The Next Assembly Line Robot - Antifreeze
now has a new use. Scientists at the University of Minnesota have discovered a way
to exploit the surface tensions properties of ethylene glycol to cause pairs of
components with complementary shapes to be attracted to each other and self-assemble.
In an experiment, hundreds of LED chips and silicon carriers were mixed in a container
of ethylene glycol, heated, and then shaken to cause the complementary LED/carrier
shapes to mate while in the mixture. The system was then heated to a temperature
that allowed solder dollops in the carriers to melt and make a connection to the
LED die pads. After cooling and rinsing, the assembled parts were removed and inspected.
600 assemblies were produced in just two minutes - a 100% yield! A second and final
similar step then assembled the LED/carrier pairs onto a surface-mount package and
yielded 97%. This process is being considered for similar high volume manufacturing
operations that involve parts too small to be efficiently handled with robotic or