Thermistor Assembly Sealing for Accurate Sensor Positioning
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Solution Overview
Problem
The softness of Dumet wires makes it difficult to accurately position the thermistor assembly within the protective case due to bending issues, and the instability of the sealing resin dimensions and shape further complicates precise placement.
Innovation Solution
A thermistor assembly with two rigid lead members connected to the thermistor, sealed by a first resin portion, is inserted into a case with a second resin portion that seals the first resin portion, ensuring accurate positioning through transfer molding and curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Dumet wire is used as lead wire to seal thermistor in glass, then the lead wire can be connected to the thermistor, but the softness of the Dumet wire causes it to bend during insertion, making accurate positioning difficult
Solution Approach 1:
The lead wire is divided into two distinct segments: a Dumet wire portion for reliable thermistor connection and positioning, and a separate lead wire portion for electrical connection. This segmentation allows each portion to perform its specific function optimally without the drawbacks of using a single material for both purposes.
Solution Approach 2:
A resin portion is introduced as an intermediary material to fix and secure the lead wire in place. This resin acts as a mediator that holds the lead wire at the correct position during insertion and prevents bending, enabling accurate positioning while maintaining connection reliability.
2Manufacturing precision
If a lead wire with rigidity is connected to the Dumet wire and sealed by dipping in sealing resin, then the lead wire does not bend, but the shape and dimensions of the sealing resin are unstable, making accurate positioning difficult
Solution Approach 1:
The sealing method is changed from dipping to transfer molding. This parameter change in the manufacturing process allows for precise control of the resin's shape and dimensions, ensuring stable and repeatable positioning accuracy while eliminating the instability associated with dip sealing.
Solution Approach 2:
The dipping process is replaced with a transfer molding process. This substitution transitions from a less controlled mechanical dipping method to a more precisely controlled molding process that produces consistent resin shapes and dimensions for accurate positioning.
3Reliability
If transfer molding is used to seal the thermistor with a first resin portion, then the thermistor is securely sealed, but an additional sealing step with second resin portion is required
Solution Approach 1:
The sealing process is segmented into two distinct stages: first resin portion sealing during transfer molding to secure the thermistor, and second resin portion sealing to seal the lead wire. This segmentation allows each sealing step to focus on specific components, improving overall sealing reliability while organizing the complexity into manageable stages.
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 allows for the accurate positioning of the thermistor within the case without bending, providing a stable and precise temperature sensor assembly.
Implementation Method 1
a molding step of molding a first resin portion by a transfer molding such that the thermistor is sealed by the first resin portion
Implementation Method 2
an injection step of injecting resin into an accommodation area of a case
Implementation Method 3
a curing step of curing the resin
Data Source
AI summary
A thermistor assembly includes a thermistor; two lead members with rigidity; and a first resin portion, wherein first end portions of the two lead members are connected with the thermistor, and the thermistor is sealed by the first resin portion.