Conformal Coating EMI Shielding for 3D PCBAs

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Solution Overview

Problem

Conventional EMI shields for printed circuit board assemblies (PCBAs) are not well-suited for three-dimensional configurations, as they can crack and fail to properly fill internal volumes, leading to increased size and component costs, and are not effective in preventing electromagnetic interference (EMI) in complex geometries.

Innovation Solution

A method involving an electrically non-conductive conformal coating over a substantial majority of the PCBAs, combined with an electrically conductive adhesive that fills the internal volume, eliminating the need for containment enclosures and enhancing mechanical robustness by preventing cracking and ensuring effective EMI shielding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional containment enclosures are used for EMI shielding, then EMI protection is provided, but the size of the PCB apparatus increases and component costs increase

Engineering Contradiction:

ImproveEMI protectionVSAvoidPCB apparatus size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The invention extracts the EMI shielding function from separate containment enclosures and integrates it directly into the PCB assembly through conformal coatings and conductive adhesive, eliminating the need for additional shielding components and reducing overall apparatus size

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges multiple functions (EMI shielding, mechanical support, crack prevention, and internal volume filling) into a single integrated system using conformal coatings and conductive adhesive, replacing multiple separate components with a unified solution

Inventive Principle:

Principle #5Merging (Combining)

2Object-affected harmful factors

If insulating coatings are applied to folded three-dimensional PCBAs, then EMI shielding is provided, but the coatings crack when the PCBA is folded

Engineering Contradiction:

ImproveEMI shieldingVSAvoidcoating integrity

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention uses flexible conformal coatings that can accommodate the three-dimensional folded geometry of the PCBA without cracking, replacing rigid insulating coatings with materials designed to flex and conform to complex shapes

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The invention employs composite material systems combining flexible insulating conformal coatings with conductive adhesive materials, creating a multi-layer structure that maintains integrity while providing EMI shielding in three-dimensional configurations

Inventive Principle:

Principle #40Composite materials

3Object-affected harmful factors

If thin solvent-based conductive coatings are applied, then EMI shielding is provided, but they cannot properly fill the internal volume of folded PCBAs

Engineering Contradiction:

ImproveEMI shieldingVSAvoidconductive material volume

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The invention uses adhesive materials with appropriate viscosity characteristics that can be applied and will properly fill three-dimensional internal volumes, replacing thin solvent-based coatings that cannot penetrate or fill complex geometries effectively

Inventive Principle:

Principle #29Pneumatics and hydraulics

Data Source

PatentUS9474160B2Printed circuit board apparatus and methods of making the same

Publication Date: 2016.10.18 ADVANCED BIONICS AG

AI summary

Printed circuit board apparatus with electromagnetic interference shields and methods of making the same.