Pad Conductive Layer Thickness Segmentation for HMD Display Reliability
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Solution Overview
Problem
Existing head-mounted displays face challenges in providing high-resolution images while ensuring the durability of the display device's pad conductive layer during inspection processes.
Innovation Solution
A display device design featuring a substrate with conductive layers, a reflective electrode layer, a pad conductive layer with a thickness greater than the reflective electrode layer, and light emitting elements. The pad conductive layer is partitioned into sub-pads with different areas, and the thickness of the first sub-pad conductive layer is 10,000 Å or more, while the second sub-pad conductive layer is 1,000 Å or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pad conductive layer thickness is increased to protect against damage during inspection, then the durability and reliability are improved, but the device complexity and manufacturing precision requirements increase
Solution Approach 1:
The pad conductive layer is divided into multiple sub-layers with different thicknesses (first sub-pad conductive layer with thickness ≥10,000 Å and second sub-pad conductive layer with thickness ≤1,000 Å). This segmentation allows each sub-layer to serve different functions: the thicker first sub-layer provides mechanical durability and protection during inspection, while the thinner second sub-layer maintains electrical conductivity and connection precision, thereby resolving the contradiction between reliability and device complexity.
Solution Approach 2:
Different regions of the pad conductive layer are assigned different thicknesses based on local requirements. The first sub-pad conductive layer with greater thickness (≥10,000 Å) is positioned where mechanical strength and damage protection are critical, while the second sub-pad conductive layer with smaller thickness (≤1,000 Å) is positioned where electrical connection precision is paramount. This local differentiation allows the structure to optimize both durability and manufacturing precision without uniformly increasing complexity throughout the entire layer.
2Reliability
If the pad conductive layer thickness is increased to prevent damage during inspection, then the reliability is improved, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
By segmenting the pad conductive layer into multiple sub-layers with distinctly different thickness ranges (≥10,000 Å for the first sub-layer and ≤1,000 Å for the second sub-layer), the manufacturing process can target specific thickness control criteria for each sub-layer independently. This segmentation makes it easier to control manufacturing precision for each segment rather than attempting to control the entire pad conductive layer thickness uniformly, thereby improving overall manufacturing precision while maintaining reliability.
Solution Approach 2:
The patent applies different thickness specifications to different local regions of the pad conductive layer based on their functional requirements. The first sub-pad conductive layer uses greater thickness (≥10,000 Å) where mechanical protection is needed, while the second sub-pad conductive layer uses smaller thickness (≤1,000 Å) where precise electrical connection is critical. This local quality differentiation simplifies manufacturing precision control by allowing each region to be optimized for its specific function rather than requiring uniform precision across the entire structure.
3Reliability
If the pad conductive layer is made thicker to ensure stable connections, then the reliability is improved, but the light emission performance may be affected
Solution Approach 1:
The pad conductive layer is segmented into a first sub-pad conductive layer (thickness ≥10,000 Å) and a second sub-pad conductive layer (thickness ≤1,000 Å). The first sub-layer provides the mechanical stability and connection reliability needed for stable connections to the circuit board, while the second sub-layer with its smaller thickness minimizes the total path length and material interference, thereby preserving light emission performance. This segmentation allows the structure to simultaneously achieve both reliable connections and good optical performance.
Solution Approach 2:
The patent applies different thickness characteristics to different sub-layers of the pad conductive layer based on their specific functional requirements. The first sub-pad conductive layer uses greater thickness to ensure stable mechanical connections and electrical reliability, while the second sub-pad conductive layer uses smaller thickness to minimize impact on light emission. This local quality differentiation allows the overall structure to optimize both connection stability and light emission performance without compromise.
Data Source
AI summary
A display device includes: a substrate; a plurality of conductive layers sequentially stacked on the substrate; a reflective electrode layer on the plurality of conductive layers; a pad conductive layer on the plurality of conductive layers; an insulating layer covering at least a portion of the pad conductive layer and the reflective electrode layer; and a plurality of light emitting elements on the insulating layer, and each comprising a first electrode, a light emitting stack, and a second electrode, wherein a thickness of the pad conductive layer is greater than a thickness of the reflective electrode layer.