Durable and resistant to heat, sheet structures of DuPont’s Nomex have been used in some very high profile applications such as space suits, composites for aircraft and racing yachts, as well as Formula 1 protective apparel. Over the years, Nomex has been developed into a whole family of specialised forms. It is available today as filament, staple, yarn, felts, woven/non-woven fabrics, resin and unique sheet structures, making it a versatile fibre for an ever increasing range of applications..
In the electronics industry, the rapid pace of development means that manufacturers are always on the look out for faster, thinner, lighter and lower cost ways to make wiring boards. Now, a new non-woven sheet structure made entirely from a special synthesis of Nomex and its aramid stablemate Kevlar may provide a practical inexpensive solution. Dubbed Thermomount, the new material is claimed to provide a high performance board at a lower cost than one built from more conventional means.
Until now, wiring board manufacturers have had the choice of cheap and cheerful laminates offering low performance to match the low price, or a premium priced article giving selective high performance.
The properties of Thermount include a lower dielectric constant, lower in-plane coefficient of thermal expansion, high dimensional stability and lower weight. For the board manufacturer, these properties translate into reduced stresses on wiring joints, faster signal speeds and improved registration yields.
The performance of a Thermount board is not dependant on the resin system used. In fact, since the presence of Thermount physically modifies some of the behavioural characteristics of the resin binder, it can be used with practically all resin systems currently in common use. No special fabrication equipment is necessary and there are no other process penalties associated with using the board.
The result is a wiring board which closely matches the performance characteristics of ceramic multilayer technology, yet is lighter, thinner and around one-fifth the cost.