铜柱栅阵列互连结构压曲失稳力学行为研究
发布时间：2018-08-29 10:29
【摘要】：随着电子产品向体积微型化、功能多样化的方向发展,对电子产品中封装器件可靠性的要求不断提高。目前,为应对产品高密度、微型化需求而提出的球栅阵列(Ball Grid Array-BGA)封装器件的可靠性还明显低于周边引脚器件,IBM公司开发的柱栅阵列(Ceramic Column Grid Array-CCGA)封装器件的可靠性较BGA封装器件有显著增加,为适应无铅化发展趋势而采用铜柱代替钎料柱,从而形成铜柱栅阵列(Copper Column Grid Array-Cu CGA)封装器件。近年来,国内外学者主要关注铜柱栅阵列互连结构在热循环载荷作用下的可靠性,而对机械载荷作用下的力学行为研究较少。为全面考察多种载荷形式下形状参数对铜柱栅阵列互连结构承载能力的影响,本文借助有限元仿真软件MSC.Marc,结合非线性压曲失稳理论,通过展现铜柱栅阵列互连器件中Cu焊柱的压曲失稳过程,考察形状参数(Cu柱长径比、钎焊圆角高度以及焊盘中心距)对铜柱栅阵列互连结构承载能力的影响,并对轴向压力载荷作用下Cu焊柱的力学行为及其失效形式进行研究,得到如下结论:1.压曲失稳前,Cu焊柱中Von Mises应力分布均匀且Cu柱处Von Mises应力明显大于钎焊圆角处Von Mises应力。钎焊圆角处的Von Mises应力呈现出以Cu柱轴线为圆心并向外逐渐减小的变化趋势;压曲失稳后,Cu柱与钎焊圆角中轴对称的应力分布特征被打破。比较铜柱栅阵列互连结构中各Cu焊柱的变形情况,可以看出Cu焊柱弯曲方向不同,表明失稳变形方向具有随机性的特点。2.钎焊圆角高度为0.33 mm,Cu焊盘直径为1.0 mm,Cu直径为0.32 mm时,随着Cu柱长径比由5增加至16.5,铜柱栅阵列互结构的临界载荷呈现降低的变化趋势。采用扰动压曲分析及弧长法压曲分析理论所得到的临界载荷差异很小。由非线性(扰动)压曲分析可知,长径比为5~11.5的Cu焊柱压曲失稳前会因内部性能薄弱的钎焊圆角的局部区域存在超过钎料极限强度的拉伸应力而首先引发局部微裂纹;长径比为11.5~16.5的Cu焊柱则会首先发生压曲失稳失效。综合考虑钎焊圆角局部微裂纹可靠性隐患和Cu焊柱压曲失稳失效,建立Cu柱长径比和铜柱栅阵列互连结构临界应力的关系方程:轴向临界压应力值在5~11.5长径比范围内几乎保持恒定,而在11.5~16.5长径比范围内则随Cu柱长径比λ_0增加以正比于λ_0~(-2)的规律降低,该变化规律与描述大柔度压杆力学行为的欧拉公式相符合。3.当Cu柱长径比为10时,随着钎焊圆角高度的增加,铜柱栅阵列互连结构临界载荷增大;而随着焊盘中心距的增加,铜柱栅阵列互连结构临界载荷值略有降低。上述铜柱栅阵列互连结构中Cu焊柱发生压曲失稳前因钎焊圆角局部区域存在超过钎料极限强度的拉伸应力而首先引发局部微裂纹,降低结构可靠性。
[Abstract]:With the development of miniaturization of electronic products and diversification of functions, the reliability of packaging devices in electronic products has been improved. At present, in order to cope with the high density of products, The reliability of the spherical gate array (Ball Grid Array-BGA) packaging device proposed for miniaturization is also significantly lower than that of the peripheral pin device developed by IBM. The reliability of the cylindrical gate array (Ceramic Column Grid Array-CCGA) packaging device is significantly higher than that of the BGA packaging device. In order to adapt to the development trend of lead-free, copper column is used instead of solder column to form copper column gate array (Copper Column Grid Array-Cu CGA) packaging device. In recent years, scholars at home and abroad have focused on the reliability of copper column-gate array interconnection structures under thermal cycling load, but less on the mechanical behavior under mechanical load. In order to investigate the influence of shape parameters on the load-carrying capacity of copper column-gate array interconnection structures under various load forms, the finite element simulation software MSC.Marc, is used in this paper and the nonlinear buckling theory is used. The influence of shape parameters (Cu column aspect ratio, brazing angle height and pad center distance) on the bearing capacity of copper column gate array interconnection structures was investigated by demonstrating the buckling instability process of the Cu soldering post in the copper column gate array interconnection devices, and the effect of the shape parameters (Cu column aspect ratio, brazing angle height and pad center distance) on the bearing capacity of the copper column gate array interconnection structures was investigated. The mechanical behavior and failure mode of Cu welding post under axial pressure loading are studied. The conclusion is as follows: 1. The Von Mises stress distribution is uniform and the Von Mises stress at the Cu post is obviously larger than that at the brazing corner before the bending instability. The Von Mises stress at the brazed fillet shows a tendency of decreasing gradually with the axis of Cu column as the center and gradually decreases after buckling, and the axisymmetric stress distribution in the brazed fillet is broken after buckling. By comparing the deformation of each Cu post in the copper column gate array interconnection structure, it can be seen that the bending direction of the Cu post is different, which indicates that the direction of instability deformation is stochastic. 2. The critical load of copper column gate array interstructure decreases with the increase of the ratio of length to diameter of Cu column from 5 to 16.5 when the soldering angle height is 0. 33 mm,Cu and the pad diameter is 0. 32 mm. The critical load difference obtained by using perturbation buckling analysis and arc length buckling analysis theory is very small. According to the nonlinear (perturbed) buckling analysis, it can be seen that the tensile stress in the local region of the brazing fillet with weak internal performance will cause local microcracks first before the buckling of the Cu soldering post with the aspect ratio of 5 to 11.5. The failure of buckling and buckling occurs first when the aspect ratio of Cu is 11.5- 16.5. Considering the reliability hidden trouble of local micro-crack in soldering fillet and the failure of buckling of Cu welding post, The relation equation between the aspect ratio of Cu column and the critical stress of copper column-gate array interconnection structure is established. The axial critical compressive stress value is almost constant in the range of 51.5-aspect ratio. However, in the range of 11.5 / 16.5 aspect ratio of Cu columns, the ratio of length to diameter 位 0 decreases with the increase of the ratio of length to diameter of Cu column, which is in line with the Euler's formula describing the mechanical behavior of large flexible compression bar. When the ratio of length to diameter of Cu column is 10:00, the critical load increases with the increase of brazing angle height, and decreases slightly with the increase of pad center distance. In the above copper column grid array interconnection structure, the local micro-cracks are first caused by the tensile stress in the local region of the brazed fillet due to the local tensile stress of the brazing fillet, which decreases the reliability of the structure before the buckling of the Cu solder post occurs.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN05
