Stacked RF Filter Package With Shared Substrate Cap
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Solution Overview
Problem
Radio frequency (RF) filters in wireless devices occupy significant space, limiting the number of frequencies small devices can operate and communicate at, due to their large form factor.
Innovation Solution
A package design featuring stacked filters with a shared substrate cap, utilizing a first and second polymer frame, interconnects, an encapsulation layer, and through encapsulation vias, which reduces the lateral size and component count while maintaining effective signal filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple RF filters are included in a wireless device to enable operation at different frequencies, then the number of operating frequencies increases, but the device space required increases
Solution Approach 1:
The patent transitions from a planar arrangement of filters to a three-dimensional stacked configuration. Multiple RF filters are arranged vertically along the z-axis rather than horizontally in the x-y plane, enabling multiple frequency operations while maintaining a compact footprint. The substrate cap and interconnect structures facilitate this vertical stacking, allowing filters to be positioned at different heights while remaining electrically connected.
Solution Approach 2:
The patent implements a nested structure where multiple filter assemblies are contained within a shared substrate cap housing. Each filter is individually enclosed in its own cavity formed by the substrate cap, while the entire assembly is integrated into a compact package. This nesting approach allows multiple filters to coexist in a confined space, reducing the overall device area while maintaining individual filter functionality.
2Adaptability or versatility
If multiple RF filters are included in a wireless device to enable operation at different frequencies, then the number of operating frequencies increases, but the device complexity increases
Solution Approach 1:
The substrate cap serves multiple functions simultaneously: it provides structural housing for the filters, forms individual cavities for each filter, provides mounting surfaces for interconnects, and enables electrical connections between stacked filters. This multi-functionality reduces the number of separate components needed, thereby reducing device complexity while supporting multiple frequency operations.
Solution Approach 2:
The patent combines multiple filter assemblies into a single integrated package structure. Rather than using separate housings and mounting structures for each filter, the design merges them into a unified substrate cap assembly with shared structural elements and integrated interconnect pathways, simplifying the overall device architecture.
3Area of stationary object
If RF filters are made smaller to reduce device space, then the device footprint decreases, but the filtering effectiveness may be compromised
Solution Approach 1:
The patent compensates for reduced lateral filter dimensions by extending the filter assembly in the vertical dimension. The stacked configuration allows each filter to maintain adequate active area for effective signal processing, while the overall footprint is reduced by utilizing the z-axis for additional filter placement rather than expanding the x-y plane.
Data Source
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AI summary
A package that includes a first filter (312) comprising a first polymer frame (318), a substrate cap (320), a second filter (332) comprising a second polymer frame (338), at least one interconnect (340), an encapsulation layer (450) and a plurality of through encapsulation vias (452). The substrate cap is coupled to the first polymer frame such that a first void (321) is formed between the substrate cap and the first filter. The second polymer frame is coupled to the substrate cap such that a second void (323) is formed between the substrate cap and the second filter. The at least one interconnect is coupled to the first filter and the second filter. The encapsulation layer encapsulates the first filter, the substrate cap, the second filter, and the at least one interconnect. The plurality of through encapsulation vias are coupled to the first filter.