Folded Multi-Die Flip Chip Package With Shared Heat Sink

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Solution Overview

Problem

Existing 3D packaging solutions for multiple integrated circuit dies face challenges such as large package footprints and inefficient heat dissipation, particularly in side-by-side and stacked configurations.

Innovation Solution

A packaging solution featuring a flexible multi-layer support substrate with a center portion and peripheral portions connected by a flexible coupling region, where integrated circuit dies are mounted in flip chip orientation, and a shared heatsink with tabs and fins provides improved thermal coupling and reduced footprint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If multiple integrated circuit dies are mounted side-by-side on a support substrate, then electrical connectivity between dies is achieved, but the package footprint occupies an overly large area

Engineering Contradiction:
Improveelectrical connectivityVSAvoidpackage footprint
Core Design Contradiction:
Ease of operationVSArea of stationary object

Solution Approach 1:

The patent transitions from a two-dimensional side-by-side die arrangement to a three-dimensional stacked configuration using through-silicon vias (TSVs). This vertical stacking allows multiple dies to be electrically connected through the substrate thickness rather than requiring lateral expansion, thereby reducing the package footprint while maintaining full electrical connectivity between all dies.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Area of stationary object

If multiple integrated circuit dies are stacked one on top of the other with TSVs, then package footprint is reduced, but the configuration becomes overly complex and expensive

Engineering Contradiction:
Improvepackage footprintVSAvoidstacked die configuration
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent divides the support substrate into distinct regions: a central portion and peripheral portions connected by flexible coupling regions. This segmentation allows the substrate to be folded into a compact three-dimensional configuration, reducing the package footprint without requiring complex stacked die arrangements with TSVs. Each die remains accessible on different faces of the folded substrate, simplifying the overall device architecture.

Inventive Principle:
Principle #1Segmentation

3Temperature

If multiple integrated circuit dies are mounted side-by-side sharing a heatsink, then heat dissipation is provided, but the package footprint occupies an overly large area

Engineering Contradiction:
Improveheat dissipationVSAvoidpackage footprint
Core Design Contradiction:
TemperatureVSArea of stationary object

Solution Approach 1:

The patent implements vertical stacking of dies with the heatsink positioned at the bottom of the stack, thermally coupled to all dies through the substrate thickness. This three-dimensional thermal pathway allows efficient heat dissipation from multiple dies without requiring lateral expansion of the heatsink area, thereby reducing the package footprint while maintaining effective thermal management.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Area of stationary object

If the support substrate uses a flexible coupling region to connect center and peripheral portions, then package footprint is reduced through folding, but additional securing structures are needed

Engineering Contradiction:
Improvepackage footprintVSAvoidsecuring structures
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent integrates the heatsink with the support substrate by thermally coupling the heatsink to the central portion of the substrate. This merging of functions allows the heatsink to serve dual purposes: thermal management and mechanical anchoring of the folded substrate configuration. The heatsink's thermal coupling provides structural stability without requiring additional securing structures, eliminating the need for separate fastening components.

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution achieves a compact package footprint, enhanced heat dissipation through shared heatsink utilization, and improved package rigidity without the need for additional securing structures, addressing the limitations of previous packaging configurations.

Implementation Method 1

a flexible coupling region; wherein the at least one peripheral portion is folded relative to the center portion at the flexible coupling region

Methodology Applied
Scientific EffectFlexibility: Elasticity

Implementation Method 2

the lower surface of the base plate is thermally coupled to a back of said first circuit device

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

an outer surface of at least one fin of the heatsink is thermally coupled to a back of said second circuit device

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4557366A1Multidie flip chip package with heat sink
Publication Date: 2025.05.21 STMICROELECTRONICS INT NV
  • EP4557366A1 patent drawingFigure 1~3
  • EP4557366A1 patent drawingFigure 4~5
  • EP4557366A1 patent drawing

AI summary

A substrate includes a center portion and a peripheral portion connected to the center portion by a flexible coupling region. A first die is mounted to an upper surface of the substrate at the center portion and a second die is mounted to the upper surface of the substrate at the peripheral portion. A heatsink includes a base plate, fins extending from an upper surface of the base plate and tabs extending from a lower surface of the base plate. The tabs of the heatsink are mounted to the upper surface of the substrate at the center portion, and the lower surface of the base plate is thermally coupled to a back of the first die. The peripheral portion is folded relative to the center portion at the flexible coupling region. An outer surface of the fin of the heatsink is thermally coupled to a back of the second device.