Optical Assemblies With Direct-Molded Spacers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical assemblies face issues with adhesive migration and moisture absorption in spacer wafers, leading to misalignment and dimensional changes that negatively impact optical performance.
Innovation Solution
The fabrication of optical assemblies involves molding spacers directly onto the optics wafer using a vacuum injection technique, eliminating the need for adhesives and reducing the risk of misalignment and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is used to bond wafers together, then the wafers can be attached and aligned, but the adhesive may migrate to areas that negatively impact optical performance
Solution Approach 1:
The patent removes the adhesive layer from the wafer bonding process entirely. Instead of using adhesive to bond the spacer wafer to the optics wafer, the process relies on direct mechanical bonding through the wafer stacking and dicing process, eliminating the source of adhesive migration that could harm optical performance.
Solution Approach 2:
The spacer wafer itself serves as the bonding interface between optical components. By making the spacer wafer the direct bonding element rather than using it merely as a spacing element with adhesive, the patent eliminates the need for separate adhesive layers while maintaining structural integrity.
2Length of stationary object
If thin spacer wafers are used to separate optical members, then the overall height of the assembly is reduced, but distortion of the wafers can occur during processing
Solution Approach 1:
The spacer wafer is bonded to the optics wafer before the dicing process. This preliminary bonding action provides mechanical support and stability to the thin spacer wafer during subsequent handling and processing steps, preventing distortion that would otherwise occur with thin, unbonded wafers.
Solution Approach 2:
The patent combines multiple functions into the spacer wafer: it provides spacing, serves as a bonding substrate, and acts as a structural support element. By merging these functions, the thin wafer can maintain its integrity without requiring additional support structures that would increase assembly height.
3Ease of manufacture
If spacer wafers composed of epoxy material are used, then they can provide spacing and bonding, but they may absorb moisture resulting in relatively large dimensional changes
Solution Approach 1:
The patent changes the material parameters of the spacer wafer by using materials with low moisture absorption characteristics. This parameter change ensures that the spacer wafer maintains dimensional stability while still providing the necessary bonding capability, eliminating the trade-off between ease of manufacture and compositional stability.
4Productivity
If wafer-level processes are used to fabricate multiple assemblies in parallel, then productivity is increased, but adhesive migration and misalignment can occur
Solution Approach 1:
By removing the adhesive layer from the wafer-level bonding process, the patent eliminates the primary source of misalignment and optical contamination. The direct wafer-to-wafer bonding through stacking and dicing provides inherent alignment precision while maintaining the high productivity benefits of parallel wafer-level fabrication.
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 enhances the optical performance by preventing adhesive migration and moisture absorption, ensuring precise alignment and stability of the optical components.
Implementation Method 1
molding spacers directly onto the surface of the optics wafer. The spacers can be molded, for example, using a vacuum injection technique such that they adhere to the optics wafer without adhesive
Data Source
Figure 1
Figure 2
Figure 3
AI summary
This disclosure describes optical assemblies that can be fabricated, for example, using wafer-level processes. The process can include providing a wafer stack that includes an optics wafer, and molding spacers directly onto the surface of the optics wafer. The spacers can be molded, for example, using a vacuum injection technique such that they adhere to the optics wafer without adhesive.