Curved Cover Elastic Wave Device Parallelism
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Solution Overview
Problem
Elastic wave devices with WLP structures face issues due to non-uniform mounting substrates, leading to poor parallelism between sealing resin and terminal electrodes, causing failures in contact during inspection.
Innovation Solution
The elastic wave device design includes a piezoelectric substrate with an IDT electrode and support, sealed by a cover, mounted on a substrate with a sealing resin whose thickness is greater than the substrate, ensuring good parallelism by curving the cover towards the substrate or having a larger resin volume, and using a bump for secure mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the mounting substrate thickness is decreased to reduce device size, then the device size is reduced, but the substrate is likely to warp and the degree of parallelism between the sealing resin and terminal electrode deteriorates
Solution Approach 1:
The cover is designed with a curved surface that curves toward the piezoelectric substrate side. This curvature compensates for the warping of the thin mounting substrate, maintaining the parallelism between the sealing resin upper surface and the terminal electrode on the substrate, thereby preventing contact failures during inspection.
2Adaptability or versatility
If the mounting substrate has non-uniform thickness due to internal wiring, then the device functionality is achieved, but the degree of parallelism between the sealing resin and terminal electrode deteriorates
Solution Approach 1:
The curved cover surface adapts to the non-uniform thickness of the mounting substrate caused by internal wiring arrangements. The curvature allows the sealing resin to maintain good parallelism with the terminal electrode despite the substrate's varying thickness, preventing inspection contact failures while preserving device functionality.
3Manufacturing precision
If the sealing resin thickness is increased to improve parallelism, then the degree of parallelism between the sealing resin and terminal electrode is improved, but the device size increases
Solution Approach 1:
Instead of increasing the sealing resin thickness to achieve parallelism, the invention uses a curved cover that compensates for substrate warping. This approach maintains good parallelism between the sealing resin and terminal electrode while keeping the device size compact, avoiding the need for excessive resin thickness.
Solution Approach 2:
The invention changes the geometric parameter of the cover from flat to curved, which fundamentally alters how parallelism is achieved. This parameter change allows the system to maintain good electrical contact without increasing the sealing resin thickness, thereby controlling device size.
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 improves the parallelism between the sealing resin and terminal electrodes, reducing the likelihood of contact failures and enhancing inspection reliability.
Implementation Method 1
an elastic wave element including a piezoelectric substrate (13)
Implementation Method 2
A thickness of the mounting substrate is less than a thickness of the sealing resin (7)
Data Source
AI summary
An elastic wave device includes an elastic wave element including a piezoelectric substrate with a first main surface and a second main surface that face each other, an IDT electrode disposed on the second main surface of the piezoelectric substrate, a support disposed on the second main surface of the piezoelectric substrate so as to surround the IDT electrode in plan view, and a cover that is disposed on the support and seals the IDT electrode together with the support and the piezoelectric substrate, a mounting substrate above which the elastic wave element is mounted, and a sealing resin that is disposed on the side of the side of the upper surface of the mounting substrate and seals the elastic wave element. A thickness of the mounting substrate is less than a thickness of the sealing resin that corresponds to a distance from a surface of the sealing resin in contact with the upper surface of the mounting substrate to a surface of the sealing resin on an opposite side of the mounting substrate.