# PCB Design and Power Traces / Plane

We have power traces in inner layer (the yellow traces). We have linked all our nets with traces taking care of track width based on current flowing into the nets.

Now, we are wondering if we should keep this like this or if we should create a polygon for each track (which I suppose might be benefical to spreading flow over a larger surface).

What would you do ? Would you create polygon and if yes how would you draw them to make them adjacent to each other and to delimit their borders ?

• I'd go with polygons for at least the higher current traces if not all of them. Also for some of those high current paths you may want to look at using multiple vias rather than just a single one at each point. – Andrew Sep 13 '16 at 9:13
• @Andrew thank you for your comment. This is what I saw thinking. i suppose I should use the split plane methodology and not the polygon tools to perform this? – chris Sep 13 '16 at 9:17
• With that many small areas I'd go with polygons, keep each signal within the region that it's relevant. – Andrew Sep 13 '16 at 9:20
• How high are the currents? – Bence Kaulics Sep 13 '16 at 9:22
• @BenceKaulics from 5mA to 2A (for the 50mil width track you can see called SYS) – chris Sep 13 '16 at 9:30

I would go with polygons for 2 reasons:

1) More copper = more area = less thermal problems due to current heating up the copper.

2) By filling the entire layer with copper, regardless PWR or GND, you are reducing the gaps that the prepreg can flow into when the fabricator presses the layers together. This helps keep things mechanically stable and ensures an even thickness of prepreg across your board.

Here is a useful calculator for calculating required trade width given copper thickness, current, and temp rise: http://circuitcalculator.com/wordpress/2006/01/31/pcb-trace-width-calculator/

• thank you for your comment. I had same idea for 1./ but didn't consider 2./ – chris Sep 16 '16 at 9:57

To answer your first question regarding the polygon usage. It depends on the amount of current flowing in the signal. It is generally advisable to use polygon if lot of pins/pads are connected on same net, as the area is fairly larger and more current can pass without heating(?). Veterans and experienced users can throw more light in this perspective.

Now the question regarding how to manage polygons. The answer is strictly limited to Altium Designer.

To define a polygon; you can open the Polygon Manager(Option Available in Tools) and create a polygon and connect it to a net.

When you create a polygon; it will ask you to draw a shape; you have to enclose the targeted area. This will create the polygon.

For a graphical representation of what i just said : LINK

Now to polygon clearance; this is tricky in Altium as the Design Rules are overwhelming for beginners (like me)