Light-Shielding Conductive Layer on Flexible Wiring Board
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Solution Overview
Problem
In liquid crystal apparatuses, light leakage through flexible wiring boards occurs due to the absence of a conductive layer beneath light-emitting or light-receiving devices, leading to reduced light directionality and increased thickness when attempting to use light-shielding members.
Innovation Solution
A mount structure with a light-shielding conductive layer formed using the same conductive material as the pads on the flexible wiring board, positioned beneath the light emission or reception center, prevents light leakage by blocking light in all directions relative to the optical axis, allowing for reduced thickness and improved light directionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light-shielding member is disposed on the second surface side of the flexible wiring board to prevent light leakage, then light leakage is prevented, but the thickness of the mount structure is increased
Solution Approach 1:
Instead of placing the light-shielding conductive layer on the second surface side (back side) of the flexible wiring board, the invention inverts the approach by forming the light-shielding conductive layer on the first surface side (front side) of the flexible wiring board, using the same conductive layer as the pads. This inversion allows light shielding functionality to be integrated into the existing conductive layer structure on the front surface, preventing light leakage without increasing the overall thickness of the mount structure.
Solution Approach 2:
The conductive layer that forms the first and second pads is given multiple functions: it serves both as an electrical connection element (pad) and as a light-shielding element. By forming the light-shielding conductive layer using the same conductive material and process as the pads, the invention eliminates the need for separate light-shielding components, thereby preventing light leakage without adding extra thickness to the mount structure.
2Length of stationary object
If the same conductive layer is used for both pads and light-shielding to reduce thickness, then thickness is reduced, but light leakage is not effectively prevented
Solution Approach 1:
The conductive layer is selectively formed in specific regions to serve different functions: it forms the first and second pads for electrical connection, and simultaneously forms a light-shielding conductive layer in the region beneath the light emission center. This local differentiation allows the same conductive layer to provide both electrical functionality and light shielding where needed, effectively preventing light leakage while maintaining reduced thickness.
Solution Approach 2:
The light-shielding conductive layer is formed in advance during the same manufacturing process as the pads, before the light-emitting device is mounted. By preliminarily forming the light-shielding conductive layer in the appropriate position on the first surface side of the flexible wiring board, the invention ensures that light leakage is prevented from the outset without requiring additional thickness or post-assembly modifications.
3Reliability
If a conductive layer is not formed beneath the light-emitting device to maintain electrical isolation, then electrical isolation is maintained, but light leakage occurs through the base film
Solution Approach 1:
The conductive layer is segmented into functionally distinct regions: pad regions for electrical connection and a light-shielding region for optical control. The light-shielding conductive layer is formed in the region beneath the light emission center without creating electrical connection issues, as it serves purely as an optical barrier. This segmentation allows electrical isolation to be maintained while simultaneously preventing light leakage through the base film in the light-shielding region.
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 solution effectively prevents light leakage, ensuring that light is emitted or received only from a predetermined direction, reducing the thickness of the mounting region and enhancing the efficiency and accuracy of light management in liquid crystal apparatuses.
Implementation Method 1
a light-shielding conductive layer is formed by using the same conductive layer as the first pad and the second pad on one surface side of the flexible wiring board... effectively prevents light leakage
Implementation Method 2
the light-shielding conductive layer is provided at a position beneath a light emission center or a light reception center of the semiconductor device... blocking light in all directions relative to the optical axis
Data Source
AI summary
A mount structure includes a wiring board and a semiconductor device composed of a light-emitting device or a light-receiving device mounted on one surface side of the wiring board such that an optical axis thereof is oriented in a direction that extends along a board surface of the wiring board. On the one surface side of the wiring board, a first pad on which a first terminal of the semiconductor device is mounted, a second pad on which a second terminal of the semiconductor device is mounted, and a light-shielding conductive layer are formed using the same conductive layer. The first pad and the second pad are arranged on respective sides of an imaginary center line along which the optical axis of the semiconductor device extends and the light-shielding conductive layer is provided at a position beneath a light emission center or a light reception center of the semiconductor device in plan view.