Touch Sensor Groove Substrate for Narrow Wire Pitch
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Solution Overview
Problem
Existing electrostatic capacitance type touch sensors face challenges in restricting the movement of conductive powder particles during thermocompression bonding, leading to difficulties in narrowing the pitch between wires on the FPC mounting portion.
Innovation Solution
The touch sensor employs an anisotropic conductive adhesive agent with conductive powder particles and a substrate design featuring linear projections and grooves, where the conductive layer is positioned between adjacent projections, allowing conductive powder particles to be guided into grooves and maintain contact with the conductive layer, thereby suppressing movement and enabling a narrower wire pitch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an anisotropic conductive adhesive agent with conductive powder particles is used to connect the connection terminal and conductive layer, then electrical connection is achieved, but the conductive powder particles move during thermocompression bonding making it difficult to narrow the wire pitch
Solution Approach 1:
The groove is formed in advance on the substrate portion at the mounting portion before the thermocompression bonding process. This preliminary structure guides the conductive powder particles into the groove during bonding, preventing their movement and enabling narrower wire pitch while maintaining reliable electrical connection.
Solution Approach 2:
The groove acts as an intermediary structure between the conductive layer and the conductive powder particles. It mediates the interaction by providing a confined path that directs the powder particles to maintain stable contact with the conductive layer during thermocompression bonding, thus preventing movement and ensuring reliable connection.
2Productivity
If the wire pitch is narrowed to improve device integration, then more wires can be mounted in a smaller area, but the movement of conductive powder particles during bonding becomes harder to control
Solution Approach 1:
The groove is pre-formed on the substrate portion at the mounting portion before the thermocompression bonding process. This preliminary structure guides the conductive powder particles into the groove during bonding, preventing their movement and enabling narrower wire pitch while maintaining reliable electrical connection.
Solution Approach 2:
The groove is specifically formed at the mounting portion where the conductive layer is located, providing localized guidance for the conductive powder particles. This local structural modification enables precise control of powder particle position in the critical bonding area without affecting other parts of the substrate.
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
This configuration stabilizes the electrical connection between the conductive layer and connection terminal, allowing for a reduced wire pitch and improved reliability in the touch sensor's operation.
Implementation Method 1
The adhesive agent is an anisotropic conductive adhesive agent and contains a plurality of conductive powder particles
Implementation Method 2
The portion to be mounted of the flexible printed circuit board is adhered to the FPC mounting portion of the substrate portion by thermocompression bonding via an anisotropic conductive adhesive agent
Data Source
AI summary
A touch sensor of this disclosure includes: a printed circuit board having a connection terminal; a substrate portion having a mounting portion on which the printed circuit board is mounted; a conductive layer disposed on the mounting portion of the substrate portion; and an adhesive agent connecting the connection terminal and the conductive layer to each other. A plurality of linear projections arranged in a first direction and extending in a second direction intersecting with the first direction are disposed on a surface of the substrate portion at the mounting portion, and the conductive layer is disposed on a groove portion positioned between the linear projections disposed adjacently to each other out of the plurality of linear projections.