Laser Aberration Control for Precise Subsurface Cutting
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Solution Overview
Problem
Conventional laser processing devices face challenges in preventing damage to parts deviated from the cutting line on the surface opposite to the laser light entrance side of the object, particularly when spherical aberration correction is applied, which can cause unintended damage to wiring and other functional devices.
Innovation Solution
A laser processing device and method that adjust aberration at the converging position to achieve a longer converging length and lower intensity in the region closest to the laser light entrance side, and a shorter converging length with higher intensity in the region closer to the entrance side, using the aberration as a reference to inhibit damage and control fracture formation accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spherical aberration correction is applied to improve cutting precision, then manufacturing precision is improved, but damage occurs to parts deviated from the cutting line on the opposite surface
Solution Approach 1:
The patent applies different aberration correction amounts to different depth regions. In the first depth region (0-70μm from front surface), a first aberration correction amount is used that allows longer converging length and lower intensity. In the second depth region (70μm or more from front surface), a second aberration correction amount is used that provides shorter converging length and higher intensity. This local differentiation resolves the contradiction by preventing damage in the first region while achieving precise cutting in the second region.
Solution Approach 2:
The patent changes the aberration correction parameter based on the depth region. By adjusting the aberration correction amount according to the depth from the front surface, the system optimizes the balance between converging length and intensity. This parameter change allows the laser to form modified regions at appropriate positions without causing excessive intensity that would damage parts on the opposite surface.
2Manufacturing precision
If aberration is corrected to achieve ideal converging position, then converging intensity is improved, but converging length becomes too short causing damage to wiring and functional devices
Solution Approach 1:
The patent differentiates aberration correction between depth regions. In the first depth region (0-70μm), a reduced aberration correction amount is applied, resulting in longer converging length and lower intensity, which prevents damage to wiring and functional devices. In the second depth region (70μm or more), full aberration correction is applied to achieve the required converging intensity for precise cutting.
Solution Approach 2:
The patent applies a reduced aberration correction amount in the first depth region as a protective measure before reaching the critical region where wiring and functional devices are located. This beforehand cushioning prevents excessive intensity from damaging sensitive components while still allowing the laser to penetrate through the substrate.
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
Effectively prevents damage to parts deviated from the cutting line by controlling the aberration correction, ensuring precise cutting and minimizing damage to functional devices and wiring, while optimizing the length and intensity of fractures formed.
Implementation Method 1
a laser light source emitting laser light L
Implementation Method 2
a converging optical system for converging the laser light L emitted from the laser light source L at the object
Implementation Method 3
an aberration modulator for adjusting an aberration caused by converging the laser light L at the object and occurring at a converging position
Data Source
AI summary
A laser processing device includes a laser light source, a converging optical system, a controller, and a reflective spatial light modulator. The controller and the reflective spatial light modulator, while using an aberration as a reference aberration, the aberration occurring when laser light is converged at a converging position with an amount of aberration correction in a state in which an ideal converging position is shifted by a predetermined distance to a laser light entrance side from the converging position, adjusts the aberration such that a first converging length longer than a reference converging length of the reference aberration is obtained and a first converging intensity less than a reference converging intensity of the reference aberration is obtained, when a modified region is formed within a first region closest to a front face of an object to be processed.