Additionally, the users noticed that SAC305 exhibits some limitations concerning the reliability, especially degradation of mechanical properties when exposed to elevated temperatures and during aging, fragility of solder joints in drop/shock testing, intensive tin whisker formation and voiding formation. Very soon, after the mass adoption of SAC305 alloy as Pb-free solder of choice, the price of Ag and in turn, SAC305 increased rapidly. The solder alloys containing 3-4Wt.% belong to the group of high-Ag bearing alloys. Some industries also adopted other SAC alloys such as Sn3.8Ag0.7Cu (SAC387) and Sn4.0Ag0.5Cu (SAC405), which were eutectic ternary alloys with single melting point at 217☌, but they were more expensive because of the higher silver content ( Weng, 2017). The near eutectic ternary alloy Sn3.0Ag0.05Cu (SAC305) of melting temperature in the range 217☌-219☌ was recommended by the IPC Solder Value Product Council as the preferred option for surface mount technology assembly. Finally, SAC system alloys had been chosen as the primary lead-free solders for attaching electronic devices to printed circuit boards (PCBs). Tin copper (SnCu), tin silver (SnAg) and tin silver copper (SnAgCu or SAC) were the dominate candidates for replacement. The implementation of Restriction of Hazardous Substances Directive 2002/95/EC (RoHS1) in 2006 and afterwards its extension as RoHS2 2011/65/EU in 2013 forced electronic industry to look for alternatives of tin-lead eutectic alloy Sn37Pb, which had been used for soldering for decades. ![]() The full terms of this licence may be seen at Anyone may reproduce, distribute, translate and create derivative works of this article (for both commercial and non-commercial purposes), subject to full attribution to the original publication and authors. ![]() This article is published under the Creative Commons Attribution (CC BY 4.0) licence. Copyright © 2020, Barbara Dziurdzia, Maciej Sobolewski, Janusz Mikołajek and Sebastian Wroński.
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