Laser Beam Divergence Adjustment for Clean Resin Through-Holes
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Solution Overview
Problem
Laser processing techniques for forming holes in insulating substrates with resin layers face issues of bulging and cracking due to the divergence angle difference between the discharge direction and perpendicular direction of the laser beam, which affects the precision and quality of the processed holes.
Innovation Solution
A laser processing apparatus and method that includes a divergence angle adjusting optical system, such as an NA adjusting aperture or beam expander, to reduce the difference between the first divergence angle in the discharge direction and the second divergence angle perpendicular to it, ensuring the laser beam is properly aligned and focused on the resin layer to suppress bulging and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam with large divergence angle difference is used for hole formation, then processing speed and fluence can be increased, but bulging and cracking occur around the processed holes
Solution Approach 1:
The patent applies parameter changes by adjusting the divergence angle of the laser beam through optical elements (cylindrical lenses or aperture stops) to reduce the difference between divergence angles in the discharge direction and perpendicular direction. This parameter optimization allows high fluence processing while suppressing bulging and cracking, resolving the contradiction between processing speed and hole quality
2Device complexity
If the divergence angle difference is not adjusted, then the optical system can be simpler, but the laser beam cannot be properly focused on the resin layer
Solution Approach 1:
The patent introduces optical elements (cylindrical lenses or aperture stops) that adjust the divergence angle parameter of the laser beam. These elements are configured with specific focal lengths and positions to reduce the divergence angle difference, enabling proper focusing on the resin layer while maintaining reasonable optical system complexity
3Productivity
If high fluence is applied for efficient processing, then productivity increases, but bulging and cracking are more likely to occur
Solution Approach 1:
The patent changes the divergence angle parameter of the laser beam to reduce the difference between divergence angles in different directions. This parameter optimization enables the use of high fluence for efficient processing while suppressing bulging and cracking, as the adjusted beam profile distributes energy more uniformly during focusing
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 effectively reduces bulging and cracking around processed holes, achieving cleaner, circular through-holes with improved precision and quality, even at high fluence levels required for processing, and allows for the formation of multiple holes simultaneously.
Implementation Method 1
forms a hole in a workpiece having a resin layer disposed on a processing surface by irradiating the workpiece with a laser beam discharge-excited between a pair of discharge electrodes and then output
Data Source
AI summary
A laser processing apparatus forms a hole in a workpiece having a resin layer on a processing surface by irradiating the workpiece with a laser beam discharge-excited between a pair of discharge electrodes, and includes a laser apparatus that outputs the laser beam having a first divergence angle in a discharge direction between the pair of discharge electrodes larger than a second divergence angle in a direction perpendicular to the discharge direction and a laser beam traveling direction, a transfer mask that forms a transfer pattern, an introducing optical system for guiding the laser beam to the transfer mask, a projection optical system that images the transfer pattern on the resin layer, and a divergence angle adjusting optical system that is disposed on an optical path of the laser beam and adjusts a difference between the first divergence angle and the second divergence angle to be reduced.