Rivet PCB-to-Fabric Connection for Wearable Neurostimulators
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Solution Overview
Problem
Existing methods for connecting flexible electronics to rigid electronics in wearable neurostimulators, such as conductive epoxy and crimped pin connectors, face challenges like mechanical strength, scalability, and maintaining contact, especially with stretchable components like printed fabric circuits.
Innovation Solution
A rivet system with a conductive shank extending through the fabric and PCB, applying clamping force and electrical connection, and optionally a conductive spacer or pogo assembly to maintain contact, allowing for efficient and reliable integration without additional rigid components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive epoxy is used to connect flexible electronics to rigid electronics, then electrical connection is achieved, but mechanical strength is insufficient and manufacturing is difficult to scale
Solution Approach 1:
The patent replaces the chemical bonding mechanism of conductive epoxy with a mechanical rivet system. The rivet provides both mechanical attachment and electrical conduction through its conductive body, eliminating the need for epoxy deposition and curing processes. This substitution enables scalable manufacturing through standard rivet insertion techniques while maintaining reliable electrical and mechanical connections.
Solution Approach 2:
The invention uses a composite connection system combining a conductive rivet (metal) with fabric and PCB materials. The rivet acts as both a mechanical fastener and an electrical conductor, integrating structural and conductive functions in a single component. This composite approach replaces the epoxy-conductive ink combination with a more robust metal-based solution.
2Strength
If crimped pin connectors are used to connect flexible electronics to rigid electronics, then mechanical strength is improved, but device complexity increases due to required semi-rigid backing and specific geometry
Solution Approach 1:
The patent extracts and eliminates the semi-rigid backing requirement by using a flexible fabric structure that directly accommodates the rivet. The crimped pin's complex geometry is replaced with a simple cylindrical rivet that passes through the fabric and PCB, removing the need for specialized connector housings and backing structures.
Solution Approach 2:
The invention changes the geometric parameters of the connection system from the complex crimped pin shape with specific curvature and crimp features to a simple cylindrical rivet form. This parameter simplification reduces manufacturing complexity while maintaining adequate mechanical strength through the rivet's anchoring action in the fabric and PCB.
3Reliability
If traditional connection methods are used with stretchable fabric circuits, then electrical connection is maintained, but contact reliability deteriorates during movement and stretching
Solution Approach 1:
The patent creates a dynamic connection system where the rivet allows relative movement between the fabric and PCB while maintaining electrical contact. The conductive rivet body can deform or shift slightly with fabric stretching, and the spring-loaded contact mechanism adapts to position changes, ensuring continuous electrical connection during movement and deformation.
Solution Approach 2:
The conductive rivet acts as an intermediary element between the flexible fabric circuit and the rigid PCB. It mediates the mechanical and electrical interface, accommodating the flexibility of the fabric while providing stable electrical connection to the rigid board, thus resolving the conflict between adaptability and contact reliability.
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 rivet system provides strong, scalable, and reliable electrical and mechanical connections between flexible and rigid components, enhancing the stability and efficiency of wearable neurostimulators by eliminating the need for crimped pins and reducing assembly time compared to epoxy curing.
Implementation Method 1
The rivet can apply a clamping force to the PCB and the Fabric structure that maintains their contact
Implementation Method 2
The rivet can be is constructed of an electrically conductive material and helps conduct electricity from the conductive portions of the flexible circuit to the conductive portions of the PCB circuit
Implementation Method 3
The waves can be configured to deform when the rivet is applied. The waves can urge a resilient compressive force on the adjacent portions of the fabric and the PCB to help maintain electrical contact
Data Source
AI summary
A wearable neurostimulator includes a fabric structure, a flexible circuit printed on the fabric structure with exposed electrically conductive portions, and a rigid PCB including an electrical circuit and exposed electrically conductive portions. A rivet includes a shank that extends through the fabric structure, conductive pads, PCB, and conductive vias. The rivet electrically connects the conductive portions of the PCB circuit to the conductive portions of the flexible circuit.