Camera Module Bump Support for Image Sensor Warpage Control
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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 featuring a reinforcing plate with a bump part composed of a metal wire, where the image sensor is directly supported by the bump part, minimizing adhesive area and allowing efficient heat dissipation through the reinforcing plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the image sensor is directly mounted on the printed circuit board using adhesive, then the image sensor can be positioned at a high location for proper optical alignment, but thermal expansion mismatch causes warpage that deteriorates resolution performance and reduces yield
Solution Approach 1:
The support structure is segmented into multiple layers: a first support layer (reinforcing plate) providing mechanical support and heat dissipation, and a second support layer (substrate with cavity) providing positional support and adhesive area reduction. This segmentation allows the image sensor to be positioned at the required height while maintaining flatness by distributing support functions across different structural elements.
Solution Approach 2:
The adhesive member is applied selectively only at the four corners of the image sensor rather than across the entire surface. This local application minimizes the adhesive area, reducing the overall thermal expansion mismatch effect while still providing adequate mechanical bonding. The corner-specific adhesive placement maintains positional stability without causing widespread warpage.
2Strength
If a large area of adhesive is used to bond the image sensor to the reinforcing plate, then bonding strength is improved, but thermal expansion differences cause severe warpage in a '∩' shape
Solution Approach 1:
Instead of applying adhesive across the entire image sensor surface (excessive action), the adhesive is applied only at the four corners (partial action). This partial application provides sufficient bonding strength for mechanical attachment while minimizing the total adhesive volume that would otherwise cause thermal expansion mismatch and warpage during curing and operation.
3Temperature
If the image sensor is mounted on a printed circuit board with cavity and reinforcing plate, then heat dissipation is improved, but the complex structure increases device height and manufacturing complexity
Solution Approach 1:
The reinforcing plate serves multiple functions simultaneously: it provides mechanical support for the image sensor, acts as a heat dissipation pathway due to its high thermal conductivity, and serves as a mounting base for the substrate. This multi-functionality reduces the need for separate dedicated heat sink components, simplifying the overall structure while maintaining effective heat dissipation.
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 minimizes warpage, improves operational reliability, and maintains the flatness of the active pixel region, enhancing image quality and yield by reducing adhesive-induced distortions.
Implementation Method 1
allows efficient heat dissipation through the reinforcing plate
Implementation Method 2
when the thermal curing proceeds, the configuration including the reinforcing plate, the epoxy and the image sensor is heat-expanded and then contracted
Data Source
AI summary
A camera module according to an embodiment includes a reinforcing plate; a bump part disposed on the reinforcing plate; a substrate disposed on the reinforcing plate and including a cavity vertically overlapping the bump part; and an image sensor disposed on the bump part, wherein the bump part includes a first bump disposed on the reinforcing plate and having a first height; and a second bump disposed on the first bump and having a second height different from the first height; and wherein an upper surface of the second bump is in direct contact with a lower surface of the image sensor.