Ceramic metallization puts a conductive, brazeable metal layer onto a ceramic surface. The process you choose affects bond strength, pattern resolution, cost and even which ceramics you can use. Here is a practical comparison of the three mainstream routes.
Thick-Film Mo-Mn Metallization
The molybdenum-manganese process is the traditional workhorse for high-alumina ceramics. A slurry of Mo and Mn oxides is screen-printed onto the surface and fired in a hydrogen atmosphere at 1300–1500 °C. The manganese diffuses into the ceramic grain boundaries; the result is a mechanically interlocked metal layer that is then nickel-plated to make it brazeable.
- Strengths: very strong bond, proven over decades in electron tubes and UHV components, economical for volume parts.
- Limitations: thick layers limit fine-pitch patterns; requires reducing-atmosphere furnaces.
Thin-Film Metallization
Sputtering or evaporation deposits Mo, W, Ti or TiW layers a few microns thick, usually topped with Ni or Au. Photo-lithographic patterning gives excellent feature definition.
- Strengths: fine patterns, smooth surfaces, good adhesion on polished and exotic ceramics, low material usage.
- Limitations: higher equipment cost; bond strength depends heavily on surface preparation.
Active Metal Brazing (AMB / DBC-style)
Instead of metallizing first, a braze alloy containing a reactive element — typically titanium — is placed in contact with the un-metallized ceramic. During brazing above 800 °C the titanium reacts with the ceramic to form a wetting interfacial layer, bonding ceramic directly to metal.
- Strengths: works on non-oxide ceramics such as AlN and SiC where Mo-Mn is difficult; single-step joining; excellent for power electronics substrates.
- Limitations: process window is tight; joint strength is process-sensitive; metallurgical reactions can change surface chemistry.
Which Should You Choose?
| Criterion | Thick-film Mo-Mn | Thin-film | Active metal |
|---|---|---|---|
| Best for | 95–99.7% alumina parts | Fine-pitch, polished surfaces | AlN, SiC, power substrates |
| Bond strength | Excellent | Good | Good |
| Pattern resolution | Moderate | High | Moderate |
| Relative cost | Low–moderate | Moderate–high | Moderate |
HermiCore operates thick-film, thin-film and active metal lines in-house. Whatever the ceramic — 95% to 99.7% alumina, aluminium nitride, beryllia, sapphire or diamond — we can metallize it and validate the result with helium leak testing and SEM inspection. See our metallized ceramics page or contact us with your substrate drawing.
