Semiconductor devices like this one now can be joined electronically with the new solder. (Robert Kozloff)
A research team led by the University of Chicago has demonstrated how semiconductors can be soldered and still deliver good electronic performance. The team developed compounds of cadmium, lead, and bismuth that can be applied as a liquid or paste to join two pieces of a semiconductor by heating them to several hundred degrees Celsius, which is mild by industry standards.

The paste or our liquid converts cleanly into a material that will be compositionally matched to the bonded parts, and that required development of new chemistry. Special molecules were designed that fulfill this requirement so they do not contaminate the material. After application as a liquid or paste, they decompose to form a seamless joint.

The technology could enable 3D printing of semiconductors, and could lead to the development of less expensive, solution-processed semiconductors needed for entry into new markets. Among these markets are printable electronics, 3D printing, flat-panel display manufacturing, solar cells, and thermoelectric heat-to-electricity generators for the Internet of Things.