Laser Via Formation With Sliding Focus for Uniform Bessel Beams
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Solution Overview
Problem
Conventional laser processing devices for forming through vias have a fixed focused position, leading to prolonged manufacturing lead times and inconsistent quality due to the need for slow substrate movement and increased laser energy, resulting in energy waste and rough interior surfaces.
Innovation Solution
A laser processing device incorporating a galvo mirror module, axicon lenses, and a sliding focusing module allows for adjustable focused position and reduced deformation of the Bessel-like beam, enabling rapid formation of multiple through vias with consistent quality by aligning the third lens along the scanning direction to maintain optimal laser fluence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the substrate is moved relative to the fixed Bessel beam to form multiple through vias, then multiple through vias can be formed, but the manufacturing lead time is prolonged due to slow stage movement
Solution Approach 1:
The patent transforms the fixed Bessel beam system into a dynamic one by enabling the focused position to move rapidly along the propagation direction through galvo mirror deflection. This allows the laser to form multiple through vias by changing focus position rather than moving the substrate, dramatically reducing manufacturing lead time while maintaining high productivity
Solution Approach 2:
The patent replaces the mechanical substrate movement system with an optical focusing adjustment system. Instead of physically moving the heavy substrate stage, the invention uses galvo mirrors to rapidly adjust the focus position of the Bessel beam, substituting mechanical motion with optical control to achieve faster processing
2Adaptability or versatility
If the laser beam path is adjusted to change focused position, then the focused position can be changed, but the laser beam deviates from the focus axis causing focused points to be misplaced
Solution Approach 1:
The patent employs dynamic focusing adjustment using galvo mirrors that can rapidly change the focus position along the propagation direction. This dynamic control system maintains precise focused point positioning while enabling adaptable focus depth adjustment, resolving the conflict between position adjustability and positioning accuracy
Solution Approach 2:
The patent implements a feedback mechanism where the focused position is adjusted by controlling the deflection angle of galvo mirrors. The system monitors and controls the focus position to ensure it remains on the focus axis, using feedback control to prevent beam deviation and maintain manufacturing precision during position adjustments
3Length of stationary object
If a converging lens with small converging angle and long focal length is selected to increase depth of focus, then the depth of focus increases, but larger laser energy is required causing energy waste and increased surface roughness
Solution Approach 1:
The patent changes the key parameter of focus position dynamically using galvo mirror deflection rather than relying on a fixed lens configuration. This allows the system to achieve variable depth of focus without being constrained by lens selection, enabling optimal energy efficiency while maintaining adequate depth of focus for through via formation
Solution Approach 2:
By making the focus position dynamically adjustable through galvo mirrors, the system can optimize the depth of focus for each specific processing requirement without being locked into a fixed lens configuration. This dynamic adjustment eliminates the need to over-engineer with long focal length lenses, reducing energy consumption and improving surface quality
4Length of stationary object
If a converging lens with small converging angle is selected to increase depth of focus, then the depth of focus increases, but the interior surface roughness of through vias increases
Solution Approach 1:
The patent dynamically adjusts the focus position parameter using galvo mirrors rather than relying on fixed lens parameters. This allows optimization of the focusing conditions for each processing location, maintaining consistent interior surface smoothness throughout the substrate while achieving adequate depth of focus through dynamic rather than static means
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 device enables rapid and high-quality formation of multiple through vias with reduced manufacturing time and energy efficiency by maintaining consistent laser fluence and surface smoothness across different positions.
Implementation Method 1
a conventional Bessel beam laser device is configured to convert a Gaussian beam GB into a ring beam RB through an axicon lens 91
Implementation Method 2
converts the ring beam RB into a Bessel beam BB through a converging lens 93
Implementation Method 3
The Bessel beam BB, which has long depth of focus and is non-diffracting, maintains an unchanged transversal distribution of intensity as it propagates
Implementation Method 4
The galvo mirror module is configured to reflect the incident ring beam into a reflected ring beam
Implementation Method 5
The third lens of the focusing module is configured to convert the reflected ring beam into a Bessel-like beam
Data Source
AI summary
A laser processing device for forming vias has a galvo mirror module, a first lens, a second lens, a focusing module, and a laser source. The laser source emits a laser beam through the first lens and the second lens to convert the laser beam into an incident ring beam. The galvo mirror module reflects the incident ring beam into a reflected ring beam into the focusing module to convert the reflected ring beam into a Bessel-like beam. The galvo mirror module has a scanning direction and shifts a reflection direction of the reflected ring beam to move an end of the reflected ring beam along the scanning direction. The focusing module has a third lens linearly slid along the scanning direction to reduce variations in shape and laser fluence of the Bessel-like beam focused at different positions.