Acoustic Wave Device Pillar Pad Wafer-Level Packaging
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Solution Overview
Problem
Acoustic wave devices, such as SAW and BAW devices, have a large footprint due to design and manufacturing limitations that require pads to be placed next to the substrate, necessitating singulation before pad formation, which complicates the manufacturing process and increases device size.
Innovation Solution
The method involves forming acoustic wave devices with pillars and pads that provide electrical connections, using a photo-definable dry film material for the cap and wall layer to maintain structural integrity and allow for wafer-level packaging, enabling the formation of multiple devices on a substrate before singulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pads are placed next to the substrate structure, then electrical connections can be established, but the device footprint increases and singulation is required before pad formation
Solution Approach 1:
The patent moves the pads from the substrate plane to the cap structure plane, utilizing the vertical dimension (z-axis) to relocate electrical connection points. This dimensional transition allows pads to be positioned away from the substrate edges without increasing the device footprint, while still providing accessible electrical connections for packaging.
Solution Approach 2:
The cap structure with integrated pads is formed before the final packaging stage, allowing electrical connections to be established in advance. This preliminary formation of pads on the cap enables subsequent underfill encapsulation to proceed without requiring prior singulation, simplifying the manufacturing sequence.
2Manufacturing precision
If singulation is performed before pad formation, then pads can be formed with proper electrical connections, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The cap structure containing the pads is formed in advance during the wafer-level packaging process, before final device singulation. This preliminary formation of the cap with integrated pads eliminates the need for post-singulation pad formation steps, maintaining manufacturing precision while significantly improving productivity by enabling batch processing of multiple devices.
Solution Approach 2:
The patent combines the cap structure formation and pad formation into a single integrated process step. By merging these operations, the device is manufactured as a complete unit with electrical connections already in place, eliminating separate processing steps and enhancing manufacturing throughput without compromising pad formation precision.
3Productivity
If wafer-level packaging is used, then multiple devices can be processed simultaneously improving productivity, but structural integrity must be maintained during high-temperature processing
Solution Approach 1:
The cap structure is formed using a photo-definable dry film material that provides both mechanical strength for structural integrity and compatibility with high-temperature processing. This composite approach combines the substrate, cap, and underfill material into a unified structure that maintains stability during wafer-level packaging and subsequent thermal processing steps.
Solution Approach 2:
The cap structure acts as an intermediary element between the substrate and the external environment, providing structural support and protecting the device during high-temperature processing. This intermediate cap layer enables wafer-level packaging by maintaining structural integrity throughout the processing sequence while allowing batch manufacturing of multiple devices.
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 reduces the device footprint, simplifies the manufacturing process by allowing wafer-level packaging, and maintains structural integrity during high-temperature processing, facilitating the integration of acoustic wave devices in compact electronic systems.
Implementation Method 1
a cap and wall layer formed from a photo-definable dry film material and cured
Data Source
AI summary
Embodiments described herein may provide an acoustic wave device, a method of fabricating an acoustic wave device, and a system incorporating an acoustic wave device. The acoustic wave device may include a transducer disposed on a substrate, with a contact coupled with the transducer. The acoustic wave device may further include a wall layer and cap that define an enclosed opening around the transducer. A via may be disposed through the cap and wall layer over the contact, and a top metal may be disposed in the via. The top metal may form a pillar in the via and a pad on the cap above the via. The pillar may provide an electrical connection between the pad and the contact. In some embodiments, the acoustic wave device may be formed as a wafer-level package on a substrate wafer.