Folded Capacitive Touch Sheet Assembly for PCB Alignment

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Solution Overview

Problem

Current capacitive touch devices integrated into printed items face challenges in assembly and design, particularly in creating flexible and interactive surfaces that can effectively support capacitive touch switches, conductive tracks, and circuit boards while maintaining aesthetic value and environmental sustainability.

Innovation Solution

A method of assembling a capacitive touch device using a flexible sheet with fold lines and adhesive, where capacitive touch switches, contact lands, and conductive tracks are integrated on one face, and a circuit board is bonded between folded wings, allowing for complex layouts and environmentally friendly materials like recycled paper or cardboard.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a flexible sheet with adhesive is used to bond circuit board and wings, then assembly is simplified and flexibility is improved, but assembly precision and alignment accuracy may deteriorate

Engineering Contradiction:
Improveassembly simplicityVSAvoidalignment accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The circuit board is pre-aligned with the first wing before adhesive application, and the second wing is pre-positioned to ensure proper alignment. This preliminary positioning ensures that when adhesive is applied and wings are bonded, the alignment accuracy is maintained while still benefiting from the ease of adhesive bonding.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The adhesive acts as an intermediary substance that facilitates bonding between the circuit board and wings while allowing for adjustment and alignment during the assembly process. The adhesive layer provides a buffer that enables precise alignment to be achieved and maintained during bonding.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If wing extension with aperture is used to accommodate circuit board, then adaptability and layout flexibility are improved, but device complexity increases

Engineering Contradiction:
Improvelayout flexibilityVSAvoidstructural complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The flexible sheet is segmented into multiple wings and a wing extension, with the aperture strategically positioned in the wing extension to accommodate the circuit board. This segmentation allows the circuit board to be positioned in a location that optimizes layout flexibility while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The wing extension with aperture adds a dimensional element to the assembly, allowing the circuit board to be accommodated in a three-dimensional space rather than being constrained to a flat surface. This enables greater layout flexibility without significantly increasing overall device complexity.

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

3Shape

If folded wings structure is used, then aesthetic value and compactness are improved, but manufacturing precision and assembly difficulty increase

Engineering Contradiction:
ImprovecompactnessVSAvoidfold line alignment
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

Fold lines are pre-marked on the flexible sheet during manufacturing, providing clear guidance for folding operations. This preliminary marking ensures that when assembly occurs, the fold lines can be accurately aligned, maintaining manufacturing precision while achieving the desired compact folded structure.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The adhesive serves as an intermediary that secures the folded wings in their final position, maintaining the precision of fold line alignment once the folding is completed. The adhesive bonds the wings together, preserving the aesthetic value and compactness achieved through precise folding.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Productivity

If conductive ink is used for capacitive touch switches and tracks, then environmental sustainability is improved, but electrical conductivity and reliability may deteriorate

Engineering Contradiction:
Improveenvironmental sustainabilityVSAvoidelectrical conductivity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

A composite conductive material is used that combines carbon-based conductive ink with metallic particles or conductive polymers. This composite approach maintains the environmental sustainability benefits of carbon-based materials while enhancing the electrical conductivity and reliability through the addition of metallic components.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The formulation of the conductive ink is optimized by adjusting parameters such as particle size distribution, concentration of conductive materials, and binder composition. These parameter changes enhance the electrical conductivity and reliability of the carbon-based conductive ink while maintaining its environmental sustainability advantages.

Inventive Principle:
Principle #35Parameter changes

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

Enables the creation of interactive printed articles that can pair with Bluetooth devices, providing input signals while maintaining a visually appealing and sustainable design, with effective capacitive touch functionality and reduced capacitive coupling.

Implementation Method 1

The method comprises providing adhesive on the first face of the flexible sheet so as to bond the first and second wings and to bond a circuit board to the flexible sheet

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Implementation Method 2

capacitive touch switches, contact lands and conductive tracks interconnecting the capacitive touch switches and the contact lands

Methodology Applied
Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentEP3206883B1Capacitive touch device
Publication Date: 2018.12.05 NOVALIA
  • EP3206883B1 patent drawingFigure 1
  • EP3206883B1 patent drawingFigure 2
  • EP3206883B1 patent drawingFigure 3

AI summary

Capacitive touch device A method of assembling a capacitive touch device (1) is disclosed. The method comprises providing a flexible sheet (2) having first and second faces (51, 52) and first and second wings (61, 62) divided by a fold line (31). The flexible sheet supports capacitive touch switches (21; Fig. 4), contact lands (22; Fig. 4) and conductive tracks (24; Fig. 4) interconnecting the capacitive touch switches and the contact lands on the first face of the flexible sheet. The method comprises providing adhesive (29) on the first face of the flexible sheet so as to bond the first and second wings and to bond a circuit board (17) to flexible sheet. The method comprises placing a circuit board on the flexible sheet, the circuit board having contact pads (23; Fig. 6) which are aligned with the contact lands (22; Fig. 6) and folding the flexible sheet along the fold line so as to bond the first and second wings with the circuit board interposed between the first and second wings. The flexible sheet further comprises a wing extension (63) including an aperture (36) configured to accommodate the circuit board and extending from the first wing along another fold line, wherein the method further comprises: folding the wing extension onto first wing before completing folding the second wing onto the first wing.