FAQ

 

Alumina ceramic

Alumina ceramic is characterised by its high mechanical strength, hardness, wear resistance, high insulation resistance, low dielectric losses, vacuum-tightness and chemical endurance. Alumina is used for highly stressed parts for applications in mechanical, electrical and chemical engineering, electronics, vacuum technologies, food industry and in the manufacture of grinding elements require a variety of grades. Major industrial applications: specials, rings, bushings, wire drawing dies, tubes, gauges, brazed joint metal-ceramic parts.

Brazing

Brazing is a metal-joining process whereby a filler metal is heated above and distributed between two or more close-fitting parts by capillary action. The filler metal is brought slightly above its melting (liquidus) temperature while protected by a suitable atmosphere, usually a flux. It then flows over the base metal (known as wetting) and is then cooled to join the workpieces together. It is similar to soldering, except the temperatures used to melt the filler metal are above 450 °C (842 °F).

Ceramics

A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous (e.g., a glass). Because most common ceramics are crystalline, the definition of ceramic is often restricted to inorganic crystalline materials, as opposed to the noncrystalline glasses.

Copper

Copper is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish. It is used as a conductor of heat and electricity, a building material, and a constituent of various metal alloys.

Cordierite

Cordierite is highly resistant to thermal shock, has a low thermal expansion, provides excellent insulation properties in high relative humidity conditions and is highly resistant to aggressive substances. Major industrial applications: power switch components, regulating rheostat components, catalyst substrates.

Eutectic alloys
 
Eutectic alloys melt at a single temperature. Non-eutectic alloys have markedly different solidus and liquidus temperature, and within that range they exist as a paste of solid particles in a melt of the lower-melting phase. The pasty state causes some problems during handling; it can however be exploited as it allows molding of the solder during cooling, e.g. for ensuring watertight joint of pipes, resulting in a so called 'wiped joint'.

 

Green body

A green body refers to a ceramic or porcelain compound, usually clay or powder, produced by slipcasting before it has been fired or sintered, respectively. -Sintering and Solid state chemistry.

Invar

Invar, also known generically as FeNi36 (64FeNi in the US), is a nickel steel alloy notable for its uniquely low coefficient of thermal expansion (CTE or α). The name, Invar, comes from the word invariable, referring to its lack of expansion or contraction with temperature changes.

FeNi42 (for example NILO alloy 42), has a nickel content of 42% and α ≈ 5.3 ppm/°C which matches that of silicon and therefore is widely used as lead frame material for electronic components, integrated circuits, etc.
 

FeNiCo alloys—named Kovar or Dilver P—that have the same expansion behaviour as borosilicate glass, and because of that are used for optical parts in a wide range of temperatures and applications, such as satellites.

Metallized ceramics

Metallized ceramic is a product that generally consists of a ceramic insulator and a metal conductive coating. The coating can be applied automatically or by hand. The item is then dried and fired at high temperatures in special furnaces. When the coating is applied it offers very little conductivity but after firing the coating is quite conductive.

Is nickel plating necessary?

If the metallized ceramic component is to be brazed into a package or to another component, often nickel plating is necessary to guarantee good adhesion depending on the chosen braze material. Nickel also helps protect the molybdenum contained in many thick film metallization formulation. Electrolytic nickel is commonly employed. Another popular choice for post-metallization plating is electroless nickel. Nickel plating is not always necessary but it is very common and helpful.

Solder

Solder is a fusible metal alloy used to join together metal workpieces and having a melting point below that of the workpiece(s).
Soft solder is what is most often thought of when solder or soldering are mentioned and it typically has a melting range of 90 to 450 °C (190 to 840 °F). It is commonly used in electronics and plumbing. Alloys that melt between 180 and 190 °C (360 and 370 °F) are the most commonly used. Soft solder can contain lead and/or flux but in many applications lead free solder is used.
 
By definition, using alloys with melting point above 450 °C (840 °F) is called 'hard soldering', 'silver soldering' or brazing. Perhaps the most common and most familiar form of solder is as a wire or rod. Solder can also come in a paste or as a preformed foil shaped to match the workpiece. 
 
Soldering
Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal (solder) into the joint, the filler metal having a lower melting point than the workpiece. Soldering differs from welding in that soldering does not involve melting the work pieces.
There are three forms of soldering, each requiring higher temperatures and each producing an increasingly stronger joint strength:
    -soft soldering, which originally used a tin-lead alloy as the filler metal,
    -silver soldering, which uses an alloy containing silver,
    -brazing which uses a brass alloy for the filler.
 
The alloy of the filler metal for each type of soldering can be adjusted to modify the melting temperature of the filler. Soldering appears to be a hot glue process, but it differs from gluing significantly in that the filler metals alloy with the workpiece at the junction to form a gas- and liquid-tight bond.
Soft soldering is characterized by having a melting point of the filler metal below approximately 400 °C (752 °F), whereas silver soldering and brazing use higher temperatures, typically requiring a flame or carbon arc torch to achieve the melting of the filler. Soft solder filler metals are typically alloys (often containing lead) that have liquidus temperatures below 350°C.
 
In the soldering process, heat is applied to the parts to be joined, causing the solder to melt and to bond to the workpieces in an alloying process called wetting. In stranded wire, the solder is drawn up into the wire by capillary action in a process called 'wicking'. Capillary action also takes place when the workpieces are very close together or touching. The joint strength is dependent on the filler metal used, where soft solder is the weakest and the brass alloy used for brazing is the strongest. Soldering, which uses metal to join metal in a molecular bond has electrical conductivity and is water- and gas-tight. 

 

Steatite

Steatite with its excellent mechanical and electrical properties such as strength and electric insulation resistance is suitable for applications in electrical engineering and manufacture of metallised ceramics. Major industrial applications: specials, tubes, plates, bushings, coils, supports, ceramic capillary tubes.