Components, Packaging & Manufacturing Technology Society

IEEE/CPMT Dinner Meeting:

"A Thermal Threesome: -- How to Increase Thermal Conductivity and Measure the Results"

Dr. Roger Emigh, Technical Program Manager, Johnson Matthey Electronic Materials Division; Nancy Mathis, President of Mathis Instruments (New Brunswick, NJ); and Dr. Dan White, VP of Lanxide.

Wednesday, February 10, 1999
Subsidized buffet dinner ($10) served at 6:30, Presentation (no cost) at 7:30.
Location: FAZ restaurant, at the Four Points Hotel, on Mathilda, north of Hiway 237 and Fwy 101 junction, Sunnyvale
PLEASE RSVP (for dinner and/or meeting) by email to Rena Ayeras, or call our CPMT hotline at 800-686-9366.

Speakers will be discussing the Mathis Instruments TC PROBE for fast measurement of thermal resistance; the Lanxide high thermal dissipation materials for semiconductor packaging; and the Johnson Matthey Electronic Materials product GELVET, a new thermal dissipation material.

JME Compliant, High Performance Thermal Interface Material (Roger Emigh)
In designing and implementing thermal management solutions, one of the growing challenges is conducting heat across interface gaps between components. Thermal conduction within materials is well understood and remains consistent in manufacturing situations with very predictable variations. In contrast, interface thermal resistance is difficult to predict from material properties and the same material can produce widely varying results even in nearly identical assemblies. This adds difficulty to the design process. Conventional approaches to developing interface materials have been based on loading a carrier material (adhesive, grease, wax, etc.) with thermally conductive particulate fillers. Heat is then conducted through the material by passing through a series of conductive particles. This has generally resulted in materials with good surface contact but relatively low bulk conductivity, requiring designers to minimize the thickness of the material. JME has taken a very different approach by working on an aligned structure of highly conductive fibers, resulting in very high thermal conductivity through the thickness of the material. This breaks the pattern of filling materials with discrete pieces of conductive material and allows a thicker piece of material to be used while maintaining very low thermal resistance. Because the material is compressible, it is able to comply with surface imperfections and is tolerant to variations in the interface gap, allowing for expected manufacturing variations without loss of performance. This allows for a narrower range of interface resistance values and better apriori prediction of performance. Additional benefits, which will be discussed, include long-term reliability, re-workability, and material customization.

Thermal conductivity characterization (Nancy Mathis)
Characterization of new materials (especially if uniformity is an issue) is needed in both production and application. Present techniques require expensive, time-consuming techniques, using destructive or standard sample methods. Mathis Instruments has developed a simpler, faster approach, which will be described. (See the website for more information, if you missed this talk.)

Lanxide SiC reinforced Al (Dan White)
At high power levels, and particularly in applications involving multiple prolonged on/off cycles, problems have arisen with the reliability of substrate-to-baseplate attachments in high current power modules using metal baseplates. Specifically, under thermal cycling conditions the mismatch in coefficient of thermal expansion (CTE) between the ceramic substrates for the electronic devices and the copper or aluminum baseplates results in high shear stresses in the solder joint. The result of this cyclic shear stress is often debonding or cracking of the substrate in as little as a few hundred thermal cycles.
A solution to this problem involves the use of baseplates made from silicon carbide reinforced aluminum (SiC/Al) metal matrix composites. These materials retain the excellent heat dissipation characteristics and low density of aluminum, while providing a CTE closely matched to that of the ceramic substrate, thus minimizing thermal mismatch stresses. Due to its unique combination of physical properties, SiC/Al has found many applications, including heat sinks, hybrid packages, and printed wiring board cores in high performance military/aerospace applications. Until recently, however, the absence of economical high volume manufacturing processes resulted in the lack of acceptance of SiC/Al in commercial and industrial applications, such as automotive electronics and flip-chip microprocessor lids.
The composite material, its properties, and its current and planned applications in power module baseplates will be discussed. Thermal cycling tests and theta J.C. measurements, including results comparing attachment reliability for the composite baseplates vs. copper, will also be discussed. Finally, a brief overview of the PRIMEX SiC/Al composite manufacturing process and its economic impact on high volume production of thermal management components will be presented.


Dr. Roger Emigh, Divisional Marketing Manager for Johnson Matthey Electronics, has been with JME since 1993, working on research activities in Sputtering Targets before moving to thermal/packaging research in 1995 as Research Manager for that effort. He moved into the Technical Marketing role in 1997. He holds a Ph.D. and MS from UC Berkeley in Materials Science and Engineering; and a BS from Washington State University in Physical Metallurgy.

Nancy Mathis is VP for Research and Development at Mathis Instruments. She has a Ph.D. in ChE from the University of New Brunswick, where she served as a professor.

Dr. Dan White is Marketing & Sales Manager for Lanxide Electronic Components. He holds a Ph.D. and MS from Purdue University in Materials Science, and a BS from Purdue University in Physics.
Dan started his professional career as a member of the technical staff at Lanxide Corporation in 1985. Dan moved to Lanxide's marketing department in 1989 as a market analyst with a focus in the area of high power electronics and thermal management. The information gained from this research lead to the formation of Lanxide Electronic Components (LEC) in 1990. Dan moved from Lanxide to LEC with the founding of the company and has served as its Marketing & Sales Manger, and on several occasion its Product Development Manager. Dan also holds over 50 patents in the area of ceramic and metal composite processes and materials, and is the inventor of the PRIMEX Pressureless Metal Infiltration Process.

If you are not on our Chapter's regular email or FAX distribution list for meeting anouncements, you can easily be added! Please send an Email to Rena Ayeras and let me know if you'd like email or FAX distribution. If you don't have Email, then please reply to 800 686-9366 (CPMT's 800 number), but please be advised that I would greatly prefer the Email route.

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Revised March 31, 1999