Wafer-Level Liquid Crystal Device Manufacturing with Partially Cured Adhesive Barriers
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Solution Overview
Problem
In the manufacturing of liquid crystal devices, particularly in wafer-scale production, existing methods face challenges with contamination and inefficiency due to the use of rigid barrier fillets and uncured adhesives, which lead to material loss and increased costs.
Innovation Solution
A method involving a partially cured adhesive on a bottom substrate as a liquid crystal retaining barrier, with a top substrate sealed over it, minimizes contamination by reducing diffusion and allows for precise control of spacing using external positioning or spacer structures, and optional cooling to further reduce contamination risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uncured adhesive is used as barrier fillet to retain liquid crystal, then the manufacturing process is simplified and cost is reduced, but contamination of liquid crystal by unhardened adhesive occurs
Solution Approach 1:
The adhesive is partially cured before the liquid crystal is introduced into the cell. This preliminary curing action creates a barrier that prevents contamination while maintaining the simplified manufacturing approach. The partial curing is achieved through UV exposure or other curing methods applied selectively to the adhesive layer before liquid crystal filling.
Solution Approach 2:
The adhesive's curing state is changed from fully uncured to partially cured, creating an intermediate state that provides both barrier functionality and reduced contamination risk. This parameter change allows the adhesive to maintain structural integrity as a barrier while minimizing harmful interactions with the liquid crystal.
2Object-affected harmful factors
If rigid barrier fillet is used to prevent contamination, then liquid crystal contamination is reduced, but manufacturing precision requirements become unacceptable and thick elements cannot be cost effectively produced
Solution Approach 1:
The barrier fillet material is changed from rigid to flexible through partial curing of the adhesive. This parameter change in material properties allows the barrier to function effectively in preventing contamination while being manufacturable with standard techniques and acceptable precision requirements. The flexible nature of partially cured adhesive accommodates manufacturing tolerances better than rigid materials.
Solution Approach 2:
The barrier structure uses a composite approach combining adhesive material with partial curing, creating a material that exhibits both barrier properties and flexibility. This composite solution integrates the benefits of contamination prevention with the advantages of ease of manufacture and reduced precision requirements.
3Productivity
If side filling is used in wafer-scale manufacturing, then large arrays of cells are prepared simultaneously, but significant losses of liquid crystal material occur and contamination is generated
Solution Approach 1:
The liquid crystal is introduced through a separate capillary channel that is extracted or separated from the main adhesive filling path. This extraction of the liquid crystal filling route allows for controlled delivery to each cell without the material losses and contamination issues associated with side filling through adhesive channels.
Solution Approach 2:
A separate capillary structure acts as an intermediary delivery system for the liquid crystal, distinct from the adhesive filling path. This intermediary channel enables precise liquid crystal introduction while preventing contact between the adhesive and liquid crystal, thereby eliminating contamination and reducing material loss.
4Device complexity
If adhesive is used as both container wall and bonding agent, then device complexity is reduced, but contamination occurs during assembly and curing
Solution Approach 1:
The adhesive is partially cured before liquid crystal introduction to establish it as a non-contaminating barrier. This preliminary action separates the adhesive's functions temporally: first as a contamination-free barrier, then as a bonding agent during final curing. This resolves the contradiction by maintaining structural simplicity while preventing contamination through sequential functional activation.
Solution Approach 2:
The adhesive's curing process is segmented into two stages: partial curing to create the barrier function, and complete curing to provide bonding. This segmentation of the curing process allows the adhesive to fulfill multiple roles without causing contamination, maintaining device simplicity while solving the contamination problem.
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 reduces contamination and material loss, enhances manufacturing efficiency, and allows for the production of thicker liquid crystal layers without the precision issues associated with rigid fillets, while maintaining adhesive functionality for bonding.
Implementation Method 1
By partly curing the adhesive, diffusion (and mutual contamination) between the liquid crystal and the adhesive is reduced
Implementation Method 2
the adhesive is further cured to bond together the top and bottom substrates
Data Source
AI summary
A wafer level method of manufacturing a liquid crystal optical device removes the need for a rigid barrier fillet while minimizing any risk of contamination of the liquid crystal. An uncured adhesive may be deposited on a bottom substrate and partially cured to form a liquid crystal barrier. After addition of the liquid crystal and a top substrate, the adhesive is fully cured to bond the substrate layers together. An uncured adhesive may be used together with the partially cured adhesive, and may be deposited separately or filled into an extracellular matrix surrounding a plurality of liquid crystal cells. The adhesive may be cured by a variety of means, including light that may be spatially modulated. One or both of the substrates may be deformed during assembly so as to create a structure with a lensing effect on light passing through the liquid crystal region.