Posts Tagged ‘eutectic’
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April 23rd, 2010
Gold is ‘supercool’
A great illustration of how important gold is to cutting edge research is the observation that most issues of the leading journal Nature appear to include new research on the metal; be it catalysis, nanotechnology, chemistry or materials science. The most recent issue is no exception, with a new paper – ‘Substrate -enhanced supercooling in AuSi eutectic droplets’ by researchers from the CNRS facility in Grenoble, France.
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March 24th, 2010
Seiko Instruments and gold-tin eutectic
Seiko Instruments has come up with a gold-tin eutectic bonding process that can take place at temperatures low enough to inhibit release of gases during bonding meaning that a higher level of vacuum sealing can be achieved. It is claimed that this method improves mechanical strength and also lowers fabrication costs for the intended application – a silicon based MEMS resonator.
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July 10th, 2009
Au-based die attach materials
The issues relating to the use of gold-based alloys as die attach materials in the electronic packaging industry is highlighted by Anwar Mohammed from Infineon Technologies in Solid State Technology. He writes:
“To keep up with demanding power requirements, some savvy companies rely on eutectic attach materials such as AuSn and AuSi for die attaching to obtain superior thermal performance. The die attach temperatures are much higher relatively: ~320°C for AuSn, and ~420°C for the AuSi; but the thermal conductivity is significantly better with AuSn performing at ~70W/mK and AuSi performing at >150W/mK. The disadvantage of this approach is that it is a very tricky and sensitive process with a narrow processing window that needs to be monitored carefully.”
The reason I found this interesting (other than because it explains why Au-based materials are useful in die attach applications) is that there are direct similarities with gold-based catalysts. Like the eutectics described above, these catalysts have significant performance benefits in many reactions (selectivity, activity), but applications have been limited due to processing concerns. The problems in ‘processing’ can be related to either making the catalysts or operating them under practical conditions, where the process window may be limited. Thankfully things are now progressing well. Gold catalysts can be successfully manufactured and purchased from the likes of 3M, Strem Chemicals, AuTEK and Nanostellar (automotive) and there are applications where they are able to operate under a suitable range of processing conditions.
Richard Holliday
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