Glass Pane Electrical Connection Element Design
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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, leading to potential breakage, especially with the need to replace lead-containing solders with lead-free alternatives.
Innovation Solution
A disk with an electrical connection element featuring a substrate, an electrically conductive structure, a solder mass layer, and a connection element with specific foot and transition regions, utilizing a capillary effect to control solder distribution and minimize mechanical stresses, and employing lead-free solders like tin-bismuth-silver alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-containing solders are used to connect the electrical connection element to the pane, then the ductility and ability to compensate mechanical stresses are improved, but the environmental compliance and adherence to ELV directive are worsened
Solution Approach 1:
The invention changes the geometric parameters of the connection element, specifically the angle of the transition region (between 5-45 degrees) and the dimensions of foot regions, to optimize stress distribution. This allows lead-free solders to achieve adequate mechanical stress compensation through improved geometric design rather than relying on lead's material properties
Solution Approach 2:
The invention uses a composite structure combining the connection element made of one material (e.g., steel or aluminum) with lead-free solder material (e.g., tin-based alloys). The composite design incorporates specific geometric features that enable the combination to work together effectively, compensating for the lower ductility of lead-free solders through structural optimization
2Object-affected harmful factors
If lead-free solders are used to replace lead-containing solders, then the environmental compliance is improved, but the ductility and mechanical stress compensation capability are worsened
Solution Approach 1:
The invention modifies geometric parameters including the transition region angle (5-45 degrees), foot region dimensions, and overall connection element shape to compensate for the reduced ductility of lead-free solders. These parameter changes create a structure that distributes mechanical stresses more effectively, allowing lead-free solders to achieve adequate stress compensation
Solution Approach 2:
The invention employs curved or angled transition regions rather than sharp corners, creating smoother stress distribution paths. The rounded or angled geometry helps distribute mechanical stresses uniformly across the connection element, preventing stress concentration points that would be problematic with less ductile lead-free materials
3Reliability
If the solder mass emerges with a large exit width from the space between the connection element and the electrically conductive structure, then the adhesion is improved, but the mechanical stresses in the pane are increased
Solution Approach 1:
The invention optimizes the exit width parameter of the solder mass to a specific range that balances adhesion and stress. By controlling the solder volume and the gap dimensions between the connection element and substrate, the exit width is limited to prevent excessive mechanical stress while ensuring adequate adhesion through the electrically conductive structure
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
Reduces mechanical stresses in the glass pane, ensuring stable adhesion and preventing breakage, even with lead-free solders that have lower ductility, while adhering to environmental regulations.
Implementation Method 1
utilizing a capillary effect to control solder distribution and minimize mechanical stresses
Data Source
Figure 1~1a
Figure 2~3
Figure 4~5
AI summary
The present invention relates to a disc with at least one electrical connection element, comprising: - a substrate (1), - an electrically conductive structure (2) on a region of the substrate (1), - a layer of a lead-free solder mass (4) on a region of the electrically conductive structure (2) and - a connection element (3) on the solder mass (4), wherein the connection element (3) comprises at least one chromium-containing steel with a chromium content of greater than or equal to 10.5 wt.-% and a coefficient of thermal expansion of 9 x 10-6/°C to 13 x 10-1/°C, - the connecting element (3) includes a first and a second foot region (7, 7'), a first and a second transition region (9, 11) and a bridge region (10) between the first and second transition regions (9, 11), - a first and a second contact surface (8, 8') are located on the underside of the first and second foot regions (7, 7'), - the first and second contact surfaces (8, 8') and the surfaces (9', 11') facing the substrate (1) of the first and second transition regions (9, 11) are connected to the electrically conductive structure (2) by the solder mass (4), and - the angle between the surface of the substrate (1) and each of the tangent planes (12) of the surfaces (9', 11') facing the substrate (1) of the transition regions (9, 11) < 90°.