Proximity Sensor Resin Sealing With PCB Cutouts to Prevent Voids
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Solution Overview
Problem
Proximity sensors with resin sealing face issues with void generation due to low flowability of liquid resin, especially when accommodating large circuit boards and increasing numbers of cables, leading to reduced yield and potential air bubble entrapment.
Innovation Solution
Incorporating a cutout portion with a notch or opening shape on the circuit board to facilitate even resin flow and provide a resin injection port in the clamp, allowing for improved communication between internal spaces and reducing air entrapment by ensuring smooth resin flow and venting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a relatively large circuit board is accommodated to partition an internal space of the housing, then the functional capability of the proximity sensor is improved, but the flowability of liquid resin deteriorates and air bubbles are easily entrapped
Solution Approach 1:
The circuit board is divided into multiple regions by providing cutout portions that partition the board into separate sections. This segmentation allows liquid resin to flow through the cutout regions, preventing air bubble entrapment while maintaining the board's structural integrity and functional capability.
Solution Approach 2:
The cutout portions act as intermediary channels that facilitate the flow of liquid resin between different regions of the housing. These openings serve as mediators that enable resin to bypass obstacles on the circuit board, ensuring complete filling without trapping air bubbles.
2Adaptability or versatility
If the number of cables led into the inside of the housing is increased to expand communication function, then the communication capability is improved, but the flowability of liquid resin deteriorates and voids are likely to be generated
Solution Approach 1:
The circuit board is segmented with cutout portions that create open channels through the board structure. This segmentation allows liquid resin to flow continuously through and around cable assemblies, preventing void formation even when multiple cables are present in the housing.
3Reliability
If liquid resin with high viscosity is used for sealing, then the sealing reliability is improved, but the flowability deteriorates and voids are easily generated
Solution Approach 1:
The cutout portions in the circuit board create multiple flow paths that segment the resin filling process. This allows high-viscosity resin to flow more easily through the divided channels, reducing the likelihood of void formation while maintaining sealing reliability.
Solution Approach 2:
The cutout portions introduce additional dimensional pathways through the circuit board structure. By creating openings that extend through the board thickness, the resin can flow in multiple directions, effectively reducing the impact of high viscosity on filling completeness.
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 effectively suppresses void generation in the resin sealing portion, enhancing the yield and reliability of the proximity sensor even with larger circuit boards and increased cable counts.
Implementation Method 1
The liquid resin generally has high viscosity and its flowability is not high
Implementation Method 2
injecting a liquid resin forming the resin sealing portion by curing the liquid resin
Data Source
AI summary
A proximity sensor in which generation of voids in a resin sealing portion sealing an inside of a housing can be suppressed and thus a yield is improved. The proximity sensor includes a housing, a detection coil, a circuit board and a resin sealing portion. The circuit board is accommodated in the housing to partition an internal space of the housing, and the resin sealing portion covers at least a part of the circuit board by filling the internal space of the housing and thus seals a covered portion of the circuit board. A resin injection port configured to inject a liquid resin forming the resin sealing portion by curing the liquid resin is provided in the housing, and a cutout portion having a notch shape or an opening shape is provided in the circuit board to include at least a part of a portion facing the resin injection port.