Endoscope PCB Expansion Gap for Thermal Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The electrical connections between printed circuit boards (PCBs) of different materials in endoscopes are prone to degradation and damage due to thermal expansion, especially during reprocessing with superheated steam, as they have different coefficients of thermal expansion (CTEs), leading to stress and wear at soldering points.
Innovation Solution
Incorporating an expansion gap between the contact points on the PCBs, arranged on opposing edges, to alleviate the mechanical stress caused by thermal expansion, allowing the material to expand or contract without applying excessive force on the solder joints, thereby reducing the risk of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PCBs with different materials are used to satisfy design requirements, then adaptability and space utilization are improved, but thermal expansion stress at soldering points increases due to different CTEs
Solution Approach 1:
The PCB is segmented by introducing an expansion gap that divides the continuous board into sections. This segmentation allows different parts of the PCB to expand and contract independently, reducing the transmission of thermal stress to the solder joints while maintaining the overall structural integrity and electrical connectivity of the board.
Solution Approach 2:
The expansion gap is strategically positioned at specific locations on the PCB where thermal stress accumulation occurs. By locally modifying the PCB structure at these critical points, the design allows targeted stress relief without compromising the overall functionality or requiring complete redesign of the entire PCB.
2Adaptability or versatility
If multiple PCBs are used to connect sensors and supply electrical power, then functional requirements are met, but the number of soldering points increases leading to higher stress concentration
Solution Approach 1:
The expansion gap segments the PCB into distinct regions that can move relative to each other during thermal cycles. This segmentation distributes the thermal expansion stress across multiple locations rather than concentrating it at the solder joints, thereby reducing the stress burden on each individual soldering point while maintaining multiple electrical connections.
3Strength
If rigid PCBs are used for structural support, then mechanical strength is improved, but flexibility and space utilization are reduced
Solution Approach 1:
By segmenting the rigid PCB through the expansion gap, the structure maintains rigidity in regions requiring mechanical strength while allowing controlled movement across the gap. This enables the PCB to combine the benefits of rigid support with flexible adaptation to thermal changes, resolving the contradiction between strength and flexibility.
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
The expansion gap reduces the risk of solder joint degradation and damage from repeated temperature changes, maintaining a stable electrical connection between PCBs with different CTEs, even under high thermal stress conditions.
Implementation Method 1
different materials may comprise different coefficients of thermal expansion (CTE), different thermal expansions at a given temperature change may cause stress within the PCBs and especially at the soldering points
Data Source
AI summary
An endoscope including a printed circuit board. The printed circuit board comprising at least two contact points for electrically connecting the printed circuit board, by solder, to a structural assembly. Wherein the contact points are arranged on first and second opposing edges of the first printed circuit board and the printed circuit board comprising an expansion gap arranged between the at least two contacting points and the first and second opposing edges. Furthermore, a method for electrically connecting the printed circuit board of an endoscope to a structural assembly is disclosed.