Flexible PCB Nanowire Bonding for Stress-Resistant Interconnection

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Solution Overview

Problem

The interconnection of flexible printed circuit boards is complex, time-consuming, and sensitive to mechanical stress, requiring a strong and reliable mechanical and electrical connection, especially when the boards have fine conductive traces.

Innovation Solution

A carrier assembly comprising elongated flexible printed circuit boards with conductive nanowires connecting the sub-assemblies, providing a mechanical and electrical interconnection through the intertangling and fusion of nanowires, which are applied using pressure and heat, ensuring a stable and efficient connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If soldering is used to interconnect flexible printed circuit boards, then electrical connection is achieved, but the process becomes very complex and time consuming

Engineering Contradiction:
Improveelectrical connectionVSAvoidinterconnection process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical soldering process with a nanowire-based interconnection system. Conductive nanowires are applied to contact pads on both flexible printed circuit boards, creating electrical connections through nanowire-to-nanowire contact and nanowire-to-pad contact, eliminating the need for complex soldering operations

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the scale parameter by using nanowires with diameters in the range of 1-100 nanometers. This nanoscale dimension allows for highly dense interconnections and simplifies the manufacturing process compared to traditional soldering, as nanowires can be applied as coatings or layers rather than requiring precise manual or automated soldering operations

Inventive Principle:
Principle #35Parameter changes

2Reliability

If soldering is used to interconnect flexible printed circuit boards, then electrical connection is achieved, but the process becomes time consuming

Engineering Contradiction:
Improveelectrical connectionVSAvoidinterconnection speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies conductive nanowires to the contact pads in advance, before the actual interconnection process. This preliminary application of nanowires to both FPCBs allows for rapid assembly, as the nanowires are already in place to establish electrical connections when the boards are brought together, eliminating time-consuming soldering operations during assembly

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces the time-consuming mechanical soldering process with a nanowire-based system that enables faster interconnection. The nanowires can be applied as thin films or coatings that are quickly assembled, significantly reducing the time required compared to traditional soldering operations

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If soldering is used to interconnect flexible printed circuit boards, then electrical connection is achieved, but the solder points become sensitive to mechanical stress

Engineering Contradiction:
Improveelectrical connectionVSAvoidmechanical stress sensitivity
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses thin film structures for the conductive nanowire layers, which are inherently more flexible and resistant to mechanical stress than traditional solder joints. The nanowire films can accommodate bending and flexing of the FPCBs without creating sensitive stress concentration points, maintaining electrical connection reliability under mechanical load

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the mechanical properties by using nanowires with diameters of 1-100 nanometers, which create a distributed network rather than discrete solder points. This nanoscale distribution eliminates stress concentration at individual connection points, making the interconnection much more resistant to mechanical stress and fatigue

Inventive Principle:
Principle #35Parameter changes

4Reliability

If strong mechanical connection is required for fine conductive traces, then connection reliability is improved, but the interconnection process becomes more complex

Engineering Contradiction:
Improveconnection reliabilityVSAvoidinterconnection structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the mechanical connection and electrical connection functions into a single nanowire-based system. The conductive nanowires simultaneously provide both mechanical bonding between the FPCBs and electrical conduction through their inherent conductivity, eliminating the need for separate mechanical fasteners and electrical connectors, thus simplifying the overall interconnection structure while maintaining reliability for fine conductive traces

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 method allows for a reliable, easy, and strong connection between flexible printed circuit boards, reducing the complexity and time required for interconnection while providing mechanical stability and maintaining flexibility in the assembly.

Implementation Method 1

The nanowires may be connected with one another and/or with the first and/or second area through their tips, wherein the nanowires and/or the areas are configured to be pushed into one another, for example by applying pressure

Methodology Applied
Scientific EffectPressure: Pressure Increase

Implementation Method 2

The nanowires and/or the areas are configured to be pushed into one another, for example by applying pressure and/or heat

Methodology Applied
Scientific EffectHeat: Heating

Data Source

PatentEP4255129A1Interconnection of printed circuit boards with nanowires
Publication Date: 2023.10.04 AT & S AUSTRIA TECHNOLOGIE & SYSTEMTECHNIK AG
  • EP4255129A1 patent drawingFigure 1
  • EP4255129A1 patent drawingFigure 2~3
  • EP4255129A1 patent drawingFigure 4~5

AI summary

A carrier assembly (10) comprises a first carrier sub-assembly (12a), said first carrier sub-assembly (12a) having an elongated shape and comprising at least one electrically conductive layer structure (22) and at least one electrically insulating layer structure (20), said at least one electrically conductive layer structure (22) extending up to a first area (30a) provided on one of two extremities (24) of the elongated shape, wherein a first plurality (26a) of conductive nanowires (28) is provided on said first area (30a), and a second carrier sub-assembly (12b), said second carrier sub-assembly (12b) comprising at least one electrically conductive layer structure (22) and at least one electrically insulating layer structure (20), said at least one electrically conductive layer structure (22) comprising a second area (30b), wherein a second plurality (26b) of conductive nanowires (28) is provided on that second area (30b). Said first carrier sub-assembly (12a) and said second carrier sub-assembly (12b) are connected one to each other through a connection of the first plurality (26a) of nanowires (28) with the second plurality (26b) of nanowires (28).