Acoustic Wave Package Structure for Larger Cavity and Pressure Rigidity
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Solution Overview
Problem
The challenge is to increase the area for functional elements in acoustic wave devices while maintaining sufficient rigidity and resistance to external pressure, as existing wafer level package structures face limitations in reducing the outer peripheral support layer's proportion without compromising structural integrity.
Innovation Solution
The proposed solution involves an acoustic wave device design with a piezoelectric substrate, an outer peripheral support layer, a cover portion, and a protective layer, where a through-hole is filled with a conductor to connect external terminals, and protruding portions of the outer and internal support layers overlap the hollow space to distribute stress, allowing for a reduced outer peripheral support layer area while maintaining rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the dimension of the outer peripheral support layer in the width direction is increased, then the rigidity against external pressure is improved, but the area for disposing functional elements is reduced
Solution Approach 1:
The support structure is divided into two distinct parts: an outer peripheral support layer and an inner support layer. The outer peripheral support layer maintains rigidity against external pressure, while the inner support layer provides additional structural support within the hollow space. This segmentation allows the outer peripheral support layer to be thinner without compromising overall rigidity, thereby increasing the area available for functional elements.
Solution Approach 2:
The support function is extended from a single two-dimensional outer peripheral support layer to a three-dimensional structure by adding an inner support layer within the hollow space. This dimensional transition allows the outer peripheral support layer to reduce its width while the inner support layer compensates for the reduced rigidity, thus increasing the area for functional elements without sacrificing structural strength.
2Area of stationary object
If the proportion of the outer peripheral support layer on the piezoelectric substrate is reduced, then the hollow space area is enlarged, but the rigidity against external pressure decreases
Solution Approach 1:
The support function is segmented between the outer peripheral support layer and the inner support layer. By reducing the outer peripheral support layer's proportion and adding the inner support layer, the hollow space area is enlarged while the overall rigidity is maintained through the combined support of both layers.
Solution Approach 2:
The support structure uses a composite configuration combining the outer peripheral support layer and the inner support layer. This composite structure allows the outer peripheral support layer to be reduced in proportion while the inner support layer provides complementary support, maintaining overall rigidity while enlarging the hollow space area.
3Adaptability or versatility
If the outer peripheral support layer dimension is reduced, then the degree of freedom in design is improved, but the resistance against external pressure is weakened
Solution Approach 1:
By segmenting the support structure into outer peripheral and inner support layers, the outer peripheral support layer can be reduced in dimension, increasing design freedom for functional element arrangement. The inner support layer compensates for the reduced pressure resistance, allowing both design flexibility and structural integrity to be achieved.
Solution Approach 2:
The support system transitions from a single two-dimensional outer peripheral support layer to a three-dimensional structure with an inner support layer. This allows the outer peripheral support layer to be reduced in width (increasing design freedom) while the inner support layer maintains the necessary resistance against external pressure.
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 effectively increases the space for functional elements while ensuring the device's rigidity and resistance to external pressure, preventing deformation and maintaining operational characteristics.
Implementation Method 1
an acoustic wave device having a general WLP structure has a configuration such that a plurality of functional elements are disposed on a piezoelectric substrate
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate, functional elements, an outer peripheral support layer, a cover portion, and a protective layer covering the cover portion. A hollow space is defined by the piezoelectric substrate, the outer peripheral support layer, and the cover portion, and the functional elements are disposed in the hollow space. The acoustic wave device further includes an under bump metal layer, a wiring pattern, and a through-electrode that connects these elements. In the protective layer, a through-hole to be filled with a conductor to electrically connect a solder ball and the under bump metal layer is provided. The outer peripheral support layer includes a protruding portion protruding to the hollow space. When the acoustic wave device is seen in plan view, at least a portion of the through-hole overlaps the hollow space, and an end portion of the protruding portion overlaps an inner region of the through-hole.