Coils are a design element that, if not exceedingly common, are showing up in more designs these days. They appear simple at first glance, but keeping a consistent air gap between each revolution of the spiral can involve a lot of mental arithmetic and picks in the design canvas. Why do this yourself, when the SiP productivity toolbox provides you with a feature that can make the most complex of coils in just a few short clicks?

The Coil Designer UI

If you’re running the SiP Layout product with the Allegr®o Productivity Toolbox option, look under the Route menu for Coil Designer between the Via Structure / Fanout commands and the Offset Via Generator:

It’s grouped with the Shield Router and Generator tools, also parts of the productivity toolbox. If you’d like more information on these commands, let us know, so we can talk about them more in the coming weeks.

Above, we see the main GUI for the tool. The pictures to the right help you to visualize what you’re designing, but they are static. If you change the parameters on the left, don’t expect the graphics to update dynamically.

Subclass and keepout options will help you manage things like the nearby plane shapes, but don’t overlook the Miscellaneous configurations on the bottom right. The ability to add a via at the start and/or end of the structure can be wonderful for connecting to the coil on one layer from the primary routing layer.

Previewing Your Coils 

On the cursor, you can see exactly what your configured coil will look like. Placing it over the area in the layout you need it, gives you important referential information about size, clearances, etc. Of course, you can click it into place at any time, but if you need different characteristics, or need to make changes to be able to fit into the area in question, now is the time to do it – upfront, before you impact the layout itself.

A coil is a simple cline (or shape), ultimately. It can be routed to/from (not just at the endpoints, but anywhere along the cline if you need to). It is not a symbol, so you do not need to refresh it along with other mechanical symbols. You can fix it in the design to prevent inadvertent editing and assign it to the net of your choosing. We recommend using a cline for your coils where possible, as the path of the cline provides path centerline data that a typical shape, being a general closed polygon, doesn’t offer.

Closing Remarks

Where are you using coils in your designs today? Have you used the coil designer before (maybe today was just a refresher for you, and you’ve been nodding your head throughout)? How has your experience been, how can the tool be improved? What features would turn this into a daily usage feature in your typical design flow? Let us know!