A high-tech, low temperature alternative to soldering

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MATERIALS scientists at the Northeastern University in Boston have developed a room-temperature metallic glue which could act as soldering’s substitute in certain situations.

The new material, called MesoGlue, is described within the Advanced Materials and Processes journal as a "joining solution that lets you attach items together with a metal bond, at room temperature."

Soldering has a long history. While the origins of metalworking has been dated to around 12,000 BC, the first instances of using molten metal as a way to join things together commenced at around 5,000 BC, as humans discovered naturally-occurring alloys which could melt at lower temperatures. The current tin-lead mixture used for soldering appeared during the Roman empire.

MesoGlue, however, takes a more technological approach to the problem. Engineered nanorods in the material mesh together when surfaces are joined, locking them together.

The nanorods are encased by an indium and gallium shell. Indium and gallium liquefies when they touch each other, and this occurs when the nanorods are in the process of interlocking.

This liquid metal then flows around the interlocked nanorods. The metal core of the rods then solidifies the metal into a strong bond. Despite forming in room temperatures, the resulting adhesion is able to withstand high temperatures, and crucially, is able to conduct electricity.

The researchers sought a lower temperature method of creating electrically conductive bonds because of the thermal dangers associated with high temperature soldering.

Their paper states that as component size decreases, soldering or wire bonding becomes more challenging and voids can lead to joint failure.

“A metallic glue bond eliminates the possibility of heat damage during attachment and simplifies the soldering process to merely pressing parts together to attach," the group stated.

The MesoGlue is also able to dissipate heat more efficiently than the thermal grease used to improve heat conductivity between electronic componentry and heatsinks.

Used in place of thermal grease in conventional situations between processor chips and their heatsinks, simulations found the MesoGlue thermal link resulted in CPU temperatures running around eight degrees Celsius lower on average.

Of course, while conventional solder retains its price advantage over the MesoGlue, it is unlikely the material will see wider adoption outside of specific applications where it is required.