Polycarbonate Thermal expansion coefficient

A recently introduced polycarbonate-based blend offers a low coefficient of thermal expansion. This new thermoplastic is designed for large sheet applications such as doors or siding. Its high dimensional stability will eliminate warping from exposure to varying temperatures. 

Low smoke emission (roughly comparable to that of a polycarbonate). Very low coefficient of thermal expansion in the flow direction (0-15 cm/ cm/°C) but correspondingly higher in the transverse direction (27-76 cm/ cm/°C). 

The thermal properties of polycarbonate are not outstanding and the opportunities to improve it are remote. Addition of 30 wt% of carbon or glass fibers increases deflection temperature under load only by about 20°C to the maximum attainable value of 150°C but coefficient of the thermal expansion is drastically reduced which makes it suitable for many of its potential applications. 

Other substrates that are used for MEMS include quartz, glass, and polymers. Quartz is attractive primarily because it is piezoelectric, so that it may be used as a sensor and an actuator. Quartz is, however, more difficult to micromachine than silicon. Pyrex glass is used in conjunction with silicon wafers, primarily for packaging, because of its optical transparency and close match in coefficient of thermal expansion (GTE). Polymers such as polycarbonate have been adopted as substrates for microfluidics because of their low cost channels require large areas, which makes silicon too expensive, and channels can be fabricated in polymers inexpensively by hot embossing. The advantages offered by silicon substrates are not required because microfluidic devices typically do not have complex... 

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