[Abstract]:With the development of miniaturization of electronic products and diversification of functions, the reliability of packaging devices in electronic products has been improved. At present, in order to cope with the high density of products, The reliability of the spherical gate array (Ball Grid Array-BGA) packaging device proposed for miniaturization is also significantly lower than that of the peripheral pin device developed by IBM. The reliability of the cylindrical gate array (Ceramic Column Grid Array-CCGA) packaging device is significantly higher than that of the BGA packaging device. In order to adapt to the development trend of lead-free, copper column is used instead of solder column to form copper column gate array (Copper Column Grid Array-Cu CGA) packaging device. In recent years, scholars at home and abroad have focused on the reliability of copper column-gate array interconnection structures under thermal cycling load, but less on the mechanical behavior under mechanical load. In order to investigate the influence of shape parameters on the load-carrying capacity of copper column-gate array interconnection structures under various load forms, the finite element simulation software MSC.Marc, is used in this paper and the nonlinear buckling theory is used. The influence of shape parameters (Cu column aspect ratio, brazing angle height and pad center distance) on the bearing capacity of copper column gate array interconnection structures was investigated by demonstrating the buckling instability process of the Cu soldering post in the copper column gate array interconnection devices, and the effect of the shape parameters (Cu column aspect ratio, brazing angle height and pad center distance) on the bearing capacity of the copper column gate array interconnection structures was investigated. The mechanical behavior and failure mode of Cu welding post under axial pressure loading are studied. The conclusion is as follows: 1. The Von Mises stress distribution is uniform and the Von Mises stress at the Cu post is obviously larger than that at the brazing corner before the bending instability. The Von Mises stress at the brazed fillet shows a tendency of decreasing gradually with the axis of Cu column as the center and gradually decreases after buckling, and the axisymmetric stress distribution in the brazed fillet is broken after buckling. By comparing the deformation of each Cu post in the copper column gate array interconnection structure, it can be seen that the bending direction of the Cu post is different, which indicates that the direction of instability deformation is stochastic. 2. The critical load of copper column gate array interstructure decreases with the increase of the ratio of length to diameter of Cu column from 5 to 16.5 when the soldering angle height is 0. 33 mm,Cu and the pad diameter is 0. 32 mm. The critical load difference obtained by using perturbation buckling analysis and arc length buckling analysis theory is very small. According to the nonlinear (perturbed) buckling analysis, it can be seen that the tensile stress in the local region of the brazing fillet with weak internal performance will cause local microcracks first before the buckling of the Cu soldering post with the aspect ratio of 5 to 11.5. The failure of buckling and buckling occurs first when the aspect ratio of Cu is 11.5- 16.5. Considering the reliability hidden trouble of local micro-crack in soldering fillet and the failure of buckling of Cu welding post, The relation equation between the aspect ratio of Cu column and the critical stress of copper column-gate array interconnection structure is established. The axial critical compressive stress value is almost constant in the range of 51.5-aspect ratio. However, in the range of 11.5 / 16.5 aspect ratio of Cu columns, the ratio of length to diameter 位 0 decreases with the increase of the ratio of length to diameter of Cu column, which is in line with the Euler's formula describing the mechanical behavior of large flexible compression bar. When the ratio of length to diameter of Cu column is 10:00, the critical load increases with the increase of brazing angle height, and decreases slightly with the increase of pad center distance. In the above copper column grid array interconnection structure, the local micro-cracks are first caused by the tensile stress in the local region of the brazed fillet due to the local tensile stress of the brazing fillet, which decreases the reliability of the structure before the buckling of the Cu solder post occurs.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN05
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