Film Lamination with Flex-Tails for Touch Sensor Pad Access

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Solution Overview

Problem

Film-based touch sensors with a darkening coating on the side facing away from the user, making the conductive material visible through a glass substrate, necessitate a solution to orient the darkened side towards the user while maintaining accessibility of termination pads for attachment to flex-tails.

Innovation Solution

The touch sensor is constructed with a darkening coating on the side of the metalized film facing the user, using various lamination methods involving Optically Clear Adhesive (OCA) layers and Anisotropic Conductive Film (ACF) to ensure the termination pads remain accessible and bonded correctly, allowing the darkened side to face the user, thus obscuring the conductive material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the darkening coating is placed on the side of the metalized film facing away from the user, then the conductive material is obscured, but the termination pads become inaccessible for attachment to flex-tails

Engineering Contradiction:

Improvevisibility of conductive materialVSAvoidaccessibility of termination pads

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The metalized film is segmented into two functional regions: the darkening coating covers the conductive trace areas to obscure them, while the termination pad areas remain uncovered to maintain accessibility for flex-tail attachment. This spatial segmentation allows both requirements to coexist.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The darkening coating is applied selectively rather than uniformly across the entire metalized film. The coating is present in regions where conductive material needs obscuring but absent or reduced in regions where termination pads require accessibility, creating local variations in optical properties.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If the metalized film is laminated with the darkened side facing away from the user, then the conductive material remains visible, but the termination pads remain accessible

Engineering Contradiction:

Improveaccessibility of termination padsVSAvoidvisibility of conductive material

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The conventional lamination orientation is inverted. Instead of laminating with the darkened side facing away from the user (which keeps pads accessible but conductors visible), the invention laminates with the darkened side facing toward the user, thereby obscuring conductors while maintaining pad accessibility through selective coating regions.

Inventive Principle:

Principle #13The other way round (Inversion)

3Illumination intensity

If the darkening coating is applied to the metalized film, then the aesthetic appeal is enhanced, but the bonding of termination pads to flex-tails becomes more difficult

Engineering Contradiction:

Improveaesthetic appearanceVSAvoidbonding of termination pads

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The darkening coating is applied with spatial variation in optical density or complete absence in specific regions. Termination pad areas maintain higher transparency or no coating to facilitate bonding operations, while other areas have full darkening coating for aesthetic purposes.

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

This configuration effectively hides the conductive material from view while ensuring proper bonding and functionality of the termination pads, enhancing the aesthetic appeal and operational efficiency of the touch sensor.

Implementation Method 1

anisotropic conductive film (ACF)

Methodology Applied

Scientific EffectAnisotropic conduction: Anisotropy

Implementation Method 2

optically clear adhesive (OCA) layer

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS10007368B2Film lamination with flex-tails for a touch sensor

Publication Date: 2018.06.26 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

Different lamination methods may be used to create a touch sensor with a darkened side of metalized film facing the user. One lamination method includes laminating a metalized film to an optically clear adhesive (OCA) layer such that an edge of the metalized film including the termination pads remain un-adhered to the OCA layer. Flex-tails may be bonded to the termination pads at a later time by bending up the un-adhered edge. Anisotropic Conductive Film (ACF) may be placed on the termination pads prior to laminating the metalized films. Flex-tails may be placed onto an OCA layer in a location where the termination pads on the metalized film will be located when laminated to the OCA layer. A strip of ACF may be placed on the flex-tail pads. The flex-tails may be bonded to the termination pads of the metalized film prior to the metalized film being laminated.