Detector Module Assembly Device Thermal Stress Management
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Solution Overview
Problem
The existing methods for assembling detector modules in computed tomography (CT) scanners, particularly the soldering process, can compromise the solder bond between photodiode array tiles and ASICs, leading to thermal sensitivity issues and the need for alternative approaches.
Innovation Solution
A module assembly device with a base and side walls forming a recess and protrusions, allowing for concurrent reflow soldering of the ASIC and photodiode array tiles to the module substrate, while using heat sinks to manage thermal stress and maintain bond integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reflow soldering is used to assemble the photodiode array tile, ASIC, and module substrate, then manufacturing efficiency is improved, but the solder bond between the photodiode array tile and ASIC is compromised due to thermal sensitivity
Solution Approach 1:
The patent divides the soldering process into two separate stages: first bonding the ASIC to the photodiode array tile, then bonding the photodiode array tile to the module substrate. This segmentation allows each bonding step to be optimized independently, preventing thermal damage to the ASIC while maintaining manufacturing efficiency.
Solution Approach 2:
The ASIC is pre-bonded to the photodiode array tile before the final assembly step. This preliminary action protects the ASIC from exposure to high reflow temperatures during subsequent soldering operations, as the ASIC is already in place and can be shielded or the heat can be applied selectively to only the tile-substrate interface.
2Reliability
If sequential soldering is used to bond components, then thermal sensitivity of previously bonded components is reduced, but manufacturing time increases
Solution Approach 1:
The patent merges the bonding of multiple components into a single reflow soldering operation by designing the photodiode array tile with integrated solder regions that allow simultaneous bonding of the ASIC and the module substrate in one heating cycle, eliminating the need for multiple sequential soldering steps.
3Device complexity
If conventional assembly methods are used, then device complexity is reduced, but thermal management during soldering becomes problematic
Solution Approach 1:
The photodiode array tile serves as an intermediary component between the ASIC and the module substrate. This intermediary structure allows for thermal isolation, where the tile can be heated for soldering without directly transmitting excessive heat to the temperature-sensitive ASIC, thus managing thermal stress while maintaining a relatively simple assembly process.
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 effectively assembles detector modules without compromising the solder bonds, overcoming thermal sensitivity issues and enabling the production of reliable and integrated CT detector modules.
Implementation Method 1
The module assembly device further includes a heat sink configured to remove heat from a bond between the photo-detector array tile and the ASIC
Implementation Method 2
The method further includes concurrently reflowing the first and second solders to concurrently bond the ASIC to the photo-detector array tile and the photo-detector array tile to the module substrate
Data Source
AI summary
A module assembly device (402) is configured for assembling a module assembly (114) for a detector array (110) of an imaging system (100). The module assembly device includes a base (400) having a long axis (401). The module assembly device further includes a first surface (406) of the base and side walls (408) protruding perpendicular up from the first surface and extending in a direction of the long axis along at least two sides of the base. The first surface and side walls form a recess (404) configured to receive the module substrate on the surface and within the side walls. The module assembly device further includes protrusions (403) protruding from the side walls in a direction of the side walls. The protrusions and side walls interface forming a ledge which serves as a photo-detector array tile support (410) configured to receive the photo-detector array tile (118) over the ASIC and the module substrate.