Laser Scanning Along Division Lines to Minimize Sensor Debris
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Solution Overview
Problem
Laser processing on workpieces with image sensor elements generates large debris that can cause defects, such as surface burning, and reducing laser parameters to minimize debris lowers productivity.
Innovation Solution
A laser processing method that applies a laser beam along planned division lines on a workpiece while changing the irradiation position using a scanning unit, with controlled irradiation energy and frequency to minimize debris generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser processing is performed with high energy to maintain productivity, then processing efficiency is improved, but debris size increases causing surface burning defects
Solution Approach 1:
A water-soluble protective film is applied as an intermediary layer between the laser beam and the workpiece surface. This film absorbs and disperses the laser energy, preventing direct concentration of thermal energy on the workpiece that would generate large debris. The film acts as a mediator that enables high-energy processing while protecting the underlying material from harmful thermal effects.
Solution Approach 2:
The protective film changes the thermal and optical parameters of the processing system. It modifies how laser energy is absorbed and distributed, allowing the use of higher pulse energies and longer pulse widths without generating excessive debris. The film's water solubility also changes the post-processing requirements, enabling easy removal without affecting the workpiece.
2Manufacturing precision
If a water-soluble protective film is applied to reduce debris, then surface quality is improved, but processing time increases due to film application and removal
Solution Approach 1:
The protective film is designed as a disposable, single-use component that is applied before processing and removed after. Its water-soluble nature allows for rapid removal by simple washing, minimizing the time penalty. The film's temporary presence is acceptable because its removal is so straightforward and it enables significantly better surface quality that would not be achievable without it.
3Object-generated harmful factors
If laser pulse energy is reduced to minimize debris, then debris size decreases, but productivity is lowered
Solution Approach 1:
The water-soluble protective film serves as a mediator that decouples the relationship between laser pulse energy and debris generation. It allows high pulse energies to be used while preventing the direct conversion of that energy into large debris particles. The film absorbs excess energy and controls the thermal field, enabling high-productivity processing conditions without the harmful effects.
Solution Approach 2:
The protective film fundamentally changes the energy absorption characteristics of the system. It allows the laser processing parameters (pulse energy, pulse width, frequency) to be optimized for productivity without being constrained by debris generation limits. The film modifies the thermal field distribution, enabling parameter combinations that would otherwise produce excessive debris.
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
Reduces debris size and suppresses defects on image sensor elements, maintaining productivity by optimizing laser beam parameters and eliminating the need for protective coatings.
Implementation Method 1
applying a laser beam from a laser beam irradiation unit along the planned division lines
Implementation Method 2
the workpiece is continuously processed along the planned division lines by thermal energy generated in irradiation regions of the workpiece by applying a laser beam
Implementation Method 3
a laser beam of a next pulse hits the debris, so that the laser beam is scattered, and the sensor element portion is irradiated with scattered light
Data Source
AI summary
A laser processing method includes: holding a back surface side of a workpiece by a holding table such that a front surface side of the workpiece is exposed; and applying a laser beam from a laser beam irradiation unit along a plurality of planned division lines from the front surface side of the workpiece held by the holding table. In the applying, the laser beam is applied while changing an irradiation position of the laser beam on a front surface of the workpiece by a laser beam scanning unit disposed between an oscillator that oscillates the laser beam and a condenser that condenses light from the oscillator.