Laser Cutting LTCC Substrates via Bonded Intermediary Fracture
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Solution Overview
Problem
Conventional object cutting methods fail to accurately cut materials like LTCC substrates due to laser light scattering, which prevents effective guidance of laser light into the substrate, leading to incomplete or inaccurate cutting.
Innovation Solution
The method involves bonding the end faces of a sheet-like first object and a second object, irradiating the first object with laser light to form a modified region, generating stress to create a fracture that extends through the bonded interface, and using an expandable holding member to guide the fracture and cut the second object into chips without forming a cutting start point within the second object.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser light is irradiated directly onto LTCC substrate to form modified region, then cutting can be performed, but laser light scattering prevents effective guidance into substrate causing incomplete cutting
Solution Approach 1:
A first object (silicon substrate) is introduced as an intermediary to receive laser irradiation and transmit fracture to the second object (LTCC substrate). The laser forms a modified region in the first object which then generates a fracture that propagates through the bonded interface to cut the second object, bypassing the laser light scattering issue in LTCC material.
Solution Approach 2:
The cutting process is segmented into two distinct stages: (1) laser irradiation and modified region formation in the first object, and (2) fracture generation and propagation to the second object. This segmentation allows each object to perform its optimal function - the first object receives laser energy while the second object undergoes clean fracture cutting.
2Manufacturing precision
If fracture is generated in first object to cut second object, then accurate cutting without cutting start point in second object is achieved, but strong bonding interface is required to transmit fracture without direction change
Solution Approach 1:
The first object and second object are bonded together in advance before the cutting process. This preliminary bonding action ensures that when the fracture is generated later, the interface is already prepared to transmit the fracture continuously without direction change, enabling accurate cutting of the second object.
3Ease of manufacture
If conventional direct laser cutting is used on substrates like glass or sapphire, then cutting is required, but these materials are difficult to guide laser light into causing incomplete processing
Solution Approach 1:
The first object serves as a mediator that is easier to process with laser light. The laser forms a modified region in this intermediary object, which then generates a fracture that propagates to the difficult-to-process second object (glass, sapphire, etc.), enabling cutting of materials that would otherwise be difficult to process directly.
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 approach allows for precise cutting of various substrates, including LTCC, glass, and sapphire, resulting in high-quality cut sections with enhanced bending strength and accurate chip formation without direct processing.
Implementation Method 1
irradiating a sheet-like first object to be processed for separation with laser light, so as to form a modified region in the first object along a line to cut
Implementation Method 2
generating a stress in the first object so as to cause a fracture generated from the modified region acting as a start point to reach a second-side end face of the first object and a first-side end face of the second object
Implementation Method 3
the first-side end face of the first object and the second-side end face of the second object are bonded to each other by anode bonding
Implementation Method 4
the first-side end face of the first object and the second-side end face of the second object are bonded to each other by surface-activated direct bonding
Data Source
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AI summary
A rear face 1b of an object to be processed 1A and a front face 10a of an object to be processed for separation 10A are bonded to each other by anode bonding, whereby a fracture 17 generated in a thickness direction of the object for separation 10A from a molten processed region 13 acting as a start point reaches a front face 1a of the object 1A continuously without substantially changing its direction. Then, after cutting the objects 1A, 10A, the object 10A is removed from the object 1A, so as to yield chips 19.