‘Smart’ glues to drive unleaded chips

Buffalo solder

'Smart' glues developed by British boffins could soon rid silicon chips of the lead-based solder that is currently used to attach each die to the pins that ultimately connect the chip to the host system.

The glues can be used to replace solder because they conduct electricity. They are dubbed 'smart' because they can be designed to bond only to specific materials, such as the gold electrodes and copper wires used in chip design.

Instead of soldering wires to electrodes, chip companies could simply spray smart glue into the chip. The adhesive would form connections only between the required components. Any excess glue could then be washed away with water, collected and re-used.

That would not only reduce chip makers' costs but cut the amount of toxic lead that is released into the environment.

University of Kent chemist Simon Holder announced his discovery of six smart glues at the Sixth International Conference on Materials Chemistry held in Sheffield last week, New Scientist reports.

Holder's glues are made up of styrene molecules, each of which is topped and tailed by two polymethylacrylate groups. The latter essentially stop the styrene from adhering to other materials, but in the presence of gold or copper, the molecule bends allowing the styrene to come into contact with the metal.

Holder's work isn't yet complete. His glues act as semiconductors, but he hopes to turn them into full conductors in order to make it possible for them to be used in the chip-making role he describes. ®