ROIC Substrate Replacement to Eliminate Interconnect Strain
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current electro-optical sensors face challenges in maintaining interconnect integrity between detectors and read-out integrated circuits (ROICs) due to differential thermal expansion, especially with increasing thermal cycle requirements and larger arrays operating in varying temperature environments.
Innovation Solution
The method involves replacing the initial ROIC substrate with a new one that matches the coefficient of thermal expansion (CTE) of the detector substrate, and hybridizing the detector layers to the ROIC layers using interconnects, which can be deposited before or after bonding, to eliminate interconnect strains caused by thermal cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the initial ROIC substrate is used with the detector, then the ROIC can be manufactured and assembled, but differential thermal expansion causes interconnect strain during thermal cycling
Solution Approach 1:
The patent changes the CTE parameter of the ROIC substrate by replacing the initial ROIC substrate with a new substrate having a CTE matched to the detector substrate. This parameter change eliminates differential thermal expansion and interconnect strain during thermal cycling while maintaining manufacturability of the ROIC assembly.
Solution Approach 2:
The new CTE-matched ROIC substrate acts as an intermediary between the detector substrate and the ROIC layers. It serves as a thermal expansion mediator that eliminates differential expansion stresses, allowing the ROIC to be manufactured and assembled without compromising interconnect integrity during thermal cycling.
2Measurement precision
If arrays increase in size and operate at lower temperatures, then detection capability improves, but thermal cycle requirements become more difficult to meet
Solution Approach 1:
The patent changes the thermal expansion parameter (CTE) of the ROIC substrate to match the detector substrate. This enables larger arrays to operate at lower temperatures with improved detection capability while eliminating thermal expansion mismatches that would otherwise cause interconnect failure during required thermal cycling.
3Productivity
If more thermal cycles are required, then operational demands increase, but interconnect integrity becomes harder to maintain
Solution Approach 1:
The patent changes the CTE parameter of the ROIC substrate to match the detector substrate, eliminating differential thermal expansion. This allows the system to withstand 10,000 or more thermal cycles required by modern operational demands without compromising interconnect integrity between the detector and ROIC.
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 significantly improves thermal cycle hybrid reliability, allowing for virtually unlimited cooldown cycles and reduces stresses between the detector and ROIC, minimizing image artifacts and detector bowing, thereby enhancing the overall hybrid reliability of interconnects.
Implementation Method 1
the new ROIC substrate having a coefficient of thermal expansion (CTE) that matches a CTE of the detector substrate
Data Source
AI summary
A method of eliminating interconnect strains in a stack-up is provided. The method includes providing a detector portion including a detector substrate and detector layers, providing a read-out integrated circuit (ROIC) stack-up including ROIC layers and an initial ROIC substrate, removing the initial ROIC substrate from the ROIC layers, attaching a new ROIC substrate to a first surface of the ROIC layers, the new ROIC substrate having a coefficient of thermal expansion (CTE) that matches a CTE of the detector substrate and hybridizing the detector layers to a second surface of the ROIC layers by way of interconnects.