Micro-Optic Lens Molding With Flow Stops and Air Vent Paths
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Solution Overview
Problem
Existing wafer-level manufacturing processes for micro-optic lenses face challenges in maximizing yield and reducing footprint, with methods like capillary action leading to excessive overflow and residual epoxy, while others risk under-filling and defects due to air entrapment.
Innovation Solution
A method involving a substrate with flow stop features and a mold tool configuration that includes an optical element cavity, peripheral cavity with flow stop features, and air flow paths to manage epoxy overflow and under-filling, reducing the radial extent of residual epoxy and enhancing tolerance to excess material variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If excess volume of epoxy is dispensed into the lens-shaped recess to avoid under-filling, then the lens cavity is adequately filled, but the overflow increases the footprint of each lens on the substrate
Solution Approach 1:
The substrate surface is segmented into multiple regions: a central lens formation area and a peripheral overflow collection area separated by flow stop features. This segmentation allows excess epoxy to be directed to the periphery rather than expanding the footprint of individual lenses, thereby maintaining lens filling completeness while controlling lens footprint dimensions.
Solution Approach 2:
Flow stop features act as intermediary structures between the lens cavity and the substrate periphery. These features control and redirect the flow of excess epoxy material, serving as a mediator that prevents uncontrolled overflow while ensuring adequate lens filling, thus resolving the contradiction between complete filling and footprint control.
2Manufacturing precision
If capillary action is used to draw excess epoxy radially outwardly through a narrow elongated region, then under-filling is avoided, but residual epoxy accumulates in a peripheral region increasing the overall footprint
Solution Approach 1:
The harmful residual epoxy that accumulates in the peripheral region is extracted and isolated from the functional lens area by directing it into dedicated overflow collection regions. This separation removes the adverse effect of residual epoxy from the lens footprint while maintaining the beneficial capillary action for preventing under-filling.
Solution Approach 2:
Different regions of the substrate are assigned different functions: the central region optimizes for lens filling using capillary action, while the peripheral regions are designed specifically for overflow collection. This local differentiation allows capillary action to prevent under-filling without compromising the overall footprint, as residual epoxy is confined to designated peripheral zones.
3Area of moving object
If a peripheral trench is formed in the substrate surface to collect excess epoxy, then the footprint is limited, but air in the trench is forced into the lens cavity causing under-filling and defects
Solution Approach 1:
The flow stop features are pre-configured on the substrate surface before epoxy dispensing to create controlled flow paths. This preliminary arrangement ensures that excess epoxy is directed away from the lens cavity through predetermined channels, preventing air entrapment and under-filling issues while maintaining compact footprint dimensions.
Solution Approach 2:
Instead of forming a closed peripheral trench that traps air, the invention inverts the approach by creating open flow paths with flow stop features that guide excess epoxy outward. This inverted design allows air to escape naturally while excess epoxy is directed to peripheral collection areas, resolving both footprint limitation and filling completeness requirements.
4Area of moving object
If the mold surface profile and substrate are pressed together to force excess epoxy into a peripheral trench, then footprint is controlled, but air entrapment causes under-filled lenses
Solution Approach 1:
Flow stop features serve as intermediary structures that mediate between the pressing force and the epoxy flow. These features create controlled channels that allow excess epoxy to be forced outward while maintaining continuous flow paths for air escape, thereby controlling footprint without causing under-filling defects.
Solution Approach 2:
The invention replaces the mechanical trench structure with a surface-level flow control system using flow stop features. This substitution maintains footprint control through surface geometry rather than deep mechanical trenches, eliminating air entrapment while preserving the ability to direct excess epoxy to peripheral areas.
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 method reduces the overall footprint of finished optical elements, increases yield, and minimizes defects by controlling epoxy flow and air flow, allowing for more efficient use of wafer area and higher lens density.
Implementation Method 1
As a result of capillary action in the narrow elongated region, excess epoxy is gradually drawn radially outwardly out of the lens cavity relative to the optical axis through the narrow elongated region into the peripheral cavity
Data Source
AI summary
A method for manufacturing an optical element such as a micro-optic lens may include providing a substrate having a surface profile, the substrate surface profile defining one or more flow stop features. The method may include providing a mold tool having a mold surface profile and dispensing viscous material. When the mold surface profile and the substrate surface profile are disposed towards one another and aligned relative to one another, the mold surface profile and the substrate surface profile define therebetween an optical element cavity, a peripheral cavity disposed around a periphery of the optical element cavity where the peripheral cavity includes one or more flow stop features, and an air flow path for air to flow in and out of the peripheral cavity from and to an external environment. The optical element cavity and the peripheral cavity define a peripheral constriction therebetween.