倒装LED芯片的焊料互连可靠性评估

摘要

对比测试了两类不同焊垫的倒装LED芯片的焊料互连可靠性.结果表明,采用金锡共晶合金焊垫和金焊垫的倒装LED芯片适于金锡共晶焊,具有高的互连焊点可靠性,但共晶倒装焊设备昂贵,制造成本很高;若采用普通锡基焊料封装,则由于液-固和固-固界面的焊料反应,导致焊料与焊垫之间出现严重的界面不稳定状态,进而引起不受控的焊点剥离等一系列可靠性问题.而在倒装LED芯片的焊垫材料表层增加一层焊料阻挡层,则可以通过简单的工艺流程实现高可靠的互连封装.%Solder interconnection reliability of two kinds of different pads for flip-chip LED has been investigated and compared. The flip-chip LED with Au-Sn alloy pads or Au pads is suitable for Au-Sn eutectic soldering and has highest interconnection reliability. However, the Au-Sn eutectic soldering needs expensive equipments with the high manufacturing cost. As for the package by common Sn-based solders, the interface between the solder and the pads appear serious instability because of the liquid-solid or the solid-solid interface reaction, which ultimately cause a series of reliability problems, such as the uncontrolled joint dissection. By adding a barrier layer in the electrode surface of the flip-chip LED, high reliable interconnect can be able to achieved with a simple process.