Flip-Chip Substrate Air Gap Stress Reduction
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Solution Overview
Problem
The integration and downsizing of acoustic wave devices are hindered by stress between substrates, particularly thermal stress, which deteriorates the characteristics of functional elements in existing stacking methods.
Innovation Solution
An electronic device design featuring a first substrate with a functional element and a second substrate flip-chip mounted on it through bumps, surrounded by a sealing member that seals the functional elements across an air gap, reducing stress and allowing for smaller substrate sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If two substrates are bonded together through an interlayer to stack acoustic wave elements, then integration and downsizing are achieved, but thermal stress between substrates strains the substrates and deteriorates the characteristics of functional elements
Solution Approach 1:
The patent removes the interlayer material from between the substrates, replacing it with an air gap. This extraction of the problematic interlayer eliminates the source of thermal stress while maintaining the compact stacked structure, thereby resolving the contradiction between downsizing and reliability
Solution Approach 2:
The patent introduces an air gap (inert environment) between the substrates to replace the interlayer. This air gap provides thermal isolation that reduces heat transfer between substrates, minimizing thermal stress and protecting functional element characteristics while maintaining device compactness
2Strength
If substrates are bonded through an interlayer, then structural support is provided, but stress between substrates increases
Solution Approach 1:
The patent extracts the interlayer material that causes stress concentration and replaces it with an air gap. The sealing member provides alternative structural support without transmitting thermal stress between substrates, thus maintaining strength while reducing stress
Solution Approach 2:
The patent introduces a sealing member as an intermediary element that provides structural support and sealing functions without creating thermal stress pathways. The sealing member mediates between the substrates, providing mechanical support while isolating them thermally through the air gap
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 design minimizes stress between substrates, enhances the stability of functional elements, and enables more efficient heat release and substrate selection, improving the performance and yield of acoustic wave devices.
Implementation Method 1
a second substrate that is flip-chip mounted on the upper surface of the first substrate through a bump
Implementation Method 2
seals the first functional element and the second functional element so that the first functional element and the second functional element are located across an air gap
Data Source
AI summary
An electronic device includes: a first substrate including a first functional element located on an upper surface of the first substrate; a second substrate that is flip-chip mounted on the upper surface of the first substrate through a bump, and includes a second functional element located on a lower surface of the second substrate; and a sealing member that is located on the upper surface of the first substrate, surrounds the second substrate in plan view, is not located between the first substrate and the second substrate, seals the first functional element and the second functional element so that the first functional element and the second functional element are located across an air gap.