Glass-to-metal connection
Glass-to-metal connection technology (GTMS) enables the production of vacuum-tight connections (typically 1E-8 l / s He) between glass and metal. In the form of glass feedthroughs, this technology is used when electrical components in hermetic housings have to be contacted. The advantages over plastic connections are that the electronic components can be protected against the outside environment for a long time without loss of performance. Glass feedthroughs are manufactured in a melting furnace and can be designed either as a pressure glass feedthrough or as an adapted glass feedthrough.
Glass is ideally suited for the production of mechanically reliable and vacuum-tight fusion seals with metals and ceramics. The direct wettability of many crystalline materials is what makes glass so special.
A necessary prerequisite for the stability and strength of glass seals is the limitation of mechanical stress in the glass part during production and during use. In order to ensure fusibility (this means that the thermal expansion of two sealing parts made of different materials below the transformation temperature of the glass must be coordinated with one another), glasses of a special composition were developed.
Apart from that, such glasses very often have to meet other requirements, such as high electrical insulation, special optical properties, etc. The sealability can be tested and evaluated with sufficient accuracy and reliability by optical voltage measurements through a glass section of a test seal (ISO 4790). Aside from material parameters, such as the coefficient of linear thermal expansion, transformation temperature and elasticity properties, the cooling rate and the shape can also have a significant influence on the degree and distribution of the sealing stresses.
With regard to the expansion coefficients of the technically used sealing metals (for example tungsten and molybdenum) and alloys (Ni-Fe-Co, Ni-Fe-Cr and other special materials), the corresponding sealing glasses are grouped and called "tungsten sealing glasses", "Kovar -Glasses "etc. designated. Alkaline earth borosilicate glasses and aluminosilicate glasses have the necessary tightness and heat resistance, which are particularly suitable for tungsten and molybdenum seals, which are often used for lamps.
A related process exists for plastic: hot caulking .
See also
Web links
Individual evidence
- ↑ Glass-metal connections (PDF; 2.4 MB), accessed on February 26, 2016