Modular Optoelectronic Package for High-Aspect-Ratio Thermal Crack Resistance
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Solution Overview
Problem
Optoelectronic packages with high aspect ratios are prone to cracking due to thermal expansion mismatch between materials, leading to mechanical and electrical failures in harsh environments.
Innovation Solution
A modular optoelectronic package design with flexible seams between ceramic substrate modules and glass-reinforced epoxy laminate materials, allowing the carrier to flex without cracking, and incorporating staggered pixel array circuits for stress relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single-piece rigid carrier is used to support pixel array circuits, then structural strength is improved, but the carrier is prone to cracking during thermal cycling due to CTE mismatch
Solution Approach 1:
The carrier is divided into multiple discrete substrate modules (e.g., four 10mm x 10mm modules) that are separately attached to the circuit substrate. These modular segments can independently flex and accommodate thermal expansion differences, preventing cracks that would occur in a rigid monolithic structure during thermal cycling from -55°C to +150°C.
2Area of stationary object
If the circuit substrate has a high aspect ratio (e.g., 4:1) to accommodate a large field-of-view, then detection coverage is improved, but the substrate becomes more susceptible to curving and mechanical stress
Solution Approach 1:
The long-dimensional carrier is segmented into multiple smaller substrate modules arranged in a sequence. This segmentation reduces the aspect ratio of individual modules, making them more stable and less prone to curving, while the overall array still provides the required large field-of-view coverage through the combined area of multiple modules.
3Strength
If ceramic substrate modules are used to provide mechanical strength, then structural integrity is improved, but thermal expansion mismatch with glass-reinforced epoxy laminate causes stress during thermal cycling
Solution Approach 1:
The carrier is segmented into multiple ceramic substrate modules that are separately attached to the glass-reinforced epoxy laminate circuit substrate. This segmentation allows each module to independently accommodate thermal expansion differences, reducing overall thermal stress while maintaining structural integrity through the distributed modular architecture.
Solution Approach 2:
The design accepts and accommodates the thermal expansion parameter difference between ceramic (first CTE) and glass-reinforced epoxy laminate (second CTE) by creating a modular structure that can flex. The segmented carrier changes its physical state from rigid to flexibly rigid, allowing it to adapt to thermal cycling conditions without developing excessive stress.
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
Enhances durability and reliability of optoelectronic circuits by reducing cracking and maintaining functionality over a wide temperature range.
Implementation Method 1
the circuit substrate is curved along the long axis due to a difference between the first coefficient of thermal expansion and the second coefficient of thermal expansion during a thermal cycle
Data Source
AI summary
A segmented optoelectronic semiconductor package may help to alleviate stresses resulting from bending that can cause a mechanical defect (e.g., crack) in a detector circuit. The bending can result from thermal growth/shrinkage of parts used in the optical electronic package and may be more pronounced for high aspect ratio detector circuits. The segmentation of the disclosed semiconductor package can create seams that allow the parts to flex without breaking. As a result, the disclosed semiconductor package may facilitate high aspect ratio optical detection over a wide temperature range.