electronic substrate and package ceramics
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What is an electronic substrate?
An electronic substrate is an advanced industrial material with insulating properties, useful in producing electronic components. It serves as the base on which microscopic electronic components and their connections are built.
Integrated circuits rely on these insulating materials for reliability, using them as substrates and packages. The packages seal circuits from the environment, creating single, compact units.
Alumina is a dominant ceramic used for electronic substrates and packages because of its high resistivity, good mechanical and dielectric strength, and thermal and corrosion stability. Other materials, like glass-ceramic formations, are also employed for their low dielectric constants and ability to match the thermal expansion coefficients of metals used in circuitry.
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Why are ceramics used in electronic substrates and packages?
Ceramics are used in electronic substrates and packages because of their insulating qualities, which are essential for the reliability of integrated circuits. They act as substrates, the base for microscopic electronic components, and as packages, sealing circuits from the environment into compact units.
Alumina (aluminum oxide) is a dominant ceramic used due to its high resistivity, mechanical and dielectric strength, thermal and corrosion stability, and ability to create hermetic seals. Multilayer packages such as chip carriers and pin-grid arrays house semiconductor devices in stable, sealed environments.
While alumina has benefits, its high dielectric constant and low thermal conductivity are drawbacks. Newer materials aim to improve these properties, but some, like beryllium oxide, are toxic, while others, like aluminum nitride, are poor cofiring ceramics.
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How do ceramic substrates help in electronic circuits?
Ceramic substrates play a crucial role in electronic circuits due to their insulating properties. They act as the base for microscopic electronic components, ensuring the reliability of integrated circuits.
Ceramics like alumina (aluminum oxide) offer high resistivity, mechanical and dielectric strength, and thermal and corrosion stability. Multilayer ceramic packages house semiconductor devices in thermally stable, hermetically sealed environments. These packages connect the silicon device to external circuitry.
While alumina has a high dielectric constant and low thermal conductivity, alternative materials are in development to improve these properties. Some electroceramics have low electric resistivity and are made into substrates for integrated circuits.
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What properties make ceramics good for electronic packaging?
Electronic substrate and package ceramics are advanced materials valued for their insulating properties, which are crucial in electronics for creating reliable components.
Alumina (aluminum oxide, Al2O3) is a dominant ceramic used due to its high resistivity, good mechanical and dielectric strength, and thermal and corrosion stability. It also provides hermetic seals. Multilayer ceramic packages house semiconductor devices in strong, thermally stable, sealed environments.
Ceramic packages are made of Al2O3 and glass-forming alkaline-earth silicates. These packages protect the silicon device and connect it to external circuitry.
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What are some common types of ceramic materials used in electronics?
Electronic substrates and packages rely on ceramics for their insulating properties, essential for the production of electronic components like integrated circuits.
Alumina ((Al_2O_3)), or aluminum oxide, is a dominant ceramic material in electronics due to its high resistivity, mechanical and dielectric strength, thermal and corrosion stability, and ability to create hermetic seals. However, its relatively high dielectric constant can delay signal propagation, and its low thermal conductivity makes it inefficient for heat removal.
Other ceramic materials include:
* Glass-ceramic formations Easy to process, they have low dielectric constants and match the thermal expansion coefficients of high-conductivity metals like gold and copper used in electric circuitry, but they have low strength and thermal conductivity.
* Aluminum nitride (AlN) Has high thermal conductivity but is a poor cofiring ceramic.
* Silicon nitride A hard ceramic used in high-temperature applications and in composites.4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How are ceramic substrates and packages made for use in electronics?
Electronic substrates and packages are made using advanced industrial ceramics with insulating qualities that are useful in the production of electronic components.
Manufacturing Methods
- Tape Casting Tape casting methods, such as doctor blading, are used to create substrates for integrated circuits and multilayer structures. In doctor blading, a ceramic powder slurry is cast onto a moving carrier surface, spread to a specified thickness, and then dried.
