Study on Failure Mechanism of BGA Solder Joints Crack during Wave Soldering

摘要

Along with electrical products function more and more complex, the PCBA assembly density of electrical products is more and more high. Therefore the present PCBA of components layout is almost the both sides board. Regarding both sides layout PCBA, the most efficient process route is: Top side ( reflow soldering ) 驴 Bottom side ( Wave soldering), the detail process step is: Adhesive printing on Bottom side 驴 Placement components 驴 Adhesive Curing 驴Reversal驴 Solder paste printing on top side 驴Components Placement 驴 Top side reflow soldering 驴 Bottom side wave soldering). This kind of process route brings a question that the components on the top side may be re-melt during the bottom side wave soldering. Because IMC ingredients of component pad maybe change with solder joint melting and re-melting, BGA solder joints maybe appear crack. Thus BGA component is open in electrical function, this kind of crack affects the processing quality as well as the long-term reliability of the electrical products. This paper introduces the solder joints of BGA on PCB Top side appearing crack phenomenon after the Bottom side passed wave soldering the reason for solder joints crack is that partial solder joints are dewetting on the component side IMC pad. Through many kinds of failure analysis method, the failure analysis conclusion is that BGA solder joints crack is due to the solder joints melting during wave soldering.