Display Wiring Substrate With Fine-Grain Copper for Smooth Wire Patterns
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display devices face challenges with step coverage defects of insulating layers, burnt defects, and short circuits due to irregular wire surfaces and poor straightness in wiring substrates.
Innovation Solution
A wiring substrate with conductive layers containing a metal with small grain size, such as copper alloy with a grain size of about 155 nm or less, is used to improve wire surface smoothness and straightness, thereby reducing defects and preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional metal layers with larger grain size are used in conductive layers, then manufacturing process is simpler, but wire surface smoothness deteriorates and straightness decreases
Solution Approach 1:
The patent applies composite materials by stacking multiple metal layers with different compositions and grain sizes. The lower metal layer provides structural support while the upper metal layer with smaller grain size (100-500 nm) provides smooth surface and straight wire patterns. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both manufacturing feasibility and high precision wire formation.
Solution Approach 2:
The patent changes the grain size parameter of the metal layer from conventional larger sizes to specifically controlled smaller sizes (100-500 nm). This parameter change is achieved through controlled deposition conditions and heat treatment processes, transforming the metal layer's microstructure to produce smooth surfaces and straight wire patterns without significantly complicating the manufacturing process.
2Manufacturing precision
If insulating layers are deposited over irregular wire surfaces, then device assembly is straightforward, but step coverage defects occur
Solution Approach 1:
The patent applies preliminary action by creating smooth wire surfaces through controlled metal layer deposition and heat treatment before depositing the insulating layer. By pre-establishing the smooth surface topology, subsequent insulating layer deposition achieves uniform step coverage without defects, eliminating the need for complex surface correction processes.
3Reliability
If wires with poor straightness are used, then manufacturing tolerances are easier to meet, but burnt defects and short circuits increase
Solution Approach 1:
The patent uses composite metal layers where the upper layer with fine grain structure (100-500 nm) provides excellent straightness and surface smoothness. This fine-grained upper layer acts as a protective barrier that prevents burnt defects and short circuits, while the overall composite structure remains manufacturable through standard deposition and heat treatment processes.
Data Source
AI summary
A display device includes conductive layers including wires and conductive patterns in a display area and a pad area, a via layer on the conductive layers, a first electrode and a second electrode on the via layer in the display area and spaced apart from each other, a first insulating layer on the first electrode and the second electrode, light emitting elements on the first electrode and the second electrode spaced apart from each other on the first insulating layer, and a first connection electrode on the first electrode and electrically contacting the light emitting elements, and a second connection electrode on the second electrode and electrically contacting the light emitting elements, each of the conductive layers includes a first metal layer and a second metal layer on the first metal layer, and the second metal layer contains copper and has a grain size of about 155 nm or less.