Graphene-Modified Metal Polymer Coatings for EMI Shielding

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Solution Overview

Problem

Formulations with high levels of metal materials tend to exhibit high shrinkage and brittleness after sintering, which can lead to stress issues and compromise the effectiveness of electromagnetic interference (EMI) shielding in electronic packages, while adding polymer resin to improve brittleness often reduces shielding effectiveness.

Innovation Solution

Incorporating graphene into metal particle-filled polymer systems to reduce curing shrinkage and improve flexibility without significantly affecting EMI shielding performance, using formulations comprising 75-95 wt% sinterable conductive metal particles, 0.2-5 wt% graphene, and 1-20 wt% diluent or polymer resin, which are sinterable at temperatures up to 250°C and provide effective EMI shielding across a wide range of frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high levels of metal materials are used in formulations, then EMI shielding effectiveness is improved, but shrinkage and brittleness increase after sintering

Engineering Contradiction:

ImproveEMI shielding effectivenessVSAvoidbrittleness

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent uses composite materials by combining metal particles with polymer resin to create a formulation that maintains EMI shielding effectiveness while reducing brittleness. The polymer matrix provides flexibility and reduces shrinkage stress, allowing the metal particle network to maintain conductivity and shielding performance without the material becoming overly brittle after sintering.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the physical and chemical parameters of the formulation by controlling the size distribution, concentration, and surface properties of metal particles, as well as the composition and molecular weight of the polymer resin. These parameter adjustments optimize the balance between shielding effectiveness and mechanical properties, reducing shrinkage and brittleness while maintaining high conductivity.

Inventive Principle:

Principle #35Parameter changes

2Strength

If polymer resin is added to improve brittleness, then flexibility is improved, but EMI shielding effectiveness is reduced

Engineering Contradiction:

ImproveflexibilityVSAvoidEMI shielding effectiveness

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies local quality by creating distinct regions within the coating where metal particles form conductive pathways for EMI shielding, while the polymer resin provides the flexible matrix. The metal particles are distributed to create percolating networks in key areas, ensuring shielding effectiveness is maintained in specific zones without requiring the entire formulation to be highly conductive, thus allowing polymer content to increase for flexibility without sacrificing overall shielding performance.

Inventive Principle:

Principle #3Local quality

3Reliability

If high levels of metal materials are used in formulations, then EMI shielding effectiveness is improved, but shrinkage increases after sintering

Engineering Contradiction:

ImproveEMI shielding effectivenessVSAvoidshrinkage

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent applies beforehand cushioning by incorporating polymer resin into the formulation prior to sintering, which acts as a cushioning matrix that absorbs and distributes the shrinkage stress during the sintering process. This pre-established polymer network prevents excessive shrinkage by providing a flexible framework that accommodates volume changes, allowing high metal particle content for EMI shielding without suffering from excessive shrinkage that would compromise the coating integrity.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 use of graphene in these formulations results in flexible, low-shrinkage conductive coatings with maintained EMI shielding effectiveness, reducing brittleness and stress issues while ensuring effective EMI shielding performance across various frequencies.

Implementation Method 1

Incorporating graphene into metal particle-filled polymer systems to reduce curing shrinkage

Methodology Applied

Scientific EffectShrinkage reduction:

Implementation Method 2

improve flexibility without significantly affecting the EMI shielding performance thereof

Methodology Applied

Scientific EffectBrittleness reduction:

Implementation Method 3

EMI shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials

Methodology Applied

Scientific EffectEMI shielding: Faraday Cage

Implementation Method 4

conductive paste adhesives have been used for EMI shielding protection

Methodology Applied

Scientific EffectElectrical conductivity: Conduction (electrical)

Data Source

PatentUS10741503B2Graphene-containing materials for coating and gap filling applications

Publication Date: 2020.08.11 HENKEL KGAA

AI summary

Provided herein are conductive formulations wherein graphene has been added into the metal system, thereby reducing curing shrinkage and improving flexibility, without significantly affecting the EMI shielding performance thereof. In accordance with certain aspects of the present invention, there are also provided methods for filling a gap in an electronic package to achieve electromagnetic interference (EMI) shielding thereof, as well as the resulting articles shielded thereby. In certain aspects of the present invention, there are also provided articles prepared using invention formulations and methods.