Circuit Substrate Test Pad for LCD Transparent Conductive Layer Detection
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Solution Overview
Problem
In liquid crystal display panel manufacturing, abnormalities in the transparent conductive layer are not detectable until the back-end process, leading to wasted manufacturing costs due to the inability to test these layers during the electrical testing of pads and lead lines.
Innovation Solution
A circuit substrate design with a pad region, non-pad regions, and lead lines where the insulating layer separates the first and second lead lines, allowing for the second pad, which includes a transparent conductive layer, to be electrically connected to both lead lines, enabling earlier detection of abnormalities through test signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical test is conducted after formation of pads, lead lines and transparent conductive layer, then manufacturing process can be completed, but abnormalities of transparent conductive layer cannot be detected until back-end process
Solution Approach 1:
The patent introduces a test lead line and test pad structure that enables electrical testing of the transparent conductive layer before the back-end process. The test lead line is configured to electrically connect to the transparent conductive layer through a test pad, allowing preliminary electrical detection of the transparent conductive layer's abnormalities (such as holes or discontinuities) before subsequent manufacturing steps. This preliminary action shifts the detection timing from back-end to an intermediate stage, enabling earlier identification and removal of defective substrates.
2Productivity
If electrical test is conducted after formation of pads and lead lines, then manufacturing process continues, but defective substrates progress to later stages causing waste
Solution Approach 1:
The test lead line and test pad structure enables preliminary electrical detection of transparent conductive layer abnormalities before the back-end process. By performing this detection earlier, defective substrates can be identified and removed at an intermediate manufacturing stage rather than progressing to later stages. This prevents waste of subsequent manufacturing resources (materials, energy, time) that would be consumed processing defective substrates, thereby reducing overall manufacturing waste while maintaining productivity.
3Measurement precision
If transparent conductive layer abnormalities are not detected early, then manufacturing cost increases due to waste
Solution Approach 1:
The patent implements a test lead line electrically connected to the transparent conductive layer through a test pad, enabling preliminary electrical measurement of the transparent conductive layer's properties. This allows accurate detection of abnormalities (such as holes, discontinuities, or conductivity issues) before the back-end process. By performing this measurement early, the system achieves precise abnormality detection that prevents defective substrates from proceeding further, thereby avoiding the energy and resource waste associated with processing defective products and reducing overall manufacturing cost.
Data Source
AI summary
A circuit substrate includes a substrate, a first lead line, a second lead line, an insulating layer and a pad. The substrate has a pad region, a first non-pad region and a second non-pad region. The first lead line extends from the first non-pad region to the pad region. The second lead line extends from the second non-pad region to the pad region. The insulating layer is interposed between the first and second lead lines. The pads are on the pad region of the substrate and one of the pads is electrically connected to the first and second lead lines. A display panel including the circuit substrate is also provided.