Glass Pane Electrical Connection with Controlled Solder Mass
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Solution Overview
Problem
Mechanical stresses in vehicle glass panes due to thermal expansion coefficient differences between glass and electrical connection elements lead to potential breakage, particularly with the use of lead-containing solders which are being phased out due to environmental regulations.
Innovation Solution
A disk with a glass substrate and an electrically conductive structure, connected via a solder element with a carefully controlled solder mass distribution to minimize mechanical stresses, using a connection element with a thermal expansion coefficient matching the glass, and a solder composition of tin, bismuth, and silver to ensure stable bonding without excessive solder escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If lead-containing solders are used to connect the electrical connection element to the pane, then the ductility and mechanical stress compensation are improved, but the environmental compliance deteriorates due to the ELV directive banning lead
Solution Approach 1:
The solder composition is changed from lead-based to lead-free by adjusting the parameters of alloy composition (e.g., tin-silver-copper ratios) to achieve comparable mechanical properties and ductility without containing harmful lead, thus resolving the contradiction between environmental compliance and mechanical performance
Solution Approach 2:
The patent employs readily available lead-free solder materials that can be easily applied and processed, replacing complex lead-containing formulations while maintaining adequate performance for the intended application lifecycle
2Reliability
If the solder mass volume is increased to ensure complete filling of the connection space, then the connection stability is improved, but the mechanical stress on the pane deteriorates due to excessive solder escape
Solution Approach 1:
The solder mass is precisely dosed to match the exact volume of the connection space between the electrical connection element and the pane, ensuring complete filling without excess solder that would escape and create mechanical stress, thus achieving both connection stability and stress reduction
Solution Approach 2:
Instead of using excessive solder mass to ensure complete filling, the patent applies the exact appropriate amount of solder needed, avoiding both insufficient filling and excessive solder escape that would cause mechanical stress on the pane
3Stress or pressure
If the vertical distance between the connection element and the electrically conductive structure is increased to create a concave meniscus, then the solder escape is reduced, but the connection strength deteriorates
Solution Approach 1:
The vertical distance between the connection element and the electrically conductive structure is optimized to a specific range that enables the formation of a concave meniscus during soldering, which contains the solder within the connection space and prevents escape, while maintaining adequate connection strength through proper spacing
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 reduces mechanical stresses and ensures a stable, lead-free electrical connection that withstands temperature variations without glass breakage, maintaining the integrity of the disk across a wide temperature range.
Implementation Method 1
a soldering process with the solder mass
Implementation Method 2
Due to different thermal expansion coefficients of the materials used, mechanical stresses occur during production and operation
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to a disk with an electrical connection element comprising:- a substrate consisting of glass (1) with a first coefficient of thermal expansion, - an electrically conductive structure (2) with a layer thickness of from 5 µm to 40 µm on a region of the substrate (1), - a connection element (3) with a second coefficient of thermal expansion, wherein the difference between the first and second coefficients of thermal expansion is -6/°C, - a layer of a soldering compound (4), which electrically connects the connection element (3) to subregions of the electrically conductive structure (2), wherein the soldering compound (4), which exceeds a layer thickness t of 50 µm, emerges from the interspace between the connection element (3) and the electrically conductive structure (2) with an exit width b of < 1 mm, in relation to the contact face of the connection element (3).