Solder-Mountable Strain Sensor Resistor for Compact PCB Integration
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Solution Overview
Problem
Conventional strain gauges face challenges in measuring strain on small electronic devices due to their form and adhesive attachment methods, which can lead to unstable adhesiveness and complex manufacturing processes, especially when integrated with other electronic components on circuit boards.
Innovation Solution
A strain sensor resistor with a thin-film strain-sensitive resistive layer and a tip shape allowing solder mounting on a circuit board, featuring a rectangular insulation substrate with front and back surface electrodes, enabling stable and space-efficient strain measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional strain gauge with adhesive attachment is used, then strain measurement can be performed on various surfaces, but the adhesiveness may be insufficient and the measurement stability is compromised
Solution Approach 1:
The patent replaces the adhesive attachment method with a solder mounting method. The strain sensor resistor is designed with electrode layers that enable direct soldering to the circuit board, eliminating the need for adhesives and mechanical attachment processes. This substitution provides more reliable mechanical and electrical connection while simplifying the manufacturing process.
Solution Approach 2:
The strain sensor resistor integrates both sensing function and mounting function into a single component. The electrode layers serve dual purposes: electrical connection for strain measurement and mechanical attachment through soldering to the circuit board, eliminating the need for separate attachment components.
2Volume of moving object
If strain-resistive elements are formed directly on a circuit board, then space is saved and compactness is improved, but the entire circuit must be rebuilt when a single element fails
Solution Approach 1:
The patent segments the strain sensing function from the circuit board by providing the strain sensor resistor as a separate, modular component that can be solder-mounted onto the board. This allows individual replacement of defective sensors without rebuilding the entire circuit, while still achieving compact integration.
Solution Approach 2:
The patent changes the mounting method parameter from direct formation (permanent integration) to solder mounting (removable integration). This parameter change enables both compact installation and easy replacement by allowing the component to be detached and reattached using standard soldering processes.
3Reliability
If conventional strain gauges with lead wires are used, then strain measurement can be performed, but the device size increases and integration with small electronic devices becomes difficult
Solution Approach 1:
The patent merges the lead wire function with the electrode layers that are already part of the strain sensor structure. The electrode layers serve as both the electrical connection point for strain measurement and the mounting interface, eliminating the need for separate lead wires and reducing overall device size.
Solution Approach 2:
The patent transitions from a three-dimensional structure with external lead wires extending from the strain gauge to a planar structure where all connections are made on the same surface through solder mounting. This dimensional change reduces the volume and simplifies integration with compact electronic devices.
4Reliability
If multiple mounting steps are used for strain-sensing elements and other components, then proper connections can be established, but the manufacturing process becomes more complex
Solution Approach 1:
The strain sensor resistor is designed as a universal component that can be mounted using the same soldering process as other electronic components. The electrode layers provide both electrical connection and mechanical attachment functions, allowing the sensor to be integrated in the same manufacturing step as other circuit board components, thereby simplifying the overall manufacturing process.
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 a stable connection to the circuit board, allowing accurate and reliable strain measurement with improved responsiveness and reduced manufacturing complexity, enabling direct integration with other components and reducing costs by allowing individual replacement of defective sensors.
Implementation Method 1
a thin-film strain-sensitive resistive layer formed nearly at the center of the front surface of the insulation substrate
Data Source
AI summary
A strain sensor resistor includes: a resistive element (thin-film strain-resistive layer) formed nearly at the center of an upper surface of an insulation substrate to be a base; and front surface electrodes layered and formed on either end part of the resistive element and electrically connected to the resistive element. The entire upper part of the resistive element and a part of the front surface electrodes are covered by a protective film (protective coating). Moreover, back surface electrodes electrically connected to the front surface electrodes are formed on either lower end part of the insulation substrate, and end surface electrodes are formed on either longitudinal end surface of the insulation substrate. The strain sensor resistor has a tip shape solder mountable on a circuit board etc. using the back surface electrodes.