Piezoelectric Substrate Joining to Prevent Edge Cracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for bonding piezoelectric and support substrates result in non-bonded regions due to sagging or roll-off, leading to peeling, fragment generation, and decreased yield due to material incompatibility and inappropriate grinding, which causes breakage or cracking.
Innovation Solution
A method involving outer peripheral processing, joining, and thinning steps to form a joined body with controlled surface roughness and selective grinding to minimize breakage, using suitable grindstones for each substrate material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the piezoelectric material substrate and support substrate are bonded together, then a joined body is formed, but a non-bonded region is generated in the outer peripheral portion due to sagging or roll-off
Solution Approach 1:
The invention performs preliminary action by forming a protruding portion on the outer peripheral surface of one substrate before bonding. This protruding portion prevents sagging or roll-off from occurring during bonding, thereby eliminating the non-bonded region problem while maintaining bonding quality.
Solution Approach 2:
The invention applies local quality by creating a protruding portion only at the outer peripheral portion where sagging or roll-off occurs, rather than modifying the entire substrate. This localized modification prevents the non-bonded region problem without affecting the overall bonding quality of the main substrate areas.
2Reliability
If the non-bonded portion is removed by processing, then peeling and fragment generation are avoided, but processing complexity increases
Solution Approach 1:
The invention performs preliminary action by forming the protruding portion before bonding, which prevents the non-bonded region from forming in the first place. This eliminates the need for subsequent processing steps to remove non-bonded portions, thereby reducing processing complexity while maintaining peeling resistance.
3Ease of manufacture
If the same grindstone is used for both piezoelectric material substrate and support substrate, then processing is simplified, but breakage or cracking occurs due to material incompatibility
Solution Approach 1:
The invention applies segmentation by dividing the grinding process into separate steps for the piezoelectric material substrate and support substrate, each using a grindstone optimized for its specific material. This prevents breakage or cracking while maintaining processing simplicity through systematic separation of operations.
Solution Approach 2:
The invention applies local quality by selecting different grindstones tailored to the specific material properties of each substrate type. The piezoelectric material substrate uses a grindstone optimized for its hardness and brittleness, while the support substrate uses a different grindstone suited to its material characteristics, thereby preventing breakage or cracking.
4Reliability
If the outer peripheral portion is ground to remove non-bonded region, then bonding quality improves, but mechanical strength decreases due to ground surface
Solution Approach 1:
The invention performs preliminary action by forming the protruding portion before bonding, which prevents the non-bonded region from forming. This eliminates the need for subsequent grinding of the outer peripheral portion, thereby maintaining the mechanical strength of the original surface while ensuring bonding quality.
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 processing breakage and cracking, improves yield, and maintains mechanical strength by ensuring suitable grindstone selection and controlled surface roughness, particularly in the outer peripheral portions.
Implementation Method 1
an outer peripheral processing step of forming an outer peripheral processed portion, ground inward from an edge portion along a main surface of one of a piezoelectric material substrate (11) and a support substrate (13)
Implementation Method 2
a joining step of joining one of the piezoelectric material substrate (11) and the support substrate (13), which is formed thereon with the outer peripheral processed portion (R), to a main surface of the other one
Data Source
AI summary
Provided is a method for manufacturing a joined body, the method including: an outer peripheral processing step of forming an outer peripheral processed portion, ground inward from an edge portion along a main surface of one of a piezoelectric material substrate and a support substrate; a joining step of joining one of the piezoelectric material substrate and the support substrate, which is formed thereon with the outer peripheral processed portion, to a main surface of the other one, with a main surface side of the one of the piezoelectric material substrate and the support substrate serving as a joining surface side; and a thinning step of thinning the joined piezoelectric material substrate. Therefore, there are provided a joined body etc. in which a corner portion is not formed in an outer peripheral portion and breakage or cracking is less likely to occur in the outer peripheral portion in subsequent steps.