# Should arrays of thermal vias be square or hexagonal?

Title pretty much says it all: Should arrays of thermal vias be square or hexagonal?

The closest packing of a circular array with constrained distances would be on a hexagonal grid. For a given unit distance $$\d\$$ between points, the required area per point is $$\d^2\sqrt{3}/2 \approx 0.866d^2\$$. (See for example https://en.wikipedia.org/wiki/Hexagon#Parameters where the distance between center and edge is $$\r=d/2\$$, half the distance between hex cell centers.) Square grid arrays with distance $$\d\$$ between points require an area of $$\d^2\$$ per point. So hexagonal arrays can pack in about 15.5% more thermal vias per unit area than a square array having the same minimum distance between vias. (Which should provide lower thermal resistance and higher thermal capacity.)

Aside from the fact that square arrays are simpler to create, is there any other reason to prefer a square array of thermal vias over a hexagonal array?

• I use square/rectangular arrays for general purpose things, because they are slightly easier to make. And I do use hex arrays when I want to squeeze in as many vias as possible, e.g. for cooling. For very small pads under components, I anyway often end up with a situation where 4 vias on a rectangle are the most I can fit in that rectangular pad - with the next best thing being 5 in a 5-on-dice kind of pattern. Jan 20, 2023 at 19:00
• A quincunx: en.wikipedia.org/wiki/Quincunx
– vir
Jan 20, 2023 at 20:43
• there's a word I haven't heard in a long time!!! en.wikipedia.org/wiki/Galton_board Jan 20, 2023 at 22:17