Crystal Oscillating Element Mesa Edge Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing crystal oscillating elements face challenges in achieving optimal crystal impedance and vibration characteristics due to variations in etching time and the formation of crystal planes, which affect the thickness and shape of the crystal blank, leading to inconsistent performance.
Innovation Solution
A crystal oscillating element with a mesa portion and an outer peripheral portion, where the outer peripheral portion is thinner than the mesa portion, and projecting portions that do not exceed the height of the mesa portion, along with specific mask formations during etching to control the formation of crystal planes, ensuring consistent etching and improved vibration characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outer peripheral portion is cut down more to increase the number of crystal planes, then crystal impedance reduction is improved, but manufacturing precision deteriorates due to inconsistent etching results
Solution Approach 1:
The patent applies preliminary action by forming a mask pattern before etching that pre-determines the crystal plane formation. The mask includes a mesa mask portion and edge mask portions positioned to control etching at specific locations, ensuring consistent crystal plane formation regardless of etching time variations. This preliminary masking structure guides the etching process to produce the desired crystal planes reliably.
Solution Approach 2:
The patent changes the parameter of mask pattern configuration to control crystal plane formation. By adjusting the position and shape of edge mask portions relative to the mesa mask portion, the patent optimizes etching depth and crystal plane development without relying on etching time alone. This parameter change enables precise control over crystal impedance while maintaining manufacturing consistency.
2Reliability
If etching time is increased to form more crystal planes, then vibration characteristics are improved, but device complexity increases due to multiple etching steps
Solution Approach 1:
The patent merges multiple etching functions into a single integrated mask pattern. The mask simultaneously defines the mesa portion boundaries and the edge portions that will form crystal planes. This consolidation allows one etching step to achieve both mesa formation and crystal plane development, reducing process complexity while maintaining vibration characteristics.
Solution Approach 2:
The mask pattern serves multiple functions: it defines the mesa portion shape, controls crystal plane formation at edges, and regulates etching depth. This multi-functional mask design eliminates the need for separate masking steps for each function, simplifying the overall manufacturing process while ensuring consistent vibration characteristics.
3Reliability
If the crystal blank thickness is reduced to improve vibration characteristics, then frequency response is improved, but strength deteriorates
Solution Approach 1:
The patent applies local quality by creating different thickness regions within the crystal blank. The mesa portion maintains sufficient thickness for structural strength, while edge portions with crystal planes provide enhanced vibration characteristics. This localized thickness variation allows the crystal blank to simultaneously achieve good mechanical strength and optimal vibration performance.
Solution Approach 2:
The patent introduces asymmetry in the crystal blank structure by forming crystal planes only at specific edge portions rather than uniformly throughout. This asymmetric crystal plane distribution optimizes vibration characteristics in critical areas while preserving the overall structural integrity of the thicker mesa portion, balancing strength and vibration performance.
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 configuration enhances the degree of freedom in designing vibration characteristics, reduces stress on the crystal blank, and maintains consistent crystal impedance by controlling the formation of crystal planes, thereby improving the reliability and performance of the crystal oscillating element.
Implementation Method 1
a method of successively performing etching for forming an outer shape (side surfaces) of a crystal blank
Data Source
AI summary
The oscillating element includes a crystal blank, a pair of excitation electrodes, and a pair of pad portions. The crystal blank includes a pair of major surfaces, at least partially configured by crystal planes, and side surfaces which connect outer edges of the pair of major surfaces. Further, it includes a mesa portion and an outer peripheral portion which surrounds the mesa portion and has a thickness between the pair of major surfaces thinner than that of the mesa portion. The excitation electrodes are individually located on the pair of major surfaces. The pair of pad portions are located on one of the pairs of major surfaces and are electrically connected with the excitation electrodes. At least a portion of an edge part which is in contact with a crystal plane includes a projecting portion, which does not exceed the height of the mesa portion from the outer peripheral portion.