CMOS Image Sensor Bump Assembly for Optical Axis Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge lies in accurately assembling a CMOS image sensor on a wiring board to a housing without tilting, especially when the wiring board is not flat, which can cause shifts in the optical axis, affecting the depth of focus and assembly precision.
Innovation Solution
The solution involves using a bump unit with conductive bumps on both the sensor chip and the wiring board, where the bumps are formed by conductive members with the same composition, allowing for precise alignment and adherence, and incorporating a protective member and adhesive to ensure accurate assembly and prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a CMOS image sensor is mounted on a non-flat wiring board, then the mounting process becomes simpler, but the optical axis alignment accuracy deteriorates
Solution Approach 1:
A bump unit with a convex portion is introduced as an intermediary component between the sensor chip and the wiring board. The convex portion of the bump unit fits into a corresponding concave portion on the wiring board, providing a precise positioning reference that ensures accurate optical axis alignment even when the wiring board surface is not perfectly flat. This mediator structure resolves the contradiction by enabling both simplified mounting and high precision alignment.
2Device complexity
If the wiring board surface is not flattened, then the manufacturing complexity is reduced, but the assembly accuracy deteriorates
Solution Approach 1:
The bump unit with its convex positioning portion serves as a mediator that compensates for the non-flat surface of the wiring board. Instead of requiring the wiring board to be perfectly flattened (which would increase device complexity), the convex portion of the bump unit provides the necessary geometric reference for accurate assembly, thereby maintaining high assembly accuracy without additional wiring board processing steps.
Solution Approach 2:
The convex portion is formed on the bump unit in advance during the bump formation process, before the actual mounting operation. This preliminary creation of the positioning feature allows the bump unit to self-align with the corresponding concave portion on the wiring board during assembly, ensuring accurate positioning without requiring post-assembly adjustments or complex wiring board preparation.
3Reliability
If a bump unit with conductive members is used for joining, then the electrical connection is improved, but the structural complexity increases
Solution Approach 1:
The bump unit merges multiple functions into a single integrated structure: it provides electrical connection through the conductive members, mechanical support through the convex portion, and precise positioning through the fit between the convex portion and the concave portion on the wiring board. By combining these functions into one component rather than using separate elements for each function, the overall device complexity is minimized while maintaining high reliability.
Data Source
AI summary
Provided are an imaging apparatus and an electronic device in which even if an image sensor is mounted on a wiring board, the wiring board on which the image sensor is mounted can be assembled to a housing with high accuracy. Provided is an imaging apparatus including a sensor chip and a wiring board having a glass base material. The imaging apparatus is joined to at least one of the sensor chip or the wiring board via a bump unit including a plurality of bumps, and each of the plurality of bumps is formed by conductive members having substantially the same composition.