Spin Coating Radiation Curing Resin Thickness Accuracy
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Solution Overview
Problem
Current methods for manufacturing optical information recording media with thin light-transmitting layers, such as those used in Blu-ray discs, face challenges in achieving high thickness accuracy and reducing manufacturing time due to the difficulty of forming thin substrates and the high cost of materials, particularly when using spin coating techniques.
Innovation Solution
A method involving two coating steps for forming a radiation curing resin light-transmitting layer, where the first step uses a higher rotation speed and shorter time to create a thin foundation, followed by a second step with lower rotation speed and longer time to achieve uniform thickness, along with a curing step using radiation, which reduces manufacturing time and resin volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single spin coating step is used to form a thick light-transmitting layer (100 μm), then the manufacturing process is simple, but the resin does not spread uniformly due to friction variations, resulting in poor thickness accuracy
Solution Approach 1:
The single coating process is divided into multiple coating steps. The first step forms a thin foundation layer at low rotation speed to ensure uniform spreading, and subsequent steps add additional resin at higher rotation speeds to achieve the target thickness. This segmentation resolves the contradiction by maintaining thickness accuracy while enabling thick layer formation.
Solution Approach 2:
A thin foundation layer is formed first before adding the main resin layer. This preliminary action creates a base that reduces friction variations, allowing subsequent resin to spread more uniformly even at higher rotation speeds, thus achieving both thickness accuracy and efficient thick layer formation.
2Manufacturing precision
If spin coating is used to form a light-transmitting layer with high thickness accuracy, then the quality is improved, but the manufacturing time becomes extremely long
Solution Approach 1:
The coating process is segmented into multiple steps with different rotation speeds and resin volumes. Early steps use low rotation speeds for uniform spreading, while later steps use higher rotation speeds to quickly build up thickness. This allows the process to achieve high thickness accuracy without requiring excessively long manufacturing time.
Solution Approach 2:
The rotation speed parameter is dynamically changed during the coating process. Starting with low rotation speeds for uniform foundation formation, then increasing to higher speeds for rapid thickness buildup. This parameter optimization resolves the contradiction between thickness accuracy and manufacturing time.
3Reliability
If the thickness of the recording/reproducing base material is reduced to around 0.1 mm, then the influence of laser spot aberration decreases and compatibility with existing hardware is improved, but the material becomes extremely difficult to form using injection molding and requires extremely high thickness accuracy
Solution Approach 1:
The conventional injection molding process is replaced with a spin coating process using radiation curing resin. This substitution enables the formation of extremely thin (0.1 mm) light-transmitting layers with high thickness accuracy that cannot be achieved through traditional mechanical molding methods.
Solution Approach 2:
The manufacturing approach changes from mechanical injection molding to chemical radiation curing. This parameter change in the manufacturing process enables precise control of thin layer thickness and allows formation of 0.1 mm substrates with the required optical quality and thickness uniformity.
4Ease of manufacture
If conventional injection molding is used to form the base material, then the manufacturing process is well-established, but it becomes extremely difficult to form substrates with thickness less than 0.3 mm
Solution Approach 1:
Injection molding is replaced with spin coating followed by radiation curing. This substitution of manufacturing methods enables precise control of substrate thickness at the 0.1 mm level, overcoming the fundamental limitation of injection molding while maintaining ease of manufacture through a well-established coating process.
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 approach allows for the efficient production of optical information recording media with uniform light-transmitting layers, reducing manufacturing time and material costs while maintaining high thickness accuracy, enabling mass production and compatibility with existing hardware.
Implementation Method 1
coating a radiation curing resin by a spin coating or the like, and then curing the resin
Data Source
AI summary
The present invention relates to a method of manufacturing an optical information recording medium, which forms a light-transmitting layer made of a radiation curing resin on a substrate having a signal recording layer, a liquid foundation is formed by coating the radiation curing resin in a first coating step. Next, a radiation curing resin is further coated on the foundation in a second coating step. After this, a curing step is performed. By separating the dropping and spreading of the radiation curing resin into two steps, not only the manufacturing time can be reduced, but also the volume of the used radiation curing resin can be reduced.