Flexible Touch Sensor Direct PCB Interconnect
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Solution Overview
Problem
Conventional touch sensors face issues with multiple interconnects leading to increased electrical resistance, larger bezel sizes, and manufacturing costs due to the use of rigid circuits and Anisotropic Conductive Film, which also result in strain and disconnections when bending, especially in mobile devices.
Innovation Solution
The implementation of flexible touch sensors with integrated interconnects that form a direct bond with a printed circuit board, reducing the number of connections and using flexible substrates with traces that can bend without breaking, thereby minimizing electrical resistance and bezel size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple interconnects are used to connect touch sensor to printed circuit board, then connection reliability is improved, but electrical resistance increases and device complexity increases
Solution Approach 1:
The patent merges multiple separate interconnects into a single integrated flexible printed circuit board that provides both mechanical support and electrical connection. The FPCB integrates the substrate and interconnect functions, eliminating the need for separate rigid circuit boards and multiple connection points, thus reducing device complexity while maintaining connection reliability through the flexible nature of the FPCB that accommodates bending without disconnection
2Manufacturing precision
If rigid circuits and Anisotropic Conductive Film are used for connection, then manufacturing precision is improved, but manufacturing cost increases and device thickness increases
Solution Approach 1:
The patent replaces rigid circuits and thick Anisotropic Conductive Film with a flexible printed circuit board that is thin and flexible. The FPCB maintains manufacturing precision through standard FPCB fabrication processes while reducing overall device thickness and eliminating the need for separate rigid circuit boards and ACF layers, thereby reducing device complexity
Solution Approach 2:
The patent extracts and eliminates the rigid circuit board and separate ACF components from the assembly, retaining only the essential connection function through the integrated FPCB. This removal of unnecessary components reduces manufacturing complexity and device thickness while maintaining the required connection precision
3Reliability
If dedicated connection device is used, then connection reliability is improved, but bezel area increases and space consumption increases
Solution Approach 1:
The patent merges the dedicated connection device functions into the flexible printed circuit board itself, which provides both structural support and electrical connection in a single thin component. This integration eliminates the need for separate connection devices that would require additional bezel area, while the FPCB's flexibility ensures reliable connection even in bent configurations
4Area of stationary object
If FPC is bent to reduce bezel size, then bezel area is reduced, but strain on interconnects increases causing disconnections
Solution Approach 1:
The patent uses a flexible printed circuit board that is inherently designed to bend without damage. The FPCB's flexible nature allows it to accommodate bending required for reduced bezel size while maintaining interconnect integrity, eliminating the strain and disconnection issues associated with rigid circuits or improperly designed flexible connections
Data Source
AI summary
Flexible touch sensor techniques are described. A touch sensitive device includes a printed circuit board (PCB) having a touch controller and a flexible printed circuit having a flexible substrate and touch sensors formed thereon using a plurality of flexible traces arranged to detect proximity of an object. The plurality of flexible traces are extended along the flexible substrate to directly terminate onto a connector of the printed circuit board thereby forming a communicative coupling between the touch sensors and the touch controller, which thereby permits the touch controller to determine a location of the proximity of the object in relation to the touch sensors.