Side Trace Protective Layer for Narrow-Bezel Circuit Substrates
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Solution Overview
Problem
The challenge in minimizing the border region of display panels is due to the thickness of flexible circuit boards and their difficulty in conforming to the side surfaces, which affects the yield and integrity of the side traces.
Innovation Solution
A circuit device with a protective layer made of cured silver paste, epoxy resin, or acrylic-based insulating material covering the turning regions, enhancing the adhesion and integrity of side traces by reducing the impact of broken surfaces and microcracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If flexible circuit board is used to connect pads on front surface to back surface, then border area can be reduced, but the thickness of flexible circuit board and difficulty in conforming to side surface worsens the manufacturing precision and reliability of side traces
Solution Approach 1:
The side trace is divided into multiple segments: a first side trace on the front surface, a second side trace on the back surface, and a third side trace on the side surface connecting them. This segmentation allows each trace to be optimized independently for its location, improving overall manufacturing precision while maintaining compact border design
Solution Approach 2:
A protective layer is introduced as an intermediary structure that covers the turning regions where side traces meet the front and back surfaces. This protective layer fills microcracks and provides mechanical support, enhancing side trace integrity without increasing border area
2Area of stationary object
If flexible circuit board is bent to conform to side surface, then border area can be minimized, but the difficulty in complete conformance and microcrack formation worsens the reliability of side traces
Solution Approach 1:
The protective layer is applied beforehand to cover and protect the turning regions where microcracks are most likely to form during bending. This pre-protection prevents crack propagation and delamination, ensuring side trace reliability in the compact border design
Solution Approach 2:
The protective layer is made from composite materials including cured silver paste, epoxy resin, or acrylic-based insulating material. These composite materials provide both mechanical strength to prevent microcrack formation and electrical insulation to maintain side trace functionality
Data Source
AI summary
A circuit device includes a circuit substrate, a protective layer and a side trace. The circuit substrate has a first surface, a second surface opposite to the first surface, and a side surface. A first turning region is provided between the first surface and the side surface. A second turning region is provided between the second surface and the side surface. The circuit substrate includes a carrier plate and a first circuit structure. The first circuit structure is located on the carrier plate, and includes a pad located on the first surface. The protective layer at least partially covers the first turning region and the second turning region. A material of the protective layer includes cured silver paste, epoxy resin or an acrylic-based insulating material. The side trace is located on the protective layer, and extends from the pad across the side surface to the second surface.