Colored Ceramic Vacuum Chuck for Low Reflectance
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Solution Overview
Problem
Existing vacuum chucks for glass substrates in FPD manufacturing suffer from high reflectance issues due to regular and diffuse reflections, particularly in the ultraviolet region, and black anodized aluminum surfaces are prone to abrasion and uneven thin-film formation, making it difficult to achieve low total reflectance.
Innovation Solution
A colored ceramic vacuum chuck is manufactured using a sintered body with 55-75% alumina, Si, Ca, and Mg oxides, with a coloring agent, and shot blasted with abrasive grains to form pins and a rim, followed by shot peening with spherical glass beads to reduce total reflectance to 7% or less at 360 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If black anodized aluminum is used for the vacuum chuck, then total reflectance is reduced to 6-8%, but the thin-film surface is prone to abrasion and peel-off
Solution Approach 1:
The patent creates a composite structure where a colored ceramic coating is applied over the black anodized aluminum substrate. The ceramic layer protects the thin black film from abrasion and peel-off while maintaining the low reflectance properties. This composite approach combines the optical benefits of the black film with the mechanical durability of ceramic.
Solution Approach 2:
The vacuum chuck surface is treated with shot peening to create localized surface modifications. This process creates a roughened surface layer that provides both mechanical strengthening and optical property modification, making the surface more resistant to damage while controlling reflection characteristics.
2Productivity
If numerous protruding pins are formed on the vacuum chuck to reduce contact area, then vacuum efficiency improves, but surface uniformity in reflectance deteriorates due to shot blasting variations
Solution Approach 1:
The mask pattern is formed on the vacuum chuck surface before the shot blasting process. This preliminary action ensures that the pins and rim are created with precise positioning and uniform surface treatment. The mask protects specific areas during shot blasting, ensuring consistent reflectance properties across all protruding elements.
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 solution provides a ceramic vacuum chuck with a high Young's modulus capable of supporting large substrates, achieving uniform low reflectance and extending the chuck's lifespan by reducing total reflectance and surface roughness differences.
Implementation Method 1
a colored ceramic vacuum chuck having a sufficiently low total reflectance even if a colored film is not formed
Implementation Method 2
a plurality of pins for supporting the substrate, and a rim at least partially enclosing the plurality of pins, are formed on the upper surface by shot blasting using abrasive grains
Implementation Method 3
the whole of the upper surface is shot peened using spherical particles
Data Source
AI summary
In the present invention, a ceramic vacuum chuck 2 having an upper surface for adsorbing a substrate is formed from a colored ceramic sintered body comprising 55-75% by weight alumina (Al2O3), at least 3% by weight Si in terms of oxide (SiO2), at least 0.4% by weight Ca in terms of oxide (CaO), at least 0.4% by weight Mg in terms of oxide (MgO), coloring agent, and 1% or less of impurities. A plurality of pins 4 for supporting the substrate, and a rim 6 are formed on the upper surface by shot blasting using abrasive grains, and the whole of the upper surface is shot peened using spherical particles.