Researchers in IIT Bombay have achieved a breakthrough in making glass substrates that have significant advantages over the conventional silicon substrates in applications such as 5G devices.
Substrates are the base on which a thin film of a material (like Silicon oxide) is coated on which circuits are etched. Typically, substrates have been made of Silicon, for many advantages — it doesn’t expand much on heating, making it easy to coat stuff on it. However, the micro electromechanical systems (MEMS) industry has been toying with other material for substrates — and glass has been high up on the list.
Glass substrates (technically, fused silica, which is a pure form of glass without any metallic impurities) are much cheaper — one estimate has it that it is 80 per cent cheaper than Silicon substrates.
But nothing in the world comes without a flipside. Glass is brittle and for technical reasons, not so easy to fabricate.
Professor Pradeep Dixit of IIT Bombay and his team have used additive manufacturing technology (aka 3D printing) to address this problem. In a research project supported by a ₹1.45-crore grant from the Department of Scientific and Industrial Research, under the government of India’s IMPRINT initiative (which stands for Impact Research Innovation and Technology), Prof Dixit have developed a low-cost technique for manufacturing fused silica and other non-conducting hard materials using ‘electrochemical discharge machining method’.
“Increasing demands for hand-held, portable electronic devices with faster signal speed, reduced packaged size and better functionalities have pushed the usage of glass as the substrate material,” Prof Dixit explained to BusinessLine. Signal loss in high- frequency transmission is relatively higher in Silicon, which is after all, a semiconductor. Further, with the advent of wireless charging, it is easier for 5G signals to reach the device’s modem if the substrate is fused silica.
However, due to its hard and brittle nature, the creation of microfeatures is challenging, he says. Yet, considering the potential of glass-based materials in industrial electronics, it was essential to develop a cost-effective method to machine non-conductive brittle materials.
In this research, IIT Bombay has reached technology readiness level (TRL) of 5, on a scale of 1 to 9 – the higher the number the more ready it is for the market. “We are doing more experiments and are in contact with research institutes to test this process on a larger scale,” Prof Dixit said.
“Today, there are no low-cost micromachining technologies for non-conductive materials in India and this method may emerge as the potential technology in the manufacture of semiconductors. The researchers at IIT Bombay are in talks with Semiconductor Lab (SCL), Chandigarh “to bring this technology to manufacturing level”.
MEMS is a manufacturing technology of great promise, and it refers to making electro mechanical products that are of extremely small sizes. For instance, one illustration of a company in this business shows a miniaturised SUV sitting on one side of a matchstick. Products made with MEMS have applications in several areas in electronics, such as sensors. As such, any attempt to make them cheaper would be of immense value to the society.