Flexible Substrate Tension Control in Roll-to-Roll Deposition
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Solution Overview
Problem
Roll-to-roll deposition systems face challenges in maintaining the flatness and reducing stress on flexible substrates during processing, leading to defects and reduced yield in devices like solar cells due to wave formation and tension issues within the constrained vacuum chamber environment.
Innovation Solution
An automated deposition system with a controller and sensor assembly that monitors and adjusts the tension and alignment of the flexible substrate using position sensors and actuators to maintain proper tension and alignment, preventing wave formation and stress, and ensuring consistent substrate transport through the processing chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flexible substrate is conveyed through the vacuum chamber using traditional roll-to-roll mechanisms, then the deposition process can be completed, but waves and wrinkles form on the substrate causing stress and reducing device yield
Solution Approach 1:
The system dynamically adjusts the tension applied to the flexible substrate during conveyance through the vacuum chamber. By varying the tension force in real-time based on substrate position and processing conditions, the system maintains substrate flatness while enabling continuous roll-to-roll deposition, thus resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent changes the tension parameter of the substrate during processing. By controlling and adjusting the tension applied to the substrate as it moves through the deposition chamber, the system prevents wave formation and maintains substrate flatness, thereby achieving both high productivity and manufacturing precision.
2Manufacturing precision
If tension is applied to the flexible substrate to maintain flatness, then wave formation is reduced, but stress accumulates in the substrate and deposited layers
Solution Approach 1:
The system applies tension periodically and intermittently rather than continuously. By applying tension only when needed to maintain flatness during specific phases of substrate conveyance and deposition, and releasing it when not needed, the system reduces cumulative stress while maintaining substrate flatness, thus resolving the contradiction between manufacturing precision and stress reduction.
Solution Approach 2:
The tension applied to the substrate is dynamically adjusted throughout the processing cycle. The system increases tension when flatness is compromised and decreases or releases tension when flatness is maintained, preventing excessive stress accumulation while ensuring substrate flatness is preserved during critical deposition phases.
3Area of stationary object
If the roll-to-roll mechanism is contained within a small processing region, then space is optimized, but access to deposition devices is limited for defect correction
Solution Approach 1:
The system segments the vacuum chamber into distinct functional zones: a compact processing region for deposition and a separate access region for maintenance and defect correction. This spatial segmentation allows the processing region to remain small for space optimization while providing dedicated access pathways for operators to reach deposition devices, thus resolving the contradiction between area optimization and ease of operation.
Solution Approach 2:
The patent introduces an intermediary access mechanism that allows operators to reach deposition devices without requiring large open spaces. This intermediary system enables defect correction and maintenance activities while maintaining a compact processing region, thus balancing space optimization with operational accessibility.
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 system effectively reduces distortion and stress on the flexible substrate, improving the properties of deposited layers and maintaining consistent tension, thereby enhancing the quality and yield of devices like solar cells.
Implementation Method 1
a series of evaporation sources are used to deposit the different elements of the CIGS absorber layer
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A deposition system for guiding a flexible substrate along a path is provided. The deposition system includes a first frame having a first sidewall and a second sidewall separated from each other in a first direction, a payout hub coupled to the first sidewall and the second sidewall, and having a rotational axis extending in the first direction, a first roller positioned apart from the payout hub in a second direction, where a length of the substrate extends in the second direction from the payout hub to the first roller during processing, a first sensor located a first distance in the second direction from the payout hub, a second sensor located a second distance in the second direction from the payout hub, and a first actuator, coupled to the payout hub, the first actuator operable to adjust a position of the payout hub in the first direction.