Program of courses

In this course we present an overview over Newtonian particle methods for representing the dynamics of fluids, solids, soft and granular matter in situations important for Microsystem Technology.

Modelling the system dynamics by ensembles of interacting particles following Newton’s second law, one is able to address systems that are hard to represent otherwise, e.g., by meshing.

In the first session, we focus on Dissipative Particle Dynamics (DPD) and related Methods. DPD was originally introduced as an explicit model for solvents on mesoscopic time and length scales. Due to its generic nature, however, it has been applied in many other situations as well. We first outline some theoretical foundations and in the following show how the approach can be applied in an explorative manner to microfluidic problems such as capillary impregnation, the simulation of aggregation assays or blood separation devices.

The second session will present Smoothed Particle Hydrodynamics (SPH) as a quite general scheme for a meshless discretization of the continuum equations in hydro- and elastodynamics. A brief theoretical account of this simulation scheme is given, followed by application examples such as the simulation of the complex dynamics of injection moulding, or the description of the elastodynamics of interacting silicon cantilevers. Then an approach is presented for a mesoscopic simulation of elastodynamics by means of DPD. The approach is applied to the coarse-grained description of the mechanical properties of carbon nano tubes.

Finally an outline is presented on how the various particle methods can be merged seamlessly into a unifying software design.

Presenter Bio

Xuejun Fan is currently an Associate Professor in the Department of Mechanical Engineering at Lamar University, Beaumont, Texas. He was a Senior Staff Engineer at Intel Cooperation, Chandler, Arizona, from January 2004 to August 2007, a Senior Member Research Staff with Philips Research Lab at Briarcliff Manor, New York from 2001 to 2004, and a Member Technical Staff and Group Leader at the Institute of Microelectronics (IME), Singapore from 1997 to 2000.

Dr. Fan’s interests and expertise lie in the areas of reliability, material characterization and modeling for microelectronic packaging. He has been very active as a keynote speaker and instructor at IEEE conferences including ECTC, EPTC, InterPack, EuroSimE and ICEPT. He has published more than 80 scientific papers and filed 14 patents in US patent office.

Dr. Fan held a faculty position at Taiyuan University of Technology, Shanxi, China from 1989 to 1997. He received the Young Scientist Fellowship from Japan Society for the Promotion of Science (JSPS) in 1993 and worked at the University of Tokyo for a year. He was a Visiting Professor at the University of British Columbia, Vancouver, Canada from 1996 to 1997. Dr. Fan was promoted to a Full Professor at Taiyuan University of Technology, Taiyuan, Shanxi in 1991, and became one of the youngest professors in China that year when he was 27. He was one of the 30 Nominees for the title of “1991 Ten Outstanding Youth of China”, and was one of 5 recipients for the second-best prize of Young Faculty Award for the Excellence in Teaching and Research in 1994 by Fok Ying-Tung Education Foundation.

Course Scope:

This course will present a state-of-art and in-depth overview of recent advances in moisture related reliability studies in IC packaging. The course provides fundamental knowledge and understandings on the failure mechanisms associated with moisture such as delamination/cracking during reflow, material and interface degradation during HAST, as well as the electrochemical metal migration and corrosion under biased HAST condition. General reliability test practice, qualification, and the different failure mechanisms will be presented. The accelerated test methodology and experimental validations will be discussed. The course will cover moisture diffusion principles and the characterization of moisture related properties, such as diffusivity, solubility, saturated moisture concentration, and the hygroscopic swelling, and adhesion. The vapor pressure evolution at elevated temperature, especially for lead-free applications and reliability concern, will be discussed. The impact of hygroscopic swelling on copper/low K structures as well as under bump metallurgy (UBM) failures will be described. The key challenges in reliability performance for ultra-thin 3-D stack-die chip scale packages and the selection of wafer level film (WLF) will be discussed. The optimization of reflow profile to reduce the failure rate will be introduced. Several case studies related to moisture-induced failures in different types of packages such as flip chip package, TSOP, QFN, and stack-die chip scale packages will be presented.

Course Objectives: 1. Fundamental understanding on moisture-induced failure mechanisms under different accelerated testing conditions; 2. Knowledge on material behaviors in the presence of moisture and the impact on reliability performance; 3. Identification of key material properties related to moisture and material selection guidelines; 4. Familiarity of the existing tools to perform the moisture related modeling and material characterization. 5. Case studies for preventing packages from moisture-induced failures such as flip-chip package, QFN package, Stack-die chip scale packages and TSOP packages.

