Flexible Piezoresistive Sensor Assembly for Reliable PCBA Integration
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Solution Overview
Problem
Conventional sensor technologies are not well-suited for bridging the gap between computing devices and the physical world, particularly in applications envisioned by the 'Internet of Things', where flexible and adaptable sensing solutions are required to translate physical information into digital formats effectively.
Innovation Solution
The development of piezoresistive sensors integrated with flexible substrates, where conductive traces are formed directly on the substrates, allowing for the creation of sensors that change resistance in response to mechanical forces, enabling the detection of force magnitude, direction, and velocity, and are connected to printed circuit board assemblies (PCBAs) using conductive adhesives and mechanical members for secure alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional sensor technology is used, then manufacturing and integration are straightforward, but the sensors are not well-suited for flexible substrates and IoT applications requiring adaptation to physical world interfaces
Solution Approach 1:
The patent employs flexible substrates as the base for sensor integration, allowing the sensor system to conform to curved surfaces and flexible form factors required for wearable and IoT applications. This enables the sensor assembly to adapt to various physical configurations while maintaining functional reliability.
Solution Approach 2:
The patent uses conductive adhesive as a composite material that simultaneously provides mechanical bonding between rigid and flexible components while establishing electrical connections. This dual-function material resolves the contradiction by enabling reliable integration without requiring separate mechanical and electrical attachment systems.
2Ease of manufacture
If conductive adhesive is used to connect pads and conductors, then electrical connections are established, but the connection reliability depends on alignment precision and adhesive quality
Solution Approach 1:
The conductive adhesive serves as an intermediary material between the rigid PCBA pads and flexible substrate conductors. It compensates for minor misalignments and provides a robust electrical connection that is tolerant to manufacturing variations, thereby reducing the stringency of alignment precision requirements.
Solution Approach 2:
The patent utilizes the conductive properties of the adhesive material to establish electrical connections, changing the connection method from rigid mechanical-electrical contact to a compliant conductive bond. This parameter change allows for greater tolerance in alignment while maintaining connection reliability.
3Reliability
If mechanical members are used to secure PCBA to substrate, then secure alignment is achieved, but the assembly complexity increases
Solution Approach 1:
The mechanical members serve multiple functions simultaneously: they provide structural support, ensure alignment between components, and maintain contact pressure for reliable electrical connections. This multi-functionality reduces the need for separate dedicated alignment and support features, thereby limiting the increase in assembly complexity.
Solution Approach 2:
The patent combines mechanical fastening and electrical connection functions into a single integrated assembly process. The mechanical members that secure the PCBA to the substrate also ensure proper alignment and contact, merging structural and electrical requirements into one unified solution rather than requiring separate mechanisms.
4Adaptability or versatility
If piezoresistive sensors are integrated with flexible substrates, then versatile physical interaction detection is enabled, but the sensor trace pattern complexity increases
Solution Approach 1:
The sensor trace pattern is segmented into multiple conductive traces arranged in specific geometric configurations on the flexible substrate. Each trace or trace combination serves a specific sensing function, allowing the system to detect various types of physical interactions (touch, pressure, deformation) through differentiated trace response patterns.
Solution Approach 2:
The patent implements local variations in trace geometry, material properties, or trace density at different regions of the flexible substrate to optimize sensing characteristics for specific detection purposes. This local quality differentiation enables versatile detection capabilities while maintaining a relatively simple overall trace pattern structure.
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
These sensors provide versatile, flexible solutions capable of detecting various physical interactions, including touch events and deformations, enabling a wide range of applications from wearable electronics to diverse IoT applications with improved accuracy and reduced signal line requirements.
Implementation Method 1
a sensor includes a flexible piezoresistive substrate and a sensor trace pattern including two or more conductive traces formed directly on the piezoresistive substrate. Resistance between the conductive traces varies with distortion or deformation of the piezoresistive substrate.
Data Source
AI summary
Sensors incorporating piezoresistive materials are described. One class of includes conductive traces formed directly on or otherwise integrated with the piezoresistive material.