塑料封装球栅阵列温度循环可靠性研究
|
摘要
本论文通过温度循环(-40～125℃)使两组PBGA器件(充胶／未充胶)加速失效，利用金相检测、染色剂渗透、扫描电镜观察、C模式超声扫描以及有限元分析等手段研究器件的热循环可靠性问题。深入了解充胶对PBGA器件焊点可靠性的影响，为充胶应用提供实验依据。通过一系列的实验，得到以下实验结果：
· 在本论文设定的温度循环条件下，未充胶PBGA样品的热疲劳品寿命在500周左右，充胶样品的焊点寿命高于2700周；
· 对于未充胶器件，中心距(DNP)是决定焊点应力、应变大小的最主要因素，裂纹总是从中心距较大处萌生并向中心处扩展；
· 温度循环的过程中焊盘附近焊料组织明显粗化。充胶样品粗化尤为严重；
· Ni-Sn金属间化合物包括两层：其中，靠近Ni焊盘的那层比较平整，同时，EDS结果分析表明其化学式近似为NiSn，而靠近焊料的那层呈板条状，化学式近似为NiSn_3，文献表明其为亚稳相；
· 充胶使得样品最大应力范围降了接近一个数量级并降低了DNP的作用，同时，器件失效模式变为芯片粘接层分层；
· C-SAM结果表明本论文采用的充胶样品，芯片粘接层分层起始于500周左右，而经过2700周循环的样品，分层几乎扩展到整个界面。
Zhang Liji (Material Physics and Chemistry) Directed by Professor Xie Xiaoming
This paper is intended to solve problems for those who are designing, using PBGAs. Failure mechanism, as well as cycles to failure of two groups of PBGA samples ( with / without underfill) for thermal cycling conditions in the range of -40 ~125 , were presented. The experiment shows that solder ball in the samples without underfill cracked after 500 times cycle, no crack was found in the underfilled samples even after 2700 cycles. However, the die attach layer delaminated after 500 cycles and PCB cracked in the underfilled samples after long time cycling. C-SAM is employed to investigate the delamination in the underfilled samples. Highly concentrated stress-strain induced by the CTE mismatch between the BGA component and the PCB board, coarsened grain and two kinds of intermetallic compounds (NiSn / NiSns) which formed during reflow and thermal cycle and their impact on the reliability of solder joints are discussed in this paper. The initiation of the crack and its propagation are also presented in this paper. By means of dye penetrant test, the author reveals the distribution of microcrack in the solder ball array. In addition, this paper includes results of simulation, which further verified its conclusions.
· 在本论文设定的温度循环条件下，未充胶PBGA样品的热疲劳品寿命在500周左右，充胶样品的焊点寿命高于2700周；
· 对于未充胶器件，中心距(DNP)是决定焊点应力、应变大小的最主要因素，裂纹总是从中心距较大处萌生并向中心处扩展；
· 温度循环的过程中焊盘附近焊料组织明显粗化。充胶样品粗化尤为严重；
· Ni-Sn金属间化合物包括两层：其中，靠近Ni焊盘的那层比较平整，同时，EDS结果分析表明其化学式近似为NiSn，而靠近焊料的那层呈板条状，化学式近似为NiSn_3，文献表明其为亚稳相；
· 充胶使得样品最大应力范围降了接近一个数量级并降低了DNP的作用，同时，器件失效模式变为芯片粘接层分层；
· C-SAM结果表明本论文采用的充胶样品，芯片粘接层分层起始于500周左右，而经过2700周循环的样品，分层几乎扩展到整个界面。
Zhang Liji (Material Physics and Chemistry) Directed by Professor Xie Xiaoming
This paper is intended to solve problems for those who are designing, using PBGAs. Failure mechanism, as well as cycles to failure of two groups of PBGA samples ( with / without underfill) for thermal cycling conditions in the range of -40 ~125 , were presented. The experiment shows that solder ball in the samples without underfill cracked after 500 times cycle, no crack was found in the underfilled samples even after 2700 cycles. However, the die attach layer delaminated after 500 cycles and PCB cracked in the underfilled samples after long time cycling. C-SAM is employed to investigate the delamination in the underfilled samples. Highly concentrated stress-strain induced by the CTE mismatch between the BGA component and the PCB board, coarsened grain and two kinds of intermetallic compounds (NiSn / NiSns) which formed during reflow and thermal cycle and their impact on the reliability of solder joints are discussed in this paper. The initiation of the crack and its propagation are also presented in this paper. By means of dye penetrant test, the author reveals the distribution of microcrack in the solder ball array. In addition, this paper includes results of simulation, which further verified its conclusions.
