Effect of high intensity magnetic field on intermetallic compounds growth in SnBi/Cu microelectronic interconnect

Abstract

The growth kinetics of intermetallic compounds (IMCs) (Cu 6Sn 5 and Cu 3Sn) in eutectic Sn58 wt.%Bi/Cu joints were studied, after they were aged at 85, 100 and 120 °C for different times in 0, 12 Tesla (T) magnetic fields, respectively. The Cu is believed to be dominant species, when Cu and Sn inter-diffuse to form IMCs in the interconnect. When the solder joints were aged in the magnetic field, magnetic field direction (denoted by magnetic flux density B → ) was arranged to be parallel and anti-parallel as well as perpendicular to that of Cu diffusion. The results indicated that chemical compositions of the IMCs formed in magnetic fields were the same as those formed without magnetic field. The IMC growth rate in magnetic field was higher than that without magnetic field. And the activation energy for IMC growth in 12 T magnetic field was 43.29 kJ/mol, lower than 84.45 kJ/mol for IMC growth without magnetic field. The accelerated IMC growth was independent of magnetic field direction. The phenomenon resulted from promoted interfacial reaction by magnetic field.