EMC Performance The need: –implement transmission lines on flex –protect lines against electromagnetic interference Question –how good does the protection have to be? Answer –replicate performance of wire harness

EMC Protection in Wire Harness No standards (except ABS and airbags) Wire harness supplied to us appears to contain no shielded wires or twisted pair More data required

Twisted Pair on Flex Twisted pair can be implemented on flex Twisted pair on PCB subject of various patents

US Patent 5,646,368 (IBM)

Large Area PTH PTH = plated through hole Use it to make conductive through holes in flex to implement twisted pair PTH processing over a large area would be slow and expensive

Large Area PTH and Construction Options Large area PTH reduces attractiveness of construction options 2 and 3

Is Twisted Pair on Flex Necessary? Twisted pair with wires is cheap and easy Performance for car networks seems not to be critical May not be appropriate for flex Required by ISO CAN standard?

EMC Testing Try to establish suitable balanced transmission line structure for flex –simulated twisted pair with vias –simulated twisted pair with bridges –parallel pair coplanar –parallel pair opposite sides –various shielding options

EMC Testing Compare twisted wire pair with flex structures Use Ford component EMC test procedures, based on SAE and ISO standards Radiated susceptibility tests are appropriate

Requirements EMC testing chamber and equipment –not available at Loughborough University –MIRA? Sample twisted wire pair

Questions Are there any other transmission line structures to be implemented on flex?

Conclusions There are no general standards for twisted pair performance in cars Plated through hole processing on a large area substrate would be slow and expensive We propose to establish suitable transmission line structures on flex by comparative measurement with twisted wire pair