Solderless Window Connector Bonding for Heat-Sensitive Conductive Ink

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Solution Overview

Problem

Conductive inks used in window assemblies for vehicles are not sufficiently heat resistant for conventional soldering applications, leading to compromised bonding interfaces, especially when ceramic frit is absent, and organic compounds exhibit low adhesion to transparent substrates, making traditional soldering ineffective.

Innovation Solution

A method of forming a solderless electrical connector on a curved glass substrate by applying a conductive ink with a thermal degradation temperature and an adhesive, which is cured at a temperature below the ink's thermal degradation point to establish electrical contact without compromising the ink's integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional soldering is used to bond electrical connector to conductive ink, then electrical connection is achieved, but the conductive ink is damaged due to excessive heat

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoidthermal damage to conductive ink
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a low-melting-point solder alloy (e.g., Bi-Sn-based alloy with melting point 138°C-227°C) as an intermediary bonding material between the electrical connector and conductive ink. This intermediary enables reliable electrical connection while its low melting point prevents thermal damage to the heat-sensitive conductive ink, resolving the contradiction between connection reliability and thermal protection.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the key parameter of soldering temperature by selecting a solder alloy with melting point significantly lower than conventional solder (150°C-330°C). By using alloys like Bi-Sn with melting points in the 138°C-227°C range, the process temperature is reduced to below 250°C, preventing degradation of the conductive ink while maintaining effective bonding.

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

This method enables the electrification of conductive inks in window assemblies without the need for soldering, ensuring reliable bonding and maintaining the conductive ink's conductivity, thus addressing the limitations of traditional soldering techniques.

Implementation Method 1

applying an adhesive onto the surface of the curved glass substrate adjacent to the applied conductive ink. The method also includes curing the adhesive at a temperature below the thermal degradation temperature of the applied conductive ink to form the solderless electrical connector in electrical contact with the applied conductive ink

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentEP4304295A1Method of manufacturing a window assembly with a solderless electrical connector
Publication Date: 2024.01.10 AGC AUTOMOTIVE AMERICAS CO
  • EP4304295A1 patent drawingFigure 1
  • EP4304295A1 patent drawingFigure 2~4
  • EP4304295A1 patent drawingFigure 5~7

AI summary

A method of manufacturing a window assembly having a solderless electrical connector includes forming a curved transparent substrate and applying a conductive ink having a thermal degradation temperature onto a surface of the curved transparent substrate. The method further includes applying an adhesive onto the surface of the curved transparent substrate adjacent to the conductive ink and optionally onto the applied conductive ink, and curing the adhesive at a temperature below the thermal degradation temperature of the conductive ink to form the solderless electrical connector with the solderless electrical connector being in electrical contact with the applied conductive ink.