Image Sensor Mounting Structure for Low-Warpage Camera Modules
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Solution Overview
Problem
Conventional camera modules experience warpage issues due to differences in thermal expansion coefficients between the image sensor, adhesive member, and reinforcing plate, leading to reduced resolution performance and yield.
Innovation Solution
A camera module design that includes a wire part on a reinforcing plate supporting the image sensor, with a reduced adhesive area and direct contact between the sensor and wire, minimizing warpage and enhancing heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the image sensor is directly mounted on the printed circuit board using a cavity type PCB and reinforcing plate, then heat dissipation is improved, but warpage occurs due to thermal expansion differences
Solution Approach 1:
The adhesive member is applied selectively only at the four corner regions of the reinforcing plate rather than covering the entire surface. This localized application reduces the total adhesive area, minimizing its thermal expansion contribution while maintaining sufficient bonding strength to prevent warpage during thermal curing processes.
Solution Approach 2:
The invention changes the physical state and material properties of the adhesive member by selecting a material with a low coefficient of thermal expansion (50 ppm/°C or less). This parameter change allows the adhesive to better match the thermal expansion characteristics of the image sensor and reducing differential expansion stresses that cause warpage.
2Reliability
If the image sensor is mounted on a printed circuit board, then electrical connection is achieved, but heat generated from the image sensor is not emitted effectively
Solution Approach 1:
The reinforcing plate serves as an intermediary component between the image sensor and the printed circuit board. It provides both mechanical support for mounting the image sensor and acts as a heat dissipation pathway, conducting heat away from the image sensor to the PCB through its thermally conductive material composition.
3Strength
If epoxy is applied on the reinforcing plate to bond the image sensor, then bonding strength is improved, but warpage increases due to thermal expansion differences
Solution Approach 1:
The adhesive member is applied selectively only at the four corner regions of the reinforcing plate rather than covering the entire surface. This localized application reduces the total adhesive area, minimizing its thermal expansion contribution while maintaining sufficient bonding strength to prevent warpage during thermal curing processes.
Solution Approach 2:
The invention uses a composite material approach by selecting an adhesive member with specific material properties (low coefficient of thermal expansion of 50 ppm/°C or less) that differs from conventional epoxies. This composite material strategy creates a more thermally stable bonding layer that reduces warpage while maintaining bonding strength.
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
The design effectively minimizes warpage and improves reliability and performance by efficiently transferring heat away from the image sensor, maintaining resolution and increasing yield.
Implementation Method 1
heat generated from the image sensor is not emitted, and thus there is a reliability problem due to heat generation
Implementation Method 2
an epoxy for bonding an image sensor is applied on the reinforcing plate
Implementation Method 3
warpage occurs due to a difference between a coefficient of thermal expansion of the image sensor, a coefficient of thermal expansion of the printed circuit board, and a coefficient of thermal expansion of the epoxy
Data Source
AI summary
A camera module according to an embodiment includes a circuit board including a cavity; a reinforcing plate including a first region corresponding to the cavity and a second region in which the circuit board is disposed; a wire part disposed in the first region of the reinforcing plate; and an image sensor disposed on the wire part, wherein a lower surface of the image sensor is in direct contact with the wire part, and wherein the wire part and the image sensor are electrically separated from each other.