What is the dimension of the heat sink on the HQ304/ HQ240 / HQ160 packages?
There are two different design versions of HQ packages. The HQ240 / HQ208 / HQ160 version and the HQ304 version. The difference between these two is that the former has the copper heatsink metal exposed at the bottom of the package. For the HQ304 package, the exposed Nickel plated copper is at the top.
The HQ 240 / HQ208 / HQ160 packages that have been manufactured prior to this PCN (http://direct.xilinx.com/bvdocs/notifications/pcn97009a-data.pdf),have an exposed metal heat sink made of Copper at the bottom of the package (on the side facing the board). As of this PCN, all products built in HQ and HT packages with the heatsink facing the board have insulation for the copper / copper-nickel metal plates. In the HQ240, the dimensions of the exposed heatsink is 24mm x 24 mm. For the HQ160 and HQ208 it is 21mm x 21mm.
For details on the HQ package, please see: