MIT Researchers Extend Pick-and-Place to Tiny, Microscopic Components
An electroadhesive stamp, "somewhat like a gecko's foot," extends pick-and-place assembly technology to components as small as 20nm.
Researchers at the Massachusetts Institute of Technology (MIT) have built an "electroadhesive stamp" system which can extend the pick-and-place concept into the microscopic scale — potentially easing the assembly of smaller, more powerful circuits in the future.
Mass-produced circuit boards are typically populated using a pick-and-place machine. As the name implies, the machine picks up components and places them on the circuit board — after a mask has been used to apply solder paste. The board then passes through a soldering station, and then it can be sent on for testing.
As technology progresses, however, component sizes are getting ever smaller — as anyone who's ever dropped a surface-mount resistor on the floor and watched it vanish into thin air can attest. The smaller the component, the harder it is for a machine to pick it up — and tomorrow's microscopic components need something a little smarter than a rubber hose pulling a vacuum.
"Electronics manufacturing requires handling and assembling small components in a size similar to or smaller than grains of flour," explains researcher and former MIT postdoc Sanha Kim. "So a special pick-and-place solution is needed, rather than simply miniaturising [existing] robotic grippers and vacuum systems."
The solution: an "electroadhesive stamp," which can pick up and accurately place objects as small as 20nm in width - 1,000 times thinner than a human hair. The stamp is made from ceramic-coated carbon nanotubes which become charged when a voltage is applied, attracting the object to be picked up; cutting the voltage removes the charge, dropping the component into place.
Describe by MIT Professor John Hart as "somewhat like a gecko's foot," the stamp builds on earlier work to create "dry Scotch tape" from carbon nanotubes by maximising surface contact. "We took the opposite approach," Professor Hart explains, "and said, 'let’s design a nanotube surface to minimise the contact area, but use electrostatics to turn on adhesion when we need it.'"
More information on the project, which has been published in the journal Science Advances, is available from MIT News.