Thin Glass Substrate Cooling Rate Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing thin glass substrates for flexible displays, such as the down draw method, face challenges in achieving uniform sheet thickness and high surface quality, particularly for substrates thinner than 200 µm, which are necessary for fine thin-film electric circuits, due to difficulties in stable glass drawing and increased production costs.
Innovation Solution
Regulating the average cooling rate of the glass to 400 °C/min or more in the temperature range above the annealing point, combined with the overflow down draw method, allows for the production of glass substrates with uniform thickness and low thermal shrinkage, eliminating the need for polishing and enhancing surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the down draw method is used to produce thin glass substrates (≤200 μm), then the sheet can be made thin for flexible displays, but it is difficult to stably draw the glass and maintain uniform sheet thickness
Solution Approach 1:
The patent applies parameter changes by optimizing the cooling rate in the temperature range from annealing point to (annealing point - 100°C) to between 10-300°C/min, and controlling the drawing speed and furnace temperature distribution. These parameter adjustments enable stable drawing of thin glass substrates (≤200 μm) while maintaining uniform sheet thickness without requiring post-polishing treatment.
2Length of moving object
If the sheet thickness is reduced to ≤200 μm for flexibility, then suppleness is improved, but polishing becomes technically difficult and production costs greatly increase
Solution Approach 1:
The patent applies preliminary action by ensuring high surface quality is achieved during the glass forming process itself through controlled cooling and drawing conditions. This preliminary optimization of surface quality eliminates the need for subsequent polishing treatment, making the manufacturing of thin substrates (≤200 μm) both feasible and cost-effective.
3Manufacturing precision
If the cooling rate is increased to 400°C/min or more above the annealing point, then surface quality and thickness uniformity are improved, but thermal shrinkage may increase
Solution Approach 1:
The patent applies segmentation by dividing the cooling process into distinct stages: rapid cooling (400-2500°C/min) in the temperature range from (annealing point + 200°C) to (annealing point + 50°C) for surface quality, followed by controlled cooling at 10-300°C/min from annealing point to (annealing point - 100°C) for shrinkage control. This segmented approach allows simultaneous achievement of high surface quality and low thermal shrinkage.
4Measurement precision
If a fine circuit pattern is required for high precision displays, then the surface roughness requirement becomes more stringent, but achieving such quality in thin substrates becomes more difficult
Solution Approach 1:
The patent applies parameter changes by optimizing the cooling rate (400-2500°C/min) and drawing conditions to inherently produce glass substrates with excellent surface quality (low surface roughness). This parameter optimization enables the production of thin substrates (≤200 μm) with surface quality sufficient for fine circuit patterns without requiring additional surface treatment.
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 results in glass substrates with excellent surface quality and low thermal shrinkage, suitable for flexible displays, enabling the formation of fine thin-film electric circuits without the need for polishing, thus reducing production costs and improving substrate quality.
Implementation Method 1
an average cooling rate in a temperature range of from the (annealing point + 200 °C) to the (annealing point + 50 °C) is controlled to the range of from 400 to 2,500 °C/min
Implementation Method 2
an average cooling rate in a temperature range of from the annealing point to the (annealing point - 100 °C) is controlled to the range of from 10 to 300 °C/min
Data Source
Figure 1
Figure 2(a)~2(c)
AI summary
Disclosed is a manufacturing method of 100µm or thinner glass substrates which have the quality required of substrates on which thin film circuits are formed; also disclosed is the thin glass substrate manufactured according to that method. The method for manufacturing glass substrates between 10 and 200µm thick involves a formation step for forming molten glass into a ribbon form by the downdraw method, a slow cooling step for slowly cooling the glass ribbon, and a cutting step for cutting the glass ribbon. In the temperature range of (slow cooling point + 200C) to (slow cooling point + 50C), the average cooling speed is adjusted to the range of 300-2500 C/minute.