Endoscope Imaging Unit Joint Protection Against Autoclave Thermal Stress
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Solution Overview
Problem
Endoscopic imaging units face reliability issues during autoclave sterilization due to the expansion of fillers, which can break the joints between TAB tapes and electronic parts, leading to potential failures in capturing in-vivo images.
Innovation Solution
The imaging unit incorporates a semiconductor package with a chip size package (CSP) design, where sensor electrodes are connected to a circuit substrate via bumps, and a filler with a lower linear expansion coefficient is used, along with a cover member to prevent filler infiltration into the joint, creating an internal air space that reduces the impact of temperature changes during sterilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filler is used to seal the space around the semiconductor package and circuit substrate, then the joint is protected from external factors, but the filler expands during autoclave sterilization and breaks the joint between TAB tapes and electronic parts
Solution Approach 1:
The sealing space is divided into two regions: a first space around the semiconductor package filled with first filler, and a second space around the circuit substrate filled with second filler having different thermal expansion characteristics. This segmentation allows each filler to be optimized for its specific component, preventing thermal expansion from damaging the joints during autoclave sterilization.
Solution Approach 2:
Different fillers with specific local properties are used in different regions. The first filler is positioned to seal around the semiconductor package while the second filler seals around the circuit substrate. This local quality approach ensures that each filler's thermal expansion characteristics are appropriate for its specific location, preventing joint breakage during temperature cycles.
2Reliability
If the filler is used to protect electronic parts, then sealing is achieved, but the filler infiltrates the joint between semiconductor package and circuit substrate during sterilization
Solution Approach 1:
The sealing function is segmented between two fillers positioned in separate spaces. The first filler seals the first space around the semiconductor package, while the second filler seals the second space around the circuit substrate. This segmentation prevents filler infiltration into the joint region while maintaining effective sealing of both components.
Solution Approach 2:
The circuit substrate acts as an intermediary structure that physically separates the two filler materials. By positioning the second filler on the circuit substrate side and the first filler on the semiconductor package side, the substrate prevents direct contact and infiltration between fillers, protecting the joint while maintaining sealing performance.
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 enhances the reliability of the joint between the semiconductor package and the circuit substrate, maintaining image capture functionality even after repeated sterilization processes by preventing filler infiltration and minimizing the effects of thermal expansion.
Implementation Method 1
there is a risk that the joint between the TAB tapes and the electronic parts may be broken due to expansion of the filler
Implementation Method 2
sensor electrodes of the CSP and connection electrodes of a circuit substrate are directly connected to each other with bumps
Data Source
AI summary
An imaging unit includes: a semiconductor package including an imaging device and having a back surface on which a sensor electrode is formed; a circuit substrate including a connection electrode that is connected to the sensor electrode via a bump; a surrounding part configured to cover the semiconductor package and the circuit substrate; a filler with which a space that is enclosed by the surrounding part is filled to seal a circumference of the semiconductor package and the circuit substrate; and a first cover configured to prevent the filler from infiltrating a joint between the semiconductor package and the circuit substrate.