Mask Frame Assembly for OLED Deposition with Tensioned Strips

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Solution Overview

Problem

In the manufacturing of organic light emitting display devices, existing mask frame assemblies face issues with position errors in unit masking pattern portions due to sagging caused by self-weight and uneven tension, leading to inaccurate deposition of the organic emitting layer.

Innovation Solution

A mask frame assembly with unit mask strips that are tensioned and fixed to a frame, featuring unit masking pattern portions with increasing width and curvature towards the central portion, maintaining a constant pitch after fixation, and using nickel or nickel alloy strips with laser welding for precise alignment and deposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If unit mask strips are fixed to the frame without applying tensile force, then the manufacturing process is simpler, but position errors occur due to sagging caused by self-weight

Engineering Contradiction:

Improveease of fixing mask stripsVSAvoidposition accuracy of masking pattern portions

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

A tensile force is applied to the unit mask strips in the lengthwise direction before they are fixed to the frame. This preliminary action prevents sagging caused by self-weight during deposition, thereby maintaining position accuracy of the masking pattern portions while still allowing for relatively simple manufacturing through laser welding fixation.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If the width of unit masking pattern portions is uniform, then the design is simpler, but position errors occur due to uneven tension distribution

Engineering Contradiction:

Improvecomplexity of mask strip designVSAvoidalignment accuracy of opening patterns

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The width of each unit masking pattern portion varies along the lengthwise direction, being wider at the central portion and narrower at the end portions. This local variation compensates for uneven tension distribution when the mask strip is stretched, ensuring that the opening patterns maintain accurate alignment and constant pitch after fixation to the frame.

Inventive Principle:

Principle #3Local quality

3Productivity

If the pitch between opening patterns is not compensated, then the manufacturing process is simpler, but deposition accuracy decreases due to pitch variation after fixation

Engineering Contradiction:

Improvespeed of mask assemblyVSAvoiddeposition accuracy of organic emitting layer

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The pitch between opening patterns is pre-compensated during mask strip fabrication by varying the width of unit masking pattern portions. This preliminary compensation ensures that after the mask strip is stretched and fixed to the frame, the pitch between opening patterns becomes substantially constant, thereby maintaining high deposition accuracy without requiring complex post-assembly adjustments.

Inventive Principle:

Principle #10Preliminary action

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 solution ensures accurate and precise deposition of the organic emitting layer by maintaining constant pitch and alignment of opening patterns, enhancing the quality of image display in organic light emitting display devices.

Implementation Method 1

both of end portions of the unit mask strips in a lengthwise direction of the unit mask strips are welded and fixed to the frame. Before the tensile force is applied to both of end portions of the unit mask strips and the unit mask strips are fixed to the frame, a width of each of the unit masking pattern portions in a widthwise direction perpendicular to the lengthwise direction increases as a function of a closeness of a portion of the unit masking pattern portion where the width is measured to a central portion of each of the unit masking pattern portions

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

both of end portions of the unit mask strips in a lengthwise direction of the unit mask strips are welded and fixed to the frame

Methodology Applied

Scientific EffectLaser welding: Laser Beam Welding

Implementation Method 3

a mask frame assembly for thin film deposition that includes a frame including an opening portion and a plurality of unit mask strips

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentUS8604489B2Mask frame assembly for thin layer deposition and method of manufacturing organic light emitting display device by using the mask frame assembly

Publication Date: 2013.12.10 SAMSUNG DISPLAY CO LTD

AI summary

A mask frame assembly for thin film deposition includes a frame including an opening portion, and a plurality of unit mask strips that are fixed to the frame after a tensile force is applied to both of end portions of the unit mask strips in a lengthwise direction of the unit mask strips. Each of the plurality of unit mask strips includes a plurality of unit masking pattern portions each including a plurality of opening patterns. Before the tensile force is applied to both of the end portions of the unit mask strips in the lengthwise direction and the unit mask strips are fixed to the frame, a width of each of the unit masking pattern portions in a widthwise direction perpendicular to the lengthwise direction increases as a function of a closeness of a portion of the unit masking pattern portion where the width is measured to a central portion of each of the unit masking pattern portions.