OLED Screen-Printing Mask Bubble Structures for Thermal Stress
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Solution Overview
Problem
Organic light-emitting diode (OLED) display panels face erosion due to oxygen and moisture, and existing packaging methods using frit result in thermal stress due to mismatched thermal expansion coefficients between frit and substrate materials, affecting the longevity of OLED products.
Innovation Solution
A screen-printing mask with a masking layer and grids, where some grids are filled with a second blocking material to form bubble structures in the frit pattern, reducing thermal stress by preventing frit from spreading and improving mechanical properties through varied natural frequencies in the frit pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If frit is applied on the periphery of the packaging cover by screen-printing and then heated to melt and bond the packaging cover and array substrate, then bonding strength is improved, but thermal stress accumulates due to mismatched thermal expansion coefficients
Solution Approach 1:
The patent introduces bubble structures at specific locations within the frit pattern to create local variations in the material structure. These bubbles are strategically positioned to act as stress relief zones where thermal expansion mismatches can be accommodated, while the surrounding frit maintains its bonding function. This local modification allows the system to maintain overall bonding strength while reducing accumulated thermal stress.
Solution Approach 2:
The patent incorporates bubble structures (porous regions) within the frit pattern to create a composite structure with varying density. These porous regions provide compliance and flexibility to accommodate thermal expansion differences between the frit, packaging cover, and array substrate. The bubbles act as micro-springs that can compress or expand during thermal cycling, reducing stress accumulation while maintaining structural integrity.
2Reliability
If frit is heated to melt and bond the packaging cover and array substrate, then bonding is achieved, but thermal stress remains after the packaging process
Solution Approach 1:
The patent pre-introduces bubble structures into the frit pattern before the bonding process. These pre-formed bubbles serve as cushioning elements that are already in place to absorb and distribute thermal stresses during heating and cooling cycles. By having these stress-relief features built-in beforehand, the system can undergo thermal processing with reduced risk of stress accumulation and packaging failure.
3Ease of manufacture
If uniform frit pattern is applied for packaging, then simplicity is maintained, but mechanical properties such as shock-proof and shatter-proof resistance are insufficient
Solution Approach 1:
The patent modifies the uniform frit pattern by introducing bubble structures at specific locations. This creates a non-uniform frit pattern where certain regions have enhanced mechanical properties due to the presence of bubbles that can absorb impact energy. The bubbles act as stress concentrators that prevent crack propagation, thereby improving shock-proof and shatter-proof resistance while maintaining relatively simple manufacturing processes.
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
The bubble structures effectively reduce thermal stress and enhance the mechanical properties of the packaged OLED products, such as shock-proof and shatter-proof resistance, thereby improving the yield and durability of OLED array substrates.
Implementation Method 1
laser radiation is then used to heat up and melt the frit after the pre-baking process
Implementation Method 2
The melted frit bonds the packaging cover and the array substrate
Implementation Method 3
the thermal expansion coefficient of the frit often does not match the thermal expansion coefficient of the materials, e.g., glass and/or metal, on the array substrate. After the packaging process, thermal stress remains in the packaged OLED products
Data Source
AI summary
The present disclosure provides a screen-printing mask for packaging organic light-emitting diode (OLED) products. The screen-printing mask includes a screen and a masking layer on the screen, the screen including a plurality of grids, and the masking layer including a plurality of blocking regions and a plurality of opening regions, the blocking regions being filled with a first blocking material, the opening regions corresponding to regions of an OLED substrate to be filled with a packaging material. In the opening regions, a first portion of the grids is exposed and a second portion of the grids is filled with a second blocking material, the first portion being a substantial portion of the grids.