Reasearch On The Electromigration Behavior Of The Miniature Lead-free Solder Joint

Along with the development of the electronic products miniaturization and high integration, the components of the lead-free solder joints size is becoming smaller and the current throughout the joints is getting bigger in the field of electronic packaging, which lead to electromigration often happened. The failure of electronic components seriously affect the service life of electronic products. Interface intermetallic compounds(IMC) are the key factor that influence the reliability of the welded joint. Temperature, magnetism and current all have effect on interface intermetallic compounds, but the electromigration research mainly focused on a single action of current or temperature and curren. The research of electromigration behavior under the function of temperature, current and magnetic field has not been reported, so it is necessary to study the behavior of electromigration in multi-fields coupling.The Sn3.0Ag0.5Cu solder alloy was chosed as the object of reference, the electromigration loading device was designed to study the influence of different factors on the electromigration behavior. Joule heat will raise the temperature of the solder joints and increases occurrence of electromigration behavior of solder joints at high current density. Thus lead to the intermetallic compounds significantly increase in the anode interface and the intermetallic compounds increase after the first reduction in the cathode interface. The anode interface intermetallic compounds increase of only 8.8μm at 48 h after silicone oil is added. However, the anode interface intermetallic compounds increase of 21.4μm without silicone oil. Silicone oil can effectively eliminate the heating effect of current to ensure the accuracy of the experiment.The results also show that the effects of high current density and low current density on electromigration behavior are very different. The thickness of anode interface intermetallic compounds increase no matter whether under high current density or low current density, and the higher the current density is, the greater the amount of thickness increase. The cathode interface intermetallic compounds decrease at high current densities, and the greater the current density is, the faster of cathode interface intermetallic compounds reduce. While at low density current, cathode interface intermetallic compounds increase instead of decrease and the higher current density is, the less the thickness of cathode interface intermetallic compounds increase.When current density was 0.8×104A/cm2, magnetic field intensity was 0.4T and the temperature was 120 ℃, 130 ℃ and 150 ℃ respectively, the electromigration behaviors of Cu/SnAg Cu/Cu butt welds were studied. Experimental results show that the higher the temperature is, the more obvious the electromigration phenomenon is, and the more the anode interface intermetallic compounds increase, and the more cathode interface intermetallic compounds reduce.