Bulk-acoustic wave filter flow suppressing part
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Solution Overview
Problem
During the manufacturing of bulk-acoustic wave filter devices, the melted bonding part can flow into the ground part, compromising the hermetic seal and device performance.
Innovation Solution
A flow suppressing part is introduced between the bonding and ground parts, which is vertically stepped and thinner than both, incorporating a piezoelectric layer and a dam layer to prevent the bonding part's melted material from flowing into the ground part, thereby maintaining a reliable seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bonding part is melted to bond the substrate wafer and cap wafer, then hermetic sealing is achieved, but the melted bonding part flows into the ground part causing contamination
Solution Approach 1:
A flow suppressing part is introduced as an intermediary element between the bonding part and ground part. This flow suppressing part includes a dam layer that acts as a barrier to prevent the melted bonding part material from flowing into the ground part, while still allowing the bonding process to proceed effectively.
Solution Approach 2:
The flow suppressing part is prepared in advance before the bonding process. The dam layer is formed with a height higher than the expected flow of bonding material, creating a pre-established barrier that prevents material flow into the ground part during the melting and bonding process.
2Volume of moving object
If the bonding part is positioned adjacent to the ground part for compact design, then device miniaturization is achieved, but melted bonding material can contaminate the ground part
Solution Approach 1:
The flow suppressing part serves as a mediator that enables close positioning of the bonding part and ground part while preventing harmful material flow. The dam layer creates a physical barrier that allows compact design without the risk of contamination.
Solution Approach 2:
The space between the bonding part and ground part is segmented by the flow suppressing part. This segmentation creates distinct zones: a bonding zone where material can melt and flow, and a protected ground part zone that is isolated from contamination by the dam layer barrier.
Data Source
AI summary
A bulk-acoustic wave filter device includes: a lower electrode layer disposed on the substrate; a bonding part disposed on the lower electrode layer, at an edge of the substrate; a ground part spaced apart from the bonding part; and a flow suppressing part disposed between the bonding part and the ground part, and offset with respect to the bonding part and the ground part.