Thin Silicon Chip Integration in Contact Lenses
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Solution Overview
Problem
Existing methods for assembling silicon chips, such as flip chip bonding and wire bonding, are not suitable for integrating silicon chips into contact lenses due to the thickness and size limitations of standard silicon chips, which are too thick to fit onto a contact lens and require bumped pads that are not compatible with the lens material.
Innovation Solution
The method involves thinning silicon chip substrates to less than 100 microns, patterning metal lines on both the chip and lens substrate to create contact pads, and using low-temperature assembly bonding materials like anisotropic conductive films or solder solutions to bond the chip to the lens substrate, which is then sealed and molded into a contact lens shape to fit the eye's curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard silicon chips are used with flip chip bonding or wire bonding, then reliable electrical interconnection is achieved, but the chip thickness and size become too large to fit onto a contact lens
Solution Approach 1:
The patent changes the thickness parameter of the silicon chip from standard thickness to ultra-thin (less than 100 microns) to enable contact lens integration. This parameter modification allows the chip to fit within the contact lens structure while maintaining electrical functionality through alternative bonding methods that do not require thick solder bumps.
Solution Approach 2:
The patent extracts the solder bumps from the chip assembly process, replacing them with thin bonding materials such as anisotropic conductive films or solder paste. This removal of the bulky solder bump component enables the chip to achieve the required thin profile for contact lens integration while still providing reliable electrical connections.
2Reliability
If solder bumps are deposited on chip pads for flip chip bonding, then strong electrical connections are formed, but the bumped pads are not compatible with contact lens material
Solution Approach 1:
The patent changes the bonding material from thick solder bumps to thin bonding materials with thickness compatible with contact lens requirements. This parameter change enables the use of materials such as anisotropic conductive films or solder paste that can be applied in thin layers, achieving both strong electrical connections and compatibility with contact lens materials.
Solution Approach 2:
The patent introduces intermediary bonding materials such as anisotropic conductive films or solder paste that serve as mediators between the chip pads and lens substrate. These intermediary materials provide the necessary electrical conductivity and mechanical bonding while being thin enough to allow direct bonding to the contact lens substrate without requiring thick solder bumps.
3Length of moving object
If thin silicon chips are fabricated and bonded using low-temperature methods, then contact lens integration is enabled, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces traditional high-temperature mechanical soldering processes with low-temperature bonding methods using anisotropic conductive films or solder paste. This substitution reduces the thermal and mechanical stress on ultra-thin chips during assembly, enabling the integration of chips with thickness less than 100 microns while maintaining acceptable manufacturing precision through gentler processing conditions.
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 allows for the successful integration of thin silicon chips within contact lenses, enabling electrical operations and biocompatibility, while overcoming the size and thickness limitations of standard silicon chips, allowing for the assembly of multiple electrical components like sensors and LEDs.
Implementation Method 1
using low-temperature assembly bonding materials like anisotropic conductive films or solder solutions to bond the chip to the lens substrate
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3
AI summary
A contact lens having a thin silicon chip integrated therein is provided along with methods for assembling the silicon chip within the contact lens. In an aspect, a method includes creating a plurality of lens contact pads on a lens substrate and creating a plurality of chip contact pads on a chip. The method further involves applying assembly bonding material to the each of the plurality of lens contact pads or chip contact pads, aligning the plurality of lens contact pads with the plurality of chip contact pads, bonding the chip to the lens substrate via the assembly bonding material using flip chip bonding, and forming a contact lens with the lens substrate.