Looking at Chip on Flex Filtering
Lightning never strikes the same place twice; but, once is enough to send an aircraft into electrical failure, which can have catastrophic results. For this reason, the commercial aircraft industry has long sought a reliable and economical solution for the protection of its onboard electrical systems. Transient Voltage Surge Suppression (TVSS) for interconnect systems is typically implemented by using either back-to-back Zener diodes or metal oxide varistors (MOVs) to create a “transorb” at each electrical entry point. These transorbs must be specified to voltage; and, in order to achieve true protection, they must be physically attached to every contact in the interface connector. Specifying conventional components for TVSS has historically resulted in a relatively high cost, labor-intensive solution that either had limited power dissipation, or significantly increased the physical size of the connector.
The most practical method for achieving robust, cost-effective and space-saving protection against voltage transients is to incorporate the TVSS within the interconnect system itself. Filtering from chip capacitors on flexible circuit boards (“chip-on-flex”, or CoF technology) provides the necessary platform to surface mount TVSS devices that are robust enough to withstand a powerful surge, yet lightweight and compact.
Connectors with integral CoF TVSS devices can replace the fragile ceramic planar capacitor arrays in the connector with a robust, state-of-the-art flex circuit. Off-the-shelf chip capacitors placed on the flex circuit can be surface-mounted next to the feed-thru contact without soldering, making them highly durable. The ability to use surface mount components ensures the interconnect system will not be susceptible to voltage surges, extreme temperatures, vibration, and high-frequency noise that can creep in with leaded devices. These new cost-effective, robust filter connectors with TVSS capabilities offer compact protection from lightning strikes, voltage surges and EMP strikes in an integrated connector package that is competitively priced to conventional filtered connectors.