Compensator Plate Design for Thermal Stress in Copper Soldered Connections
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Solution Overview
Problem
Existing electrical connection elements in motor vehicles face mechanical stress issues due to differing coefficients of thermal expansion between materials, leading to damage and increased production costs, especially with the transition from lead-containing to lead-free soldering compounds.
Innovation Solution
Incorporating compensator plates with a coefficient of thermal expansion matching the substrate, allowing the use of conventional copper connection elements with lead-free soldering compounds, thereby compensating thermal stresses and standardizing the soldering process across various materials and shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper connection elements are used with lead-free soldering compounds, then electrical conductivity is improved, but mechanical stresses cause breakage due to high coefficient of thermal expansion
Solution Approach 1:
The invention uses a composite structure consisting of a copper connection element (for electrical conductivity) combined with a compensator plate made of material having low thermal expansion (for mechanical stability). This composite approach allows both high electrical conductivity and resistance to thermal stress-induced breakage.
Solution Approach 2:
The invention changes the thermal expansion parameter by introducing a compensator plate with different thermal expansion characteristics than the copper connection element. This compensator plate has a coefficient of thermal expansion matched to the glass pane, thereby compensating for the high thermal expansion of copper during temperature cycling.
2Reliability
If iron-nickel or iron-nickel-cobalt alloys with low coefficient of thermal expansion are used, then mechanical stress compensation is improved, but production costs increase due to difficult formability
Solution Approach 1:
The invention segments the connection element into two functional parts: a copper component (for electrical conductivity and ease of manufacture) and a separate compensator plate (for mechanical stress compensation). This segmentation allows each part to be optimized independently - the copper part for electrical performance and the compensator plate for thermal expansion management - while using conventional, easily formable materials.
3Reliability
If titanium connection elements are used to match coefficient of thermal expansion, then thermal stress is reduced, but solderability and weldability deteriorate
Solution Approach 1:
The invention introduces a compensator plate as an intermediary component between the copper connection element and the glass pane. This compensator plate serves as a mediator that provides thermal expansion matching with the glass while the copper connection element maintains its excellent solderability. The compensator plate absorbs the thermal stress without requiring the connection element itself to have matched thermal properties.
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 solution prevents damage to the substrate, extends tool service life, reduces production costs, and maintains temperature stability while optimizing material properties, ensuring consistent mechanical and electrical performance.
Implementation Method 1
Due to different coefficients of thermal expansion of the materials used, mechanical stresses occur during production and operation that strain the panes and can cause breakage of the pane
Implementation Method 2
a leadfree soldering compound, which connects the compensator plate via at least one contact surface to at least one part of the electrically conductive structure
Data Source
AI summary
A disk with at least one connecting element having compensator plates, including; a substrate having an electrically conductive structure on at least one partial region of the substrate, at least one compensator plate on at least one partial region of the conductive structure, at least one electric connecting element on at least one partial region of the at least one compensator plate, a lead-free soldering mass which connects the compensator plate via at least one contact surface including; one partial region of the electrically conductive structure, wherein the difference of the thermal expansion coefficient of the substrate and the compensator plate is less than 5×10−6/° C. and wherein the connecting element comprises copper.