Polytetrafluoroethylene PTFE-based composites

The use of polytetrafluoroethylene or PTFE for printed wiring substrate fabrication is a relatively well-established practice brought about by the need for improved high-frequency materials. The critical properties in this field of application are a low dissipation factor, a uniform dielectric constant which exhibits little variation with frequency over a wide bandwidth up to 15 GHz, combined with environmental and temperature stabilities. These properties can be achieved in a number of teflon/glass or teflon/glass/ceramic composites based on both fabrics and random glass. The dissipation factor at 1 MHz is more than 100 times less than a typical epoxy FR4, as shown in Table 9.4. 

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