on these results, SAC-Bi was selected for inclusion in the Joint Commission on Aging Aircraft-Joint Group on Pollution Prevention (JCAA-JGPP), where test environments were intended to reflect aerospace and military testing and deployment conditions. 11 Despite these promising results, the alloys had not been extensively characterized or developed after the reliability test programs.…”

Utilization of a Porous Cu Interlayer for the Enhancement of Pb-Free Sn-3.0Ag-0.5Cu Solder Joint

“…To date, Sn-3.0Ag-0.5Cu (SAC305) solder alloy has been proposed as a promising alternative to replace the lead containing solder alloys in electronic applications due to its favourable mechanical properties including superior resistance to creep and thermal fatigue [3,7,8]. This solder is generally applied in commercial microelectronic devices where the operating temperature usually does not exceed 260 • C. However, due to the higher melting temperature of SAC305 solder alloy (217 • C) compared to the conventional Sn-Pb solder alloy (183 • C), SAC305 solder alloy is thus more viable for middle-temperature-ranged applications [9].…”

Surface properties and wetting characteristics of liquid Ag–Bi–Sn alloys

“…High-temperature solders with melting temperatures above 550 K are widely used in the electronics industry for advanced packing technologies [3,4]. The Ag 4.7 Bi 95.3 eutectic alloy exhibits an acceptable melting point (535.5 K), has hardness similar to that of Pb-5Sn (wt%), and affordable cost.…”