BENGALURU: The pleasure of owning the latest smartphone turns into pain when it inexplicably goes blank after someone accidentally drops it on the floor. The ultra-smart laptop or tablet may also suffer from the same malady.
In the Thermo-Electro-Mechanical Behaviour Laboratory, the Department of Materials Engineering at the Indian Institute of Science, Praveen Kumar and his team design ways to improve mechanical strength of materials for a variety of applications, especially electronics. They identify, investigate and engineer solutions for all possible causes for failure in futuristic devices — such as mechanical shock, high currents and excessive heat.
Kumar’s team is developing ways to increase the strength of ‘CNT’ foam, to replace the standard polymer foam used inside electronic gadgets for shock absorption. CNT (Carbon Nano Tube) foam is a dense mesh of carbon nano tubes, routinely studied for mechanical applications. The team’s recent experiments show that applying a voltage of 1V during a fall can increase the shock absorption capacity of CNT foam by three times. This new finding can be implemented in the near future because “such a small voltage is easily available in your phone or laptop’s battery,” says Kumar.
To get smaller, multi-functional gadgets, engineers pack in more transistors in an electronic chip and more chips in a circuit board. This leads to higher current densities confined in a small space, leading to more heat generation. Laptops today can heat up to 60°C with continuous usage. This temperature is high enough to cause structural weakness in the environmentally-benign lead-free solders used in circuits today. Additionally, high current densities weaken the bond between the tin-based solders and copper wires, further reducing their life.
Kumar’s group is designing solutions for these problems too and is also developing new materials that can withstand high currents.
“It was all serendipity”, reminisces Kumar about the experiment where they first observed that they could melt metal and control the direction of its flow using electric field. This gave birth to ‘Electro-lithography’ - a new method of creating patterns using only electric field.
“Conventional lithography needs UV light and masks with precisely drawn outlines to create device patterns on the semiconductor. It is one of the most expensive steps in the fabrication of any semiconductor device today. In comparison, electro-lithography is inexpensive and simpler to execute. All it needs is a movable electrode tip and metal,” says Kumar.
Using electro-lithography, Kumar and his colleagues have written patterns as small as 40 nm on semiconductors.
Their research aims to provide lasting solutions and new techniques that can give us more reliable and economical electronic devices in the future.