Flexible Wiring Board with Irregular Conductive Shielding
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Solution Overview
Problem
Existing flexible wiring boards have insufficient electromagnetic shield properties, particularly in the configuration discussed in Japanese Patent Application Laid-Open No. 2015-133474, where the shield property of the electromagnetic shield layer is not adequately effective.
Innovation Solution
A flexible wiring board design featuring a conductive portion with an irregularity shape, where protruding and recess portions are alternately arranged, creating a thickness difference of 10 micrometers or more, enhancing the shield layer's ability to suppress electromagnetic noise by prolonging the current path of noise currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat electromagnetic shield layer is used, then the manufacturing process is simple, but the shield property is insufficient
Solution Approach 1:
The electromagnetic shield layer is designed with an irregularity shape featuring alternating protruding and recessed portions, breaking the symmetry of traditional flat shield layers. This asymmetric structure increases the path length for noise currents and enhances the shield property without requiring additional components or complex assembly processes.
Solution Approach 2:
The shield layer incorporates curved surface features through protruding and recessed portions rather than maintaining a completely flat surface. These curvature elements increase the effective path length for electromagnetic noise currents, improving shielding effectiveness while remaining integrated into the single-layer structure.
2Reliability
If the thickness of the conductive portion is increased uniformly, then the shield property improves, but the flexibility and bendability deteriorate
Solution Approach 1:
Instead of uniformly increasing the thickness throughout the entire shield layer, the invention applies thickness variations locally through protruding and recessed portions. The protruding portions provide enhanced shielding where needed, while the recessed portions maintain flexibility, allowing the shield layer to bend without excessive rigidity.
Solution Approach 2:
The invention transitions from a two-dimensional flat shield layer to a three-dimensional structure with varying thickness. By adding the thickness dimension through protruding and recessed portions, the shield achieves improved electromagnetic shielding performance without proportionally increasing the overall material usage or rigidity.
3Reliability
If a roughened surface is applied to the shield layer, then the shield property improves slightly, but the manufacturing precision control becomes difficult
Solution Approach 1:
Rather than creating a continuously roughened surface that is difficult to control, the invention segments the shield layer surface into distinct protruding and recessed portions. This segmentation allows for better control of the surface geometry during manufacturing, as the discrete features can be more precisely defined and reproduced than continuous roughness patterns.
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 significantly improves the shielding effect against electromagnetic wave noise, effectively reducing radiated noise and enhancing the flexibility and bendability of the wiring board.
Implementation Method 1
a conductive portion overlapping the wiring layer at least partially in a planar view, wherein the conductive portion includes an irregularity shape in which a protruding portion and a recess portion are alternately arranged
Data Source
AI summary
A wiring board includes a wiring layer and a conductive portion. The wiring layer includes a signal line. The conductive portion overlaps the wiring layer at least partially in a planar view. The conductive portion includes an irregularity shape in which a protruding portion and a recess portion are alternately arranged in a direction in which the conductive portion extends, on at least one of a first surface closer to the wiring layer, and a second surface existing on an opposite side of the first surface. A difference between a thickness of the conductive portion in the protruding portion and a thickness of the conductive portion in the recess portion is 10 micrometers (μm) or more.