Solid-state intermetallic compound (IMC) growth behavior plays an important role in solder joint reliability of electronic packaging assemblies. The morphology and growth of interfacial IMC compounds between 95.5Sn-3.8Ag-0.7Cu Pbfree solders and nickel/gold (Ni/Au) surface finish on BGA solder joint specimen is reported. Digital imaging techniques were employed in the measurement of the average IMC growth thickness. The IMC growth behavior subjected to isothermal aging exposure at 125°C, thermal cycling (TC), and thermal shock (TS) with upper soak temperatures of 125°C are compared. An equivalent isothermal aging time is proposed for comparison of IMC layer growth data. It was noted that IMC layer growth under thermal cycling and thermal shock aging gives an acceleration factor of 1.4 and 2.3 based on the equivalent isothermal aging time.
Excessive intermetallic compound (IMC) growth in solder joints will significantly decrease the reliability of the joints. IMC growth is known to be influenced by numerous factors during the component fabrication process and in service. It is reported that, other than temperature and holding time, stress can also influence the IMC growth behavior. However, no existing method can be used to study the effect of stress state on IMC growth in a controlled manner. This paper presents a novel method to study the effect of stress on interfacial IMC growth between Sn-Ag-Cu solder and a Cu substrate coated with electroless Ni immersion Au (ENIG). A C-ring was used and in-plane bending induced tensile and compressive stresses were applied by tightening the C-ring. Results revealed that in-plane compressive stress led to faster IMC growth as compared with in-plane tensile stress.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.