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 Researchers invent process to make sustainable rubber, plastics
25.04.2017 | University of Delaware

nachricht Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging
24.04.2017 | Pohang University of Science & Technology (POSTECH)

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>