Conductive Pillar Wafer-Level Package for Acoustic Resonator Stress
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Solution Overview
Problem
Existing acoustic resonators face challenges with heat dissipation and thermal grounding, leading to performance degradation due to differences in thermal expansion coefficients between the resonator and mounting structures, which can induce stress and affect the resonator's functionality.
Innovation Solution
A wafer-level package design incorporating electrically and thermally conductive pillars and layers with specific materials and dimensions to absorb stress and enhance thermal dissipation, using copper for pillars and tin-silver solder for layers, which have different thermal expansion coefficients and conductivity properties to mitigate stress and improve heat removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resonator is mounted on a substrate with different thermal expansion coefficients, then the resonator can be electrically connected and mechanically supported, but stress is induced due to thermal expansion mismatch which degrades resonator performance
Solution Approach 1:
The patent introduces an intermediate layer between the resonator and substrate that serves as a stress-absorbing interface. This intermediate structure allows thermal expansion mismatch between different materials to be accommodated without transmitting damaging stress to the resonator, thereby maintaining resonator performance while enabling mechanical support and electrical connection.
Solution Approach 2:
The patent modifies the physical parameters of the mounting structure by using materials with specific thermal expansion coefficients and conducting experiments at different temperatures. By controlling and matching thermal expansion parameters between components, the stress induced during temperature changes is minimized, preventing resonator performance degradation.
2Temperature
If heat dissipation structures are added to the resonator package, then thermal management is improved, but the package complexity increases
Solution Approach 1:
The patent designs the package structure to serve multiple functions simultaneously. The same structural elements that provide mechanical support and electrical connection also function as heat dissipation pathways. By making the package components multi-functional, effective thermal management is achieved without proportionally increasing package complexity.
Solution Approach 2:
The patent combines the heat dissipation function with the existing mechanical and electrical support structures. Rather than adding separate dedicated heat sinks or thermal management components, the thermal conduction pathways are integrated into the existing package architecture, reducing overall complexity while improving heat dissipation.
3Device complexity
If electrical grounding is achieved through the same component used for heat dissipation, then the number of components is reduced, but the thermal and electrical performance may be compromised
Solution Approach 1:
The patent segments the grounding and heat dissipation functions into separate but integrated pathways. By providing dedicated electrical grounding paths while maintaining separate thermal conduction routes, the structure achieves both functions effectively without relying on a single component to perform both roles, thus preventing performance compromise.
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 effectively reduces stress-induced degradation in acoustic resonators, enhances thermal and electrical conductivity, and improves the overall performance by optimizing the structure's thermal and electrical properties while maintaining hermeticity and preventing contamination.
Implementation Method 1
electrically and thermally conductive pillars and layers with specific materials and dimensions to absorb stress and enhance thermal dissipation, using copper for pillars and tin-silver solder for layers
Implementation Method 2
electrically and thermally conductive pillars and layers with specific materials and dimensions to absorb stress and enhance thermal dissipation, using copper for pillars and tin-silver solder for layers
Implementation Method 3
using copper for pillars and tin-silver solder for layers, which have different thermal expansion coefficients and conductivity properties to mitigate stress and improve heat removal
Data Source
AI summary
An apparatus include a device substrate having an upper surface, and a frame layer having an upper surface. The frame layer is disposed over the upper surface of the device substrate, and a first opening exists in the frame layer. The apparatus also includes a seed layer disposed over the device substrate and substantially bounded by the first opening; and a lid layer having an upper surface. The lid layer is disposed over the upper surface of the frame layer. A second opening exists in the lid layer, and the second opening is aligned with the first opening. The apparatus also includes an electrically and thermally conductive pillar disposed in the first opening and the second opening.