Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Microelectronics: A tougher seal for rugged environments

28.02.2013
Sensors used in harsh conditions, such as deep-sea oil wells, must withstand extreme temperatures and pressures for hundreds of hours without failing. Researchers in Singapore have investigated two metal alloys that could give micro-electromechanical system (MEMS) sensors better protection in the toughest environments
Sensors used in harsh conditions, such as deep-sea oil wells, must withstand extreme temperatures and pressures for hundreds of hours without failing. Vivek Chidambaram and co-workers at the A*STAR Institute of Microelectronics, Singapore, have investigated two metal alloys that could give micro-electromechanical system (MEMS) sensors better protection in the toughest environments

Typical MEMS sensors measure temperature, pressure or vibration, and they are hermetically sealed inside a strong metal casing to prevent air or moisture degrading the sensors’ electronics. Chidambaram’s team wanted to find cheaper, more durable alternatives to the metal solders, such as gold–tin or copper–tin, which are typically used to seal the case. They tested a 70:30 aluminum–germanium mixture, which has a melting point of about 420 °C. This temperature — the eutectic point — is much lower than that for either metal on its own.

Unlike most conventional packaging materials, aluminum and germanium are compatible with the processes used to manufacture the MEMS. Using the aluminum–germanium sealant should make MEMS manufacturing easier and cheaper, and could also improve the device’s performance, says Chidambaram.

The researchers built a stack of 4 alternating wafers of aluminum and germanium, each less than a micrometer thick, and heated the sandwich under pressure to about 400 °C for 2 hours. Although the wafers did not liquefy, this “thermal aging process facilitated bonding prior to melting,” explains Chidambaram. Raising the temperature to 475 °C for another 2 hours fully melted the mixture, which then formed a strong seal after cooling — a process known as transient liquid-phase bonding.

Next, the researchers used acoustic microscopy, scanning electron microscopy and X-ray spectroscopy to reveal any voids or other defects in the seals. They found that the thermal aging process improved the quality of the seal. Tests showed that it was strong enough to withstand a shear of 46 megapascals — similar to the pressure exerted by almost half a ton per square centimeter — and was impermeable to water. The material lost little of its strength after being exposed to 300 °C for hundreds of hours.

Chidambaram and his team also tested a platinum–indium seal — which has the highest re-melting point (894 °C) of all the solders being considered for these applications — but it lost its strength after long durations at 300 °C, leaving the aluminum–germanium mixture in pole position as a better seal for MEMS. “Cost effectiveness, better thermo-mechanical properties, and its eutectic microstructure makes it an attractive alternative,” says Chidambaram.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Microelectronics

Journal information

Chidambaram, V., Yeung, H. B. & Shan, G. Development of metallic hermetic sealing for MEMS packaging for harsh environment applications. Journal of Electronic Materials 41, 2256–2266, 2012

A*STAR Research | Research asia research news
Further information:
http://www.research.a-star.edu.sg
http://www.researchsea.com

More articles from Materials Sciences:

nachricht New design improves performance of flexible wearable electronics
23.06.2017 | North Carolina State University

nachricht Plant inspiration could lead to flexible electronics
22.06.2017 | American Chemical Society

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>