Embedded RF Filter Package Structure for High Integration
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Solution Overview
Problem
Existing wireless devices face challenges in packaging RF filters due to high complexity, cost, and size, as each filter is assembled separately in ceramic packages, leading to packing density issues and increased costs.
Innovation Solution
A method for forming an embedded filter package that integrates RF filters, such as SAW and BAW filters, with peripheral components like antennas and delay lines in a single structure, using a POL build-up process with dielectric layers and metal interconnects to reduce complexity and cost while enhancing integration and packing density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each RF filter is assembled separately in ceramic packages, then the filter provides adequate protection and performance, but the device complexity and packing density are worsened
Solution Approach 1:
The patent merges multiple separate filter packages into a single integrated package structure. Multiple RF filters (SAW and BAW filters) are combined within one package housing with shared mounting substrate and interconnection system, eliminating the need for multiple separate ceramic packages and reducing overall device complexity while maintaining protection and performance
Solution Approach 2:
The package structure serves multiple functions simultaneously: it provides mechanical protection for multiple filters, electrical interconnection between filters and external circuits, structural mounting support, and shielding. This multi-functional integration reduces the number of separate components needed and simplifies the overall device architecture
2Reliability
If each RF filter is assembled separately in ceramic packages, then the filter provides adequate protection and performance, but the manufacturing cost is increased
Solution Approach 1:
The patent combines multiple filter assembly operations into a single manufacturing process. Filters are mounted on a common substrate within one package, and electrical interconnections are established in a single wiring process, eliminating repetitive assembly steps for each separate package and reducing labor and material costs
Solution Approach 2:
The package is designed with modular components (mounting substrate, wiring layers, housing sections) that can be manufactured separately and assembled efficiently. This segmentation allows for standardized manufacturing processes and easier quality control while reducing overall complexity and cost
3Reliability
If each RF filter is assembled separately in ceramic packages, then the filter provides adequate protection, but the form factor and packing density are worsened
Solution Approach 1:
Multiple filters that would traditionally require separate package volumes are merged into a single shared package housing. The filters are arranged on a common mounting substrate within the same protective enclosure, significantly reducing the total volume occupied by filter assemblies and improving packing density
Solution Approach 2:
The package structure employs nested arrangements where filters are positioned in layers or stacked configurations within the housing. The wiring and interconnections are integrated within the same package volume rather than requiring external connections, maximizing space utilization and minimizing overall form factor
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 approach results in lower cost, smaller form factor, and higher integration with improved RF performance by embedding filters within an insulating substrate, providing shorter path lengths and better grounding, thus overcoming the limitations of traditional packaging methods.
Implementation Method 1
an electrical input signal being converted to an acoustic wave by interleaved metal interdigital transducers (IDTs) 104 created on a piezoelectric substrate 106
Implementation Method 2
the acoustic wave in the SAW filter often propagates along or very near the surface
Implementation Method 3
metal patches 112, 114 are formed/provided on top and bottom sides of a quartz crystal substrate 116 to excite acoustic waves responsive to an electrical input signal provided thereto via electrical ports 118, with the acoustic waves bouncing from the top to bottom surface (i.e., propagate vertically) to form a standing acoustic wave
Data Source
Figure 1~2
Figure 3A~3E
Figure 4~5
AI summary
A filter package and method of manufacturing thereof is disclosed. The filter device (14) package (10, 12) includes a first dielectric layer (18) having an acoustic wave filter device (14) attached thereto, the acoustic wave filter device (14) comprising an active area (34) and I/O pads (30). The filter device (14) package (10, 12) also includes an adhesive (24) positioned between the first dielectric layer (18) and the acoustic wave filter device (14) to secure the layer to the device, vias (26) formed through the first dielectric layer (18) and the adhesive (24) to the I/O pads (30) of the acoustic wave filter device (14), and metal interconnects (28) formed in the vias (26) and mechanically and electrically coupled to the I/O pads (30) of the acoustic wave filter device (14) to form electrical interconnections thereto, wherein an air cavity (32) is formed in the adhesive (24) between the acoustic wave filter device (14) and the first dielectric layer (18), in a location adjacent the active area (34) of the acoustic wave filter device (14).