Effect of cooling rate on Ag<inf>3</inf>Sn formation in Sn-Ag based lead-free solder

Abstract

Effect of solidification cooling rate on Ag 3 Sn formation and its morphological appearance in Sn-Ag based lead-free solder was investigated. Depends on cooling rate, three types of Ag 3 Sn compound with different morphologies may form by solidification. They are particle-like, needle-like, and platelike respectively. Small particle-like Ag3Sn in large amount was occurred by rapid cooling, where plate liked Ag 3 Sn was formed by slow cooling condition. Extremely slow cooling such as furnace cooling results large plate-like or pillar-like Ag 3 Sn to form, particularly in solder matrix adjacent to the solder/Cu interface. The enrichment of Sn in Cu 6 Sn 5 IMC layer formation at interface causes Sn depletion at the adjacent area near the interface. As a result, Ag atoms were enriched relatively which favored formation and growth of primary Ag3Sn in liquid phase.

Investigating the thermomechanical properties and intermetallic layer formation of Bi micro-alloyed low-Ag content solders

“…The main aim of these studies was to find lead-free solder alloys with lower cost, but with the same quality properties as the commercially available SAC alloys (SnAgCu -Tin-Silver-Copper) by reducing silver content. Although silver improves the mechanical properties of a lead-free solder joint, the main concern with those alloys is that when improper cooling rate is applied during reflow soldering, large Ag 3 Sn intermetallic compounds (IMC) may form [1][2][3][4][5][6]. Generally, three types of Ag 3 Sn compounds morphology can be found: particle-like, needle-like, and also plate-like.…”

Application of ZnO Nanoparticles in Sn99Ag0.3Cu0.7-Based Composite Solder Alloys

“…The excellent interface bonding between the refined and dispersed Ag 3 Sn particles and the solder matrix results in a better load-transferring ability [39]. The yield stress of the solder joints (due to the piling of dislocations) during a load transfer depends on the interphase spacing between the refined and dispersed Ag 3 Sn particles [42]:…”