Interposer

BGA with an interposer between theintegrated circuit dietoball grid array

Pentium II: example of an interposer in dark yellow,integrated circuit dietoball grid arraychip carrier

Aninterposeris an electrical interface routing between one socket or connection to another. The purpose of an interposer is to spread a connection to a wider pitch or to reroute a connection to a different connection.

Interposer comes from the Latin word "interpōnere", meaning "to put between".They are often used inBGApackages,multi-chip modulesandhigh bandwidth memory.

A common example of an interposer is anintegrated circuit dieto BGA, such as in thePentium II.This is done through various substrates, both rigid and flexible, most commonlyFR4for rigid, andpolyimidefor flexible.Silicon and glass are also evaluated as an integration method.Interposer stacks are also a widely accepted, cost-effective alternative to3D ICs.There are already several products with interposer technology in the market, notably theAMD Fiji/Fury GPU,and theXilinx Virtex-7 FPGA.In 2016,CEA Letidemonstrated their second generation 3D-NoCtechnology which combines small dies ( "chiplets" ), fabricated at theFDSOI28 nm node, on a 65 nmCMOSinterposer.

Another example of an interposer is the adapter used to plug aSATAdrive into aSASbackplane with redundant ports. While SAS drives have two ports that can be used to connect to redundant paths or storage controllers, SATA drives only have a single port. Directly, they can only connect to a single controller or path. SATA drives can be connected to nearly all SAS backplanes without adapters, but using an interposer with a port switching logic allows providing pathredundancy.

See also

• Die preparation
• Integrated circuit
• Semiconductor fabrication