A NEW DISPENSING SOLDER PASTE FOR LASER SOLDERING TECHNOLOGY

摘要

Laser soldering method becomes attractive in the packaging and assembly of surface-mounted devices and microelectronics. The method transfers laser energy for reflow process with a non-contact procedure and determines the soldering location precisely. It is critical to consider formulated solder paste due to the amount of heat absorbed by flux and alloys when applying the method to reliable joints. A new solder paste of alloy composition of Sn-3.0Ag-0.5Cu in a dispensing way is developed for the automatic laser soldering processes. This paper presents the results of soldering BGA spheres on circuit boards with minimal voiding and no splash or solder balling issues. Cross-sectional studies showed the reduction of intermetallic formation in well-formed solder joints. In addition, the joints have high shear strength due to lower thermal stress during the process. This new solder paste was proved to be suitable for repair of electronic components and manufacturing electronic parts that cannot be soldered in a conventional reflow oven.