Exploring Low Loss Suspension Interconnects for High Data Rates in Hard Disk Drives

For high data rate applications, current suspension interconnect solutions should stay above 50 Ohm differential impedance (Z_diff ) due to footprint limitations and frequency dependent ohmic losses of the stainless steel plane at low Z_diff . This paper describes the impedance and bandwidth (BW) design space of today´s interconnects and also shows why this technology is still compatible with current system front-ends up to 3 Gb/s. Furthermore, the benefits of reduced power and higher overshoot using less than 50 Ohm impedance and high bandwidth interconnects are explored with a system model. Three alternate low impedance interconnect structures are used to demonstrate these benefits, and are explored analytically and evaluated for mechanical tradeoffs.