OLED Substrate Inward Contraction Structure for Evaporation Alignment
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Solution Overview
Problem
In OLED device manufacturing, the mismatch in expansion rates between the glass substrate and the mask during evaporation leads to position deviations between the evaporated material and the pixel defining layer, causing abnormal color mixing and yield issues.
Innovation Solution
The OLED substrate features a pattern opening area with an inward contraction structure, aligned with the evaporation conditions, including sections with varying contraction amounts to match the expanded mask positions, and a photo mask with compensation patterns to ensure precise alignment during evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a regular pixel opening area structure is used, then the manufacturing process is simple, but the light-emitting layer position deviates from the pixel defining layer during evaporation causing color mixing
Solution Approach 1:
The pixel defining layer pattern opening area is pre-designed with an inward contraction structure before evaporation. This preliminary geometric adjustment compensates for the thermal expansion that will occur during the evaporation process, ensuring that the expanded pixel defining layer aligns with the mask pattern after evaporation, thereby preventing light-emitting layer position deviation and color mixing.
Solution Approach 2:
The geometric parameters of the pattern opening area are specifically modified by introducing an inward contraction amount. This parameter change adjusts the initial dimensions and shape of the pixel openings to account for thermal expansion during evaporation, transforming the regular pixel opening structure into a compensated structure that maintains alignment accuracy under thermal conditions.
2Reliability
If the pixel defining layer is expanded during evaporation, then the material coverage increases, but the position deviation from the mask pattern causes yield issues
Solution Approach 1:
The inward contraction structure in the pixel defining layer performs a preliminary counter-action to the expected thermal expansion during evaporation. By pre-adjusting the pattern opening area to be smaller than the final expanded size, the design anticipates and compensates for the expansion effect, ensuring that the expanded pixel defining layer precisely matches the mask pattern position, thereby preventing alignment deviation and improving product yield.
Solution Approach 2:
The invention explicitly accounts for thermal expansion effects during the evaporation process. The pixel defining layer is designed with an inward contraction structure that compensates for the thermal expansion that occurs when the substrate and mask are heated during evaporation. This thermal compensation ensures that the expanded pixel defining layer aligns with the mask pattern, maintaining manufacturing precision and reliability.
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 configuration ensures that the light-emitting layer is accurately positioned within the pattern openings, reducing abnormal color mixing and improving product yield by aligning the expanded pixel defining layer with the evaporation mask positions.
Implementation Method 1
an organic light-emitting material is evaporated on a substrate through a mask
Implementation Method 2
a light-emitting layer formed on the pixel defining layer by evaporation
Implementation Method 3
the mismatch in expansion rates between the glass substrate and the mask during evaporation
Data Source
AI summary
The resent disclosure provides an OLED substrate, a photo mask, and a method of manufacturing the OLED substrate. In one embodiment, an OLED substrate includes: a base substrate; an anode layer on the base substrate; a pixel defining layer on the anode layer, the pixel defining layer having a pattern opening area, the pattern opening area including a plurality of pixel openings arranged in an array manner; and a light-emitting layer formed on the pixel defining layer by evaporation; wherein the pattern opening area has an inward contraction structure with respect to a regular pixel opening area structure in which a plurality of pixel openings are arranged in a manner of an regular array where rows in the regular array are equally spaced from each other and are parallel to each other and columns in the regular array are equally spaced from each other and are parallel to each other.