December 18, 2020 by Emmanuel Ikimi
Electronic devices we use daily, including smartphones, computers, and portable cameras, owe much of their functionality to the unique properties of semiconductors and ceramic materials. We look at technical ceramics, which are emerging as one of the electronics industry’s materials of choice due to their unique physical properties.
Technical (aka ‘engineered’ or ‘advanced’) ceramics are ceramic materials that possess superior electrical, mechanical, and thermal properties. These materials are enhanced and tailored via their chemical compositions to provide improved and specialised properties required by a wide range of applications in the electronics industry. The most common type is silicon nitride, i.e. a ceramic material composed of silicon and nitrogen. Others are made up of zirconium oxide, aluminium titanate, or a metal matrix composite.
A printed circuit board with various ceramics-based components. Image Credit: Pixabay.
The mainstay of technical ceramic’s industry applications is at the component manufacturing level. Different compositions of ceramics are used to manufacture a variety of components with insulating, dielectric, piezoelectric, or magnetic properties. The materials also provide hermetic structural protection for most integrated circuits.
Ceramic compositions that exhibit low electrical conductivity, such as aluminium oxide (alumina), are ideal for designing passive components. These types of ceramics are employed in multilayer ceramic capacitors (or MLCCs) to separate multiple layers of electrodes that make up the component. They are also used in resistors to dissipate energy in the form of heat. Other ceramic compositions can permeate magnetic fields, making them suitable for use in the manufacture of inductors. Ceramics combined with iron oxides and strontium carbonate form magnetic ceramics (also known as ferrite) with high magnetic properties.
Although engineered ceramics are desired for their unique insulating properties, some compositions can be used to create semiconducting or superconducting materials (for example, lanthanum barium copper oxide—or LBCO—discovered in 1986 by Nobel prize winners Georg Bednorz and Alex Müller). There are many other types of technical ceramics with distinct properties that are suitable for various applications in the electronics industry—examples of which are covered below.
The practical properties of technical ceramics mean that they are increasingly relevant to various areas of the electronics industry. In the next three sub-sections, we look at some key examples of industry applications relevant to the technology.
As the general trend in electronics products seems to be towards miniaturisation, the electronics industry continually looks to create increasingly compact electronic devices. One of such applications is a printed circuit board, or PCB, that can be bent and placed in a much smaller enclosure than would a flat and rigid board. Flexible copper-based PCBs are already in use today, but they are mostly limited in practice, as most flexible PCBs require a rigid section to hold the components. On top of this, flexible sections are limited to holding the copper connections and interconnecting sections of the PCB.
The main justification is that electronic components are rigid and cannot be placed on curved surfaces. This is one area where flexible ceramics may thrive. If conventional components can be manufactured using a combination of polymers and ceramic powder, this could potentially usher in a new era of flexible, miniaturised devices. According to new research, notable advancements in this regard are being made by a material science startup, Eurekite.
Aluminium oxide (aka alumina) is currently the most common material for electronics substrates. Pictured: a close-up of a mother board’s chips that are packaged with black alumina. Image Credit: Pixabay.
With the increasing demand for highly-integrated and functionality-packed system-on-chips—which of course imposes stringent signal processing, power, and heat dissipation requirements—significant materials science research efforts have been directed towards the development of improved ceramic compositions with lower dielectric constants and higher thermal conductivity than that found in alumina, which is currently the most widely used substrate in the industry today.
Arrays of interconnected components built on chips of silicon, aka integrated circuits, traditionally utilise ceramic substrates and packages that provide electrical insulation and hermetically-sealed mechanical support. With their superior mechanical and thermal properties, technical ceramics can produce improved and durable substrates and packaging materials.
Supercapacitor manufacturing has advanced greatly in recent years. This is largely due to the demand for more efficient energy storage devices than that offered by batteries. Batteries have high energy densities but a limited number of charge/discharge cycles (even in electric vehicles); plus, they are adversely affected by high temperatures. Supercapacitors, on the other hand, have millions of charge-discharge cycles with minimal degradation over their useful lives. They can mitigate many of the limitations of batteries, although they do nevertheless have limited energy storage capacities.
Supercapacitors, although constructed in a different way than regular capacitors, share many of the same properties. And while this may make them a desirable replacement for batteries, supercapacitors are big electrolyte-based devices. This means that there is a complex manufacturing and design process for any engineers who wish to fabricate and scale the technology for use in miniaturised devices. Therefore, there is a requirement for solid-state supercapacitors that can be used to power small devices—and technical ceramics can be viable candidates. An article by the Indian Institute of Technology, Mandi’s School of Engineering considers the use of anti-ferroelectric ceramics as a means to potentially meet the above challenges.
A first-person view of a silicon ceramic chip held up close for inspection. Image Credit: Bigstock.
Technical ceramics, aka engineered ceramics—despite their useful applications being mostly at the raw material level—should continue to be relevant in the rapidly growing electronics industry, particularly due to their above-mentioned qualities, such as their superior electrical, mechanical, and thermal properties.
Technical ceramics are enhanced and tailored via their chemical compositions to provide improved properties that enable a wide range of electronic applications. The increasing need for highly integrated and efficient electronic devices will continue to drive research in the development of technical ceramic materials.
