Endoscopic Image Sensor Intermediate Unit Thermal Stress
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Solution Overview
Problem
Endoscopic devices face issues with faulty electrical connections between image sensors and drive circuit boards due to thermal expansion during high-temperature sterilization processes, such as autoclaving, as existing technologies do not account for differences in thermal expansion coefficients of components.
Innovation Solution
Incorporating an intermediate unit with a thermal expansion coefficient matching or closely matching that of the image sensor section, along with solder balls and underfill, to secure and electrically connect the image sensor and substrate, while an elastic member can be used for additional stress absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the image sensor and substrate are directly connected without an intermediate unit, then the device structure is simple, but the electrical connection becomes unreliable under thermal expansion stress
Solution Approach 1:
An intermediate unit is introduced between the image sensor and substrate to serve as a mediator that absorbs thermal expansion stress. This intermediate unit includes an intermediate member with matched thermal expansion coefficient and solder balls that flexibly connect the image sensor and substrate, preventing direct stress transmission while maintaining electrical connection reliability.
Solution Approach 2:
The thermal expansion coefficient parameter of the intermediate member is specifically selected to match or closely approximate that of the image sensor. This parameter matching reduces differential thermal stress at the joint interfaces during temperature changes, thereby maintaining connection reliability without requiring complex compensation mechanisms.
2Reliability
If components with different thermal expansion coefficients are directly joined, then assembly is simple, but thermal stress causes connection failure during sterilization
Solution Approach 1:
The intermediate unit acts as a buffer between components with different thermal expansion coefficients. The intermediate member's thermal expansion property is specifically designed to match the image sensor, creating a gradual transition that reduces stress concentration at joint interfaces during autoclave sterilization processes.
Solution Approach 2:
The intermediate unit is pre-installed between the image sensor and substrate to provide beforehand cushioning against thermal expansion stress. This preventive measure ensures that when thermal stress occurs during sterilization, the intermediate unit has already been positioned to absorb and distribute the stress, preventing connection failure.
3Manufacturing precision
If a rigid spacer is used to fix component positions, then positioning is precise, but thermal stress causes faulty electrical connections
Solution Approach 1:
The connection structure transitions from a completely rigid spacer to a semi-flexible configuration using solder balls and underfill. This dynamic design allows the joint interfaces to accommodate thermal expansion movements while maintaining precise positioning, as the solder balls can deform elastically to absorb dimensional changes without causing connection failure.
Solution Approach 2:
The intermediate unit employs a composite structure combining the intermediate member (with matched thermal expansion properties), solder balls (for flexible electrical connection), and underfill (for mechanical support and stress distribution). This composite approach simultaneously achieves precise positioning and thermal stress resistance.
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 configuration ensures a reliable electrical connection between the image sensor and substrate even at high temperatures, preventing connection failures and improving assembly workability by absorbing thermal expansion stresses.
Implementation Method 1
an intermediate member formed using a material having a coefficient of thermal expansion that is the same as a coefficient of thermal expansion of the image sensor section, or a coefficient of thermal expansion that is close to the coefficient of thermal expansion of the image sensor section
Implementation Method 2
an electrically conductive, elastically deformable elastic member provided between the image sensor section and the substrate
Implementation Method 3
solder balls that electrically connect the intermediate member and the substrate
Data Source
AI summary
There is provided an endoscopic device, including: an image sensor section including an image sensor that senses and converts lights into an electrical signal; a substrate that is electrically connected to the image sensor section; and an intermediate unit, interposed between the image sensor section and the substrate, that electrically connects the image sensor section and the substrate.