Acoustic Wave Device Layout for Reflow Distortion Compensation
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Solution Overview
Problem
The challenge in mounting acoustic wave devices on a substrate is the mechanical distortion caused by differences in the coefficients of linear expansion between the piezoelectric substrate and the mounting substrate, leading to variations in the characteristics of the acoustic wave device during the reflow process.
Innovation Solution
The solution involves mounting a first device with a lower coefficient of linear expansion as a substrate and a second device with a higher coefficient of linear expansion as a piezoelectric substrate adjacent to each other on the mounting substrate, such that the distortions caused by the reflow process are canceled out, thereby reducing or preventing the deterioration in the characteristics of the acoustic wave device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic wave devices are mounted on a mounting substrate using reflow method, then electrical connection between devices and substrate is achieved, but mechanical distortion occurs due to difference in coefficients of linear expansion
Solution Approach 1:
The patent changes the physical parameter (coefficient of linear expansion) of the substrate by selecting materials with specific expansion coefficients. The first substrate has a lower coefficient than the mounting substrate, while the second substrate has a higher coefficient, transforming the material selection parameter to achieve distortion compensation.
Solution Approach 2:
The patent introduces asymmetry in the coefficient of linear expansion relationships between adjacent substrates. Instead of using identical substrates with the same expansion coefficient, it employs asymmetric material selection where one substrate has lower expansion and another has higher expansion, creating a balanced system that compensates for mounting substrate distortion.
2Productivity
If multiple acoustic wave devices are mounted on one substrate, then device integration is achieved, but distortion increases due to cumulative effect of coefficient of linear expansion differences
Solution Approach 1:
The patent applies local quality by assigning different material properties to different locations in the device array. Specifically, acoustic wave devices at corner positions use substrates with different expansion coefficients compared to those at other positions, creating locally optimized distortion compensation for each region of the mounting substrate.
Solution Approach 2:
The patent changes the substrate material parameter (coefficient of linear expansion) based on the positional parameters of the acoustic wave devices. By selecting substrates with appropriate expansion coefficients for specific positions (particularly corners), it dynamically adjusts the physical parameters to compensate for position-dependent distortion effects.
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 approach significantly reduces or prevents mechanical deformation and maintains the performance of the acoustic wave device by canceling out distortions at the interface between the devices, thereby preserving the characteristics of the acoustic wave components.
Implementation Method 1
the piezoelectric substrate of the acoustic wave device and the mounting substrate have different coefficients of linear expansion. As a result, when cooling in the reflow process, mechanical distortion occurs in the acoustic wave device itself due to a difference in the coefficient of linear expansion
Data Source
AI summary
A high-frequency apparatus includes a first device and a second device, and a mounting substrate on which the first and second devices are mounted. At least the second device is an acoustic wave device including a piezoelectric substrate and a functional element. The first device and the second device are adjacent to or in a vicinity of each other on the mounting substrate. A coefficient of linear expansion of a substrate of the first device is lower than a coefficient of linear expansion of the mounting substrate, and a coefficient of linear expansion of the piezoelectric substrate of the second device is higher than the coefficient of linear expansion of the mounting substrate.