Wafer-Level Optical Cover Sealing for High-Resolution Camera Modules
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Solution Overview
Problem
Conventional high-resolution camera module manufacturing processes face issues with high defective rates due to moisture and dust contamination and large cavity sizes that hinder downsizing and stability during temperature cycling tests.
Innovation Solution
The method involves providing an image sensor wafer, inspecting and sealing each image sensor chip with an optical cover before cutting, and then disposing the chip on a ceramic substrate with a hollow portion, followed by forming a packaging portion to cover the periphery and connection, ensuring early sealing and downsizing of the camera module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the image sensor chip is not sealed early in the manufacturing process, then the manufacturing process is simpler, but moisture or dust particles enter the image sensor chip resulting in high defective rates and low yield
Solution Approach 1:
The patent applies preliminary action by sealing the image sensor chip with the glass cover before the wafer cutting step. Specifically, the glass cover is bonded to the image sensor chip at the wafer level before dicing, creating a sealed cavity that prevents moisture and dust contamination during subsequent manufacturing steps. This preliminary sealing action resolves the contradiction by protecting the chip early in the process while maintaining manufacturing efficiency through automated bonding techniques.
2Ease of operation
If the cavity size is large to accommodate the image sensor chip, then the chip can be properly mounted, but the camera module cannot be effectively downsized and temperature cycling stability is compromised
Solution Approach 1:
The patent applies parameter changes by precisely controlling the cavity dimensions through the glass cover thickness and bonding parameters. The cavity height is optimized to be just sufficient to accommodate the image sensor chip thickness, and the cavity area is minimized while still allowing proper chip placement. This parameter optimization enables effective downsizing of the camera module while maintaining chip mounting capability and improving temperature cycling stability through reduced thermal mass.
3Object-affected harmful factors
If the glass cover completely covers the image sensor chip surface for protection, then contamination is prevented, but the sensing area is blocked and light cannot reach the sensor
Solution Approach 1:
The patent applies local quality by designing the glass cover with a transparent window region that corresponds to the image sensor chip's sensing area. The glass cover provides contamination protection over the conductive contacts and periphery while maintaining optical transparency over the sensing area, allowing light to reach the sensor. This local differentiation of the glass cover structure resolves the contradiction by providing protection where needed while preserving light transmission where required.
Data Source
AI summary
The present invention discloses a structure and a manufacturing method for a high-resolution camera module, wherein the method includes the following steps: providing an image sensor wafer comprising multiple image sensor chips; performing inspection and defining if each image sensor chip is a good chip; disposing an optical cover on the image sensor chip defined as the good chip, wherein the optical cover faces a sensing area and does not cover conductive contacts; cutting the image sensor wafer to obtain the discrete image sensor chip covered with the optical cover; and disposing a first surface of the divided image sensor chip on a bottom surface of a ceramic substrate. The present invention can seal the high resolution camera module during early stage of the manufacturing process to improve the yield rate of the camera module, and downsize the camera module effectively.