Short Course #4 MEMS Reliability and Packaging
Slobodan Petrovic, Instructor
From accelerometers to biomedical devices, from pressure sensors to optical displays, and from tunable lasers to DNA sensors, MEMS (microelectromechanical systems) technology is becoming integral part of modern life. One of the biggest challenges hampering further progress of MEMS devices is the development of effective packaging solutions. Packaging provides protective housing and interface between the mechanical structure performing its intended function and the environment. Unlike electronic packaging, where high density packaging methods have been developed, MEMS packaging evolution has been slow and not adequately meeting the diverse requirements of performance and reliability. As a result of great diversity in the type of MEMS devices the packaging considerations vary drastically not only from one device type to the next, but also among the different products in the same device category. For some devices like accelerometers, packaging must provide complete isolation from the surrounding, while for others such as DNA sensors, it must enable intimate contact with the environment or optical transparency as in display devices. It is, therefore, not surprising that there are no standards in MEMS packaging and that universal solutions may not be possible.
The main purpose of packaging is to transform a micromachined structure or system into a useful device that performs its function and successfully communicates with the environment through electrical, fluidic, or optical connections. Packaging inevitably reduces the advantages of MEMS structure small size, it sometimes affects the performance, and it significantly adds to the overall cost of a MEMS device. It is a conservative estimate that packaging and testing are responsible, on average and depending on the device type, for 75% of the overall device cost. Consequently, one of the main challenges in MEMS manufacturing is to develop packaging solutions that meet the necessary performance and reliability criteria, while keeping the cost of assembly to minimum.
This is a survey course structured in such a way to provide a comprehensive overview of a broad array of packaging and reliability issues. While some prior knowledge by the participants of MEMS in general is helpful, the packaging discussion will require a fairly detailed explanation of the principles of operation, fabrication methods, and materials used in building MEMS structures. The course is therefore open to participants with no prior MEMS knowledge and would provide a reasonably broad general introduction into the field. Because each MEMS design deserves its own distinctive packaging approach, packaging considerations will be, whenever possible, illustrated using specific device examples; and every opportunity will be used to demonstrate the uniqueness of a packaging solution and its interaction with a micromachined structure. Using this dynamic teaching method, besides learning in depth about packaging and reliability, the participants will have the opportunity to gain knowledge about MEMS in general through the eyes of a packaging and reliability specialist.
The intended outcome of the course is to provide a comprehensive overview of the MEMS packaging and reliability principles; with a particular emphasis on sensors and actuators used in industrial, medical, and automotive applications. Examples of these applications include accelerometers, pressure sensors, angular rate sensors, micropumps, valves, and thermal inkjet heads. The packaging discussion will also cover a wide range of other MEMS principles and devices such biological and chemical sensors, optical imaging and displays, as well as photonic applications used in the fiber-optics industry. These applications will be illustrated using examples such as lab-on-a-chip, DNA sensor, radiation imager, micromirror device, tunable laser, and wavelength locker. Three extensive case studies that will be used to most effectively demonstrate diverse packaging principles are: accelerometers, pressure sensors, and digital micromirror devices.
The seminar will be divided in 3 major sections: packaging design considerations, packaging types, and reliability and failure analysis.
The following major topics will be covered:
packaging design approach
protective coatings and media compatibility
wafer level packaging
plastic molded packages
power for MEMS and packaging considerations
numerical analysis and finite element modeling
accelerated life modeling
About the Instructor
Slobodan Petrovic is an associate professor at Arizona State University, where he teaches courses in MEMS, sensors, and alternative energy. His research interests are in the areas of MEMS fuel cells, sensor media compatibility, hydrogen generation and storage, and nanocatalysts for energy applications. Prior to joining ASU Dr. Petrovic held appointments at Clear Edge Power (formerly Quantum Leap Technology) as a Vice-President of Engineering; at Neah Power Systems as Director of Systems Integration; and at Motorola, Inc. as a Reliability Manager. Dr. Petrovic has over 25 years of experience in MEMS, sensors, energy systems; fuel cells and batteries; industrial electrochemical processes; and catalysis. He has over 50 journal publications and conference proceedings; 2 book contributions and 24 pending or issued patents.