Thin Welded Temperature Sensor With Insulated Joint Structure
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Solution Overview
Problem
Existing temperature sensors face challenges in miniaturization, heat resistance, and accuracy due to thick joint materials and insulation degradation during welding processes, limiting their reliability and responsiveness, especially at high temperatures.
Innovation Solution
A thin temperature sensor design featuring a heat-sensitive element on an insulating substrate with a low-melting-point lead member joined by welding, sealed by insulating films to prevent additional material addition and maintain insulation, ensuring heat resistance up to 200°C or higher.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soldering or conductive paste is used to join the heat sensitive element and lead wire, then electrical connection is achieved, but the joint part thickness increases to 30-100 μm causing increased heat capacity and deteriorated thermal responsiveness
Solution Approach 1:
The patent removes additional joining materials (solder, conductive paste) from the joint part by using direct welding between the lead wire and electrode pattern, eliminating the intermediary layers that caused increased thickness and heat capacity
Solution Approach 2:
The patent introduces a laser beam as an intermediary to achieve direct welding between the lead wire and electrode pattern, enabling metallurgical bonding without traditional joining materials, thus reducing joint part thickness to minimize heat capacity while ensuring reliable electrical connection
2Reliability
If soldering is used to join the heat sensitive element, then electrical connection is established, but heat resistance is limited to 150° C. or lower due to solder melting point
Solution Approach 1:
The patent changes the joining method from soldering (low melting point) to welding (high melting point), fundamentally altering the temperature parameter at which the joint can operate, thereby enabling heat resistance up to 200° C. or higher while maintaining electrical connection reliability
3Length of stationary object
If FPC is used to join the heat sensitive element by welding, then the temperature sensor can be made thinner, but the insulating layer is irradiated by welding laser light causing insulation deterioration
Solution Approach 1:
The patent segments the welding process into two separate operations: first welding the heat sensitive element to the FPC, then welding the lead wire to the electrode pattern. This segmentation prevents the insulating layer from being irradiated by laser light during the second welding operation, maintaining insulation performance while achieving thinness
Solution Approach 2:
The patent performs the welding of the heat sensitive element to the FPC before welding the lead wire, preliminarily establishing the electrical connection in a way that protects the insulating layer from subsequent laser irradiation during lead wire attachment
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 solution provides improved temperature measurement accuracy, reliability, and responsiveness while maintaining thinness and ensuring insulation, addressing the limitations of existing sensors.
Implementation Method 1
a lead member having a joint part electrically connected to the electrode layer by being joined to the electrode layer by means of welding
Data Source
AI summary
Provided are a thin and insulating temperature sensor which is heat resistant and can have improved reliability, responsiveness, and temperature measurement accuracy, and a device equipped with the temperature sensor, the temperature sensor being provided with: a heat sensitive element which has an insulating substrate, a heat sensitive film formed on the insulating substrate, and electrode layers formed on the insulating substrate and electrically connected to the heat sensitive film; a lead member having joint parts electrically connected to the electrode layers by being joined thereto by means of welding, and lead parts integrally extending from the joint parts; and a pair of insulating films which sandwich and seal at least the heat sensitive element and the joint parts of the lead member from both sides.