I'm designing a board around 2 Texas Instruments TPS65988. In the datasheet a layout example is shown where "fins" are placed around pads to provide further thermal dissipation. A pour to create this region sounds to me the best option to draw these regions. However, designing them with lines is very time consuming and not precise at all, even with a grid of 0.025mm setted in Altium, given the total dimensions of these fins (TPS65988 is a 7.15 x 7.15 mm QFN IC).

I tried to draw Solid Regions (faster to draw, more precise) but unfortunatelly I don't know how to exclude vias not connected to the same net of these fins from those solid regions (look at the bottom left via in picture below). It's very easy with Polygon Manager... But I can't find a easy way to do the same with solid regions.

So, my question is... How do they draw them? What is the best way to draw them in a fast and straighforward procedure?

enter image description here

  • \$\begingroup\$ "I don't know how to exclude vias not connected to the same net" This will be done by the tool when you pour a polygon and your Design Rules say to have X gap between polygons and unrelated nets. (I avoid specific terminology, since it's been a while since I played in Altium). \$\endgroup\$ – Kevin Kruse Feb 21 '19 at 20:44
  • \$\begingroup\$ Solid regions just cover all the space inside them, they don't exclude vias or anything else. The ability to automatically pour around vias and other objects is exactly the advantage of using a polygon rather than a region. \$\endgroup\$ – The Photon Feb 21 '19 at 22:32
  • \$\begingroup\$ 2nd, remember the physical edges of the copper can probably vary by at least 0.025 mm due to uncertainty about the etching speed, registration of the masks, etc. So trying to design things to the nearest micron is pointless. What you have in your picture looks pretty good to me. \$\endgroup\$ – The Photon Feb 21 '19 at 22:36
  • \$\begingroup\$ @KevinKruse yes, I know! I was trying to understand if there was something like that also for solid regions. \$\endgroup\$ – SashaLag Feb 22 '19 at 0:06
  • \$\begingroup\$ @ThePhoton thank you! Sometimes I forget about it. Anyway what I have in picture is from TI datasheet. I dream of having something like that also in my PCB. I will give polygon another shot then! \$\endgroup\$ – SashaLag Feb 22 '19 at 0:06

I would do as you first intended and use polygon pours - but instead of just one, I'd draw multiple smaller ones.

That makes it much easier to be fast and precise, as you can have a larger grid setting for most of the fills.

Otherwise, if you end up using a Solid Region, you will have to ensure your component is affected by the Design Rules properly.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.