Quote from: BkkCoins on May 04, 2013, 01:32:00 PM

This one shows holes and heat sink pads under the thermal vias. It's the bottom mask - areas of exposed copper. The thermal pads are 1cm square. I forget now the hole diameter, maybe 4mm but if there is a good standard size let me know. (Don't measure here as this includes a ring around the hole)

http://i.imgur.com/zMSgPvm.png

BkkCoins this article has a nice table of thermal resistance reduction for different vias arrays that can serve you as a reference their model uses a 10mm square die vs the 7mm Avalon chips has.

http://www.electronics-cooling.com/2004/08/thermal-vias-a-packaging-engineers-best-friend/

Abrazos,
Dieguito