Chip Edge Separation Using Internal Laser Cracks and Back Grinding
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Solution Overview
Problem
The existing methods for manufacturing chips, such as irradiating the peripheral edge portions with a laser beam to prevent chipping, may cause thermal damage and reduce the flexural strength of the chips.
Innovation Solution
A method involving internal processing with a laser beam to form modified regions and cracks in the workpiece, allowing for the removal of first and second to-be-removed portions, thereby reducing thermal damage and maintaining chip strength by using these cracks as boundaries for edge separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the back surface side peripheral edge portions of the chips are irradiated with a laser beam to prevent chipping, then the flexural strength of the chips is improved, but thermal damage remains on the chips
Solution Approach 1:
The patent segments the workpiece into multiple chips by forming grooves on the front surface and removing material from the back surface. The laser beam is used to form modified regions and cracks along the groove boundaries, enabling precise segmentation without irradiating the entire chip surface, thus preventing thermal damage while maintaining strength at critical edges.
Solution Approach 2:
The patent performs preliminary actions by forming grooves on the front surface and creating modified regions with laser irradiation before the actual chip separation. Cracks are induced in advance along the groove paths, so that when the back surface is ground, the chips separate cleanly along predetermined lines without requiring laser irradiation of the final chip edges, avoiding thermal damage.
2Volume of moving object
If the workpiece is ground to divide it into chips, then the chips are thinned and downsized, but the peripheral edge portions are chipped away and flexural strength is reduced
Solution Approach 1:
The patent performs preliminary laser irradiation to form modified regions and induce cracks along the groove boundaries before the grinding process. This preliminary action creates predetermined separation paths, so that when the back surface is ground to thin the chips, the material separates cleanly along the crack lines rather than chipping randomly at the edges, preserving flexural strength.
Solution Approach 2:
The patent introduces cracks as an intermediary mechanism between the grinding process and chip separation. The cracks act as stress concentrators and separation guides, allowing the grinding force to propagate cleanly through predetermined paths rather than causing uncontrolled chipping at the peripheral edges, thus maintaining chip strength during thinning.
3Ease of manufacture
If the back surface is ground until the workpiece is divided using grooves as boundaries, then the chips are separated, but the grinding process causes chipping at the back surface side peripheral edge portions
Solution Approach 1:
The patent performs preliminary laser irradiation to form modified regions and induce cracks along the groove boundaries before the grinding process. This preliminary action creates predetermined separation paths, so that when the back surface is ground, the chips separate cleanly along the crack lines rather than chipping randomly at the edges, preserving flexural strength.
Solution Approach 2:
The patent converts the potentially harmful effect of laser irradiation into a beneficial crack formation mechanism. The laser-induced cracks, which could be considered damage, are actually used as useful separation guides that direct the grinding process to produce clean chip edges without chipping, thus converting a harmful effect into a beneficial manufacturing feature.
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
This method effectively reduces thermal damage and suppresses the reduction in flexural strength of the chips, providing chips with minimized chipping and maintained structural integrity.
Implementation Method 1
irradiating the first to-be-removed portions with a laser beam of a wavelength having transmissivity for the workpiece to form a plurality of modified regions located in the first to-be-removed portions, respectively, and a plurality of cracks spreading from the modified regions
Data Source
AI summary
Disclosed is a method for manufacturing chips by removing, from a workpiece with devices formed on a side of its front surface, first to-be-removed portions located around the devices and second to-be-removed portions located on a side of its back surface with respect to the devices. This method includes an internal processing step of irradiating the first to-be-removed portions with a laser beam to form modified regions there, and cracks spreading from the modified regions such that each crack reaches corresponding one of the second to-be-removed portions through corresponding one of intermediate portions located between the devices and the second to-be-removed portions, a first removal step of removing the first to-be-removed portions, and a second removal step of grinding and removing the second to-be-removed portions and using the cracks as boundaries to separate, from the chips, their back surface side peripheral edge portions.