Interposer

[1] An interposer can be made of either silicon or organic (printed circuit board-like) material.

[5] A common example of an interposer is an integrated circuit die to BGA, such as in the Pentium II.

[8][9] There are already several products with interposer technology in the market, notably the AMD Fiji/Fury GPU,[10] and the Xilinx Virtex-7 FPGA.

[12] Another example of an interposer is the adapter used to plug a SATA drive into a SAS backplane with redundant ports.

SATA drives can be connected to nearly all SAS backplanes without adapters, but using an interposer with a port switching logic allows providing path redundancy.

BGA with an interposer between the integrated circuit die to ball grid array
Pentium II: example of an interposer in dark yellow, integrated circuit die to ball grid array chip carrier