Guard Traces for Moisture Protection in Touch Sensors
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Solution Overview
Problem
Conventional touch sensor manufacturing processes are susceptible to moisture damage, which can corrode metal traces and affect the device's performance.
Innovation Solution
Incorporating guard traces made of metal, such as copper, between the edge of the touch sensor and the metal traces that route the drive and sense lines to bond pads, these guard traces are uncoupled from the drive and sense lines and can be coupled to ground using copper or indium tin oxide, acting as a sacrificial layer to protect the inner metal traces from moisture damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional roll-to-roll manufacturing processes are used, then manufacturing efficiency and cost are improved, but the touch sensor becomes susceptible to moisture damage and corrosion
Solution Approach 1:
The patent applies preliminary action by forming guard traces during the manufacturing process before the touch sensor is completed and exposed to moisture. These guard traces are pre-positioned between the edge of the touch sensor and the metal traces, creating a protective barrier in advance that prevents moisture from reaching and corroding the functional metal traces during subsequent use.
2Area of stationary object
If metal traces are placed close to the edge for compact design, then device size is reduced, but moisture can more easily reach and corrode the metal traces
Solution Approach 1:
The patent uses an intermediary element (the guard trace) positioned between the edge of the touch sensor and the functional metal traces. This guard trace acts as a mediator that blocks moisture propagation while allowing the metal traces to remain in their compact positions near the edge, thus maintaining both compact device size and protection against moisture.
3Reliability
If guard traces are added to protect metal traces from moisture, then reliability is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent merges the guard trace formation with the existing manufacturing process by depositing the guard traces as part of the same metal layer deposition step used for creating the functional metal traces. This combining of operations allows the protective guard traces to be added without requiring separate manufacturing steps, thus improving reliability while minimizing increases in device complexity and manufacturing complexity.
Data Source
AI summary
Processes for manufacturing touch sensors with one or more guard traces to reduce the effect of moisture damage are provided. One example process can include forming one or more guard traces between an edge of the touch sensor and the metal traces that route the drive and sense lines to bond pads. The one or more guard traces can be uncoupled from the drive lines and sense lines to protect the inner metal traces from moisture damage. In some examples, ends of the one or more guard traces can be coupled to ground by copper. In other examples, ends of the one or more guard traces can be coupled to ground by indium tin oxide or the one or more guard traces can be coupled to ground by a strip of indium tin oxide. In yet other examples, the guard trace can be floating (e.g., not coupled to ground).