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Glass-to Metall Seals

Glass-to Metal Leak-Proof Compounds According to ОСТ 107.460092.002-86

Modern relays like other elements of electronic equipment have in the structure current carrying leads which should be reliable insulated from the package and from each other. Plastics, ceramics and other materials can be used as dielectrics.

Glass has many properties, its primary virtue is its direct, mechanically strong and leak-proof seal-ability with metal.


Thermal Environment, °С

From - 60 to+ 150

Relative Humidity, %

98 at 35°С

Atmospheric Pressure, Pa


Vibration  in the  Frequency Range, Hz/g


Insulation Resistance of Dielectrics,  mOhm

Up to 1x106

Glass-to metal seals are resistant to mechanical and climatic loads and defined in the Standard GOST 20.57.406-81.

Leads experience in the seals no mechanical damages or hermetic failure against the following stresses:

  • Tensile strength of flexible wire leads, ribbon leads and spade terminals;
  • Kinking of flexible wire leads;
  • Rotational torque of screw terminals.

Leak-proof glass-to metal seal guarantees hermetic tightness, mechanical strength, insulation resistance and low gas permeability.

In the bushing production matched glass-to metal seals C48-2 and cobalt-nickel alloy 29NC (covar) are mainly used. Application of glass type C48-5 and C48-2 is also possible.

Recommendations for variation of mix materials, types and basic dimensions of leak-proof glass-to metal compounds see in ОСТ 4Г0.010.042.

Glass dielectrics can be produced in two different ways: in the first case glass capillaries used as a preform are cut in pieces of required size; in the second case a pellet of glass dielectric is made of glass powder.

Mixed glass is used for increasing thermal and mechanical strength of glass dielectrics.

  1. plug;
  2. glass dielectric;
  3. armature base;
  1. glass bead;
  2. pin;
  1. base;
  2. glass dielectric;
  3. lead;
  1. pin;
  2. glass dielectric;
  3. threaded bush;
  4. contact