Driving Backplane Reflective Layer Layout to Prevent Pad Shorting
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Solution Overview
Problem
In mini-LED display devices, the existing driving backplane design suffers from issues such as short circuits caused by residual solder paste accumulating in gaps within the reflective layer, leading to reduced product yield and increased risk of scrapping due to bridging connections between pads.
Innovation Solution
The proposed driving backplane design includes a substrate with pad groups and line groups, featuring line hollowed-out regions on either side of the pads, and a reflective layer with window regions that expose the pads and spacer regions, ensuring a sufficient distance between the solder paste gaps and pad groups to prevent short circuits, and a method for manufacturing this structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the reflective layer is designed with gaps to accommodate manufacturing processes, then the ease of manufacture is improved, but residual solder paste accumulates in the gaps causing short circuits between pads
Solution Approach 1:
The patent extracts and removes the harmful element (gaps in the reflective layer) that causes solder paste accumulation. By eliminating the gaps entirely and providing a continuous reflective layer coverage over the pad spacer region, the design removes the root cause of short circuits while maintaining manufacturing feasibility through alternative structural arrangements.
Solution Approach 2:
The patent introduces an intermediary structure (the line hollowed-out region extending beyond the pad spacer region) that acts as a barrier between the solder paste and the pad spacer region. This intermediary structure prevents direct contact between residual solder paste and the electrical connection area, thereby preventing short circuits while allowing the reflective layer to be continuously applied.
2Area of stationary object
If the pad spacer region is reduced to minimize distance, then the area is reduced, but the risk of bridging connections increases
Solution Approach 1:
The patent extends the protection mechanism from the traditional two-dimensional pad spacer region into the third dimension by creating line hollowed-out regions that protrude laterally beyond the pad spacer region. This dimensional extension creates an additional protective barrier without increasing the footprint area, effectively preventing bridging connections while maintaining compact design.
Solution Approach 2:
The patent implements preliminary protective structures (line hollowed-out regions) before the solder paste application process. These pre-formed structures create physical barriers that prevent solder paste from reaching the pad spacer region, thereby proactively eliminating the risk of bridging connections before the harmful effect can occur.
3Reliability
If the line hollowed-out regions are enlarged to increase distance from pads, then the protective distance is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent merges multiple functions into the line hollowed-out regions: they serve as both the electrical connection pathway and the protective barrier structure. By combining these functions, the design eliminates the need for separate protective structures, thereby reducing the number of manufacturing steps and precision requirements while maintaining effective protection against solder paste accumulation.
Data Source
AI summary
A driving backplane includes a substrate, pad groups and line groups. A line of each line group is connected to a pad of a pad group. At least one pad of a pad group and a line connected thereto define line hollowed-out regions. The line hollowed-out regions include a first line hollowed-out region and a second line hollowed-out region that are disposed on two sides of the pad(s) in a second direction. The driving backplane further includes a reflective layer covering a first surface of the substrate and the line groups. Each window region in the reflective layer includes a first region, a second region and a third region that are arranged in the second direction. The second region exposes a pad group and a pad spacer region corresponding to the pad group, and the first region and the third region expose portions of the first surface of the substrate.