Compliant Pad Spacer Composition for 3D IC Reflow Stress Relief

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Solution Overview

Problem

The challenge in three-dimensional IC packaging is substrate warpage and structural collapse due to thermal management issues during the soldering reflow process, which affects the integration and reliability of high-density packaging.

Innovation Solution

The use of a compliant pad spacer made from insulating materials, such as silicon-based polymer composites with ceramic fillers like boron nitride, alumina, or rare earth elements, provides mechanical support and flexibility to minimize substrate warpage and prevent structural collapse by distributing stress and maintaining electrical insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If rigid support structures are used among substrates, then structural stability is improved, but stress concentration and mechanical damage risk increase

Engineering Contradiction:
Improvesubstrate stabilityVSAvoidstress concentration
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent employs compliant pad spacers made from flexible materials that can deform under stress, distributing mechanical loads across the substrate interface rather than concentrating stress at discrete points. This flexible support structure maintains substrate stability while avoiding the stress concentration problems associated with rigid supports.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The invention changes the mechanical parameters of the support structure by using materials with specific compliance characteristics. The compliant pad spacer has controlled elasticity and deformation properties that allow it to adapt to thermal expansion and contraction, providing stable support without transmitting excessive stress to the substrates.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If thermal management is enhanced during soldering reflow, then substrate warpage is reduced, but process complexity increases

Engineering Contradiction:
Improvesubstrate warpage controlVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The compliant pad spacer acts as an intermediary element between substrates that mediates thermal stress effects. During soldering reflow, it absorbs and distributes thermal expansion forces, reducing substrate warpage without requiring complex external thermal management systems or process modifications.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If insulating materials are used for compliant pad spacer, then electrical insulation is improved, but thermal conductivity decreases

Engineering Contradiction:
Improveelectrical insulationVSAvoidheat dissipation
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent applies local quality by providing electrical insulation only where needed at the substrate interface, while allowing thermal management through other pathways. The compliant pad spacer provides localized electrical isolation to prevent short circuits, while the overall thermal management is achieved through the assembly design and alternative heat dissipation routes.

Inventive Principle:
Principle #3Local quality

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

The compliant pad spacer effectively reduces substrate warpage and structural collapse during thermal processes, ensuring reliable integration and reducing the likelihood of short circuits while maintaining structural integrity and heat resistance.

Implementation Method 1

The compliant pad spacer may be utilized to provide adequate support among the substrates or boards, such as interposers, packaging substrates or printed circuit broads (PCBs), so as to minimize the likelihood of substrate warpage or structural collapse in the IC packaging

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The compliant pad spacer is fabricated from an insulating material

Methodology Applied
Scientific EffectElectrical insulation: Electrical Resistance

Implementation Method 3

The compliant pad spacer includes silicon-based polymer composites having ceramic fillers disposed therein. The ceramic fillers include at least one of boron nitride, alumina, or rare earth elements

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP4325559A1Compliant pad spacer for three-dimensional integrated circuit package
Publication Date: 2024.02.21 GOOGLE LLC
  • EP4325559A1 patent drawingFigure 1A
  • EP4325559A1 patent drawingFigure 1B
  • EP4325559A1 patent drawingFigure 2A~2B

AI summary

A compliant pad spacer utilized in a three-dimensional IC packaging is provided. The compliant pad spacer may be utilized to provide adequate support among the substrates or boards, such as packing substrates, interposers or print circuit broads (PCBs), so as to minimize the effects of substrate warpage or structural collapse in the IC packaging. In one example, the compliant pad spacer includes an insulating material, such as silicon-based polymer composites having ceramic fillers disposed therein.