Photodiode Wiring Layout Across Substrate Steps to Prevent Cracks
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Solution Overview
Problem
Optical sensors with organic semiconductor materials experience stress concentration and wiring cracks at the step between the sensor substrate and protective layer due to differences in area, leading to potential damage when the housing is bent.
Innovation Solution
A detection device design that includes a first substrate with a smaller area second substrate covering the photodiode, insulating layers, and a sealing film, with wiring lines intersecting the boundary between these substrates in a specific direction to distribute stress and reduce cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a ring-shaped housing is bent toward a vertical direction, then the device can be worn or mounted flexibly, but stress is concentrated on the step between the sensor substrate and protective layer, causing wiring cracks
Solution Approach 1:
The patent divides the substrate structure into multiple segments: a first substrate, a second substrate with smaller area, and an intermediate substrate. This segmentation creates a gradual transition zone that distributes stress across multiple interfaces rather than concentrating it at a single step, preventing wiring cracks while maintaining housing flexibility.
Solution Approach 2:
The patent applies different structural qualities to different regions: the first substrate provides overall support, the intermediate substrate serves as a transition zone with specific mechanical properties, and the second substrate covers the sensor area. This local differentiation optimizes stress distribution while maintaining flexibility in the housing.
2Adaptability or versatility
If the area of the protective layer is made smaller than the sensor substrate, then the housing can be bent, but stress concentration occurs at the step between substrates
Solution Approach 1:
The patent introduces an intermediate substrate between the first substrate and the second substrate, creating a stepped structure with gradual area reduction. This segmentation eliminates the single large step that causes stress concentration, replacing it with multiple smaller transitions that distribute mechanical stress more evenly across the structure.
Solution Approach 2:
The intermediate substrate acts as a mediator between the first substrate and the second substrate. It provides a transition zone that mechanically couples the two substrates while absorbing and distributing stress, preventing direct stress transmission that would cause cracking at a single sharp step.
3Ease of manufacture
If wiring lines are positioned to connect electrodes, then electrical function is achieved, but wiring lines intersect the boundary between substrates and are susceptible to stress-induced cracks
Solution Approach 1:
The patent segments the substrate structure to create a transition zone that relieves stress at the boundary. This segmentation allows wiring lines to pass through the intermediate substrate region where stress is distributed, rather than concentrating at a single sharp step, thereby maintaining wiring integrity while preserving electrical connectivity.
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 effectively reduces stress on wiring lines, minimizing cracks and ensuring durability when the device is bent, thereby enhancing the reliability of the detection device.
Implementation Method 1
Optical sensors capable of detecting fingerprint patterns and vein patterns are known
Data Source
AI summary
A detection device includes: an active area including an active layer; a coupling area with a coupling part provided at an end of a first substrate; a peripheral area between the active area and the coupling area; a sealing film sealing the active area and the peripheral area; and a first wiring line coupling a lower electrode to the coupling part. The peripheral area includes: a first portion including the first insulating layer, the sealing film, the second insulating layer, and the second substrate; and a second portion including at least one of the sealing film, the second insulating layer, and the second substrate as compared with the first portion. The first wiring line intersects a boundary line provided between the first and second portions along a longitudinal direction of the second substrate formed in a band shape that intersects a direction from the coupling area toward the active area.