Ceramic to Metal Brazing and Sealing Techniques:
A ceramic to metal seal generally means a hermetic seal, hermetic joint, or hermetic bond. Occasionally, there will be no hermeticity requirement (entirely structural). Some have an intermediate sealing or filler material and some do not.
STC Material Solutions has extensive experience as a supplier for the following five types of ceramic to metal seals, joints and bonds:
1. Brazing or soldering metallized ceramic to metal (Thermo-metallurgical bonding).
2. Active Metal Element Brazing non-metallized ceramic to metal (Diffusion bonding driven by thermo-metallurgical bonding).
3. Diffusion bonding ceramic and metal with nothing in-between.
4. Glass sealing non-metallized ceramic and metal (Fusion bonding using a sealing glass)
5. Cofired bonding Ceramic and Metal directly sealed with no braze or glass in-between (Oxidation – sintering driven chemical bonding)
Terminologies such as “thermo-metallurgical bonding”, “fusion bonding ceramic and metal” and “Oxidation – sintering driven chemical bonding” are methodologies STC Material Solutions created and has been practicing for many years. We are unique in the processes, ability to choose the correct technique for the customer’s specific need and solving any issues that arise during development.
Fusion bonding is done with glass and metal or glass and metal oxide at high temperature. At the interface, a transition region of glass, metal oxide, and pure metal is formed.
Diffusion bonding usually requires a few prerequisites to enhance the adhesion. Minimal, surface roughness, high pressure, and interdiffusion friendly materials are key.
Thermo-metallurgical bonding is a chemical reaction through oxidation of a metal and sintering together with all the metal oxides.
The well-established process of ceramic to metal sealing requires a metallization layer applied on the ceramic and then secondarily brazing the metallized ceramic and the metal component together using a braze (or solder). This two-step process may sound indirect as some of the processes listed above do not require ceramic metallization. However, every application/assembly/configuration has pros and cons of each process in terms of overall quality. Braze can be replaced with a solder for certain low temperature applications. STC Material Solutions has even developed an innovative flux-less soldering process such that there will be no entrapped flux interference in the sealing. Every technique has its own strength and weaknesses in a variety of applications and STC Material Solutions has the experience and knowledge to guide customers to the best available option specifically to their project needs.
STC Material Solutions offers the following four different processes of metallization. These techniques are primarily designed for ceramics but can be compatible with glasses as well.
1. UHT Metallization: Primarily for sapphire, translucent alumina and 99.5 % and up Al2O3.
2. HT Metallization: Primarily for Al2O3 96% and up, sapphire and few other oxides. This can be used for BeO and AlN as well.
3. MT Metallization: Primarily for carbon products including diamond and graphite, nitride, carbides, BeO and zirconia.
4. LT Metallization: For all glasses and ceramics including all above and others such as exotic crystals including sulfide and sulfate, Ge, etc.
Note: The terminologies of UHT, HT MT and LT are unique to IJ Research and we purposefully use them to distinguish the multiple techniques. Please refer to additional Corporate Literature called Metallization for further details.
Please contact STC Material Solutions using 1-714-546-8522 or firstname.lastname@example.org.