Segmented Pane Connection Element for Thermal Stress Reduction
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Solution Overview
Problem
Existing electrical connection elements for motor vehicle panes face mechanical stress issues due to differing coefficients of thermal expansion, leading to potential breakage and poor adhesion when using lead-free solders, and are difficult to reshape for adjustable bridge positioning.
Innovation Solution
A two-piece connection element with a connection bridge, where the connection element is made from a material with a suitable coefficient of thermal expansion and the connection bridge is made from a copper-containing material, allowing for optimal thermal stress reduction and reshaping without compromising electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-free solder materials are used to replace lead-containing solders, then environmental compliance is improved, but mechanical stress compensation capability deteriorates due to lower ductility
Solution Approach 1:
The connection element is divided into two separate components: a base connection element made of low-CTE material (Invar or Kovar) and a separate copper-containing connection bridge. This segmentation allows each component to have optimized properties - the base element provides thermal expansion matching and mechanical stability, while the copper bridge provides ductility for stress compensation and electrical conductivity.
Solution Approach 2:
The invention uses a composite structure combining two different materials (low-CTE alloy and copper) in a functional assembly. The base connection element uses Invar or Kovar for thermal stability, while the copper connection bridge provides electrical conductivity and mechanical flexibility, creating a composite system that achieves properties neither material could provide alone.
2Reliability
If copper-containing connection elements are used, then electrical conductivity is improved, but mechanical stress on glass increases due to greater coefficient of thermal expansion
Solution Approach 1:
The connection element is segmented into a base element (low-CTE material) and a separate copper connection bridge. The base element directly contacts the glass and provides thermal expansion matching, while the copper bridge is connected to the base element and provides electrical conductivity, isolating the copper's thermal expansion effects from the glass.
Solution Approach 2:
The low-CTE base connection element acts as an intermediary between the glass pane and the copper connection bridge. It mediates the thermal expansion differences by providing a stable interface with the glass while connecting to the copper bridge, preventing direct transmission of thermal stress from copper to glass.
3Stress or pressure
If connection bridge is made from low-CTE material to match glass expansion, then mechanical stress is reduced, but electrical conductivity and reshaping capability deteriorate
Solution Approach 1:
The connection element is segmented into a base element (low-CTE material) and a separate copper connection bridge. The base element provides thermal expansion matching with the glass, while the copper bridge provides superior electrical conductivity and reshaping capability, allowing each function to be optimized independently.
Solution Approach 2:
Different parts of the connection system have different material properties optimized for their specific functions. The base connection element has low-CTE properties for thermal stability at the glass interface, while the copper connection bridge has high electrical conductivity and ductility for electrical connection and reshaping, creating local quality optimization throughout the system.
4Ease of manufacture
If connection element and connection bridge are made from same material, then manufacturing simplicity is improved, but adaptability to different requirements deteriorates
Solution Approach 1:
The connection system is segmented into a base connection element and a separate connection bridge that can be manufactured from different materials. This allows each component to be optimized for its specific function while maintaining relatively simple manufacturing processes for each individual component.
Solution Approach 2:
The system uses a composite construction with a low-CTE base element and a copper connection bridge. Each material is selected and manufactured according to its specific requirements, then assembled together, providing material property optimization without requiring complex multi-material manufacturing of a single integrated component.
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 reduces mechanical stress on the pane, ensures better adhesion, and allows for easy adjustment of the bridge position, maintaining a defined and accessible connection while minimizing voltage drop and avoiding damage during reshaping.
Implementation Method 1
a leadfree solder material (5), which connects the electrical connection element (3) to the electrically conductive structure (2)
Implementation Method 2
the material composition of the connection element (3) is selected such that the difference between the coefficients of thermal expansion of the substrate (1) and the connection element (3) is less than 5×10−6/° C.
Data Source
AI summary
A disk with at least one connecting element having a connecting bridge, including; a substrate having an electrically conductive structure on at least one partial region of the substrate, at least one electric connecting element on at least one partial region of the electrically conductive structure, a connecting bridge on at least one partial region of the connecting element and a lead-free solder mass that connects the electric connecting element in at least one partial region with the electrically conductive structure, wherein the difference of the thermal expansion coefficient of the substrate and the connecting element is less than 5×10−6/° C., wherein the connecting bridge is formed in a massive manner and contains copper and wherein the material compositions of the connecting element and the connecting bridge differ.