Outline

1. Introduction
2. Moisture related reliability test and specifications – MSL, HAST, BHAST etc
3. Typical failure modes and failure mechanisms in the presence of moisture
4. Moisture diffusion – theory and applications
5. Moisture absorption vs. water absorption
6. Characterization of moisture related material properties
7. Vapor pressure evolution at reflow temperature - what's the impact when lead-free soldering is applied?
8. Case study – underfill selection in flip chip BGA applications
9. Case study – wafer level film failures in 3-D stacked chip scale packages
10. Hygroscopic swelling – the impact on low K/Cu interconnect with silicon-package interaction
11. Effect of moisture on material properties
12. Accelerated test with moisture - can we further accelerate the test?
13. Case studies – QFN, TSOP, Flip-Chip

Who should attend:

The course is designed for staff members, technical managers, design and manufacturing personnel, and reliability engineers in microelectronic companies. Although the course reviews most recent advances in moisture related reliability issues, the course does not assume prior knowledge of these issues and hence is of interest for both experts and new actors in this area.

Course Outline

• Thermal Stress
  • Analytical models for continuous interconnect and discrete interconnects
  • Design analysis using Excel
• Viscoelasticity
  • Material characterization technique
  • Analogous modeling technique
• Drop/Shock
  • Analytical modeling techniques
    • Dynamics of drop/shock
    • Resultant stresses in the solder joints
    • Shock verses CTE mismatched: Which is more severe?
    • Design analysis using Excel
  • FE modeling techniques
    • Explicit verse implicit
    • Direct integration verse mode superposition
  • Experimental techniques
    • High strain-rate material characterization
    • Ball impact shear
    • High speed cyclic bending

Short Description

Failure due to mismatched thermal expansion is an age-old problem in electronic packaging. Numerical technique such as finite element analysis is extensively used for such analysis. However, the interpretation of FE output is challenged by the presence of stress/strain singularity. Besides providing better insights to the physics of the problem, analytical equations, which effectively cost nothing, can be used for first cut analysis, or as a check to FE solutions. While analytical solutions for mismatched thermal expansion are available [x], there are very limited reports for discrete solder joints. This will be presented in the short course. The analysis will be demonstrated using examples in Excel, which shall show the speed and ease of such analysis.

While most organic materials exhibit viscoelastic (or viscoplastic) behavior, these are ignored in most analysis for reason of simplicity. However, accounting for time-dependent behaviour is needed for accurate analysis, which is particularly essential for adhesive interconnection that relies mainly on mechanical contact. This short course will present the experimental technique for characterizing viscoelastic properties of polymer using Dynamic-Mechanical Analyser (DMA) and time-temperature superposition technique.

Failure of board level solder joints due to drop-shock is a relatively new phenomenon for the electronic packaging industry, but this is becoming more important due to the increased occurrence of such failure. Board level solder joints are as vulnerable to drop-shock as to mismatched thermal expansion. Which is more damaging? Will a joint robust against thermal stress be as effective against drop-shock? These questions will be addressed in the short course. While numerical modeling of impact and shock are regularly performed in some fields of engineering, this is a relatively new topic to this industry. A brief discussion of the modeling techniques will be presented. The strain-rate of the solder joints experience in the drop-shock condition falls in the regime of “medium strain rate” which is too high for measurement using the conventional mechanical uniaxial tester and too low for the Split Hokinson Pressure Bar. A simple drop-test technique suitable for the medium strain rate regime will be presented in the short course. There has been increasing interest in introducing component level tests, such as ball impact shear or ball impact pull, as a quality test for drop-shock applications. However, there remains doubt on the validity of the test and the interpretation of the test results. The current JEDEC board level test standard JESD-B111 presents some limitations and new board level test methods are being explored. High speed cyclic bend test came across as a promising test method. These two test methods will be examined closely in the short course.

Short Biography

E.H. Wong completed diploma in mechanical engineering in 1980, part time correspondent degree from Engineering Council, UK in 1988, MSc Applied Mechanics from University of Manchester Institute of Science and Technology (UMIST) in 1990, and recently PhD from University of Sydney. Prior to joining IME in 1996, he has spent more than a decade in defense industry as a project leader and specializing in product and process development. He is currently a senior member of technical staff with the Institute of Microelectronics (IME) and has been active in the area of moisture-induced and mechanical-induced failure of electronic packaging. He has published/co-published more than 100 journal and conference papers.

RF-MEMS design, multi-physics simulation and reliability analysis

RF-MEMS is a disruptive technology, commonly regarded as key for future telecommunication systems as it potentially alleviates several of the natural trade-offs presented by current telecommunication systems. It allows indeed defining, among other things, high quality, cost effective, highly integrated, low power consumption and tunable passive components, e.g. capacitors, inductors, transmission lines, varicaps and switches.

RF-MEMS switches and varicaps have been demonstrated in various research institutes for more than a decade. These high potential components however did not yet break into the market as their development, until recently, often repeatedly bounced on the reliability wall. These new components lacked thorough understanding of their specific failure mechanism and detailed underlying physical behaviour. Further, the actual process complexity, or non-standardization, of RF-MEMS is another key issue for that still-young family of technologies.

