Multi-chip module


A multi-chip module is generically an electronic assembly where multiple integrated circuits, semiconductor dice and/or other discrete components are integrated, usually onto a unifying substrate, so that in use it can be treated as if it were a larger IC. Other terms for MCM packaging include "heterogeneous integration" or "hybrid integrated circuit". The advantage of using MCM packaging is it allows a manufacturer to use multiple components for modularity and/or to improve yields over a conventional monolithic IC approach.
A Flip Chip Multi-Chip Module is a multi-chip module that uses flip chip technology. A FCMCM may have one large die and several smaller dice all on the same module.

Overview

Multi-chip modules come in a variety of forms depending on the complexity and development philosophies of their designers. These can range from using pre-packaged ICs on a small printed circuit board meant to mimic the package footprint of an existing chip package to fully custom chip packages integrating many chip dies on a high density interconnection substrate. The final assembled MCM substrate may be done in one of the following ways:
The ICs that make up the MCM package may be:
  • ICs that can perform most, if not all of the functions of a component of a computer, such as the CPU. Examples of this include implementations of IBM's POWER5 and Intel's Core 2 Quad. Multiple copies of the same IC are used to build the final product. In the case of POWER5, multiple POWER5 processors and their associated off-die L3 cache are used to build the final package. With the Core 2 Quad, effectively two Core 2 Duo dies were packaged together.
  • ICs that perform only some of the functions, or "Intellectual Property Blocks", of a component in a computer. These are known as chiplets. An example of this are the processing ICs and I/O IC of AMD's Zen 2-based processors.
An interposer connects the ICs. This is often either organic or is made of silicon. Each has advantages and limitations. Using interposers to connect several ICs instead of connecting several monolithic ICs in separate packages reduces the power needed to transmit signals between ICs, increases the number of transmission channels, and reduces delays caused by resistance and capacitance. However, communication between chiplets consumes more power and has higher latency than components within monolithic ICs.

Chip stack MCMs

A relatively new development in MCM technology is the so-called "chip-stack" package. Certain ICs, memories in particular, have very similar or identical pinouts when used multiple times within systems. A carefully designed substrate can allow these dies to be stacked in a vertical configuration making the resultant MCM's footprint much smaller. Since area is more often at a premium in miniature electronics designs, the chip-stack is an attractive option in many applications such as cell phones and personal digital assistants. With the use of a 3D integrated circuit and a thinning process, as many as ten dies can be stacked to create a high capacity SD memory card. This technique can also be used for High Bandwidth Memory.
The possible way to increasing the performance of data transfer in the Chip stack is use Wireless Networks on Chip.

Examples of multi-chip packages