Laser Micro-Machining Heat Affected Zone Reduction
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Solution Overview
Problem
In laser micro-machining, the large plasma plume generated during the process creates an undesirable Heat Affected Zone (HAZ) due to excessive heating of un-machined material, limiting the maximum laser pulse repetition rate and thus reducing throughput.
Innovation Solution
The method involves subdividing the laser beam into noncontiguous machining elements with a high aspect ratio, such as long line illumination fields, to minimize the plasma plume volume relative to the machined perimeter, achieved by dividing the beam and translating the mask and workpiece relative to each other along a scan axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the laser pulse repetition rate is increased to improve throughput, then productivity increases, but the Heat Affected Zone (HAZ) increases due to excessive heating from large plasma plume
Solution Approach 1:
The patent divides the continuous laser beam into multiple discrete pulses in the temporal domain. By using pulsed laser operation with controlled pulse repetition rates, the continuous heating process is segmented into discrete thermal events, allowing heat to dissipate between pulses and reducing the cumulative HAZ while maintaining high throughput through optimized pulse frequency
2Productivity
If the laser fluence is increased to improve material removal rate, then productivity increases, but the plasma plume volume increases causing larger HAZ
Solution Approach 1:
The patent optimizes the laser fluence parameter to operate at an optimal level that achieves sufficient material removal rate without generating excessive plasma plume volume. By carefully controlling the fluence parameter within a specific range, the process maintains high productivity while limiting HAZ formation through balanced energy input
3Object-affected harmful factors
If the laser pulse rate is reduced to decrease HAZ, then the Heat Affected Zone decreases, but throughput decreases
Solution Approach 1:
The patent employs dynamic control of the laser pulse repetition rate, adjusting the pulse frequency in real-time based on process conditions, material type, and machining stage. This dynamic parameter adjustment allows the system to maintain low HAZ during critical machining phases while maximizing throughput during less sensitive operations, achieving both goals through adaptive control
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 approach decreases the plasma plume volume, allowing for increased throughput while maintaining the machining site area, effectively reducing the HAZ and enabling higher laser pulse repetition rates without compromising material properties.
Implementation Method 1
Through a combination of conduction, convection and radiative transfer of energy from the region of the laser beam's interaction with the machining material
Implementation Method 2
Through a combination of conduction, convection and radiative transfer of energy from the region of the laser beam's interaction with the machining material
Implementation Method 3
Through a combination of conduction, convection and radiative transfer of energy from the region of the laser beam's interaction with the machining material
Implementation Method 4
Material removal is typically accompanied by a plasma plume rising from the surface of the machined regions after a laser pulse is delivered
Implementation Method 5
the plasma plume possesses a very high temperature and the ions produced have high velocities
Data Source
AI summary
Embodiments of the present invention are directed to methods and systems for laser micro-machining, which may include dividing a long line illumination field into a plurality of individual fields, wherein each of the plurality of fields includes an aspect ratio of about 4:1 or greater, directing the plurality of individual fields onto at least one mask, wherein each individual field illuminates a corresponding area on the mask and translating the mask and/or workpiece relative to one another along a scan axis.