Flip-chip bumps
Beginner
Tiny solder dots spread across the face of a chip. The chip is flipped over and stuck down onto its base by those dots.
Novice
A packaging method in which small solder bumps are placed on the chip’s top surface and the chip is mounted upside down, so the bumps connect directly to the package. The connections are short, and the bumps can sit in a grid across the chip rather than only along its edge.
Expert
Bumps form a grid at a fixed pitch. Each signal or supply net is assigned to a bump and connected to its I/O cell through a redistribution layer (RDL), an extra metal layer on top of the chip. Bump planning therefore couples to I/O cell placement, the power grid and macro placement.
Explained in Floorplanning (Design Flow).
See also: I/O ring (pad ring), Pad-limited vs. core-limited.