Rivet-Joined Multi-Material Electrical Connection for Thermal Stress
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Solution Overview
Problem
Mechanical stresses caused by different coefficients of thermal expansion between materials in electrical connection elements for motor vehicle panes lead to breakage, and the use of lead-containing solders is prohibited due to environmental regulations, making it necessary to find a lead-free solution that can compensate for these stresses.
Innovation Solution
A multi-piece electrical connection element with subelements made from different materials, where one subelement is soldered to the conductive structure and the other is connected to an electrical cable, using rivets for durable connection, allowing for selection of materials based on thermal expansion, conductivity, and formability without the need for matching melting points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-containing solders are used to compensate mechanical stresses, then ductility and stress compensation are improved, but environmental compliance deteriorates due to ELV directive restrictions
Solution Approach 1:
The electrical connection element is divided into multiple subelements made of different materials, each optimized for specific functions. The first subelement contacts the pane with matched thermal expansion, while the second subelement connects to the cable, eliminating the need for lead-based solder while maintaining stress compensation through material selection and rivet connection.
Solution Approach 2:
The connection element uses composite construction with subelements of different materials (e.g., steel, stainless steel, or other alloys) joined by rivets. This composite structure allows each subelement to be optimized for its specific function, achieving both environmental compliance and mechanical stress compensation without lead-containing solders.
2Reliability
If multi-piece connection elements with different materials are used to optimize thermal expansion matching, then stress reduction is improved, but manufacturing complexity increases due to welding difficulties
Solution Approach 1:
Rivets serve as intermediary connection elements joining the subelements together. This rivet-based connection system eliminates the need for welding between dissimilar materials with different melting temperatures, simplifying manufacturing while maintaining the mechanical stress resistance benefits of multi-material construction.
3Object-affected harmful factors
If leadfree solders are used to comply with environmental regulations, then environmental compliance is improved, but ductility and stress compensation capability deteriorate
Solution Approach 1:
The invention changes the fundamental connection approach from solder-based (relying on material ductility) to rivet-based mechanical connection. This parameter change allows the use of leadfree materials while maintaining connection reliability through the rivet's mechanical properties rather than relying on the ductility of leadfree solder.
4Strength
If welding is used to connect subelements with different melting temperatures, then connection strength is improved, but manufacturing feasibility deteriorates due to material incompatibility
Solution Approach 1:
Rivets act as an intermediary connection method that avoids direct welding between subelements with different melting temperatures. The rivet provides sufficient connection strength through mechanical interlocking and deformation, eliminating the manufacturing feasibility issues associated with welding dissimilar materials while maintaining strong subelement bonding.
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 effectively reduces mechanical stresses and ensures stable connections, enabling the use of materials optimized for thermal expansion and conductivity, while avoiding the limitations of lead-free solders' reduced ductility and the challenges of welding materials with different melting temperatures.
Implementation Method 1
The first subelement and the second subelement are connected to one another by means of at least one rivet
Implementation Method 2
If the difference in the coefficients of thermal expansion of the substrate, customarily soda lime glass, and the connection element is small, only slight mechanical stresses occur
Data Source
AI summary
An electrical connection element for the electrical contacting of an electrically conductive structure on a substrate is described. The electrical connection element has at least two solid subelements made from different materials, the first subelement being adapted for soldering to the electrically conductive structure, and the second subelement being adapted for connection to an electrical connection cable. The first subelement and the second subelement are connected to one another by way of at least one rivet.