The Effects Of High Magnetic Field On The Growth Behaviors Of Tin-copper Intermetallic Compounds (IMC) Layers

The high magnetic field (HMF) not only can control the process of physical or chemical reaction, but also can apply heavy intensity magnetizing energy to mass on the scale of atom or molecule, to change its arrange, match, migration and diffusion behaviors. Then the atom behaviors of the dissimilar substance will be obviously different with or without HMF.This paper investigated the effects of high magnetic field on the growth behaviors of tin-copper intermetallic compounds (IMC) layers. The effects on the intermetallic compound growth behaviors of the Sn/Cu soldering and diffusion welding joints interfaces were studied. And Sn-3Ag-0.5Cu/Cu joints were studied, too. The results are shown as follows:1 With the prolonging of the aging time, the shape of IMC had changed from small sawtooth type to wave type gradually. The growth rates of the Sn-3Ag-0.5Cu/Cu IMC were enhanced in the high magnetic field, and the growth activation energy is about 16kJ/mol (without HMF) and 51kJ/mol (with HMF). The HMF reduced the growth activation energy of the Sn-3Ag-0.5Cu/Cu joints.2. The appearance of the IMC changed clearly after ageing. The IMC of the soldering samples is fluctuant, and the crystals are claviform;the fluctuation of the diffusion welding samples' IMC is slight, and the crystals are regular polyhedron. The growth velocity of the IMC increased with the rising of the ageing temperature. The IMC growth velocity of soldering joints were faster than that of the diffusion welding joints, and the diffusion activation energy of the soldering joints is lower than that of the diffusion welding joints. The activation energy of the soldering joints is 52kJ/mol;the diffusion welding joints is 94kJ/mol. The growth of the IMC is controlled by grain interface diffusion when the aging temperature is lower, and controlled by body diffusion when the aging temperature is higher.3. The IMC growth velocity of the two types of welding joints increased with the rising of temperature when they were aged in the HMF. The IMC growth rate of the soldering joints were placed with the magnetic direction along the Sn diffusion direction (Direction II) is higher than that along the Cu diffusion direction (Direction I ). The effects of the HMF direction on the diffusion welding joints are unobvious. The growth rates of the soldering joints are quickly than that of the diffusion welding joints.4. The effects of the HMF on the IMC growth behaviors are the same with the Sn-3Ag-0.5Cu/Cu joints and Sn/Cu joints no matter what solder and substrate were welded. The IMC growth rates of the soldering joints were placed with the magnetic direction along the solder diffusion direction (Direction II) is higher than that along the substrate diffusion direction (Direction I). The IMC growth rates are the fastest when the solder is multi-components alloy because of the effects of alloy elements.5. According to the XRD-results, we found that the high magnetic field effects on the phase and the Cu^Sns crystals alignment is unobvious.