Folded HDI Tape Camera Module for Low-Profile Wearables
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Solution Overview
Problem
Existing camera modules have large physical package dimensions, which are not suitable for next-generation wearable devices such as augmented reality (AR) and virtual reality (VR) glasses that require smaller form factors.
Innovation Solution
A camera module is fabricated using high-density interconnect (HDI) tape folded around an image sensor die, with passive electronic components coupled together to reduce dimensions, and the HDI tape is folded or bent to enclose the image sensor die while maintaining electrical connectivity through flexible insulator layers and bonding bumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional camera module packaging is used, then manufacturing and assembly are straightforward, but the physical package dimensions become too large for wearable devices
Solution Approach 1:
The flexible interconnect tape is folded around the image sensor die in a nested configuration, with the tape enclosing the sensor die multiple times to create a compact three-dimensional structure. This nesting approach allows the interconnect to be integrated within the sensor package rather than extending externally, dramatically reducing the overall camera module volume while maintaining all necessary electrical connections.
Solution Approach 2:
The interconnect transitions from a traditional two-dimensional planar layout to a three-dimensional folded structure by bending the flexible tape around the sensor die in multiple directions. This dimensional transformation enables the interconnect to achieve longer trace lengths within a smaller footprint, allowing comprehensive electrical connectivity without increasing the camera module's external dimensions.
2Volume of moving object
If the camera module is reduced in size, then it becomes suitable for wearable devices, but the interconnect length and routing become more difficult
Solution Approach 1:
The patent employs a flexible interconnect tape with thin-film construction that can be bent and folded without compromising electrical integrity. This flexibility allows the interconnect to conform to the compact folded geometry around the sensor die, enabling size reduction while maintaining manufacturability through standard flexible PCB fabrication processes that accommodate bending radii and stress relief features.
Solution Approach 2:
The interconnect tape is divided into multiple folded segments that wrap around different sides of the sensor die, with each segment handling specific electrical connections. This segmentation allows complex routing to be broken down into manageable sections, each fabricated and tested independently before final assembly, thereby simplifying the overall manufacturing process despite the three-dimensional complexity.
3Length of stationary object
If the interconnect is folded around the image sensor die, then stack height is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The flexible interconnect tape is pre-formed with the required fold geometry and trace routing before assembly to the sensor die. This preliminary fabrication of the folded structure allows precise alignment features to be built into the interconnect itself, such as positioning tabs and registration marks, which guide the assembly process and ensure accurate placement without requiring high-precision alignment during final assembly.
Solution Approach 2:
The patent utilizes changes in material properties, specifically the flexibility and elastic recovery characteristics of the interconnect tape, to accommodate manufacturing tolerances. The flexible material can withstand the stresses of folding and assembly while maintaining dimensional stability, allowing for practical manufacturing precision levels rather than requiring ultra-precise alignment, thereby reducing the stringency of manufacturing specifications.
Data Source
AI summary
A camera module includes an image sensor die, high-density interconnect (HDI) tape, and a number of passive electronic components. The image sensor die has a first side and a second side. The first side includes a pixel array, and the second side is opposite the first side. The HDI tape is a flexible substrate coupled to the image sensor. The HDI tape is at least partially folded or bent around the image sensor to couple to the HDI tape to the first and second sides of the image sensor die. The passive electronic components are coupled to the second side of the HDI tape and provide rigidity to the camera module.