Resistance Welding of Thin Copper Film to Thick Busbars
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Solution Overview
Problem
Existing methods struggle to form material-locking connections between copper alloys with significantly different thicknesses and between thin films, particularly when sensitive electronic elements are involved, as ultrasonic welding can be detrimental to these components.
Innovation Solution
A resistance welding method is employed to connect a copper element with a thickness of up to 70 micrometers to an aluminum element with a thickness of over 800 micrometers, using a rounded contact area and controlled electrical current and force to create a material-locking connection, avoiding the need for ultrasonic welding and ensuring weldability of sensitive electronic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ultrasonic welding is used to connect thin films, then material-locking connections can be formed, but sensitive electronic elements are damaged
Solution Approach 1:
The patent replaces ultrasonic welding (mechanical vibration-based process) with resistance welding (electrical current-based process). The rounded contact area of the first electrode concentrates electrical current to generate Joule heat for material-locking connection, avoiding the mechanical vibrations and forces that damage sensitive electronic elements while achieving reliable material-locking connections
2Ease of manufacture
If resistance welding is used to connect copper alloys with significantly different thicknesses, then connections can be formed, but welding quality deteriorates
Solution Approach 1:
The patent applies local quality by designing the first electrode with a rounded contact area specifically adapted for the thin copper film (≤70 μm). This localized geometric feature concentrates the electrical current and force at the precise contact point, enabling effective welding of thin films to thick substrates (≥800 μm) while maintaining connection quality despite the significant thickness difference
Solution Approach 2:
The patent changes key welding parameters including using a rounded contact area geometry, controlling force magnitude and distribution, and optimizing electrical current characteristics. These parameter adjustments enable successful resistance welding of copper alloys with significantly different thicknesses (≤70 μm to ≥800 μm) while maintaining connection reliability
3Manufacturing precision
If a rounded contact area is used on the first electrode, then copper film travel is avoided, but electrode design complexity increases
Solution Approach 1:
The patent applies spheroidality by designing the first electrode contact area as rounded rather than flat or sharp-edged. This curved geometry distributes pressure and electrical current more evenly across the thin copper film, preventing travel or displacement of the copper film during welding. The rounded shape is a simple geometric modification that effectively solves the position accuracy problem without significantly increasing electrode design complexity
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 method enables reliable material-locking connections with varying thicknesses, specifically allowing for the secure joining of flexible printed circuit boards to power buses or battery modules, while protecting sensitive electronic elements from damage.
Implementation Method 1
two electrically conductively formed elements are connected to one another based on the Joule current heat of the electrical current flowing through the connection area. For this purpose, the two elements are heated as connecting partners until the respective welding temperature is reached
Implementation Method 2
a force is applied to the connection area at least with a contact area of the first electrode. The contact area of the first electrode is rounded. It is advantageous if the first element is formed as a copper film. In particular, travel or arrival of the copper film can be avoided in this case by means of a method according to the invention, which in particular comprises a rounded contact area of the first electrode
Implementation Method 3
an electrical current flows between a first electrode, in particular a positive electrode, and a second electrode, in particular a negative electrode. In this case, the electrical current flows in such a way that the first element and the second element are connected in a material-locking manner in a connection area
Data Source
AI summary
A method for forming a material-locking connection between a first element formed of copper with a thickness of less than or equal to 70 micrometers with a second element formed of copper or aluminum and a thickness of greater than or equal to 800 micrometers by means of resistance welding, wherein, to form the material-locking connection between a first electrode, in particular a positive electrode, and a second electrode, in particular a negative electrode, an electrical current flows, such that the first element and the second element are connected in a material-locking fashion in a connection area, while a force is applied on the connection area at least with a contact area of the first electrode wherein the contact area of the first electrode is rounded.