Camera Module Resin Multilayer Board Flatness Control
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Solution Overview
Problem
Existing camera modules with thermoplastic resin flexible boards face issues with non-uniform deformation and tilting of image sensors due to heating or pressing during mounting, affecting optical characteristics.
Innovation Solution
A camera module design featuring a resin multilayer board with a flat plate portion and a rigid portion, where via-hole conductors are positioned in the rigid portion to avoid the thermoplastic resin layer on the flat plate portion, ensuring uniform resin flow and maintaining flatness during mounting, and embedded components are placed in the rigid portion to prevent optical interference and dust entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heating or pressing is applied during image sensor mounting on a thermoplastic resin FPC, then the image sensor can be securely mounted, but the thermoplastic resin flows non-uniformly around via-hole conductors causing FPC deformation and image sensor tilt
Solution Approach 1:
The FPC is divided into a flexible region (with via-hole conductors) and a mounting region (flat plate portion without via-hole conductors). This segmentation allows the mounting region to maintain uniform flatness during heating/pressing while the flexible region provides necessary flexibility and electrical connectivity.
Solution Approach 2:
The flat plate portion is designed with different local properties compared to the rest of the FPC - specifically, it has no via-hole conductors and uses thermoplastic resin layers with controlled thickness and composition. This local quality difference ensures uniform resin flow and maintains high flatness in the mounting area during thermal processing.
2Ease of operation
If via-hole conductors are present in the FPC to provide electrical connectivity, then the image sensor can be electrically connected, but they cause non-uniform resin flow and deformation when heated
Solution Approach 1:
Via-hole conductors are extracted from the mounting area (flat plate portion) and relocated to the flexible region. This extraction eliminates the source of non-uniform resin flow in the critical mounting area, ensuring flatness is maintained during heating and pressing operations.
Solution Approach 2:
The via-hole conductors are positioned in the flexible region where they can still provide necessary electrical connectivity through alternative routing, separating their functional role from the structural requirements of the mounting area. This spatial reorganization resolves the conflict between connectivity needs and flatness maintenance.
3Adaptability or versatility
If the FPC is made flexible using thermoplastic resin to enable bending and conformal mounting, then adaptability is improved, but the resin deforms under heat and pressure affecting optical characteristics
Solution Approach 1:
The FPC is segmented into a flexible region (providing adaptability) and a rigid mounting region (providing stability). The flexible region contains the thermoplastic resin layers with via-hole conductors that enable bending, while the rigid mounting region maintains dimensional stability for optimal optical performance.
Solution Approach 2:
Different regions of the FPC are assigned different local qualities: the flexible region has thermoplastic resin layers optimized for flexibility and electrical connectivity, while the flat plate portion has controlled resin composition and thickness optimized for dimensional stability and flatness during mounting operations.
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 design stabilizes the optical characteristics by preventing sensor tilt and ensuring high flatness, reducing non-uniform resin flow, and enhancing light shielding and dust protection.
Implementation Method 1
If the FPC is formed from a thermoplastic resin, the thermoplastic resin is plasticized even at a relatively low temperature. Thus, in a mounting method involving heating or pressing, flowing of the thermoplastic resin occurs.
Data Source
AI summary
A camera module includes an image sensor IC, a resin multilayer board including thermoplastic resin layers stacked in a direction perpendicular or substantially perpendicular to a light receiving surface of the image sensor IC, a mounting electrode which is stacked on the thermoplastic resin layer and on which the image sensor IC is mounted, and a via-hole conductor electrically connected to the mounting electrode. The resin multilayer board includes a flat plate portion including a surface on which the mounting electrode is mounted, and a rigid portion including a greater number of thermoplastic resin layers than that of the flat plate portion, and the via-hole conductor is arranged in the flat plate portion so as to avoid the thermoplastic resin layer on which the mounting electrode is stacked.