Thermalmechanical behavior of PBGA package during laser and hot air reflow soldering

In this presentation, temperature distribution in a laser reflowed solder balls and warpage of the package upon temperature change was simulated using a finite element method, effects of different laser heating processes on the temperature distribution were discussed in detail. Results of the simulation show that the reflowed solder balls by the laser heating power did not damage the silicon chip and the package while taking advantages of the laser short heating time. Lower temperature as well as smaller deformation were found within the package as comparing with the traditional heating method such as the hot air reflow. Also, experiments on the PBGA solder ball after laser reflow were carried out. Results show that the surface of the solder bumps by the laser reflow using optimized parameters is much smoother than that obtained by the hot air reflow process.