Camera Module With Substrate Cavity For Image Sensor
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Solution Overview
Problem
Existing camera module designs are limited by the height of the image plane, which restricts the Effective Focal Length (EFL) and Total Track Length (TTL), preventing optimization of lens characteristics and space for the lens, as the image sensor is typically mounted on top of a printed circuit board with limited thickness.
Innovation Solution
A camera module design featuring an image sensor located in a cavity within the substrate, connected by a bridge member and sealed with adhesive, where the bridge member includes an infra-red filter, and additional mechanical support is provided by a sheet member to enhance strength and rigidity without increasing substrate thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the image sensor is mounted on top of the substrate, then the mechanical structure is simple and easy to manufacture, but the image plane height is high which limits the EFL and TTL
Solution Approach 1:
The image sensor is moved from the top surface of the substrate into a cavity within the substrate, utilizing the third dimension (depth) to reduce the image plane height. This dimensional transition allows the sensor to be positioned lower while maintaining mechanical connectivity through the bridge member, thereby increasing the EFL and TTL without compromising manufacturing feasibility.
Solution Approach 2:
The image sensor is nested within the cavity of the substrate, with the bridge member providing mechanical support from within the substrate structure. This nesting approach allows the sensor to be housed inside the substrate volume, reducing the overall image plane height while maintaining structural integrity and ease of assembly.
2Length of stationary object
If the substrate thickness is reduced to lower the image plane height, then the EFL and TTL are increased, but the mechanical strength and rigidity of the substrate are compromised
Solution Approach 1:
The substrate is segmented to create a cavity that houses the image sensor, with the bridge member providing localized structural support. This segmentation allows the substrate to be thinner overall while the bridge member compensates for the reduced thickness by providing targeted mechanical reinforcement at the sensor mounting location, preventing warpage and maintaining strength.
Solution Approach 2:
The bridge member acts as an intermediary element between the image sensor and the substrate, providing mechanical support and reinforcement. This intermediary structure allows the substrate to be thinner without compromising strength, as the bridge member carries the mechanical load and prevents warpage, enabling reduced image plane height while maintaining substrate integrity.
3Length of stationary object
If the image sensor is placed in a cavity in the substrate, then the image plane height is lowered to increase EFL and TTL, but the device complexity increases
Solution Approach 1:
The bridge member serves multiple functions: it provides mechanical support for the image sensor, acts as an infra-red filter, and reinforces the substrate structure. This multi-functionality reduces the need for additional separate components, thereby minimizing the increase in device complexity while achieving the goal of lowering the image plane height to increase EFL and TTL.
Solution Approach 2:
The bridge member combines multiple functions into a single component: structural support, infra-red filtering, and mechanical reinforcement. By merging these functions into one element rather than using separate components, the design achieves reduced image plane height without proportionally increasing device complexity, as the same component performs multiple roles in the system.
Data Source
AI summary
A camera module has a lens module mounted on a substrate. The image sensor is located in a cavity in the substrate and is connected to the substrate by a bridge member, the infra-red filter. The image sensor is attached to the infra-red filter by a ring of adhesive surrounding the imaging area of the image sensor. The adhesive attaching the image sensor to the infra-red filter comprises spacers. The infra-red filter is attached to the substrate by adhesive. The cavity may extend through the substrate. The image sensor is further connected to the substrate by a sheet member, which may be made of metal. The sheet member is affixed to the bottom of the substrate and covers the hole in the substrate formed by the extension of the cavity through the substrate. A method of assembly of the camera module includes: providing a substrate with a cavity; locating the image sensor in the cavity; connecting the infra-red filter to the image sensor and the substrate; and mounting the lens module on the substrate.