Piezoelectric Vibration Member Flange Roughness Adhesion
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Solution Overview
Problem
The interface strength between the lid and the adhesive in hermetically sealed piezoelectric vibrators is often insufficient, leading to separation issues, particularly at high reflow heating temperatures, due to poor wettability caused by small surface roughness.
Innovation Solution
A piezoelectric vibration member design featuring a lid with a recess and a flange portion where the surface roughness of the flange's side surface is greater than the recess, and a bonding layer that extends from the substrate to the flange's side surface, enhancing adhesion through increased surface contact and anchor effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surface roughness of the lid is small, then the manufacturing precision is improved, but the adhesion strength between the lid and adhesive deteriorates
Solution Approach 1:
The patent applies different surface roughness characteristics to different regions of the lid: the sealing surface has small roughness for manufacturing precision, while the flange portion has large roughness for adhesion strength. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The patent extends the bonding interface from a single-plane contact to a multi-dimensional structure by adding a flange portion that provides lateral surface area. The bonding layer extends from the sealing surface to the flange, creating additional bonding area in another dimension, thereby improving adhesion without compromising the precision of the sealing surface.
2Productivity
If reflow heating temperature is increased to 260°C, then the productivity is improved, but the lid may separate from the substrate due to increased pressure
Solution Approach 1:
The patent prepares the lid surface in advance by forming a flange portion with large surface roughness before bonding. This pre-prepared surface structure acts as a cushion that can accommodate thermal expansion and pressure variations during high-temperature reflow heating, preventing separation and maintaining bonding reliability at elevated temperatures.
Solution Approach 2:
The patent creates a composite bonding structure where the bonding layer interfaces with both the substrate and the flange portion of the lid. This composite configuration distributes thermal stresses and improves overall bonding reliability during high-temperature reflow processes.
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 design significantly improves the adhesion strength between the lid and the bonding layer, preventing separation and ensuring reliable hermetic sealing of the piezoelectric vibrator even at elevated temperatures.
Implementation Method 1
a bonding layer that bonds the substrate and the lid together so as to hermetically seal the piezoelectric vibrator
Implementation Method 2
the wettability of the adhesive deteriorates, and consequently, a decrease in the interface strength between the lid and the adhesive is likely to occur
Data Source
AI summary
A piezoelectric vibration member that includes a substrate having a main surface on or in which a piezoelectric vibration member is mounted, a lid having a recess that is open so as to face the main surface and which includes a flange portion that projects outward from an opening edge of the recess, and a bonding layer that bonds the substrate and the lid together so as to hermetically seal the piezoelectric vibrator in a space between the recess and the main surface. The surface roughness of a side surface of the flange portion is greater than the surface roughness of the surface of the recess, and the bonding layer extends from the main surface of the substrate to the side surface of the flange portion.