FPC Layer Edge Staggering to Prevent Bending-Induced Tearing
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Solution Overview
Problem
The bendable portion of flexible printed circuit boards (FPCs) in display devices is prone to stress concentration and edge tearing due to uniform edge alignment of multiple layers, leading to potential failure during bending and distortion.
Innovation Solution
The FPC design incorporates varying inward contraction amounts for trace layers and electromagnetic shielding layers at the edges, ensuring non-equal inward contractions to alleviate stress concentration and prevent edge tearing, while using a staggered arrangement of these layers to distribute stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform edge alignment of multiple layers is used in FPC bendable portion, then manufacturing is simplified, but stress concentration and edge tearing occur
Solution Approach 1:
The patent applies asymmetry by making the edge alignment of the first electromagnetic shielding layer different from that of the trace layers. Specifically, the first electromagnetic shielding layer has a first edge that is not aligned with the second edge of the trace layers, creating an asymmetric structure that prevents stress concentration at the edges during bending operations.
2Device complexity
If multiple layers are aligned at edges, then structural simplicity is maintained, but stress distribution becomes concentrated
Solution Approach 1:
The patent applies local quality by creating different edge alignment characteristics in different regions of the FPC structure. The trace layers maintain one edge alignment configuration while the first electromagnetic shielding layer has a different edge alignment, creating localized variations in stress distribution that prevent concentration at critical edges.
Data Source
AI summary
Provided is a display device, including a display panel and a FPC. The FPC includes a fixed portion and a bendable portion. The bendable portion has a first side edge extending along a length direction of the bendable portion. The FPC includes a plurality of layers, in which the first trace layer has a first inward contraction amount relative to the substrate layer in a first region of the first side edge, the second trace layer has a second inward contraction amount relative to the substrate layer in the first region of the first side edge, and the first electromagnetic shielding layer has a third inward contraction amount relative to the substrate layer in the first region of the first side edge. At least two of the first inward contraction amount, the second inward contraction amount, and the third inward contraction amount are not equal.