Formation Mechanism of Porous Cu3Sn Intermetallic Compounds by High Current Stressing at High Temperatures in Low-Bump-Height Solder Joints
نویسندگان
چکیده
Electromigration tests of SnAg solder bump samples with 15 μm bump height and Cu under-bump-metallization (UBM) were performed. The test conditions were 1.45 ˆ 104 A/cm2 at 185 ̋C and 1.20 ˆ 104 A/cm2 at 0 ̋C. A porous Cu3Sn intermetallic compound (IMC) structure was observed to form within the bumps after several hundred hours of current stressing. In direct comparison, annealing alone at 185 ̋C will take more than 1000 h for porous Cu3Sn to form, and it will not form at 170 ̋C even after 2000 h. Here we propose a mechanism to explain the formation of this porous structure assisted by electromigration. The results show that the SnAg bump with low bump height will become porous-type Cu3Sn when stressing with high current density and high temperature. Polarity effects on porous Cu3Sn formation is discussed.
منابع مشابه
Electromigration enhanced intermetallic growth and void formation in Pb-free solder joints
A kinetic analysis was formulated for electromigration enhanced intermetallic evolution of a Cu–Sn diffusion couple in the Sn-based Pb-free solder joints with Cu under bump metallurgy. The simulated diffusion couple comprised the two terminal phases, Cu and Sn, as well as the two intermetallic phases, Cu3Sn and Cu6Sn5, formed between them. The diffusion and electromigration parameters were obta...
متن کاملRecent advances on kinetic analysis of electromigration enhanced intermetallic growth and damage formation in Pb-free solder joints
A comprehensive kinetic analysis was established to investigate the electromigration (EM) enhanced intermetallic compound (IMC) growth and void formation for Sn-based Pb-free solder joints with Cu under bump metallization (UBM). The kinetic model takes into account Cu–Sn interdiffusion and current stressing. Derivation of the diffusion coefficients and the effective charge numbers for the inter...
متن کاملSecondary IMC formation induced by Kirkendall voiding in Cu/Sn3.5Ag solder joints
In this investigation on the formation of multiple-layered Kirkendall voids at Cu/Sn– 3.5Ag solder joints, Sn–3.5Ag solder balls were reacted with Cu under bump metallurgy (UBM), which was electroplated using bis-sodium sulfopropyl–disulfide, C6H12O6S4Na2 (SPS) additive. The sequence of multilayer Kirkendall voids and Cu–Sn IMC (intermetallic compounds) formations are explained with the aid of ...
متن کاملMeasurement of electromigration activation energy in eutectic SnPb and SnAg flip-chip solder joints with Cu and Ni under-bump metallization
Electromigration activation energy is measured by a built-in sensor that detects the real temperature during current stressing. Activation energy can be accurately determined by calibrating the temperature using the temperature coefficient of resistivity of an Al trace. The activation energies for eutectic SnAg and SnPb solder bumps are measured on Cu under-bump metallization (UBM) as 1.06 and ...
متن کاملMechanism of electromigration-induced failure in the 97Pb–3Sn and 37Pb–63Sn composite solder joints
The electromigration-induced failure in the composite solder joints consisting of 97Pb–3Sn on the chip side and 37Pb–63Sn on the substrate side was studied. The under-bump metallization ~UBM! on the chip side was 5 mm thick electroplated Cu coated on sputtered TiW/Cu and on the substrate side was electroless Ni/Au. It was observed that failure occurred in joints in a downward electron flow ~fro...
متن کامل