SAW Package Roof Support Structure for Heat and Signal Integrity
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Solution Overview
Problem
Existing packaged surface acoustic wave devices are limited by their size and thickness, and they suffer from low heat dissipation, mechanical ruggedness, and electrical performance due to structural constraints.
Innovation Solution
The packaged surface acoustic wave device incorporates a conductive pillar and roof structure that supports the roof structure without electrical communication, along with a multilayer piezoelectric substrate and conductive vias to enhance heat dissipation and mechanical support, while maintaining electrical pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a traditional packaged surface acoustic wave device structure is used, then the device is protected within a package, but the size and thickness of the packaged device increase
Solution Approach 1:
The patent introduces a three-dimensional stacked architecture with multiple functional layers (support substrate, piezoelectric layer, roof structure, conductive pillars) arranged vertically. This dimensional reorganization allows heat dissipation pathways to extend through the thickness direction rather than only laterally, improving thermal management while maintaining a compact footprint.
Solution Approach 2:
The patent employs composite material structures including conductive pillars made of highly thermally conductive materials (such as tungsten or copper) integrated into the package, combined with piezoelectric materials and dielectric layers. This composite approach optimizes both mechanical support and heat dissipation functions within the limited package volume.
2Volume of moving object
If the package structure is reduced to decrease size, then the device becomes smaller, but mechanical ruggedness deteriorates
Solution Approach 1:
The patent divides the package into distinct functional segments: a support substrate providing mechanical foundation, a piezoelectric layer for acoustic wave generation, a roof structure for protection, and conductive pillars for both electrical and mechanical support. This segmentation allows each layer to be optimized for its specific function while contributing to overall mechanical strength.
Solution Approach 2:
The patent utilizes vertical stacking of multiple layers to achieve mechanical ruggedness without increasing lateral dimensions. The conductive pillars extend vertically to provide structural reinforcement, and the multilayer configuration distributes mechanical stresses across different planes, enhancing overall package strength while maintaining a compact form factor.
3Reliability
If conventional packaging is used, then the device is protected, but electrical performance is limited
Solution Approach 1:
The conductive pillars in the patent serve multiple functions simultaneously: they provide electrical connectivity between the interdigital transducer electrode and external terminals, act as thermal conduction pathways for heat dissipation, and offer mechanical support to the roof structure. This multi-functionality reduces the need for separate components, simplifying the overall structure while improving electrical performance.
Solution Approach 2:
The patent introduces conductive structures as intermediary elements that facilitate efficient electrical signal transmission between the piezoelectric layer and external circuitry. These conductive pathways are strategically positioned to minimize signal loss and interference, acting as mediators that enhance electrical performance without requiring complex external connections.
4Temperature
If heat dissipation is improved through enhanced structures, then thermal performance increases, but device thickness increases
Solution Approach 1:
The patent directs heat dissipation pathways primarily through the vertical thickness direction using conductive pillars that extend from the piezoelectric layer to the roof structure or external heat sinks. By utilizing the thickness dimension for thermal management, the patent achieves effective heat dissipation without requiring large lateral expansion, thus maintaining a relatively thin profile.
Solution Approach 2:
The patent incorporates materials with high thermal conductivity (such as tungsten or copper for conductive pillars) into the package structure. These thermally conductive materials are strategically placed to create efficient heat transfer pathways, enabling effective heat dissipation through the thickness direction while minimizing the need for increased overall device dimensions.
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 heat dissipation, mechanical ruggedness, and electrical performance of the packaged SAW devices, allowing for smaller and thinner designs suitable for radio frequency applications.
Implementation Method 1
a piezoelectric layer over the support substrate, an interdigital transducer electrode over the piezoelectric layer
Implementation Method 2
The conductive pillar supports the roof structure and defines at least a portion of an electrical pathway between the interdigital transducer electrode and the conductive via
Data Source
AI summary
A packaged surface acoustic wave device is disclosed. The packaged surface acoustic wave device can include a support substrate that has a first side and a second side opposite the first side. The support substrate including a conductive via extending vertically between the first side to the second side. The packaged surface acoustic wave device can include a piezoelectric layer over the first side of the support substrate, an interdigital transducer electrode over the piezoelectric layer, a roof structure over the interdigital transducer electrode, and a conductive pillar between the first side of the support substrate and the roof structure. The conductive pillar supports the roof structure and defines at least a portion of an electrical pathway between the interdigital transducer electrode and the conductive via. A maximum horizontal dimension of the conductive pillar is greater than a maximum horizontal dimension of the conductive via.