Vacuum Brazing of Kovar Alloy and Alumina Ceramics for India’s Electronics Industry
Kovar-Alumina Joining for Advanced Electronics Applications
Joining Kovar alloy (Fe-Ni-Co) and alumina (Al₂O₃) ceramics is vital for electronic packaging, sensor assemblies, hermetic feedthroughs, and precision devices. Alumina provides excellent electrical insulation and thermal stability, while Kovar’s controlled thermal expansion matches alumina, enabling reliable metal-ceramic joints. Strong, hermetic, and stress-free bonds are essential for Micro-Electro-Mechanical Systems (MEMS) devices, high-frequency components, vacuum-sealed assemblies, chip carriers, TO (Transistor Outline) packages, power device housings, and MEMS sensors. Vacuum brazing is preferred for its purity, precision, and long-term reliability.
Vacuum Brazing Process for Kovar and Alumina
Active metal brazing in a high-vacuum furnace ensures precise Kovar-alumina joining. The key steps include:
Preparation: The Kovar and alumina ceramic surfaces are thoroughly cleaned to remove oxides and contaminants.
Assembly: A brazing filler metal (braze alloy), which has a melting point lower than Kovar or alumina, is placed in the joint gap. A common choice is a silver-copper-titanium (Ag-Cu-Ti) alloy, where titanium is the "active" element.
Heating in Vacuum: The assembly is heated in a high-vacuum furnace, typically at pressures of 10-4 Pascal or lower.
Bond Formation: At high temperatures, titanium in the filler metal reacts chemically with the alumina ceramic, forming a thin reaction layer (e.g., titanium oxide) that is wettable by the molten braze. Simultaneously, the molten alloy flows into the joint via capillary action, forming a strong metallurgical bond with Kovar.
Cooling: The assembly is cooled in a controlled manner to minimize residual stresses, which is critical due to the difference in thermal expansion between Kovar and alumina.
Advantages of Vacuum Brazing for Kovar alloy and alumina ceramics
Vacuum brazing provides flux-free, hermetic, and void-free joints with excellent thermal and mechanical stability. Uniform heating prevents micro-cracks and maintains tight tolerances, making it ideal for precision electronic components. In the Indian electronics and semiconductor industry, vacuum brazing enables manufacturers to produce high-reliability, precision components locally while meeting global standards. It supports efficient, stress-free, and long-lasting joints, enhancing the performance and competitiveness of India’s growing electronics and semiconductor ecosystem.
Vacuum Furnace Solutions for Kovar alloy and alumina ceramics welding
Normantherm, with more than 15 years of expertise, offers advanced vacuum furnaces for reliable Kovar–alumina joining. With ultra-high vacuum, precise temperature control, and programmable heating, our furnaces ensure strong, repeatable joints. Supporting Indian manufacturers, Normantherm optimizes brazing parameters to deliver world-class quality for electronic packaging, MEMS components, and precision assemblies, fueling India’s growing electronics and semiconductor ecosystem.
Editor: Sahera Khatun
Copyright: Normantherm Vacuum Furnace
