Quite interesting. If I am not mistaken, FCLGA is flip-chip land grid array. What this means is basically a package as we know from Intel and AMD processors: FC means that die is soldered and then glued on a mini-PCB (called "substrate"). LGA means that this mini-PCB has pins that go into a socket on the main electronics board.

As said by Dexter770221, that it's flip-chip might explain the difference in testing vs. mass production: they simply stick multiple dies on one substrate. (This is, by the way, what Hashfast has been doing, but please don't tell Icebreaker )

Fun fact about LGA: it gives you the opportunity to make the substrates swappable, similar to what we know from Intel and AMD. A reaction to their problems with chips burning? A way for future upgrade which allows you to keep the base miner and just buy a new generation of chips from AM every few months? Who knows.


Intel Core I3 FC-LGA with two dies on a substrate. This thing is of course swappable, but might be also soldered onto the board (ie, in notebooks).

Some refs:
http://en.wikipedia.org/wiki/Flip_chip
http://en.wikipedia.org/wiki/Land_grid_array