Acoustic Wave Device Sealing with Variable Filler Resin
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Solution Overview
Problem
Acoustic wave devices face reliability issues due to deformation of the element substrate affecting frequency and thermal expansion differences in the sealing resin, which are not adequately addressed by existing technologies.
Innovation Solution
An acoustic wave device with a sealing part containing a resin and insulating fillers of lower thermal expansion, where the filler content and particle size differ between areas to match the thermal expansion of the cover and mounting surface, effectively sealing the device and reducing thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform sealing resin is used to cover the acoustic wave device, then the device is sealed, but thermal expansion differences cause deformation of the element substrate and reduce reliability
Solution Approach 1:
The sealing resin is divided into a first sealing resin and a second sealing resin with different filler contents. The first sealing resin is applied to a first area of the acoustic wave device while the second sealing resin is applied to a second area, creating local variations in thermal expansion characteristics that match the local thermal expansion of the cover and mounting board, thereby preventing element substrate deformation
Solution Approach 2:
The sealing resin is formulated as a composite material containing a resin matrix and insulating fillers. By adjusting the filler content and particle size distribution in different regions, the thermal expansion coefficient of the sealing resin is tailored to match the local thermal expansion characteristics of the cover and mounting board, reducing thermal stress and preventing deformation
2Reliability
If the sealing resin has high filler content to match thermal expansion, then thermal stress is reduced, but the resin becomes harder to apply and may affect adhesion
Solution Approach 1:
Different filler contents are used in different areas: the first sealing resin has a first filler content for one region while the second sealing resin has a second filler content for another region. This allows each region to be optimized for its specific thermal expansion requirements while maintaining manufacturability in each local area
Solution Approach 2:
The filler content and particle size parameters of the sealing resin are varied spatially across different areas of the acoustic wave device. This parameter optimization allows the sealing resin to achieve appropriate thermal expansion matching in each region while maintaining workable viscosity and adhesion properties for manufacturing
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
The solution provides suitable sealing and reduces deformation and thermal stress, enhancing the reliability and adhesive strength of the acoustic wave device.
Implementation Method 1
The sealing part contains a resin and insulating fillers which have a coefficient of thermal expansion which is lower than that of the resin. The content of the fillers differs between an area including at least a portion of the area between the cover and the mounting surface and another area.
Data Source
AI summary
An electronic component has a mounting board having a mounting surface, a SAW device mounted on the mounting surface, and a sealing part covering the SAW device and filled between the SAW device and the mounting surface. The SAW device has an element substrate, an excitation electrode provided on a major surface of the element substrate and a cover covering the excitation electrode. SAW device is mounted on the mounting surface so as to make top surfaces of the cover face the mounting surface. The sealing part contains a resin and insulating fillers having a coefficient of thermal expansion lower than that of the resin. The content of the fillers differs between an area (for example AR1) including at least a portion of an area between the cover and the mounting surface and other areas (for example AR2 and AR3).