The glass transition temperature (Tg) is an important normative dimension for the base material that determines the temperature at which the resin matrix converts from a glassy, brittle condition into a soft, elastic one.

The Tg value of the base material sets here an upper boundary, at which the resin matrix decomposes and a subsequent delamination occurs. The Tg is thus not the value of the maximum operational temperature, but rather that which the material can endure for only a very short time. A guideline for a continuous thermal load is an operating temperature approximately 25°C below the Tg.

When the glass transition temperature (Tg) is over 170°C, it is referred to as a high Tg material.

High Tg materials have the following properties:

• high glass flow temperature value (Tg)
• high temperature durability
• long delamination durability
• Low Z axis expansion (CTE)

The decomposition temperature Td of a resin system depends on the binding energies within the polymers, and not on the glass transition temperature Tg. A good indicator for this characteristic is the T260 or T288 value, which specifies the time until delamination at 260°C or 288°C, respectively.

*Conductive Anodic Filament, undesirable conducting filament in the substrate of a circuit board

Depending on the stock on hand, the materials listed may be replaced by technically equivalent or similar products. For critical tolerances, please discuss your requirements with our engineers.

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