Lens Assembly Corner Voids for Thermal Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in wafer-level optics fabrication of lens assemblies arises from the significant difference in thermal expansion coefficients between glass and plastic layers, leading to stress concentration at the bonding interface, particularly in the corners, which can cause delamination or cracking under temperature extremes.
Innovation Solution
Incorporating corner voids aligned over the four corners of a glass layer in plastic layers to mitigate stress caused by thermal expansion differences, achieved through pre-drilling or pre-molding voids in the plastic layers before or during the formation of optical elements, compatible with existing WLO processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If glass and plastic layers are bonded together in a wafer stack, then the lens assembly can be manufactured using wafer-level optics processes, but stress concentration occurs at the bonding interface corners due to different coefficients of thermal expansion
Solution Approach 1:
The patent extracts or removes material from the corners of the wafer stack to create voids. These corner voids are specifically positioned at the bonding interface between glass and plastic layers, removing the stressed corner regions that would otherwise be prone to delamination and cracking under thermal expansion differences.
Solution Approach 2:
The patent introduces asymmetry by creating non-uniform void structures at the corners of the wafer stack. Rather than a uniform structure, the corner voids are strategically placed asymmetrically at the four corners, changing the stress distribution pattern from concentrated at corners to dispersed throughout the void regions.
2Reliability
If corner voids are incorporated in plastic layers, then stress is reduced and delamination is prevented, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-forming the corner voids in the plastic layers before the final bonding process. The voids are created in advance during plastic layer fabrication, so that when the wafer stack is assembled and subjected to thermal cycling, the stress-relief feature is already in place and functional.
Solution Approach 2:
The patent applies local quality by modifying only the corner regions of the plastic layers where voids are created, while leaving the rest of the plastic layer structure intact. This localized modification provides stress relief exactly where needed at the bonding interface corners without affecting the overall structural integrity or optical properties of the plastic layers.
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
The corner voids effectively reduce stress, preventing delamination and cracking, ensuring the integrity of the lens assembly under temperature variations.
Implementation Method 1
stress concentration at the bonding interface, particularly in the corners, which can cause delamination or cracking under temperature extremes
Data Source
AI summary
An apparatus, system, and method for a lens assembly has corner voids. The lens assembly may include a glass layer including four corners and a plastic layer including an optical element. In some examples, the plastic layer includes four corner voids aligned over the four corners of the rectangle glass layer.