• Case Study

Renishaw

Design Force offers easier controlled impedance routing for high frequency signals using electromagnetic field solvers.

Controlled impedance routing is a prerequisite for good digital circuit signal integrity, and signals – particularly high frequency ones – require constant characteristic impedance from driver to receiver. Renishaw uses Zuken’s CR-8000 suite for controlling impedance. Constraint Manager is used to specify the limits of characteristic impedance and Lightning is used to create impedance templates. This allows them to select a group of nets, using a net class, and then use the field solver to automatically calculate the impedance specified – adjusting the track widths to match.

A major benefit of the migration to CR-8000 is that Renishaw’s PCB designers have the ability to visualize and manipulate board designs in 3D.

Pete Leonard, Electronic Design Manager for Group Engineering, Renishaw, comments: “We can place components in a 3D environment, taking into account any constraints that may have come over from our mechanical engineers and then switch back to 2D for routing.

What if’ scenarios can be viewed by bending the flexible PCB.

During the design of the flexible PCB, Renishaw’s PCB designers created a user-defined layer called ‘BendLine’ (a case- sensitive reserved name). On this BendLine layer, polylines were drawn to represent the axes around which the flexible PCB needs to bend. Properties such as bend direction, angle and radius were then applied to each of the polylines. Renishaw’s PCB designers were then able to move components around in this 3D environment. They were also able to import (via .stp file) the housing around which the flexible PCB must bend.