Heated Windscreen Busbar Adhesive Placement

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Solution Overview

Problem

Existing busbars used in heated windscreens lack a secure and consistent method for installation, often resulting in air gaps and irregularities due to the absence of a tin coating, which can lead to oxidation and structural instability.

Innovation Solution

A busbar with a dimensionally invariant conductive substrate and a strategically applied adhesive material, where the adhesive is secured through heat and pressure, ensuring precise placement and preventing oxidation, while maintaining electrical conductivity and structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If adhesive material is applied across the entirety of the major surface of the copper strip, then adhesion area is maximized, but adhesive may ball or become inhomogeneously distributed leading to air gaps and irregularities during installation

Engineering Contradiction:
Improveadhesion strengthVSAvoidadhesive distribution uniformity
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The adhesive material is applied only to a central portion of the major surface of the conductive substrate, specifically within a width that is 0.6 to 1.2 times the width of the conductive substrate, rather than covering the entire surface. This localized application prevents adhesive from reaching the edges where it would ball or become inhomogeneous, while still providing sufficient adhesion area for secure bonding during installation.

Inventive Principle:
Principle #3Local quality

2Reliability

If the busbar is made thin to avoid air gaps between glass panes, then the risk of heating element failure is reduced, but the busbar becomes more susceptible to oxidation and environmental degradation

Engineering Contradiction:
Improveheating element reliabilityVSAvoidoxidation susceptibility
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The busbar is constructed as a composite structure with a conductive substrate (copper or copper alloy) that provides electrical conductivity, and a protective coating layer applied to the major surfaces that prevents oxidation and environmental degradation. This composite approach maintains the thin profile needed to avoid air gaps while incorporating protective functionality to resist harmful environmental factors.

Inventive Principle:
Principle #40Composite materials

3Strength

If adhesive material is applied to the entire major surface, then maximum bonding area is achieved, but installation complexity increases due to need for precise positioning and potential adhesive overflow

Engineering Contradiction:
Improvebonding strengthVSAvoidinstallation ease
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The adhesive material is confined to a central portion of the major surface rather than the entire surface. This localized application simplifies installation by eliminating the need for precise edge-to-edge positioning and prevents adhesive overflow beyond the busbar edges. The central placement provides a generous tolerance zone for installers while maintaining sufficient bonding area for secure attachment.

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

The solution provides a secure, consistent, and efficient method for busbar installation, preventing oxidation and ensuring reliable electrical connectivity without air gaps, enhancing the busbar's durability and performance in heated windscreen applications.

Implementation Method 1

The adhesive material may be secured to the conductive material through the application of heat and/or pressure.

Methodology Applied
Scientific EffectHeat: Heating

Implementation Method 2

The adhesive material may be secured to the conductive material through the application of heat and/or pressure.

Methodology Applied
Scientific EffectPressure: Pressure Increase

Implementation Method 3

In the absence of a tin coating, and in order to prevent oxidation of the copper strip, the polymeric coating and adhesive layer has to be applied across the entirety of each major surface of said copper strip.

Methodology Applied
Scientific EffectOxidation prevention: Oxidation

Data Source

PatentEP2925100B1Busbars
Publication Date: 2022.02.09 STRIP TINNING
  • EP2925100B1 patent drawingFigure 1A~1B
  • EP2925100B1 patent drawingFigure 2
  • EP2925100B1 patent drawingFigure 3A~3B

AI summary

A busbar (1) for installation on or in a structure, the busbar (1) comprises a length of electrically conductive material (2) having a, preferably dimensionally invariant, adhesive material (3) secured along at least part of a major surface along the length thereof, wherein the adhesive material (3) is inboard of one both of the longitudinal edges of the electrically conductive material (2).