Interlayer Coating for Stable Ultrashort Laser Joining
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Solution Overview
Problem
Existing methods for joining materials using ultrashort laser pulses face challenges in controlling the joining behavior and achieving stable connections, particularly when joining transparent and non-transparent partners, due to poor controllability and fracture toughness issues.
Innovation Solution
Applying a coating with physical properties similar to one or both joining partners between them before using ultrashort laser pulses to create a stable weld seam, where the coating is applied by methods like vapor deposition and has similar chemical constituents, allowing for improved heat absorption and mixing of materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating is applied between joining partners to improve joining stability, then the fracture toughness of the connection is enhanced, but the device complexity and manufacturing process become more complex
Solution Approach 1:
The coating is applied to the joining partners before the actual laser joining process. This preliminary preparation ensures that the joining interface is pre-conditioned with material having similar physical and chemical properties, which facilitates better heat distribution and material mixing during the subsequent ultrashort laser pulse joining, thereby enhancing joining stability without requiring complex real-time adjustments
Solution Approach 2:
The coating acts as an intermediary layer between the two joining partners. This intermediate layer has physical and chemical properties that are similar to both joining partners, enabling it to mediate the joining process by improving heat absorption and material mixing. The coating serves as a bridge that facilitates stable bonding between dissimilar materials, resolving the contradiction between joining stability and process complexity
2Productivity
If ultrashort laser pulses are used to join transparent and non-transparent partners, then the joining speed is high, but the joining behavior is poorly controllable
Solution Approach 1:
The invention changes the physical and chemical parameters of the joining interface by applying a coating with specific properties similar to both joining partners. This modification enables better control over heat absorption and material mixing during the ultrashort laser pulse process, making the joining behavior more controllable while maintaining high joining speed. The coating parameters are optimized to achieve desired joining characteristics
3Power
If the laser focus is positioned in the interface region, then the energy absorption is concentrated for efficient joining, but the heat distribution becomes difficult to control
Solution Approach 1:
The coating serves as an intermediary layer at the interface where the laser focus is positioned. This intermediate layer with similar physical properties to both joining partners enables more uniform heat distribution while maintaining energy concentration. The coating mediates the thermal field, preventing localized overheating and improving heat distribution control during the joining 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 method enhances the fracture toughness of the connection and achieves a more stable joining modification by ensuring better mixing and bonding of materials, resulting in a stronger weld seam.
Implementation Method 1
If ultrashort laser pulses, i.e. laser pulses in the picoseconds range or in the femtoseconds range (e.g. 50 fs-50 ps), are focused into the volume of glass, e.g. quartz glass, then the high intensity at the focus leads to nonlinear absorption processes
Implementation Method 2
With each of the successive pulses, the temperature can then be increased to the melting point of the glass and ultimately locally melt the glass
Implementation Method 3
the high intensity at the focus leads to nonlinear absorption processes... accumulation of heat or an increase in temperature in the glass in the focus region
Data Source
AI summary
A method for joining two joining partners includes applying a coating to at least one of the two joining partners so as to be arranged between the two joining partners before joining and joining the at least two joining partners to one another using ultrashort laser pulses of a laser beam of an ultrashort pulse laser. At least one joining partner is substantially transparent to the ultrashort laser pulses of the ultrashort pulse laser, and the coating comprises physical properties similar to at least one joining partner and/or a chemical constituent similar to at least one joining partner.