This course introduces the design and simulation of electrostatic MEMS devices, laying the accent on the specific reliability issues associated with these devices and the environment they have to function in. To that purpose, the course uses RF-MEMS capacitive devices produced in thin-film technology as case study. To emphasize the multi-physics reliability challenges, the course discusses among others the dielectric charging, thermal stability, packaging and finally the RF-specific power-handling issues. Finally, the course will be closed by presenting opportunities emerging from the careful study of the cited reliability issues.

• Introduction
  • MEMS
  • Electrostatics and transducers
• Basics of electrostatic actuation
  • Comb-drives vs. parallel-plate
  • Voltage and charge drives
  • Contact
• Application to RF-MEMS
  • Flash course of RF
  • Switches
  • Switchable filters
• Reliability study and approach
  • Techniques, figures of merit and instrumentation
  • FMEA
  • Statistical significance
• Main reliability issues of RF-MEMS
  • Impact of the dielectric charging
  • Impact of the environment and packaging
  • Impact of RF power
• Opportunities
  • EFFA, i.e. Electrostatic Fringing-Field Actuator
  • Dielectric charging as a tuning mechanism.
  • RF-power as a driving mechanism.
• Conclusions and closing remarks

The Instructor:

Xavier Rottenberg was born in Brussels, Belgium in April 1976. He received the M.S. degree in Physics Engineering from “Université Libre de Bruxelles” in 1998. He received in 1999 a supplementary degree at the end of a third cycle in Theoretical Physics from the same University. He worked one year at the Royal Meteorological Institute of Belgium in the field of remote sensing from space. He joined the Interuniversity MicroElectronics Center (IMEC) in 2000 where he contributes to the research in the field of (RF-)MEMS design, modellisation and integration. Xavier Rottenberg (co‑)authored over 40 international scientific journal/conference papers in the area of RF-MEMS devices and circuits and issued patents in these fields. His PhD defense at the K.U.Leuven, dpt. TELEMIC, is scheduled for 2008.

Thermal Management of Microsystems: Current Capabilities and Future Challenges for Simulation Tools

Professor Chris Bailey, MBA, Ph.D. University of Greenwich, London UK

Course Description

This short course will provide details and understanding of the issues related to thermal issues in Microsystems and their packaging. Thermal management technologies will be discussed including both passive and active cooling approaches. Thermal Modelling techniques and associated simulation tools will be the focus of the course which will give details on current capabilities and future challenges.

Attendees will gain a basic understanding of thermal issues associated with Microsystems components and packaging, trends in cooling technologies (both passive and active), and current state of capabilities in modelling tools and challenges for the future. This course is designed for engineers and R&D specialists who want to learn more about the capability of thermal management simulation tools in predicting the thermal performance and reliability of microelectronic and microsystems packaging. Focus will be on the capability of simulation tools, how to use them effectively, and what the trends will be for the future.

TOPICS:

• Thermal Trends in Microelectronics and Microsystems
• Modes of Heat Transfer
  • Conduction, Radiation, Convection
• Thermal Issues:
  • Packaging, Test, In-Service Performance
  • Thermal failures, Warpage, Stress…..
• Thermal Management Technologies
  • Passive Cooling
  • Active Cooling
• Thermal data
  • Junction Temperature, Thermal resistance
  • Theta-ja, Theta-jc, Theta-jb
  • JEDEC Standards
• Thermal Modelling Techniques
  • Heat Conduction Solvers
  • Computational Fluid Dynamic Solvers
  • Software Tools
  • Importance of Turbulence
  • Thermal Modelling and Numerical Optimisation
  • Integration with CAD
  • Multi-Physics Modelling
• Thermal Stress
  • Accelerated Life Tests
• Modelling Examples:
  • Thermal Issues at Board Assembly
  • Passive Cooling
  • Active Cooling
  • Accelerated Life Testing
• Future Challenges for Thermal Modelling Tools

Instructor:

Chris Bailey is Professor in Computational Mechanics and Reliability at the University of Greenwich, London, UK. He received his PhD in Computational Modeling in 1988, and an MBA in Technology Management in 1996. He has published over 200 papers on Design and Simulation of micro-technology based processes and products and has worked on many UK and EU projects. He has over twenty years of experience in developing and using virtual prototyping tools and teaches regularly both at Greenwich throughout the world on short courses.

Chris is a member of the NAFEMS Multi-Physics Modelling working group, a senior member of IEEE-CPMT, and a UK Committee member of IMAPS. In 2007 he was and Programme Chair for High Density Packaging Conference in Shanghai, China, and also the local organizer of the IEEE sponsored EuroSime conference in London. In 2008 he will be the General Chair for the Electronics System-integration Technology Conference (ESTC-2008) in Greenwich, London.

Exact content will be available before end of January