A multi-chip module is generically an electronic assembly where multiple integrated circuits, semiconductor dies 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, such as "hybrid" or "hybrid integrated circuit", also refer to MCMs. The individual ICs that make up an MCM are known as chiplets. Intel and AMD are using MCMs to improve performance and reduce costs, as splitting a large monolithic IC into smaller chiplets allows for easy performance improvements, more ICs per wafer, and improved yield, as smaller dies have a reduced risk of getting destroyed by dust particles during semiconductor fabrication. Each chiplet is physically smaller than a conventional monolithic IC die,. An example of MCMs in use for mainstream CPUs is AMD's Zen 2 design.
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. Multi-Chip Module packaging is an important facet of modern electronic miniaturization and micro-electronic systems. MCMs are classified according to the technology used to create the HDI substrate.
MCM-L – laminated MCM. The substrate is a multi-layer laminated printed circuit board.
MCM-D – deposited MCM. The modules are deposited on the base substrate using thin film technology.
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.
AMD Ryzen, Ryzen Threadripper and Epyc CPUs based on Zen 2 architecture are MCMs of one, two, four or eight chips containing CPU cores and one bigger I/O chip
