Wafer-Level Photosensitive Module Bonding
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Solution Overview
Problem
Conventional camera module fabrication using chip on board (COB) technology faces challenges in reducing die thickness, requires physical pressing which can cause damage, and involves costly wire bonding processes that need to be performed in a clean environment, leading to high fabrication costs.
Innovation Solution
A photosensitive module is formed using a wafer-level packaging process where a sensing device with a substrate, conducting pads, and a redistribution layer is bonded to a circuit board, allowing for reduced thickness and eliminating the need for wire bonding, with a cover plate used for support and later removed to expose the pads for optical component mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If COB technology is used to attach die to PCB, then electrical connection is achieved, but die thickness cannot be reduced and physical damage may occur
Solution Approach 1:
The patent replaces the mechanical pressing and wire bonding system with a direct bonding system where the die is bonded directly to the PCB using adhesive material, eliminating the need for mechanical pressing and wire bonding processes. This allows for thinner die without risk of physical damage while maintaining reliable electrical connection.
2Ease of manufacture
If wire bonding processes are performed, then electrical connection is established, but fabrication cost increases due to clean room requirements
Solution Approach 1:
The patent eliminates wire bonding processes entirely by directly bonding the die to the PCB with adhesive material that provides both mechanical support and electrical connection. This substitution removes the requirement for clean room environments and expensive wire bonding equipment, significantly reducing fabrication costs while maintaining reliable electrical connection.
3Ease of manufacture
If adhesive glue is used for bonding, then assembly is simplified, but light transmittance is reduced
Solution Approach 1:
The patent applies adhesive material only in specific localized areas where electrical connection is required, rather than covering the entire die surface. This localized bonding approach maintains simplicity in the assembly process while preserving light transmittance in the optical path areas where no adhesive is present.
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 thickness of the photosensitive module, lowers fabrication costs by avoiding clean room expenses and wire bonding, and enhances the module's reliability and light transmittance by eliminating the need for adhesive glue and wire bonding.
Implementation Method 1
A photosensitive module is formed using a wafer-level packaging process where a sensing device with a substrate, conducting pads, and a redistribution layer is bonded to a circuit board
Data Source
AI summary
A method for forming a photosensitive module is provided. The method includes providing a sensing device. The sensing device includes a substrate having a first surface and a second surface opposite thereto. A conducting pad is located on the first surface. A first opening penetrates the substrate and exposes the conducting pad. A redistribution layer is in the first opening to electrically connect to the conducting pad. A cover plate is located on the first surface and covers the conducting pad. The method also includes bonding the sensing device to a circuit board. The cover plate is removed after bonding the sensing device to the circuit board. The method further includes mounting an optical component corresponding to the sensing device on the circuit board. A photosensitive module formed by the method is also provided.