引文
1. Johan Liu, "Manufacturing and Packaging Trend for Swedish Microelectronics Industry", High Density Packaging and Component Failure Analysis, Shanghai, 2000, P. 15;
2．毕克允主编，《微电子技术》，国防工业出版社2000年2月第一版
3．赵保经主编，《中国集成电路大全---集成电路封装》，国防工业出版社，p．226；
4．中国电子学会电子封装专业委员会译《微电子封装手册》，北京，电子工业出版社，p．8，p．272；
5. John H Lau, "Ball Grid Array Technologies", New York, McGraw-Hill, Inc, 1995, p. 2, p. 410-412;
6. Lejun Wang, C.P. Wong, (2000), "Recent Advances in Underfill Technology for Flip-Chip, Ball Grid Array, and Chip Scale Package Applications, "High Density Packaging and Component Failure Analysis", Shanghai, 2000, p. 1-p. 8;
7. Bruce M. Romenesko, "Ball Grid Array And Flip Chip Technologies: Their Histories and Prospects," The International Journal of Microcircuits and Electronic Packaging, Vol. 19, No. 1, First Quarter 1996 p. 64-p. 74;
8．史保华，贾新章，张德胜著《微电子器件可靠性》，西安电子科技大学出版社，1999。4；
9. Andrew Mawer, "Plastic Ball Grid Array (PBGA)", MOTOROLA SEMICONDUCTOR TECHNICAL DATA, 1996;
1O. Reza Ghaffarian, Namsoo P. Kim, "Reliability and Failure Analysis of Thermally Cycled Ball Grid Array Assemblies", IEEE Transactions on components and packaging technologies, VOL. 23, NO. 3, September 2000, P. 528-P. 534;
11. John H. L. Pang, Kwang Hong Tan 等, "Thermal cycling aging effects on microstructual and mechanical properties of a single PBGA solder joint specimen", IEEE transaction on components and packaging technologies, VOL. 24, NO. 1, MARCH 2001, P. 10-P. 15;
12. Y.C. Chan, "Reliability studies of μBGA solder joints-effect of Ni-Sn intermetallic compound", IEEE transactions on advanced packaging, VOL. 24, NO. 1,
FEBRUARY 2001, P. 25-P. 31;
13. J. Haimovich, "Intermetallic Compound Growth in Tin and Tin-Lead Platings over Nickel and Its Effects on solderability", Welding Research Supplement, March, 1989, p. 102-p. 114;
14. A.C. Harman, "Rapid Tin-Nickel intermetallic growth: some effects on solderability", Proceedings of the Technical Programme InterNepcon'78, Brighton, England, 1978, p. 42-p. 49。
15. Y.L. Shen 等, "Phase structure and cyclic deformation in eutectic tin-lead alloy: a numerical analysis", Journal of electronic packaging, VOL. 123, MARCH 2001, p. 74-p. 78;
16．肖克博士论文《无铅焊料表面贴装焊点的高温可靠性研究》；
17. John H. Lau 等, "Effects of underfill material properties on the reliability of solder bumped flip chip on board with imperfect underfill encapsulants", IEEE Transactions on components and packaging technologies, VOL. 23, NO. 2, June 2000;
18．张群博士论文《倒装焊及相关问题的研究》；
19．美：L．H．范 弗莱克著，夏宗宁、邹定国译《材料科学与材料工程基础》机械工业出版社 1984年
20．R．W．卡恩等人主编：《材料科学与技术丛书》第6卷，《材料的塑性变形与断裂》颜鸣皋等译。科学出版社 1998年
2．毕克允主编，《微电子技术》，国防工业出版社2000年2月第一版
3．赵保经主编，《中国集成电路大全---集成电路封装》，国防工业出版社，p．226；
4．中国电子学会电子封装专业委员会译《微电子封装手册》，北京，电子工业出版社，p．8，p．272；
5. John H Lau, "Ball Grid Array Technologies", New York, McGraw-Hill, Inc, 1995, p. 2, p. 410-412;
6. Lejun Wang, C.P. Wong, (2000), "Recent Advances in Underfill Technology for Flip-Chip, Ball Grid Array, and Chip Scale Package Applications, "High Density Packaging and Component Failure Analysis", Shanghai, 2000, p. 1-p. 8;
7. Bruce M. Romenesko, "Ball Grid Array And Flip Chip Technologies: Their Histories and Prospects," The International Journal of Microcircuits and Electronic Packaging, Vol. 19, No. 1, First Quarter 1996 p. 64-p. 74;
8．史保华，贾新章，张德胜著《微电子器件可靠性》，西安电子科技大学出版社，1999。4；
9. Andrew Mawer, "Plastic Ball Grid Array (PBGA)", MOTOROLA SEMICONDUCTOR TECHNICAL DATA, 1996;
1O. Reza Ghaffarian, Namsoo P. Kim, "Reliability and Failure Analysis of Thermally Cycled Ball Grid Array Assemblies", IEEE Transactions on components and packaging technologies, VOL. 23, NO. 3, September 2000, P. 528-P. 534;
11. John H. L. Pang, Kwang Hong Tan 等, "Thermal cycling aging effects on microstructual and mechanical properties of a single PBGA solder joint specimen", IEEE transaction on components and packaging technologies, VOL. 24, NO. 1, MARCH 2001, P. 10-P. 15;
12. Y.C. Chan, "Reliability studies of μBGA solder joints-effect of Ni-Sn intermetallic compound", IEEE transactions on advanced packaging, VOL. 24, NO. 1,
FEBRUARY 2001, P. 25-P. 31;
13. J. Haimovich, "Intermetallic Compound Growth in Tin and Tin-Lead Platings over Nickel and Its Effects on solderability", Welding Research Supplement, March, 1989, p. 102-p. 114;
14. A.C. Harman, "Rapid Tin-Nickel intermetallic growth: some effects on solderability", Proceedings of the Technical Programme InterNepcon'78, Brighton, England, 1978, p. 42-p. 49。
15. Y.L. Shen 等, "Phase structure and cyclic deformation in eutectic tin-lead alloy: a numerical analysis", Journal of electronic packaging, VOL. 123, MARCH 2001, p. 74-p. 78;
16．肖克博士论文《无铅焊料表面贴装焊点的高温可靠性研究》；
17. John H. Lau 等, "Effects of underfill material properties on the reliability of solder bumped flip chip on board with imperfect underfill encapsulants", IEEE Transactions on components and packaging technologies, VOL. 23, NO. 2, June 2000;
18．张群博士论文《倒装焊及相关问题的研究》；
19．美：L．H．范 弗莱克著，夏宗宁、邹定国译《材料科学与材料工程基础》机械工业出版社 1984年
20．R．W．卡恩等人主编：《材料科学与技术丛书》第6卷，《材料的塑性变形与断裂》颜鸣皋等译。科学出版社 1998年