Structured Sonotrode Geometry for Compact Ultrasonic Welds
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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, then reliable electrical and mechanical connections are formed, but the collective area required is large, limiting board area for electronic components
Solution Approach 1:
The patent changes the geometric parameters of the sonotrode working surface, specifically using acute angled sidewalls (50-70 degrees) and controlled rounded depression radii (0.1-0.4 of pitch) to modify material flow characteristics during welding, achieving reliable joints with reduced footprint
Solution Approach 2:
The structured working surface with localized apexes and nadirs creates different material interaction zones, where acute angled regions control material flow direction and rounded depressions manage material accumulation, enabling compact joint design while maintaining reliability
2Ease of manufacture
If conventional welding techniques are used, then welded joints are formed, but material distribution is uneven and burrs are generated, causing electrical shorts and mechanical stress
Solution Approach 1:
The patent incorporates rounded depressions with controlled radii (0.1-0.4 of pitch) between the apexes, which guide material flow smoothly and prevent sharp burr formation, eliminating harmful factors while maintaining ease of manufacture
Solution Approach 2:
By optimizing the sidewall angles (50-70 degrees) and depression radii, the patent controls material flow velocity and direction, ensuring uniform material distribution and preventing defect formation during the welding process
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 reliable welded joint with improved mechanical and electrical reliability, reducing the footprint of the welded connection and minimizing material squeeze and burr formation, thereby increasing component density and reducing stress on the substrate.
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
An ultrasonic welding apparatus includes a sonotrode comprising a structured working surface that 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 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.