Acoustic Wave Module Support Structure for Heat Dissipation and Sealing

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Solution Overview

Problem

Acoustic wave devices with wafer level package (WLP) structures face challenges in miniaturization and heat management, as local heat generation varies among functional elements, leading to potential degradation and reduced electric power handling capability due to uneven heat distribution and deformation during sealing processes.

Innovation Solution

Incorporating a support portion within the hollow space defined by the piezoelectric substrate, outer support layer, and cover portion, with a height smaller than the outer support layer and larger than the functional elements, to create gaps that allow heat dissipation and prevent contact between the cover portion and functional elements, thereby maintaining sealing capability and reducing local heat influence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the hollow space is divided into multiple sections using partition support layers, then the sealing-related handling capability is improved, but local heat accumulation occurs in specific sections leading to reduced electric power handling capability

Engineering Contradiction:

Improvesealing-related handling capabilityVSAvoidlocal heat accumulation

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The hollow space is divided into multiple sections using partition support layers, which provides structural support during sealing processes and prevents cover portion deformation. This segmentation improves handling capability while allowing independent heat management in each section.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Heat dissipation holes are selectively formed in specific partition support layers based on local heat generation characteristics. This allows heat to be dissipated from sections where functional elements generate more heat, while maintaining the protective structure in other areas.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If pressure is applied during the sealing process, then the module is sealed with resin, but the cover portion deforms and may contact and break functional elements

Engineering Contradiction:

Improvesealing processVSAvoidcover portion deformation resistance

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

Partition support layers are formed in advance within the hollow space before the sealing process. These support layers provide preliminary structural reinforcement to the cover portion, preventing deformation when pressure is applied during resin sealing.

Inventive Principle:

Principle #10Preliminary action

3Volume of moving object

If functional elements are arranged densely to achieve miniaturization, then the device size is reduced, but heat dissipation becomes more difficult leading to increased local heat effects

Engineering Contradiction:

Improvedevice sizeVSAvoidheat dissipation

Core Design Contradiction:

Volume of moving objectVSTemperature

Solution Approach 1:

Heat dissipation holes are formed extending in the depth direction (thickness direction) of the device, providing a third dimension for heat escape. This allows heat to dissipate vertically through the partition support layers, complementing the horizontal heat dissipation paths and enabling better thermal management in compact devices.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 configuration effectively mitigates local heat effects and enhances electric power handling by allowing heat dissipation and preventing functional element damage from deformation, thus maintaining sealing-related handling capability and improving the overall performance of acoustic wave devices.

Implementation Method 1

a support portion disposed in a hollow space defined by the piezoelectric substrate, the outer support layer, and the cover portion

Methodology Applied

Scientific EffectPhysical support and spacing:

Implementation Method 2

A gap is provided between the support portion and the cover portion or between the support portion and the piezoelectric substrate

Methodology Applied

Scientific EffectHeat dissipation through gap:

Data Source

PatentUS11134344B2Acoustic wave device and acoustic wave module including same

Publication Date: 2021.09.28 MURATA MFG CO LTD

AI summary

An acoustic wave device includes a cover portion, an outer support layer, a support portion, a piezoelectric substrate, and functional elements on the piezoelectric substrate. The outer support layer is on the piezoelectric substrate around a region where the functional elements are disposed. The cover portion is opposed to the piezoelectric substrate with the outer support layer interposed therebetween. The support portion is in a hollow space defined by the piezoelectric substrate, the outer support layer, and the cover portion. The height of the support portion is smaller than that of the outer support layer and larger than that of each of the functional elements. A gap is provided between the support portion and the cover portion or between the support portion and the piezoelectric substrate.