MCM (Multiple-chip-module) packages multiple integrated circuits and semiconductor dies onto a single substrate. There are different types of MCMs based on the substrate material, including MCM-L which uses a laminated substrate, MCM-C which uses a ceramic substrate, and MCM-D which uses a deposited substrate with thin-film metals and dielectrics. The physical design of an MCM involves partitioning the circuit, placing the chips on the substrate while considering timing constraints, power constraints, and thermal characteristics, and routing the interconnects between chips.

1. MCM
(Multiple-chip-module)

2. Definition:
MCM is specialized electronic
package where multiple IC's,
semiconductor dies are packed on to a
unified substrate.

4.  They have been introduced as an
alternative packing approach to complement
the advances which were taking place in IC
technology.
 Packaging of the chips has become a more
significant factor in performance.
 Chip interconnections play a more
dominant & limited role in determining overall
system speed or performance.

5. PHYSICAL DESIGN AUTOMATION
 Physical design is similar as IC’s but design
tools were distinct and cannot be directly used
for MCM.
 In designing the CAD tools for MCM following
were taken in to consideration.
1. Clock skew rate
2. Power noise disturbance
3. Assembly effects

6. MCM -TYPES

7. Non-Programmable MCM’s
1. MCM-L (Laminated MCM)
2. MCM-C (Ceramic substrate MCM)
3. MCM-D (Deposited MCM)
For fast turn around we go for PMCM’S.

8. MCM-L
 It is the oldest technology.
 It is an advanced PCB which IC are
mounted using COB(chip on board)
Technology.

9.  It is less cost effective at higher densities where
many additional layers are required.
It is suitable technology for applications which
require low risk packing approach.
ADVANTAGES:
1.Low cost.
2.high density
3.High Performance

10. MCM-C
 Here modules are deposited on the base
substrate which uses thin film technology.
 The substrate fabrication is done with
confirmed ceramic or glass ceramic techniques.
 Due to excellent thermal
conductivity and lower
thermal expansions we
Use ceramic materials.

11.  It is not applicable for high-end applications.
 Interconnect densities = 200-400 cm/ cm2.
Advantages:
1.Low cost.
2.High density.
3.High performance.
These have been the primary packing choice
in many advanced applications requiring for
both performance & reliability.

12. MCM-D
 This consists of substrates which have high
density thin-films metals and low dielectric
materials like silicon.
Several dielectric/metallization technologies
were involved.
Advantages:
1.High performance.
2.High density.
Disadvantage:
High cost.

13. COMPARISION

14. Die Attachment techniques
 These attachment techniques are of three
types.
1. wire bonding
2. TAB (tape automated bonding)
3. Flip-chip bonding

15. Wire bonding
 The back side of the chip is attached to the
substrate & electrical connections are made .
These connections are made by thermal
compression and were made by attaching to
the very small wires from the I/o pads on the
device.

16. TAB
 This uses a thin polymer tape containing
metallic circuitry.
 The actual path is simply a set of connections
from inner leads to outer leads.

17. Flip-chip bonding
 This use smaller solder balls on the I/o pads.
These also electrically connected
This also known as Face-down bonding (or)
controlled-collapsed chip connection.

18. MCM Physical design cycle
MCM input = circuit design
MCM output = layout design.
Physical design cycle :
1. Partioning
2.Placement
3.Routing

19. Partioning
 The 1st assignment of partion is to sub-divide
the given circuit.
 Timing, i/o pin count & power constraints .
 As a result area also will also be added as one
of the constraints.
It is performance driven.
note: No. of chips sustain in sub-ckt must be less than No. of chips
sustain in MCM.

20. Placement
 Mapping of chips.
 It is performance driven.
 As a result effects thermal characteristics. Due
this there will be a effect over routing efficiency.
 Compared to IC’s they have fewer components
and sizes, shapes were less variable.
Note: Thermal characteristics were considered because bare chips
were place side by side hence during the processing certain
amount of heat is get generated.

21. Placements are involved in two ways.
1. Chip array based placement.
2. Fixed array based placement.