Invention of the Year Nominee: A New Joint Soldering Paste with High Temperature Resistance
University of Maryland researchers have developed a new Transient Liquid Phase Sintering, or TLPS, joint soldering paste that can operate under extreme thermal and mechanical loads where other formulations have failed.
The invention, one of nine nominees for the University of Maryland Invention of the Year Award, offers potential application in aviation, space exploration, and hybrid electric vehicles.
UMD Associate Professor of Mechanical Engineering Patrick McCluskey, along with Research Graduate Assistant Hannes Greve, developed this special paste.
McCluskey said that the appealing attribute of this paste is that it can be processed at lower temperatures (below 300°C) and yet also operate at extremely high application temperatures (450°C). Furthermore, the paste exhibits high electrical and thermal conductivity while also offering reliability, low cost, and wide applications across many industries.
“[The paste] can be applied to all metallization types that are common in electronic products [such as copper, nickel, tin, gold and silver]. It is an excellent solution for electronic interconnects used in high temperature environments and high power density applications,” McCluskey said.
For now, the technology is being used to attach the layer connecting the bottom of semiconductor chips to a metallic substrate. Energy harvesting using thermoelectric generators is another application.
“The high application temperatures of the TLPS sinter joints enable more efficient energy harvesting,” McCluskey said.
Pointing out some of the disadvantages of alternative technologies, McCluskey said that melting temperatures of tin and bismuth-based solder alloys are low, while zinc-based solder alloys tend to corrode and oxidize, and gold-based alloys require high processing temperatures and the cost of raw materials is high.
McCluskey’s paste can be used in sensor and actuator systems for jet engines and in the monitoring and controlling of oil and gas exploration in the earth’s crust.
According to McCluskey, the paste could also be used in space exploration electronics that require high temperature attach materials and in the engine compartments of automobiles.
“An interconnect technology that enables high operation temperatures, such as this innovation, will be needed more and more in the future to make electronics systems smaller, more efficient, and less expensive,” he said.
Customers include companies from the energy generation, distribution and harvesting industry. and oil and gas, automotive, aerospace, and motor industries.
McCluskey plans to further experiment and modify the composition and microstructure of this paste to obtain more optimal properties for a range of products.
Published April 27, 2015