Flip-Chip Image Sensor Die for Compact Camera Modules
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Solution Overview
Problem
There is a need for improved camera module designs and manufacturing processes that are cost-effective and have low manufacturing yield loss, particularly for incorporation into thin mobile devices like smartphones and tablets, while maintaining high-quality photographic capabilities.
Innovation Solution
The design incorporates a flip-chip image sensor die connected to a substrate via wire bonds, with an autofocus lens module using voice coil motors or MEMS actuators, and a manufacturing process that includes semiconductor wafer processing and assembly techniques such as wire-bonding and substrate thinning to form a compact camera module with high yield and optical alignment optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional camera module design is used, then manufacturing processes are established, but manufacturing yield loss is high and cost-effectiveness is reduced
Solution Approach 1:
The patent inverts the conventional mounting approach by flipping the image sensor die 180 degrees so that the photosensor portion faces downward toward the substrate. This inversion allows wire bonds to be formed on the periphery of the die before mounting, eliminating complex alignment procedures and reducing manufacturing yield loss while improving cost-effectiveness
2Manufacturing precision
If the image sensor die is mounted with photosensor portion facing upward, then conventional assembly procedures are used, but optical alignment is difficult and manufacturing complexity increases
Solution Approach 1:
By mounting the image sensor die in an inverted orientation with the photosensor portion facing downward, the patent simplifies optical alignment. The photosensor portion can be directly positioned over the lens aperture without requiring complex alignment mechanisms, thereby improving manufacturing precision while reducing assembly complexity
Solution Approach 2:
The substrate serves as an intermediary that supports the inverted image sensor die and provides a stable mounting surface. This intermediary structure facilitates precise positioning of the photosensor portion relative to the lens aperture while simplifying the overall assembly process
3Reliability
If wire bonds are used to connect the image sensor die to the substrate, then electrical connections are established, but coplanarity between sensor die and substrate is improved
Solution Approach 1:
The inverted mounting orientation allows wire bonds to be formed on the periphery of the image sensor die before the die is mounted to the substrate. This approach improves coplanarity between the sensor die and substrate surfaces while maintaining reliable electrical connections through the wire bonds, as the bonds are formed when the die is in a stable, accessible position
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 results in a cost-effective camera module with high manufacturing yield and improved optical alignment, enabling small form factor autofocus capabilities in mobile devices with reduced yield loss and increased coplanarity between the sensor die and substrate.
Implementation Method 1
voice coil motors or MEMS actuators
Implementation Method 2
voice coil motors or MEMS actuators
Implementation Method 3
wire bonds
Implementation Method 4
lens module with autofocus capability
Data Source
AI summary
Various embodiments are directed to a camera module, image sensor die, and methods for manufacturing the same. The image sensor die comprises a thinned wafer portion, a photosensor portion adjacent the thinned wafer portion and a carrier wafer. Vias may be formed through the carrier wafer to connect the photosensor portion to die contacts. A first side of the image sensor die opposite the die contacts may be bonded to a first side of the rigid substrate. Wire bonds may be formed between the die contacts and substrate-sensor contacts positioned on the first side of the rigid substrate.