面阵列封装互连结构热循环翘曲变形抗力

Resistance to warpage deformation of area array packaging interconnect under thermal cyclic load

借助有限元软件对钎料球、钎料柱和铜柱阵列互连结构热循环载荷下的翘曲变形行为进行研究.结果表明,三者升温过程均表现为刚度低的树脂基板呈下凹变形、而降温至0℃后呈现上凸变形,变形规律相同.不同温度下两端基板的热膨胀系数差异引发的基板内及相连焊球/焊柱内的应力及力矩是翘曲变形发生的驱动力.两焊柱阵列互连的基板翘曲位移接近,但均明显低于焊球阵列的基板,翘曲变形抗力更大.–40～125℃热循环温度范围及基板尺寸条件下,铜柱未屈服,相对钎料柱阵列互连,未表现铜柱可挠曲变形释放应力的优势.

The warpage behaviors of solder ball array interconnect, solder column array interconnect and copper column array interconnect structures under thermal cycling load were studied by finite element software. The results show that the warpage deformations of three kinds of area array interconnects is the same, the resin substrates with low stiffness exhibit a concave deformations during the heating stage above room temperature, while the convex deformation occurs after cooling to 0 °C. The stress and torque in the substrates and the ball/column array interconnects caused by the difference of thermal expansion coefficients of both ends substrates at different temperatures are the driving forces of warping. The resin substrates of the solder/copper column array interconnect have similar warpage displacements, but both of them are obviously lower than the substrates of solder ball array interconnect, and the warpage deformation resistance is higher. Under the thermal cycling temperature range from –40 °C to 125 °C and given substrate size condition, the yielding deformation of the copper column has not occurred. Comparison with the solder column array interconnect, the advantage of releasing stress by flexural deformation of the copper column is not exhibit.