Manufacturing Electronic Components with Light

Most of today's electronic components and devices are made using automated machines that require expensive and high-precision robots. As the shrinking size and precision requirements of the device increases, the cost of the machine also increases. But a recent development by an international team of researchers in Steven Neales' Micromanipulation Research Group gave way to a much cheaper and faster method to mass produce components and devices with the use of light.

Which of the following techniques or methods were used in this innovative research to help assemble electrical contacts?

    a. Optical traps and acoustic tweezers

    b. Dielectrophoresis

    c. Optoelectronic tweezers and freeze-drying

c. Optoelectronic tweezers and freeze-drying

Further Discussion:

The researchers successfully demonstrated the use of optoelectronic tweezers and freeze-drying technique to manipulate and accurately assemble a pattern of tiny solder beads to form electrical connections.

Optoelectronic tweezer (OET) is a type of micromanipulation technology that uses light-induced dielectrophoresis to hold and move micro- and nano-scale particles such as carbon nanotubes and semiconductor nanowires within a liquid environment. The tweezer is made up of a layer of silicon that when exposed to light its electrical conductivity changes. The exposed area then creates a non-uniform electric field that excites the particles or beads to precisely move by simultaneously moving the point of light. This method can move particles or solder beads measuring from the nanometer range up to about 150 microns.

3D schematic of the OET device

Using the OET, the researchers assemble a 40-µm-diameter Sn62Pb36Ag2 solder microspheres pattern and implemented an innovative "freeze-drying" method developed by Shuailong Zhang, a member of Neale’s research group, to remove the liquid without disturbing the assembled components. Freeze drying works by freezing the liquid medium while reducing the pressure and adding heat allowing the frozen medium to sublimate and interface with each other. This process successfully creates a microscale circuit of solder microspheres forming an electrical connection with a very low resistance.

Parallel assembling, freeze-drying and heating of solder beads

This technique is a promising approach to a cheaper and faster mass production of electronic and light-based components for smartphones, computers and other devices.

The researchers further aim to combine both optoelectronic tweezers and freeze-drying process in a single unit and develop an application that will allow a smartphone to control the generation of light patterns depending on the number of particles needed.


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