- Cofiring Multilayer packages are made of alumina layers produced by tape casting/doctor blading. The tapes are hole-punched or laser-cut, and then metallized with tungsten or molybdenum by screen printing. Several layers are laminated into multilayer structures and cofired at high temperatures to create a monolithic package with internal conductor paths.
Materials Used
Alumina is a dominant material because of its high resistivity, good mechanical and dielectric strength, and thermal and corrosion stability.
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electronic substrate and package ceramics, advanced industrial materials that, owing to their insulating qualities, are useful in the production of electronic components.
Modern electronics are based on the integrated circuit, an assembly of millions of interconnected components such as transistors and resistors that are built up on a tiny chip of silicon. In order to maintain their reliability, these circuits depend on insulating materials that can serve as substrates (that is, the bases on which the microscopic electronic components and their connections are built) and packages (that is, the structures that seal a circuit from the environment and make it a single, compact unit). The insulating properties of ceramics are well known, and these properties have found application in advanced ceramic materials for substrates and packages. The materials and products are described in this article.
Materials
Among the ceramics employed as electronic substrates and packages, the dominant material is alumina (aluminum oxide, Al2O3). The advantages of alumina include high resistivity, good mechanical and dielectric strength, excellent thermal and corrosion stability, and the ability to provide hermetic seals. Its major disadvantages are a relatively high dielectric constant (which delays signal propagation) and low thermal conductivity (which makes it inefficient at drawing away heat). For these reasons ceramic materials with improved properties are under development. Some of these materials are mentioned below.
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Substrates
Alumina substrates are made as either thick films or thin films. Thick-film substrates are made by tape-casting processes (primarily doctor blading) to thicknesses of less than 1.5 millimetres, or they are made by dry pressing at thicknesses greater than 1.5 millimetres. The formulation contains 96 percent Al2O3, the rest being alkaline-earth silicates that form a glass during sintering to bond the alumina particles together. The glass also serves to bond with thick-film resistors or conductors built on the surface of the substrate.
Thin-film substrates (less than 1 millimetre thick) are also made by doctor blading, a process illustrated in Figure 1 of the article advanced ceramics. Organic binder and plasticizer are added to assist in forming. The standard formulation is 99.5 percent alumina, with small amounts of magnesia (MgO) and silica (SiO2) added to control grain size during sintering.
Multilayer packages
Integrated circuits are often contained in multilayer packages such as chip carriers, dual-in-line packages, and pin-grid arrays. These structures serve to house semiconductor devices in strong, thermally stable, hermetically sealed environments.
Ceramic packages are made of 90β94 percent Al2O3, the rest of the formulation consisting of glass-forming alkaline-earth silicates. One major requirement is that the formulations be able to be cofired with tungsten or molybdenum metallization lines. The alumina layers are produced by tape casting/doctor blading, after which the tapes can be hole-punched or laser-cut, via-hole-coated (vias are conductive pathways between layers), and metallized with tungsten or molybdenum by screen printing. Several layers are then laminated into multilayer structures. Cofiring takes place at temperatures up to 1,600Β° C (2,900Β° F) in protective atmospheres of hydrogen or hydrogen-nitrogen gas in order to prevent the metals from oxidizing. The result of cofiring is a monolithic package with internal conductor paths. The silicon chip is mounted in the package, and the package is hermetically sealed with a glass or metal lid.
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The purpose of the integrated circuit package is to contain the silicon device and to connect it to the external electric circuitry. The packaging materials must have low dielectric constants (in order to minimize the delay in signal processing), and they must conduct heat away from the semiconductor devices. Alumina is poor on both counts. Higher-thermal-conductivity materials exist, but they are either toxic (as in the case of beryllium oxide, BeO) or are poor cofiring ceramics (e.g., aluminum nitride, AlN). Glass-ceramic formations have been developed that are easy to process, have low dielectric constants, and also match the thermal expansion coefficients of high-conductivity metals (gold and copper) that are used in electric circuitry. However, they have low strengths and low thermal conductivities.
Electronic substrates and packages are only one type of advanced electroceramic application. For a directory to articles on other applications, as well as articles on all aspects of advanced and traditional ceramics, see .