Structured Sonotrode Surface for Compact Ultrasonic Welding
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Solution Overview
Problem
Conventional welding techniques require a large collective area for forming reliable electrical and mechanical connections, which limits the board area available for electronic components, and result in uneven material distribution and burrs that can cause electrical shorts and mechanical stress.
Innovation Solution
An ultrasonic welding apparatus with a sonotrode featuring a structured working surface comprising apexes, nadirs, and planar sidewalls that intersect at acute angles, along with curved surfaces forming rounded depressions, which allows for efficient material flow and reduced peripheral material expansion during the welding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional welding techniques are used to form reliable electrical and mechanical connections, then welding strength and reliability are improved, but the collective area required for the welded joint increases
Solution Approach 1:
The sonotrode working surface features localized geometric structures (apexes, nadirs, and planar sidewalls at acute angles) that concentrate ultrasonic energy at specific points. This creates highly localized welding zones with intensified material flow and bonding, enabling reliable welded joints with reduced overall footprint by concentrating the welding action precisely where needed rather than distributing it across a larger area
Solution Approach 2:
The structured working surface incorporates curved surfaces that form rounded depressions between the planar sidewalls. These curved geometries facilitate controlled material flow during welding, guiding the molten or softened material into the nadirs and preventing erratic peripheral expansion, thereby reducing the required footprint while maintaining joint integrity
2Strength
If conventional welding techniques are used to ensure mechanical strength, then welded joint strength is improved, but material squeeze and burr formation increase
Solution Approach 1:
The curved surfaces forming rounded depressions in the sonotrode working surface act as containment features that guide and accommodate material flow during welding. As material is softened and流动 under ultrasonic vibration, the curved geometries direct the flow into the nadirs, preventing material from being forced outward as burrs, thus reducing harmful material squeeze while maintaining welding strength
Solution Approach 2:
The ultrasonic vibration energy that would otherwise cause uncontrolled material deformation and burr formation is converted into a beneficial effect by the structured working surface. The apexes and acute-angled sidewalls concentrate the vibrational energy to create controlled material flow, while the rounded depressions capture and contain the flowing material, transforming potential harm (burr formation) into a controlled process feature
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 achieves a welded joint with enhanced mechanical strength and reliability, reduced material squeeze, and fewer burrs, increasing the density of connections and reducing the spacing between electronic components.
Implementation Method 1
a transducer that is mechanically coupled to the sonotrode and is configured to cause the sonotrode to vibrate at an ultrasonic frequency
Implementation Method 2
forming a welded connection between the first and second joining partners by contacting the first joining partner with the structured working surface and vibrating the sonotrode at an ultrasonic frequency
Data Source
AI summary
A method of welding includes providing first and second joining partners, providing a welding apparatus that includes a sonotrode comprising a structured working surface, arranging the first and second joining partners to contact one another, and forming a welded connection between the first and second joining partners by contacting the first joining partner with the structured working surface and vibrating the sonotrode at an ultrasonic frequency, wherein the structured working surface comprises a plurality of apexes, a plurality of nadirs between immediately adjacent ones of the apexes, and planar sidewalls that extend between the nadirs and the apexes, and wherein for each of the apexes the planar sidewalls on either side of the respective apex extend along first and second planes that intersect one another at an acute angle.