Joining Using Glass Solders

The maximum joining temperature is given by the material of the parts to be joined and the actual use conditions of the joined device. It is advised to use the lowest possible joining temperature. In praxis the thermal expansion coefficient of the glass solder is linked reciprocally to the joining temperature [397], A lower thermal expansion coefficient of the glass requires that the joining temperature increases frequently. 

Composite glass solders consist of a glass phase and a crystalline phase with a low thermal expansion coefficient. The crystals are inert and dispersed in the glass phase. The thermal expansion coefficient of the composite is given by the rule of mixture of the thermal expansion coefficient of the glass phase and the inert crystalline phase. The addition of the crystalline phase allows to tailor the thermal expansion coefficient of the solder at given soldering 

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Anisotropically conductive adhesives conduct in one direction only. They are often referred to as z-axis conductive adhesives. These materials have found widespread use in LCD, Liquid crystal display, assembly due to their ability to resolve small gaps between conductor tracks and the fact that solder is not suitable for joining on glass substrates. 

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