Your Expert for Innovative Ceramic-to-Metal Integrated Systems:
Your composite partner for metallized ceramics
Metallization for ceramics has two main components. It consists of glass (manganese disilicide) and metal particles (molybdenum (Mo) or tungsten (W)). Where the glass connects to the ceramic and the metal particles connect to the metal component via the solder. Alumina Systems manufactures its own metallizing paste for this purpose. This is e.g. by means of screen printing on the unglazed ceramic (layer thickness at least 5 microns) applied.
Metalized aluminum oxide ceramic
Depending on the shape of the surface to be metallized, other methods such as ruling or brushing are used. Subsequently, the metallization is baked under forming gas (90% nitrogen (N2) and 5% hydrogen (H2)). The forming gas protects the metal particles during the burn-in from oxidation. The result is a cohesive connection between metallization and ceramic.
Nickel plating of the oxide ceramic metallized
For a sufficient wettability of the Al2O3 metallization by the solder, a thin nickel layer (0.5-5 μm) is applied galvanically or chemically (without current). All metallized ceramic components are nickel plated to wettability of the solder. Frequently, ceramic-metal assemblies are also nickel plated after soldering. Alumina Systems GmbH uses two methods for this in its own electroplating plant.
Chemically nickel metallization
This electroless nickel plating produces uniform layer thicknesses with high hardness, corrosion protection and wear resistance. It is suitable for the nickel plating of complex molded components without electrical contact. Chemical nickel plating is a coating of nickel (Ni) and phosphorus. Since the phosphor can evaporate in a vacuum, this type of nickel plating is not recommended for vacuum technology. An advantage of incorporating phosphors is the demonstrable reduction in the ferromagnetic properties of the Ni layer. Specific pretreatment methods include steels and copper alloys as well as aluminum alloys, ceramics and glass.
Homogeneous layer thickness (5 to 50 μm)
Matte to shiny surface appearance (depending on the starting surface)
Galvanic nickel metallization
For the nickel plating (electrolytic nickel plating) of pure nickel, the components must be electrically contacted. For this, individual galvanic racks must be built. The layer is ferromagnetic. The properties of the Ni layer protect the metallic components against corrosion and wear. High-gloss layers as well as matt surfaces can be produced by the appropriate combinations.
Advantages of galvanic nickel plating:
Good corrosion protection
Metallized technical ceramic gilding
As oxidation protection or for bondability using aluminum thin or thick wire, Alumina Systems can apply an additional thin gold layer in its own electroplating process in the ENIG process (Electroless Nickel / Immersion Gold). The metallized ceramic can be joined by brazing and also soldering verbunden werden.
With ENIG gold plating (Electroless Nickel / Immersion Gold) only a thin layer of 100 to 200 nm can be deposited. It serves to protect the underlying nickel layer against oxidation and ensures very good solderability and ultrasound bondability with aluminum wire. Alumina Systems can apply this gold layer through an exchange reaction on the previously nickel-plated components in its own electroplating shop.