The World's #1 Renewable Energy Network for News, Information, and Companies.
Untitled Document

Alloy Developed at Sandia Has Potential for Electronics in Geothermal Wells

An alloy that may improve high-temperature electronics in oil and geothermal wells was really a solution in search of a problem.

Sandia National Laboratories first investigated the gold-silver-germanium alloy about 15 years ago as a possible bonding material in a new neutron tube product. But a design change forced Sandia to shelve the material, said Paul Vianco, who has worked in soldering and brazing technology at Sandia for 26 years.

Then a few years ago, researchers working on other projects with applications inside a well, referred to as downhole, asked Sandia’s geothermal group to develop electronics to monitor well conditions in field operations. Circuit boards placed downhole in oil and geothermal wells must withstand high temperatures and pressures, excessive vibrations and other extreme environments.

The gold-silver-germanium alloy is suitable for those conditions, Vianco said.

It’s technically a solder, but it’s at the upper limits for what’s considered a solder — materials that melt at no higher temperature than 450 degrees Celsius (842 degrees Fahrenheit), Vianco said. The American Welding Society deems materials that melt at higher temperatures as brazing filler metals.

Sandia National Laboratories researcher Tom Crenshaw sets up a specimen in a test frame that will pull a solder joint apart to determine its tensile strength. He co-authored a paper that won the Best of Proceedings category in the Surface Mount Technology Association’s International 2012 Best Papers conference. (Photo by Norman Johnson)

Sandia Fills Niche in Downhole Uses

The alloy’s potential for downhole electronics gives Sandia a unique niche, Vianco said.

Most brazing processes occur at a peak temperature above about 700 degrees C, while most soldering occurs below 350 degrees C, leaving high-temperature electronics few filler materials from which to choose.

“So there’s this no man’s land in which the only materials that are available are aluminum-based brazing alloys that melt at about 600 degrees C,” Vianco said. But aluminum-based alloys are difficult to process for electronics.

In addition, the gold-silver-germanium alloy is lead-free, making it environmentally friendly for geothermal work in countries such as Iceland, which, like the rest of Europe, is moving away from materials that contain lead. The alloy’s fundamental mechanical and processing properties also are nearly fully characterized. That’s important because it saves about two years of development that would be required to establish how well the alloy makes a reliable solder joint, Vianco said.

“All that’s done,” he said. “We have the preliminary work completed that allows us to consider this material for a range of applications, including downhole electronics.”

Alloy Developed from Earlier Work

The alloy originally was developed from the gold-germanium system, which has traditionally been a die attachment material used in microelectronics packaging. But a higher melting temperature was required for the neutron tube application, so Vianco and colleagues John J. Stephens, now deceased, and F. Michael Hosking, now retired, added silver and adjusted the concentrations to reach a near-uniform melting point for the alloy.

“It was so close to brazing that we didn’t think that there would be much interest in the electronics industry until the option came up for downhole applications,” Vianco said.

He is now seeking funds to develop the material to a prototype stage for geothermal and oil and gas well tools. “We really think it is a material that’s suitable for these higher temperature applications,” Vianco said. “In this no man’s land of filler metal technology, there are really not a lot of options out there other than lead-containing alloys. Companies are exploring lead-bearing solders, albeit begrudgingly so.”

When interest in downhole applications arose, Vianco and his colleagues needed to pull together information on the alloy from the mid-1990s. They resurrected the data and re-evaluated it, and Vianco wrote a paper assessing its properties.

That wasn’t as easy as it might sound.

“Photographs were all on film; we had to scan these pictures into an electronic format. Documents and presentations were in unusable formats or archived on software that is no longer supported by the labs.

So everything was brought up to a level that is compatible with current computer resources,” Vianco said.

Paper Compiled Research Data

The paper, “Ag-Au-Ge Alloys for High Temperature Geothermal and Oil Well Electronics Applications,” won the Best of Proceedings category in the Surface Mount Technology Association International 2012 Best Papers conference announced in January. Vianco will receive the award at SMTA’s meeting in October in Fort Worth, Texas.

He wrote the paper largely to compile the data in case interest developed within the oil, gas and geothermal industries, and hadn’t planned to submit it for publication. But SMTA International, aware of Sandia’s leadership role in soldering technology, asked the labs to provide a paper for a session on alternative solders for electronic applications, so Vianco submitted it.

He believes Sandia might be able to use the gold-silver-germanium alloy as a joining material in high-precision components.

The paper and the publicity surrounding the award have raised awareness of the alloy and the growing  need for high-temperature materials to support downhole electronics, Vianco said.

“This is how tech transfer works the best — publish the material and let the folks who have the need become aware of it and then work with their specific applications," he said.

Untitled Document

RELATED ARTICLES

Energy Storage and Geothermal Markets Look To Team Up in the Hunt for Lithium

Meg Cichon In today's fast-paced tech environment, no one can make a splash quite like Elon Musk. So when he decided to enter the energy storage game in 2014, he did it with gusto. Musk is now in the process of building what he coined...

Regional News from the July/August 2015 Digital Edition of Renewable Energy World

Renewable Energy World Editors EcoFasten Solar announced that it launched a new mounting "Rock-It System" that it would be displaying during Intersolar. Product compliance was determined through testing per UL Subject 2703, which reviews integr...

SkyPower Inks $2.2 Billion Deal for Massive Solar Power Plant in Kenya

Eric Ombok, Bloomberg Kenya’s Energy Ministry and SkyPower Global Ltd. will sign a $2.2 billion agreement on Sunday that paves the way for the Canadian company to develop a 1-gigawatt solar project in East Africa’s biggest economy. The solar pro...

Some Hope for US Renewable Energy Tax Credits As Extension Bill Passes Committee

Vince Font In a lopsided 23-3 vote, the U.S. Senate Finance Committee voted yesterday to extend a number of renewable energy production tax credits through the end of 2016. The vote allows developers of wind, geothermal, biomass, land...

CURRENT MAGAZINE ISSUE

Volume 18, Issue 4
1507REW_C11

STAY CONNECTED

To register for our free
e-Newsletters, subscribe today:

SOCIAL ACTIVITY

Tweet the Editors! @megcichon @jennrunyon

FEATURED PARTNERS



EVENTS

StartUp Green

AREI, American Renewable Energy Institute, in partnership with ...

GRC Annual Banquet

GRC Annual Banquet Monday, September 21, 6:00 pm - 9:00 pm National Auto...

GRC Fieldtrip - Geothermal Direct Use Tours of the Peppermill Resort

Free to all attendees (limited to 30 participants per tour) Located...

COMPANY BLOGS

Clean Energy Patents Maintain High Levels in First Quarter, Solar L...

U.S. patents for Clean Energy technologies from the first quarter of 201...

Registration Opens for GRC Annual Meeting & GEA Geothermal Energy Expo

GRC Annual Meeting & GEA Expo:   Register Now for the 2015 GRC ...

New Approach to Crowdfunding Renewable Energy Assets

In our business, our goal is to help people improve their quality of lif...

NEWSLETTERS

Renewable Energy: Subscribe Now

Solar Energy: Subscribe Now

Wind Energy: Subscribe Now

Geothermal Energy: Subscribe Now

Bioenergy: Subscribe Now  

 

FEATURED PARTNERS