Elastic Wave Device Cover Protrusion for Flux Containment
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Solution Overview
Problem
Elastic wave devices face degradation and corrosion issues due to evaporated flux during bump mounting, which can affect other electronic components and the device's characteristics.
Innovation Solution
The design includes a protruding portion along the outer peripheral edge of the cover, which effectively reduces the diffusion of evaporated flux outside the cover, preventing it from reaching other components and the piezoelectric substrate, thereby minimizing corrosion and degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bump mounting is performed using flux, then the bumps can be effectively bonded to the via electrodes, but the evaporated flux causes corrosion of other electronic components and degrades device characteristics
Solution Approach 1:
The protruding portion acts as an intermediary barrier between the flux and other electronic components. It intercepts the evaporated flux and prevents it from reaching the piezoelectric substrate and surrounding components, thus mediating the harmful interaction while allowing the bump mounting process to proceed normally
Solution Approach 2:
The invention converts the harmful evaporated flux into a contained element by using the protruding portion to redirect it away from sensitive areas. The flux that would otherwise cause corrosion is now confined to a specific region, transforming a harmful diffuse effect into a controlled localized phenomenon
2Ease of manufacture
If the cover is made flat, then the manufacturing process is simpler, but evaporated flux can freely diffuse outside the cover and affect other components
Solution Approach 1:
The protruding portion adds a vertical dimension to the cover structure. By extending upward from the cover surface, it creates a three-dimensional barrier that intercepts flux in the vertical path, transforming a two-dimensional flat surface into a multi-level protective structure
3Object-affected harmful factors
If the protruding portion is provided along the entire outer peripheral edge, then flux diffusion is more effectively prevented, but the device complexity increases
Solution Approach 1:
The protruding portion is strategically positioned only at the outer peripheral edge of the cover where flux escape is most likely to occur. This localized approach provides effective flux containment at the critical boundary without adding complexity to the entire cover structure, applying protection only where needed
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 significantly reduces the impact of flux on other electronic components and the elastic wave device's characteristics, preventing corrosion and maintaining functionality.
Implementation Method 1
the flux, which is attached to the bumps, evaporates due to being heated
Implementation Method 2
A protruding portion is provided along at least a portion of an outer peripheral edge of a surface of the cover that is on the opposite side from the piezoelectric body. The protruding portion extends in a direction away from the piezoelectric body
Data Source
AI summary
An elastic wave device includes a piezoelectric substrate, an IDT electrode on the piezoelectric substrate, a support member that is provided on the piezoelectric substrate so as to surround the IDT electrode, a cover that covers the support member, via electrodes that penetrate through the support member and the cover, and bumps that are bonded to the via electrodes. The IDT electrode is located in a hollow space that is enclosed by the piezoelectric substrate, the support member and the cover. A protruding portion extends along at least a portion of an outer peripheral edge of a surface of the cover that is on the opposite side from the piezoelectric substrate, and the protruding portion extends in a direction away from the piezoelectric substrate.