A new type of solder can be melted and shaped in three dimensions under the force of a weak magnetic field. Using a magnet to pull the solder up through narrow holes makes it possible to create electrical connections between stacked silicon chips, for example. These three-dimensional chips pack more computing power in a given area, but making connections between them is expensive, a problem that the new solder might address. The solder also contains no lead, and it is stronger than other lead-free solders.
"It's like the liquid metal robot from Terminator 2: you can shape it and make it flow using a magnetic field," says David Dunand, a professor of materials science and engineering at Northwestern University, who was not involved with the research.
The new solder was developed by researchers led by Ainissa Ramirez, professor of mechanical engineering at Yale University, who was named on Technology Review's TR35 list of young innovators in 2003. The solder gains both its strength and magnetic properties from iron particles suspended in the mixture.
From Technology Review
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