What is Multi-Chip Module (MCM) ? | Types | Design Technologies based on MCM-L and MCM-C


MCM is an abbreviation of Multi-Chip Module which is defined as a single unit containing two or more chips and an interconnection substrate that functions together as a system building block.

MCM is an electronic package consisting of multiple integrated circuits (ICs) assembled into a single device.

MCM is important in modern electronic miniaturization and microelectronic systems. Multi-Chip Module differs depending on the complexity and development of their designers and the needs of end-users.

Why do we need a multi-chip module?

We need MCM for:

  1. More functionality in one single chip
  2. Increase the integration level of the system (smaller size)
  3. No packaging of individual chips
  4. Still expensive, but used for high-end applications (e.g. Military, aerospace, medical devices, and LED arrays), a complete PC in an MCM is possible



There are various multichip design technologies evolved including on MCM-L and MCM-C.

1. MCM-Ceramic (MCM-C)

This is a Multi-Chip Module design technology that involves substrates-based ceramic technologies

  1. Comparison with MCM-L:
  2. High wiring density
  3. Better electrical and thermal conductivity than MCM-L
  4. Assemblies with components on both sides.
  5. Flexible packaging
  6. High dielectric constant (not suitable for high frequencies)


2. MCM-Laminated (MCM-L)

This is the Multi-Chip Module technology which is based on laminated PCB technologies and uses micro vias that have evolved to accomplish the denser integration requirements of today’s demands.

  1. Comparison with MCM-C:
  2. Low cost
  3. Ease of repairing or reworking individual layers
  4. Poor thermal conductivity of the substrate


Types of Multi-Chip Module (MCMs)

  1. MCM-Deposited thin film (MCMD)
  2. MCM-Ceramic (MCMC); This Means MCM is built on a ceramic substrate.
  3. MCM-Laminated organic (MCML).


What are the issues of MCM?

  1. Feature size

Feature size, we are talking about interconnecting line width and pad size.

  1. Via size

The via size is used for interconnecting various copper conductors through multilayers structures. So, the conductor of the top layer needs to be interconnected to the conductor at the intermediate as well as the outer layer on the other side of the substrate, and for this, we use via structures.

Vias have to be very small if you want to build a high-density interconnects structure, so the design multichip module has to take care of lower line width smaller via size.

  1. Layer count

The layer count typically can vary from 2 to 12, 18, or 24 layers multichip modules structure. Now, optimization, in this case, is very important, layer count depends on the pad density or the pin density of the total number of components that are employed in this multichip module.

Also, the kind of fan out of that is required from a die to the substrate, because you have to take care of the power delivery, the ground pads, the ground layers, and signals to be effective in electrical performance.

  1. Dielectric constant

The dielectric constant of a substrate becomes very important, you can play around with different materials, and different fillers can be used in the case of the ceramic substrate as well as organic substrates.

  1. Dielectric thickness

The dielectric thickness is again related to the process, say for dielectric thickness and dielectric constant, will give the choice or a better design, utilizing these properties will give better electrical performance because it is normally a multilayer structure, then you can try to integrate your resistors and capacitors into the structure of multichip module substrate.

Because these resistors and capacitors are now part of the interconnect system along with the active devices because if you encapsulate having this active and the passive devices we are going to get a complete system in hand.

Applications of Multi-Chip Modules (MCM), used in LED arrays, In Computers, communication devices, and other electronic devices.

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