Polyphenylene sulphide applications

Examples of resins used include the nylon family (polyamide/PA), polypropylene (PP), polystyrene, and polyethylene. There continues to be growing applications for the higher-performance RTFs, such as polyphenylene sulphide (PPS) and polysulphone (PSU). Use is made of many other TPs (Chapter 3). 

Polyphenylene sulphide is a newer material that has good moulding characteristics and may be considered for telecommunications applications. It has a higher heat distortion temperature than PBT, is inherently non-flammable and is resistant to most solvents. 

The Ryton polyphenylene sulphide compounds are formulated for the encapsulation of semiconductors and discrete components and are particularly suited to this application because of their excellent thermal stability, resistance to chemical environments, flame retardancy and good electrical properties over a wide temperature range. In order to be suitable for the encapsulation of microcircuits and transistors the material must have good flow during moulding, good dimensional stability, low levels of impurities and low moisture absorption characteristics. 

Polyphenylene sulphide has been used commercially to encapsulate ceramic capacitors for several years and mica capacitors encapsulated in Phillips Ryton BR61B have recently received the British Standard 9000 approval (BS9070-N-002). More recently, attempts have been made to encapsulate wire-bonded integrated circuits, which is one of the most difficult applications to successfully mould with a thermoplastic material because of problems with wire-bond sweep. By paying particular attention to the melt viscosity of the PPS and having careful control of the moulding parameters it has been shown that it is possible to mould successfully both TTL and linear operational amplifier type devices. 

Polyphenylene sulphide s low dielectric constant and dissipation factor coupled with a high dielectric strength make both the filled and unfilled materials useful in a variety of applications as electrical insulators. It has been successfully employed in the manufacture of connectors, coil bobbins and pin cushion connector coil terminal supports for colour televisions. 

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