低应力柔性CCGA焊点设计及其可靠性预测

为提高大芯片面阵列封装的可靠性、降低工作载荷下钎料焊点内部的应力集中程度,基于力学原理对陶瓷柱栅阵列（ceramic column grid array,CCGA）封装结构进行了柔性互连设计和焊点形态设计.采用有限元方法研究了该低应力柔性CCGA互连结构在剪切载荷下的力学行为.结果表明,互连结构的峰值应力和峰值应变由设计的铜质的锥形漏斗体承担,性能薄弱的钎料及钎料/铜柱界面不再处于互连结构的应力应变集中位置,焊点内部应力应变较传统CCGA焊点降低显著;预测该低应力柔性CCGA互连焊点将具有更高的可靠性.

Design of lower stress and flexible CCGA solder joints and reliability expectancy

To improve the interconnect reliability of large-die area array package and reduce the stress concentration in solder joints under service load,the flexible interconnect structure for CCGA(ceramic column grid array) package and its solder joints shape are designed based on mechanics principle.Mechanical behaviors of the lower stress and flexible CCGA interconnect structure under shear load are studied by finite element method.Results showed that the designed copper tapered-funnel in both ends of copper column subjected to peak stress and peak strain of the interconnect structure,the weak solder and solder/Cu column interface away from the stress concentration location of the interconnect structure,stress and strain in solder joints decreased significantly comparing with the conventional CuCGA(ceramic copper column grid array) solder joints.So,higher interconnect reliability for large-die CCGA package can be expected due to the lower stress and flexible design.