UV Laser Adhesive Sheet Suppressing Chip Fry
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Solution Overview
Problem
Existing pressure-sensitive adhesive sheets for laser processing face challenges in holding and efficiently collecting separated workpiece pieces due to chip fry, which occurs when laser cutting, leading to thermal decomposition and processing issues in the transverse direction.
Innovation Solution
A pressure-sensitive adhesive sheet with a light-absorbing agent, such as 2-hydroxy-2-methyl-1-phenyl-propan-1-one, is used, having an absorption coefficient at 355 nm between 50 cm^-1 and 900 cm^-1, allowing for non-thermal ultraviolet absorption ablation processing, preventing chip fry and facilitating efficient collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fundamental wave (1064 nm) of YAG laser or ruby laser (694 nm) is used for cutting, then the pressure-sensitive adhesive layer can be thermally cut, but decomposition by thermal processing occurs not only at the upper layer but also at the inside of the pressure-sensitive adhesive layer or the interface between the base and the pressure-sensitive adhesive layer, causing processing in the transverse direction and insufficient suppression of chip fry
Solution Approach 1:
The patent changes the laser wavelength parameter from infrared (1064 nm) or red (694 nm) to ultraviolet (355 nm), which fundamentally alters the interaction mechanism with the pressure-sensitive adhesive layer. This parameter change enables non-thermal ablation instead of thermal cutting, eliminating the harmful thermal decomposition effects while maintaining cutting precision.
Solution Approach 2:
The patent substitutes thermal processing with photochemical processing by using ultraviolet laser light. The UV light is absorbed by the pressure-sensitive adhesive layer containing a light-absorbing agent, causing direct photodecomposition and ablation without generating significant heat, thereby replacing the thermal cutting mechanism with a non-thermal photochemical mechanism.
2Productivity
If laser light is employed for dicing the workpiece, then cutting can be performed, but a stress is imparted to the workpiece by ablation with the laser light and hence there occurs chip fry that separated pieces of the workpiece cannot be held on a pressure-sensitive adhesive sheet for laser processing to lose some pieces of the workpiece
Solution Approach 1:
The patent introduces a pressure-sensitive adhesive sheet as an intermediary between the laser processing system and the workpiece. This sheet serves multiple functions: it supports the workpiece during processing, absorbs laser energy to enable precise cutting, and holds the separated workpiece pieces through its adhesive properties, preventing chip fry and ensuring reliable collection of diced pieces.
Solution Approach 2:
The pressure-sensitive adhesive sheet is constructed as a composite material system comprising a base material and an adhesive layer containing a light-absorbing agent. This composite structure enables the sheet to simultaneously provide mechanical support, optical absorption for laser processing, and adhesive bonding capabilities, thereby solving the chip fry problem while maintaining dicing efficiency.
3Ease of manufacture
If the pressure-sensitive adhesive layer is thermally cut, then cutting can be achieved, but decomposition by thermal processing occurs not only at the upper layer but also at the inside of the pressure-sensitive adhesive layer or the interface between the base and the pressure-sensitive adhesive layer
Solution Approach 1:
The patent changes the cutting mechanism parameter from thermal to photochemical by using ultraviolet laser light (355 nm) instead of infrared or red laser light. This parameter change allows cutting to occur at the upper layer of the pressure-sensitive adhesive layer without propagating thermal decomposition to the inside of the layer or the interface with the base, thereby maintaining adhesive layer integrity while preserving cutting capability.
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 suppresses chip fry and enables efficient collection of workpiece pieces by using non-thermal ultraviolet absorption ablation, maintaining precision and accuracy in laser processing without thermal damage.
Implementation Method 1
laser light having a wavelength of an ultraviolet region or a laser light enabling light absorption via multiphoton absorption process
Implementation Method 2
irradiating the workpiece with a laser light having a wavelength of an ultraviolet region or a laser light enabling light absorption via multiphoton absorption process, thereby processing the workpiece by ablation
Data Source
Figure 1~2
AI summary
The present invention provides a pressure-sensitive adhesive sheet for laser processing, which includes a base and a pressure-sensitive adhesive layer provided on one surface of the base, the pressure-sensitive adhesive layer having an absorption coefficient at a wavelength of 355 nm of from 50 cm-1 to 900 cm-1, the pressure-sensitive adhesive layer containing a light-absorbing agent in which an absorbance of the light-absorbing agent in a 0.01% by weight acetonitrile solution at a wavelength of 355 nm is from 0.01 to 1.20, and in which the pressure-sensitive adhesive sheet is to be used at the time when a workpiece is laser-processed by a laser light having a wavelength of an ultraviolet region or a laser light enabling light absorption via multiphoton absorption process.