Showing papers by "Avram Bar-Cohen published in 2000"

Design for manufacturability of SISE parallel plate forced convection heat sinks

Abstract: The development of cost/effective heat sinks for microelectronic applications involves the achievement of a subtle balance between the thermal design, for maximum heat rejection, and "design for manufacturability," for lowest material and manufacturing costs. The study reported herein extends a previously reported methodology to forced convection cooled rectangular plate heat sinks. Using a well validated analytical model, the thermofluid performance of the side-inlet-side-exit (SISE) heat sink has been characterized, parametric optimization carried out, and the maximum heat transfer capabilities for a range of operating points has been determined. A least-material optimization has been performed to achieve optimal material use. The analysis indicates the least-material design to provide significant mass savings for a moderate penalty in thermal performance. Empirical criteria for manufacturability obtained from several heat sink manufacturers lead to qualitative guidelines.

Bypass effect in high performance heat sinks

Abstract: Studies using commercial computational fluid dynamics software, running on a supercomputer, were carried out to investigate the effects of fin density, inlet duct velocity, and clearance area ratio, on the extent of flowbypass and its impact on the thermal performance of the heat sink. Flow bypass was found to increase with increasing fin density and clearance, while remaining relatively insensitive to inlet duct velocity. An optimum geometry, for a fixed inlet duct velocity, bypass clearance, fixed heat sink volume, and constant thickness, was determined.

Design, Fabrication and Experimental-Numerical Study of PZT Sensors

Abstract: MEMS micropumps, based on PZT membranes have been designed and fabricated at the Microtechnology Laboratory of the University of Minnesota for use in fluid flow control, and as chemical and pressure sensors. Design, fabrication and numerical analyses of the PZT cantilever beams were presented at the MSM99, and are now extended to new MEMS devices; specifically reactive ion etched (RIE) bulk micromachined PZT membranes. Four major geometries including square, rectangular, circular and elliptic devices with different sizes have been successfully fabricated. The main advantage of the new devices is in providing more resonant points than the microcantilever beam, thus creating a larger working interval. Numerical studies have been carried out by using ANSYS Finite Element software. Numerical results compared well with the experimental findings.

Distance learning in thermal design of electronic systems - the IEEE/NSF project

Abstract: A three-year collaborative effort initiated by three institutions has resulted in a new paradigm for distance learning in rapidly evolving technology areas, such as electronics packaging. From the start, the team emphasized the use of multi-media technology for creating and disseminating internet delivered, re-configurable, shared modular educational materials. These modules could be used in a stand-alone fashion for re-training, or embedded in existing courses in various curricula. Using these modules, the first offering of a one semester graduate course on thermal design of electronic systems was made during Spring 1999. This included participants not only from the three original universities, but also from the industry and other universities. This course was taught once a week for three hours, live over the internet. In addition, course materials asynchronously available on the web included Power Point slides of the notes, streaming video, computational codes and virtual laboratory tours. During the second offering of this course during Spring 2000, a number of additional features have been implemented, including expanded participation and greater collaboration. This paper will concentrate on the lessons learned from teaching the second generation of this course. Ongoing efforts involving module standardization will also be described.

The Classroom of the Future: An Internet‐Delivered National Course on Thermal Management of Electronics

Abstract: Teaching inter-disciplinary material poses special challenges due to the diversity of student backgrounds. This problem is compounded if the material being taught is intended for both undergraduate and graduate students. Mechanical Engineering faculty members from three universities have come together to address this problem using a layered, multimedia delivery mechanism via the Internet. This has resulted in the first-ever, live, full-duplex, Internet course taught at any of the three partner universities: Auburn University, the University of Maryland, and the University of Minnesota. With the addition of colleagues from industrial sites such as Philips in the Netherlands and three other universities in Japan, Singapore, and Australia, the next offering will expand to become an international course. The authors hope to illustrate that a course delivered over the Internet adds significantly to the learning process in a cost-effective manner.