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倒装芯片塑料球栅阵列(FC-PBGA)封装形式独特而被广泛应用,分析研究其在实际应用过程中,在高温、电、水汽等多种综合环境应力条件作用下的失效机理对提高其应用可靠性有重要意义.本文对0.13μm 6层铜布线工艺的FC-PBGA FPGA器件,通过暴露器件在以高温回流焊过程中的热-机械应力为主的综合外应力作用下的失效模式,分析与失效模式相对应的失效机理.研究结果表明,FC-PBGA器件组装时的内外温差及高温回流焊安装过程中所产生的热-机械应力是导致失效的根本原因,在该应力作用下,芯片上的焊球会发生再熔融、桥接相邻焊球致器件短路失效;芯片与基板之间的填充料会发生裂缝分层、倒装芯片焊球开裂/脱落致器件开路失效;芯片内部的铜/低κ互连结构的完整性受损伤而影响FC-PBGA器件的使用寿命.
The FC-PBGA package has been widely used. The failure mechanism of the FC-PBGA package has been widely used. The failure mechanism of the FC-PBGA package has been greatly improved under the conditions of high temperature, electricity, water vapor and other comprehensive environmental stress. Application reliability is of great significance.In this paper, the FC-PBGA FPGA device with 0.13μm 6-layer copper wiring is exposed by the failure mode under the effect of external stress, which mainly consists of thermo-mechanical stress during reflow soldering at high temperature, The failure mechanism corresponding to the failure mode is analyzed.The results show that the internal and external temperature difference during the assembly of FC-PBGA device and the thermal-mechanical stress generated during the reflow soldering process are the root causes of failure. Under this stress, The solder ball on the chip will remelt, bridging adjacent solder balls will short-circuit the device, cracks will occur in the filler between the chip and the substrate, the device will not open due to cracking / falling off of the solder ball in the flip chip, The integrity of the copper / low κ interconnect structure is compromised and the life of the FC-PBGA device is affected.