Hi,
I am involved in a project dealing with fpgas and the pcb may only be used on one side for component placement (actives an passives). Therefore I am considering using a QFP package instead of a BGA package for decoupling purposes mainly. My application runs at 40 MHz and the IO need is small (about 100 IOs). I am considering either a 208 QFP or a 256 FBGA for a Xilinx part like spartan IIE. The other issue is about obsolescence. I noticed the QFP package is still available for Spartan III. Is it a good indicator for the life of this package for Spartan IIE or is this idea irrelevant ? Finally, the temperature of the environment will border 85°C so I believe the regular industrial grade parts we use may be out of our specs. What is the rule for Xilinx parts like spartan IIE or else ? Since the junction temperature is 100°C what happens if the part is in an ambient temperature above 85°C ? Will it keep working or will performance be degraded ? Does it depend on the process of the FPGA for a same grade ? Is there a derating one can apply if the FPGA is out of specs but not about to be destoyed because junction temperature was not reached ? Any idea is welcome !!!
JF