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OVERVIEW:

Adhesively bonded and soldered assemblies are widely used in micro- and opto-electronics. These assemblies are typically manufactured at an elevated (curing) temperature and are subsequently cooled down to a low (room, operating, testing) temperature. Because of the dissimilar materials, such assemblies experience, at low temperature conditions, thermally induced stresses and deformations that change with the change in temperature[1-3]. It is usually the thermally induced stresses that cause reliability problems in microelectronics. In opto-electronics, however, it is the strains, deformations and displacements that are of primary reliability concern. If the bow of a photonics assembly is appreciable, the optical performance of the photonic device can be compromised. Thus, there is an obvious incentive for the use of low-bow and even bow-free (temperature-change insensitive) assemblies in micro- and opto-electronics packaging engineering. In this talk we examine two important problems of reducing and even eliminating the thermally induced bow in a micro- or opto-electronic assembly:

1. Overmolded ceramic electronic package with reduced bending stress [4,5],
2. Bow-free adhesively bonded or soldered assembly for opto-electronics applications [6].

The emphasis is on the second problem. Two approaches to solve this problem are considrered: 1)by introduction of a surrogate material [7], and by making the bonding layer substantially thicker than the typical thickness of about 1-2mils. Suggestions for a low induced stress in such an assembly are developed [8].

REFERENCES

1. S.P.Timoshenko, "Analysis of Bi-Metal Thermostats", J. Opt. Soc. of America, vol.11, 1925.
2. E. Suhir, "Stresses in Bi-Metal Thermostats," J. Appl. Mech., vol.53, No.3, 1986.
3. E. Suhir, "Interfacial Stresses in Bi-Metal Thermostats," J.Appl. Mech., vol.56, No.3, 1989.
4. E. Suhir and J. Weld, "Electronic Package with Reduced Bending Stress," Patent #5,627,407, 1997.
5. E. Suhir, "Arrangement for Reducing Bending Stress in an Electronic Package," Patent #6,810,241, 2001.
6. E. Suhir, "Device and Method of Controlling the Bowing of a Soldered or Adhesively Bonded Assembly," Patent #6,239,382, 2001.
7. E. Suhir, "Analysis of Interfacial Thermal Stresses in a Tri-Material Assembly," J. Appl. Phys., vol.89, No.7, 2001.
8. E. Suhir, "Predicted Stresses in a Bow Free Adhesively Bonded Assembly for Photonics Applications", J. Appl. Phys., to be published.

Speaker Biography

Dr. Ephraim Suhir is a Fellow of the IEEE, ASME, and the SPE, and a member of the APS, IMAPS, and the JSME (Japan Society of Mechanical Engineers). He is member of the IEEE Technical Advisory Board, New Technologies Directions Committee, and member of the Board of Governors of the IEEE CPMT Society. Dr. Suhir has authored more than 250 technical publications (papers, book chapters, books, patents), including monographs "Structural Analysis of Microelectronic and Fiber Optic Systems", Van-Nostrand, 1991 and "Applied Probability for Engineers and Scientists", McGraw-Hill, 1997. Dr. Suhir is co-founder and Editor-in-Chief of the ASME Journal of Electronic Packaging. He received numerous distinguished service and professional awards, including 2001 IMAPS John A. Wagnon Technical Achievement Award; 2000 IEEE-CPMT Outstanding Sustained Technical Contribution Award; 2000 International SPE Fred O. Conley Award, and 1999 ASME and Pi-Tau-Sigma Charles Russ Richards Memorial Award. Dr. Suhir is a Distinguished Lecturer for the IEEE CPMT Society. He has presented numerous invited and keynote talks at professional conferences and taught many professional development courses on various topics including materials, reliability, packaging and mechanical problems in microelectronics and photonics engineering.