Jan. 10, 2016

Per¬haps no startup was launched for a more intriguing reason than that of Northeastern's Hanchen Huang. From the com¬pany website:
"MesoGlue was founded by Huang and two of his PhD stu¬dents: They had a dream of a better way of sticking things together."

Those "things" are every¬thing from a computer's cen¬tral pro¬cessing unit and a printed cir-cuit board to the glass and metal fil¬a¬ment in a light bulb. The "way" of attaching them is, aston¬ish¬ingly, a glue made out of metal that sets at room tem¬per¬a¬ture and requires very little pres¬sure to seal. "It's like welding or sol¬dering but without the heat," says Huang, who is pro¬fessor and chair in the Depart¬ment of Mechan¬ical and Indus¬trial Engineering.

In a new paper, pub¬lished in the Jan¬uary issue of Advanced Mate¬rials & Processes, Huang and col¬leagues, including North¬eastern doc¬toral stu¬dent Paul Elliott, describe their latest advances in the glue's devel¬op¬ment. Our curiosity was piqued: Sol¬dering with no heat? We asked Huang to elaborate.

On new devel¬op¬ments in the com¬po¬si¬tion of the metallic glue:
"Both 'metal' and 'glue' are familiar terms to most people, but their com¬bi¬na¬tion is new and made pos¬sible by unique prop¬er¬ties of metallic nanorods--infinitesimally small rods with metal cores that we have coated with the ele¬ment indium on one side and galium on the other. These coated rods are arranged along a sub¬strate like angled teeth on a comb: There is a bottom 'comb' and a top 'comb.' We then inter¬lace the 'teeth.' When indium and galium touch each other, they form a liquid. The metal core of the rods acts to turn that liquid into a solid. The resulting glue pro¬vides the strength and thermal/?electrical con¬duc¬tance of a metal bond. We recently received a new pro¬vi¬sional patent for this devel¬op¬ment through North¬eastern University."

On the spe¬cial prop¬er¬ties of the metallic glue:
"The stan¬dard polymer glue does not func¬tion at high tem¬per¬a¬tures or high pres¬sures, but the metallic glue does. The stan¬dard glue is not a great con¬ductor of heat and/?or elec-tricity, but the metallic glue is. Fur¬ther¬more, the stan¬dard glue is not very resis¬tant to air or gas leaks, but the metallic glue is.
"'Hot' processes like sol¬dering and welding can result in metallic con¬nec¬tions that are sim-ilar to those pro¬duced with the metallic glue, but they cost much more. In addi¬tion, the high tem¬per¬a¬ture nec¬es¬sary for these processes has dele¬te¬rious effects on neigh¬boring com¬po¬nents, such as junc¬tions in semi¬con¬ductor devices. Such effects can speed up failure and not only increase cost but also prove dan¬gerous to users."

What are some appli¬ca¬tions of the technology?
"The metallic glue has mul¬tiple appli¬ca¬tions, many of them in the elec¬tronics industry. As a heat con¬ductor, it may replace the thermal grease cur¬rently being used, and as an elec-trical con¬ductor, it may replace today's sol¬ders. Par¬tic¬ular prod¬ucts include solar cells, pipe fit¬tings, and com¬po¬nents for com¬puters and mobile devices."

Image: Hanchen Huang and colleagues, experts in nanotechnology, have developed a glue that binds metal to metal to glass to you-name-it, sets at room temperature, and requires little pressure to seal.