Through-Glass-Via Acoustic Filter Capping With 3D Inductors
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Solution Overview
Problem
The design complexity of mobile RF transceivers is compounded by noise interference from harmonic frequencies in carrier aggregation systems, and existing surface acoustic wave packaging technologies face challenges in efficiently fabricating high-performance filters and resonators with sufficient inductor quality and reduced electromagnetic coupling.
Innovation Solution
A passive on glass (POG) filter capping apparatus is developed, featuring a capping die with 3D inductors and through glass vias, which is electrically coupled to an acoustic filter die, allowing for increased inductor integration and reduced electromagnetic interference, enabling full filter functionality and supporting communication enhancements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If 2D inductors are used on a capping wafer in existing DSSP2 packaging, then the packaging can be implemented, but the inductors generate vertical magnetic field interference with the SAW filter and there is insufficient space for additional inductors
Solution Approach 1:
The patent transitions from 2D planar inductors to 3D inductors by utilizing vertical stacking and through-glass-via connections. This dimensional change allows inductors to be arranged in multiple layers, increasing spatial efficiency and reducing electromagnetic interference through improved geometric distribution of current paths.
Solution Approach 2:
The patent implements nested inductor structures where smaller inductors are positioned within the footprint of larger inductors, and multiple inductor windings are stacked vertically. This nesting approach maximizes the use of available space on the capping wafer while maintaining electrical isolation between adjacent inductors.
2Adaptability or versatility
If multiple passive devices with many inductors and capacitors are included to support carrier aggregation, then communication enhancements are enabled, but design complexity increases and electromagnetic coupling between inductors worsens
Solution Approach 1:
The patent combines multiple inductors and capacitors into integrated passive device structures where multiple functional elements are fabricated together on the same capping wafer. This merging reduces the total number of discrete components, simplifies interconnections, and enables carrier aggregation functionality while controlling design complexity through unified fabrication processes.
3Reliability
If the number of inductors is increased to provide sufficient phase shift for duplexers and multiplexers, then filter performance improves, but electromagnetic coupling between inductors increases
Solution Approach 1:
By stacking inductors in multiple vertical layers connected through glass vias, the patent increases the physical separation between inductor windings in the horizontal plane. This dimensional arrangement reduces mutual inductance and electromagnetic coupling between adjacent inductors while still providing the necessary total phase shift through the combined effect of multiple inductors.
4Ease of manufacture
If existing complex process flows are used to fabricate both 2D inductors and through substrate vias, then interconnects can be formed, but manufacturing complexity increases
Solution Approach 1:
The patent merges the fabrication of inductors and through-glass-vias into a unified process sequence. Inductor windings are deposited and patterned, then through-glass-vias are formed and filled, and finally additional inductor layers are completed in an integrated manner. This combined approach reduces the number of separate fabrication modules required and simplifies the overall process flow compared to manufacturing inductors and vias as distinct components.
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 POG filter capping apparatus enhances inductor quality, reduces electromagnetic coupling, and increases the number of inductors, thereby improving filter performance and supporting advanced communication technologies like 5G, while simplifying the fabrication process and reducing costs.
Implementation Method 1
The capping die may include a 3D inductor
Implementation Method 2
Existing die scale surface acoustic wave (SAW) packaging (DSSP2)
Data Source
AI summary
A passive on glass (POG) on filter capping apparatus may include an acoustic filter die. The apparatus may further include a capping die electrically coupled to the acoustic filter die. The capping die may include a 3D inductor.