Metallic Bonding Glue May Bring Extinction to Soldering and Welding

Nanotechnology has brought industry and manufacturing many benefits, and its latest gift, thanks to a group of scientists from Northeastern University and the University of North Florida, may be the ability to largely eliminate soldering and welding from the production line. They have created a room-temperature metallic glue that forms a durable metal bond using only pressure. It is said to provide the strength and thermal and electric conductance of a metal bond yet reportedly behaves even better than conventional glue.

Dubbed “MesoGlue,” the substance was created by professors Hanchen Huang and Paul Elliott of Northeastern University, together with professors Stephen Stagon and Alex Knapp of the University of North Florida, Jacksonville, which have formed an eponymous company to market it. According to Huang, the glue’s unique attributes result from metallic nanorods coated with either indium or gallium that are able to form greater lengths than before. Upon application, they stand up and form “teeth” that interlock.

“Metallic nanorods are very tiny columns that are attached to a surface,” Huang told Design News. “They resemble grass on a freshly cut lawn, or the bristles of a hairbrush. Our recent developments have made it possible to grow the metallic nanorods with a large separation. As two sets of nanorods, one set on each solid surface, are brought together, they easily interpenetrate and sinter at room temperature and under small pressure. As a result of the interpenetration and sintering, a metallic connection forms as metallic glue at the macroscale.”

MesoGlue, a metallic nanoglue created by four university researchers, can be used as a thermal interface material to connect a CPU or other power-dense devices to a heat sink.
(Source: MesoGlue)

The sintering takes place by solid surface diffusion, or formation of eutectic alloy liquid and subsequent solidification of a new alloy. In addition to creating a bond that is said to be as durable as a traditional weld -– while eliminating welding’s high temperatures that can damage nearby components -- MesoGlue is said to overcome the drawbacks of conventional glue. The bonds form much more quickly than the drying process required by glue, and the substance doesn’t have the noxious smell of glue.

It also eliminates the need for thermal paste, bringing multiple benefits to design engineers and manufacturing companies. Currently, thermal greases require pumping out of the interface due to thermal cycling and to prevent dry-out. In addition, the metallic glue is able to transfer heat more efficiently than paste, which will allow components to run cooler and last longer.

[Learn more materials & assembly trends and developments at Pacific Design & Manufacturing, Feb. 9-11, at the Anaheim Convention Center.]

MesoGlue’s advantages over soldering may help pave the way for new applications or the improvement of existing processes currently limited by soldering, such as electrical and thermal conductors in integrated circuits, and mechanical connections of electronic components in extreme environments due to high vibration or g-forces. It can also provide a leak-resistant seal for vacuum environments.

“Essentially, the metallic gluing is similar to soldering, except it does not require high temperatures or high pressures,” Huang said. “Therefore, this technology will be ideal for applications in environments that can be adversely affected by heating or mechanical pressure. The glue also works in a large range of temperature environments.”

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It won’t be a complete replacement for soldering. For starters, the cost will likely be prohibitive for low-end technologies, Huang pointed out. Thus far, MesoGlue has been used only in a laboratory environment, but it has potential once it’s used in commercial processes. This is the next goal in the development process for Huang and his partners.

“In order for this technology to be commercially used, it is critical that it be seamlessly integrated with other processes,” Huang said, “such as integrated circuit manufacturing.”

The research that led to the creation of MesoGlue was first published in the January 2016 issue of the Journal of Advanced Materials and Processes.

Tracey Schelmetic graduated from Fairfield University in Fairfield, Conn. and began her long career as a technology and science writer and editor at Appleton & Lange, the now-defunct medical publishing arm of Simon & Schuster. Later, as the editorial director of telecom trade journal Customer Interaction Solutions (today Customer magazine) she became a well-recognized voice in the contact center industry. Today, she is a freelance writer specializing in manufacturing and technology, telecommunications, and enterprise software.

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