JOURNAL BROWSE
Search
Advanced SearchSearch Tips
Control of Position of Neutral Line in Flexible Microelectronic System Under Bending Stress
facebook(new window)  Pirnt(new window) E-mail(new window) Excel Download
 Title & Authors
Control of Position of Neutral Line in Flexible Microelectronic System Under Bending Stress
Seo, Seung-Ho; Lee, Jae-Hak; Song, Jun-Yeob; Lee, Won-Jun;
  PDF(new window)
 Abstract
A flexible electronic device deformed by external force causes the failure of a semiconductor die. Even without failure, the repeated elastic deformation changes carrier mobility in the channel and increases resistivity in the interconnection, which causes malfunction of the integrated circuits. Therefore it is desirable that a semiconductor die be placed on a neutral line where the mechanical stress is zero. In the present study, we investigated the effects of design factors on the position of neutral line by finite element analysis (FEA), and expected the possible failure behavior in a flexible face-down packaging system assuming flip-chip bonding of a silicon die. The thickness and material of the flexible substrate and the thickness of a silicon die were considered as design factors. The thickness of a flexible substrate was the most important factor for controlling the position of the neutral line. A three-dimensional FEA result showed that the von Mises stress higher than yield stress would be applied to copper bumps between a silicon die and a flexible substrate. Finally, we suggested a designing strategy for reducing the stress of a silicon die and copper bumps of a flexible face-down packaging system.
 Keywords
Flexible microelectronics system;Face-down package system;Neutral line;Finite element analysis;
 Language
Korean
 Cited by
 References
1.
T. S. Kim, J. H. Kim, T. E. Kang, C. Y. Lee, H. B. Kang, M. K. Shin, C. Wang, B. Ma, U. Y. Jeong, T. S. Kim and B. J. Kim, "Flexible, Highly Efficient All-polymer Solar Cells", Nature Communications, 6, 8547 (2015). crossref(new window)

2.
V. M. Marx, F. Toth, A. Wiesinger, J. Berger, C. Kirchlechner, M. J. Cordill, F. D. Fischer, F. G. Rammerstorferc and G. Dehm, "The Influence of a Brittle Cr Interlayer on the Deformation Behavior of Thin Cu Films on Flexible Substrates: Experiment and Model", Acta Materialia, 89, 278 (2015). crossref(new window)

3.
S. Endler, H. Rempp, C. Harendt, and J. N. Burghartz, "Compensation of Externally Applied Mechanical Stress by Stacking of Ultra-Thin Chips", Proc. of 41st Euro. Solid-State Devi. Rese. Conf., 279 (2011).

4.
X. J. Sun, C. C. Wang, J. Zhang, G. Liu, G. J. Zhang, X. D. Ding, G. P. Zhang and J. Sun, "Thickness Dependent Fatigue Life at Microcrack Nucleation for Metal Thin Films on Flexible Substrates", J. Appl. Phys., 41, 195404 (2008).

5.
C. C. Lee, Y. S. Shih, C. S. Wu, C. H. Tsai, S. T. Yeh, Y. H. Peng and K. J. Chen, "Development of Robust Flexible OLED Encapsulations Using Simulated Estimations and Experimental Validations", J. Appl. Phys., 45, 27510 (2012).

6.
N. Palavesam, C. Landesberger and C. Kutter, "Finite Element Analysis of Uniaxial Bending of Ultra Thin Silicon Dies Embedded in Flexible Foil Substrates", Proc. 11th Microelectronics and Electronics (PRIME) Conference, Glasgow, 137, IEEE (2015).

7.
B. J. Kim, H. A. S. Shin, I. S. Choi and Y. C. Joo, "Electrical Failure and Damage Analysis of Multi-Layer Metal Films on Flexible Substrate During Cyclic Bending Deformation", IPFA 18th IEEE Inter. Symp., 2725 (2011).

8.
D. Wang, C. A. Volkert and O. Kraft, "Effect of Length Scale on Fatigue Life and Damage Formation in Thin Cu Films", Mater. Sci. Eng: A, 493(1), 267 (2008).

9.
S. M. Lee, J. Y. Kwon, D. S. Yoon, H. D. Cho, J. H. You, Y. T. Kang, D. H. Choi and W. B. Hwang, "Bendability Optimization of Flexible Optical Nanoelectronics Via Neutral Axis Engineering", Nano. Rese. Lett., 7, 256 (2012). crossref(new window)

10.
M. Sugano, S. Machiya, M. Sato, T. Koganezawa, K. Shikimachi, N. Hirano and S. Nagaya, "Bending Strain Analysis Considering a Shift of the Neutral Axis for YBCO Coated Conductors With and Without a Cu Stabilizing Layer", Supercond. Sci. Technol., 24, 075019 (2011). crossref(new window)

11.
D. A. van den Ende, H. J. van de Wiel, R. H. L. Kusters, A. Sridhar, J. F. M. Schram, M. Cauwe and J. van den Brand, "Bonding Bare Die LEDs on PET Foils for Lighting Applications Thermal Design Modeling and Bonding Experiments", Microelectron. Rel., 54, 2860 (2014). crossref(new window)

12.
J. van den Brand, J. de Baets, T. van Mol and A. Dietzel, "Systems-in-Foil-Devices, Fabrication Processes and Reliability Issues", Microelectron. Rel., 48, 1123 (2008). crossref(new window)

13.
J. Wolf, J. Kostelnik, K. Berschauer, A. Kugler, E. Lorenz, T. Gneiting, C. Harendt and Z. Yu, "Ultra-Thin Silicon Chips in Flexible Microsystems", ECWC13, (2014).

14.
S. Endler, S. Ferwana, H. Rempp, C. Harendt and J. N. Burghartz, "Two-Dimensional Flex Sensor Exploiting Stacked Ultrathin Chips", IEEE Elec. Devi. Lett., 33, 444 (2012). crossref(new window)

15.
F. Hou, X. Zhang, X. Guo, H. Xie, Y. Lu, L. Cao and L. Wan. "Thermo-mechanical reliability study for 3D package module based on flexible substrate", Proc. 14th International Conference on Electronic Packaging Technology (ICEPT), 1296, Dalian, IEEE (2013).

16.
B. J. Kim, M. H. Jeong, S. H. Hwan, H. Y. Lee, S. W. Lee, K. D. Chun, Y. B. Park and Y. C. Joo, "Relationship Between Tensile Characteristics and Fatigue Failure by Folding or Bending in Cu Foil on Flexible Substrate", J. Microelectron. Packag. Soc., 18(1), 55 (2011).

17.
B. J. Kim, "Reliability of Metal Electrode for Flexible Electronics", J. Microelectron. Packag. Soc., 20(4) 1 (2013).

18.
S. Kim and T. S. Kim, "Adhesion Reliability Enhancement of Silicon/Epoxy/Polyimide Interfaces for Flexible Electronics", J. Microelectron. Packag. Soc., 19(3), 63 (2012). crossref(new window)