Why is alumina widely used for electronic substrates and integrated-circuit packages?

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advanced ceramics Steps in doctor blading, a tape-casting process employed in the production of ceramic films. Ceramic powder and solvent are mixed to form a slurry, which is treated with various additives and binders, homogenized, and then pumped directly to a tape-casting machine. There the slurry is continuously cast onto the surface of a moving carrier film. The edge of a smooth knife, generally called a doctor blade, spreads the slurry onto the carrier film at a specified thickness, thereby generating a flexible tape. Heat lamps gently evaporate the solvent, and the dry tape is peeled away from the carrier film and rolled onto a take-up reel for additional processing.

Alumina (aluminum oxide, ${Al}_{2} O_{3}$ ) is the dominant material used for electronic substrates and integrated-circuit packages due to its specific combination of physical and chemical properties. Its widespread adoption is attributed to several key advantages:

Electrical Insulation: It possesses high resistivity, which is essential for preventing electrical interference between components.1
Mechanical and Dielectric Strength: It provides robust structural support and reliable electrical insulation for microscopic circuits.1
Stability: It exhibits excellent thermal and corrosion stability, ensuring the longevity of electronic components.1
Hermetic Sealing: It is capable of providing hermetic seals, which are necessary to protect sensitive semiconductor devices from environmental damage.1

While alumina is highly effective, it is not without limitations; it has a relatively high dielectric constant and low thermal conductivity. Despite these drawbacks, it remains the industry standard because alternative materials with better thermal properties are often toxic or difficult to process using standard cofiring techniques.1