Solder glasses, also referred to as frit glasses, are special glasses with a particularly low softening point (below 550°C). They are used to join glass to other glasses, ceramics, or metals without thermally damaging the materials to be joined. To ensure stress-free sealing, the coefficient of thermal expansion (CTE) needs to be closely matched to the sealing partners.
Three kinds of solder glasses can be distinguished according to their behavior during the soldering process: Vitreous solder glasses, devitrifying solder glasses, and composite solder glasses.
Vitreous solder glasses preserve their material properties during soldering and remain in the so-called “glassy” state. When reheated, they show the same softening behavior as prior to the sealing process.
Devitrifying solder glasses crystallize at least partially during the sealing process. Since this results in an increase of softening temperature, they are especially used in applications with high operating temperatures. The crystallization may lead to a change of CTE.
Composite solder glasses were developed to achieve a very low CTE while assuring low soldering temperatures at the same time. This is done by adding inert (non-reactive) fillers with low or negative coefficients of thermal expansion.
Solder glasses can be used for low temperature joints of different materials in various fields, for example:
Glass powders are manufactured in two steps:
Features / Specifications
The choice of solder glass for joining different materials is dependent on four major aspects:
All soldering glasses are supplied as glass powder and are available in different grain sizes.
Forms of Supply and Product Packaging
Our standard packaging consists of sealed plastic bottles. For alternative packaging solutions please contact us.
SCHOTT solder glasses:
Other matched CTE available upon customer request
All solder glasses are available as K3 powder. Grain size: d50 = 10 +- αµm, d99 ≤ 63µm
Other grain sizes available upon request
For more information on the different quality assurance programs, please refer to our quality assurance processes.