Ceramics and glass in communications

Modern terrestrial communications (i.e., mobile, wireless, and fixed communications) and satellite communications require a range of components for transmitting,  amplifying, switching, filtering, stopping and converting electrical, radio and optical signals. Often these components are made from ceramics and glass.

Ceramics and glass are used in the communications sector for their tunable dielectric constant, low dielectric loss, low temperature coefficient of capacitance, low coefficient of thermal expansion, high impact resistance, and high durability. Satellite communications benefit from the high wear and corrosion resistance properties of ceramics for creating electronic devices that need to withstand extreme heat and harsh environments.

Products based on these materials include primarily circuit devices, passive components, and optical filters. Circuit devices consist of high and low temperature co-fired ceramics, printed substrates, and optoelectronic integrated circuits.

Low-temperature co-fired ceramics (LTCCs) are among the most popular devices. They are made from glass-ceramics or glass plus ceramic, and sintered at low temperature (1000°C or below) with a single-firing process. LTCCs have a multilayer construction with low-melting point silver, copper, or gold metallization. The integrated module contains components such as inductors, resistors and capacitors. LTCCs are designed in the configuration of baluns, antennas, couplers, diplexers, switches, band pass filters, and low pass filters.

Electronic circuits used in communications comprise passive components, such as single and multilayer ceramic capacitors, resistors, varistors, and inductors. Other components are ceramic-to-metal seal packages, multi-chip modules, feedthroughs, semiconductor packaging, heat sinks, and thin film substrates.

Ceramics and glass are also being applied in optical wireless communications, a method of communication where information is transmitted using light, rather than electrical signals or radio waves. Optical wireless communications require various components to convert signals to light, transmit the light, and convert it back to an electrical signal. For example, of these components, glass and glass ceramics are promising materials for building optical amplifiers.

Ceramic films are also integrated into semiconductor devices to form optoelectronic integrated circuits (OICs), which contain both photonic and electronic components, and photonic integrated circuit (PICs), which contain only photonic devices.

In recent years, transparent ceramics have been introduced to manufacture optical waveguides for broadband applications and laser communication windows. Alumina and zirconia ceramics find application as insulating materials, sleeves, connector components, submounts, packaging materials, radio-frequency absorber lids, and optical isolators for optical fibers.

Satellite communications utilize dielectric materials formulated for microwave applications in the form of resonators, filters and oscillators. Piezoelectric ceramics are also common for functions such as vibration control and positioning control, and to improve signal quality.

In the communications sector, glass is used for production of optical fibers for high-speed communications; glass substrates, ball lenses, aspheric lenses and other items for optical communication devices; smart contact lenses for medical wireless connectivity; and displays for mobile devices for wireless communications, such as smartphones.

The main applications of ceramics and glass in communications are illustrated in the table below.

Main applications of ceramics and glass in communications

Where?	What?	Examples
CERAMICS
Electronic circuits	Low- and high-temperature co-fired ceramics	1
	Passive components (for example, resistors)	2
	Modules, printed substrates, and packages	3
Optical wireless communications	Optical components
	Components for fiber optics (Image courtesy Kyocera, semiconductor components division)	4
Satellite communications	Resonators	5
	Piezoelectric components	6
GLASS
High-speed communications	Optical fibers	7
Optical wireless communications	Lenses	8
Wireless communications	Displays	9