Planar magnetics design workflow

[Anonymous]

Hello all,

I have been working on the layout of several planar magnetic components lately, and I feel I might not be doing it in the best/most efficient way. I am aware that there is a spiral generation tool, but it is not that handy when you have to implement interleaving or when working with less turns and wider traces.

The way I am doing it is by first designing a component with the cutout for the core, and then drawing a template in Tplace or Tdocu, marking the point where the center of the trace should go on each turn (taking into account isolation distances, trace widths etc). After this, I create a series of concentric circumference traces.

Planar transformer template

Then, I would erase one sector of one of this circumferences, and using the routing tool with the last "wire bend" option (lets say, the free routing, with tangent traces), manually go around the vias, counting squares in the grid to keep isolation and trying to put it together as close as possible.

Planar transformer routing

With that, just repeat for another 20 turns for each winding, and I am done. Sometimes you can copy and mirror some layers, which saves tons of time.

Finished winding

Now, things that I would find really useful:

1) The traces on the same winding are part of the same net, so there is no automatic gap left between different turns according to the design rules. Is there a way or a tool to automatically keep isolation between different turns? and therefore let you pack the turns as compactly as possible.

2) With lower turn number highre current windings, it is interesting to use polygons, to fill as much space with copper as you can, also keeping a certain isolation. But when going around vias, the polygons usually leave some corners, which are not good for EMI. Is there a way to specify a minimum pour radius for polygons?

Thank you in advance!

 

[miclairmiclair]

Hi man , I love this. I have been struggling on making traces for a DIY planar too,  do you have a any advice?

[david_heatonARR5Y]

I use a bunch of half circles and decrease the radius for each one and offset the center of the bottom half circles by that change in radius. For example below, the bottom arcs are all at the origin (0,0) and the top arcs are all at (10,0) and each arc's radius is 10 larger than the last. Changing the width of the arcs and/or the offset & radius lets you min/max the used copper and gap size.

[Thorsten.Muehlke]

was always a great help!

greetings
Thorsten