Liquid Lens Arrays Fabrication Using Room Temperature Laser Bonding
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Solution Overview
Problem
The manufacturing of liquid lenses is hindered by difficulties in forming reliable bonds between components in the presence of liquids, expansion stresses at elevated temperatures, and the high cost and complexity of transitioning from one-at-a-time to wafer-scale assembly, particularly with traditional materials like aluminum or stainless steel.
Innovation Solution
A method involving the creation of axisymmetric through holes in a central plate with conductive traces, bonding with transparent glass plates, applying insulating materials, and using room temperature laser bonding to form hermetic seals, allowing for the fabrication of liquid lens arrays that accommodate thermal expansion without structural failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional materials such as aluminum or stainless steel are used for through-hole components, then structural strength is maintained, but manufacturing cost and complexity increase significantly at wafer scale
Solution Approach 1:
The patent changes the material parameter from traditional metals (aluminum, stainless steel) to glass, which enables wafer-scale batch fabrication through standard semiconductor manufacturing techniques while maintaining the required structural properties for through-hole formation and bonding
Solution Approach 2:
The patent replaces mechanical machining processes required for metal through-hole fabrication with photolithographic and etching processes that work with glass, enabling parallel wafer-scale production instead of sequential individual fabrication
2Adaptability or versatility
If bonding is performed in the presence of liquids, then liquid lens functionality is achieved, but bond reliability deteriorates due to liquid interference
Solution Approach 1:
The patent performs all bonding operations before introducing liquids into the system. Through-holes are formed, conductive traces are deposited, and plates are bonded together in a dry state, ensuring reliable bonds free from liquid interference, after which the assembled structure is sealed and liquids are introduced
3Reliability
If liquid lenses are manufactured one-at-a-time, then bond reliability is maintained, but manufacturing cost increases significantly compared to batch fabrication
Solution Approach 1:
The patent merges multiple individual lens fabrication processes into a single wafer-scale batch process. Multiple through-holes are created simultaneously in one glass plate, multiple lenses are assembled in parallel, and all bonding operations are performed on entire wafers at once, dramatically reducing per-unit cost while maintaining quality through standardized processes
4Reliability
If liquid lenses are heated to maximum shipping temperature for testing, then product reliability is verified, but bond strength deteriorates due to thermal expansion stresses
Solution Approach 1:
The patent designs the bonded structure with built-in compensation for thermal expansion. The glass material selection and bonding geometry are chosen to accommodate expansion stresses that occur during high-temperature shipping and testing, preventing bond failure while enabling reliability verification through temperature cycling
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 enables the cost-effective, high-precision fabrication of liquid lens arrays with robust bonds and reduced risk of leakage or failure, facilitating batch production and thermal excursion management.
Implementation Method 1
The use of liquid lenses, in which the shape of an interface between a polar liquid and a non-polar liquid is controlled by electrowetting to provide optical focusing and optical stabilization functions
Implementation Method 2
using room temperature laser bonding to form hermetic seals
Data Source
AI summary
A method of fabricating a liquid lens array creates an array of through holes of axisymmetric cross-section through a central plate, forms conductive traces on the side walls of each of the through holes and on a portion of the top and bottom surfaces of the central plate contiguous with each through hole, and bonds the bottom surface of the central plate around each through hole to the top surface of a transparent base plate, forming an array of cavities. The method applies an insulating layer to the side walls of each cavity, portions of the top surface of the base plate lying within each cavity, and portions of the top surface of the transparent central plate surrounding each cavity, introduces a polar liquid and a non-polar liquid into each cavity; and bonds the top surface of the central plate to the bottom surface of a transparent top plate.