Acoustic Wave Module Shield Layer for Thermal Position Stability
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Solution Overview
Problem
Acoustic wave modules with shield plates experience changes in relative positional relationships due to temperature or internal stress, affecting the characteristics of surface acoustic wave filters.
Innovation Solution
The implementation of a shield layer with a two-layer structure, where the outer layer has a higher linear expansion coefficient than the inner layer, generates a force that causes the inner layer to warp and approach the functional elements, thereby stabilizing the relative positional relationship and reducing changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield plate is provided between functional elements to improve shielding effect, then electromagnetic interference is reduced, but the relative positional relationship changes due to temperature and internal stress, affecting filter characteristics
Solution Approach 1:
The patent changes the physical parameters of the shield layer by creating a two-layer structure with different linear expansion coefficients. The first layer has a smaller linear expansion coefficient than the second layer, causing the shield layer to warp toward the functional elements when temperature changes occur. This parameter change compensates for positional drift and maintains filter characteristics stability while preserving the shielding effect.
Solution Approach 2:
The patent uses a composite shield layer structure composed of two different materials with distinct linear expansion coefficients. This composite structure exploits the differential thermal expansion behavior to generate a warping effect that counteracts positional changes, thereby maintaining both the shielding function and the stability of filter characteristics under temperature variations.
2Volume of moving object
If the thickness of the shield plate is reduced to decrease module height and size, then miniaturization is achieved, but the shield layer becomes more susceptible to deformation from internal stress and temperature
Solution Approach 1:
The patent changes the material parameters of the shield layer by selecting materials with specific linear expansion coefficients for each layer. This parameter optimization allows the thin shield layer to maintain positional stability through controlled warping, enabling miniaturization without sacrificing stability.
Solution Approach 2:
The patent converts the harmful effect of internal stress and thermal expansion into a beneficial warping effect. By designing the two-layer structure with different expansion coefficients, the natural tendency of the materials to expand differently is harnessed to create a compensatory mechanism that maintains positional stability even in a thin, miniaturized shield layer.
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 minimizes changes in the relative positional relationship between the functional elements and the shield layer, maintaining the intended design characteristics and improving adhesion, thus stabilizing the acoustic wave module's performance.
Implementation Method 1
The shield layer includes a first layer provided on a first functional element side and a second layer provided on a second functional element side. The second layer adds, to the first layer, a force that causes the first layer to warp so that the first layer at the first peripheral end portion and second peripheral end portion approaches the first functional element.
Data Source
AI summary
An acoustic wave module includes a hollow space defined by first and second piezoelectric bodies, a support layer, and a first functional element. A second functional element and a shield layer are disposed in the hollow space. The shield layer includes first and second layers disposed on the first functional element side and a second layer disposed on the second functional element side. The second layer adds, to the first layer, a force that causes the first layer to warp so that the first layer at a peripheral end portion and a peripheral end portion approaches the first functional element.