Backplane Copper Trace Build-Up for Low-Resistance Mini-LED Routing
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Solution Overview
Problem
The existing methods for producing thicker copper metal traces for Mini-LED backlight modules in large-sized LCD displays face challenges such as high preparation costs, voltage drop issues, and increased resistance due to copper oxidation, which are not effectively addressed by current electroplating or sputtering processes.
Innovation Solution
A method involving a mask exposure process to form an insulating structure layer with a groove on a base substrate, followed by repeated metal sub-layer forming steps using ashing and wet etching processes, simplifies the process flow, reduces mask exposure times, and minimizes heating and curing steps to maintain low resistance and prevent copper oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If electroplating or sputtering processes are used to produce thicker copper metal traces, then the trace thickness is increased to reduce voltage drop, but the preparation cost increases and copper oxidation occurs leading to increased resistance
Solution Approach 1:
The patent divides the metal trace formation into multiple sub-layer deposition steps, where each step deposits a thin metal layer that is then patterned and etched. This segmentation allows achieving the required total thickness (e.g., 3 μm or more) through cumulative thin layers while maintaining process control and reducing oxidation risk compared to single-step thick deposition.
Solution Approach 2:
The patent performs preliminary actions by depositing and patterning metal sub-layers sequentially before final assembly. Each sub-layer is deposited, patterned with photoresist, and etched in advance, creating a structured foundation that prevents oxidation and reduces voltage drop without requiring costly post-processing electroplating.
2Length of stationary object
If electroplating or sputtering processes are used to produce thicker copper metal traces, then the trace thickness is increased to reduce voltage drop, but copper oxidation occurs leading to increased resistance
Solution Approach 1:
The patent employs inert atmosphere techniques during metal deposition and patterning processes to prevent copper oxidation. By conducting operations in controlled environments that exclude oxygen, the metal traces maintain their low resistivity and electrical reliability, avoiding the oxidation-related resistance increase that plagues conventional methods.
Solution Approach 2:
The patent performs preliminary patterning and deposition steps that create protected metal structures before final assembly. The metal sub-layers are deposited and patterned in a controlled sequence, establishing oxidation-resistant structures in advance that maintain stable resistance characteristics throughout the manufacturing process and product lifecycle.
3Length of stationary object
If multiple mask exposure processes are used to form thicker metal traces, then the trace thickness is increased, but the process complexity and preparation cost increase
Solution Approach 1:
The patent merges multiple deposition and patterning operations into an integrated process flow. By combining the deposition of metal sub-layers with sequential patterning steps using the same groove structure and photoresist materials, the process achieves thick metal traces without requiring separate complex equipment setups for each layer, thereby reducing overall process complexity.
Solution Approach 2:
The patent utilizes the vertical dimension by forming metal sub-layers at different heights within grooves on the backplane. This three-dimensional arrangement allows multiple metal layers to be stacked and connected, achieving the required thickness and electrical performance while maintaining a compact process flow that doesn't require excessive horizontal process steps.
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
This approach reduces the preparation cost and maintains low resistance of the metal traces, improving the yield and bonding quality of the metal traces while avoiding copper oxidation, thus enhancing the performance of Mini-LED backlight modules.
Implementation Method 1
ashing the photoresist layer to make the photoresist positioned outside the groove be removed and a part of the photoresist at the groove be retained
Implementation Method 2
etching the metal thin film by a wet etching process and peeling the remaining photoresist to form a metal sub-layer positioned in the groove
Data Source
AI summary
A preparation method of a backplane includes: forming an insulating structure layer having a groove on a base substrate by a mask exposure process, the groove being used for accommodating a metal trace; and repeating a metal sub-layer forming step including an ashing process and a wet etching process multiple times to form the metal trace positioned in the groove.