Touch Screen Flex Circuit Connections Using Substrate Vias
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Solution Overview
Problem
Existing touch screens face challenges in reducing the border and thickness due to the conventional placement of flex circuits, which often require connections on opposite sides of the substrate.
Innovation Solution
The implementation of vias that connect touch electrodes to flex circuits on the same side of the substrate, allowing for reduced border and thickness, and the use of adhesive with conductive particles to ensure direct contact between the via filling material and the flex circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flex circuits are connected to touch electrodes on opposite sides of the substrate, then the connection reliability is improved, but the border width and thickness of the touch screen increase
Solution Approach 1:
The patent transitions from a conventional opposite-side connection architecture to a same-side connection architecture by introducing vias that penetrate the substrate. This dimensional change allows flex circuits to be positioned on the same side as touch electrodes, eliminating the need for border areas on opposite sides and thereby reducing the overall border width and thickness of the touch screen.
Solution Approach 2:
The patent segments the connection path into multiple components: vias penetrating the substrate, adhesive layers with conductive particles, and bonding interfaces. This segmentation allows each component to perform its specific function (electrical connection, mechanical bonding, conductive pathway) efficiently, achieving reliable connections while minimizing the overall space required.
2Ease of manufacture
If adhesive is used to bond flex circuits to the substrate, then the ease of manufacture is improved, but the adhesive compression may damage the flex circuits and conductive connections
Solution Approach 1:
The patent employs a composite adhesive material containing conductive particles embedded within the adhesive matrix. This composite structure provides dual functionality: the adhesive matrix performs mechanical bonding between the flex circuit and substrate, while the conductive particles establish electrical pathways through the adhesive layer. This eliminates the need for separate bonding and conductive connection steps, simplifying manufacturing while protecting the flex circuit from excessive compression.
Solution Approach 2:
The adhesive layer with conductive particles acts as an intermediary between the flex circuit and the substrate. It distributes the bonding stress uniformly across the interface, preventing concentrated compression forces from damaging the flex circuit. Simultaneously, it provides a conductive pathway that maintains electrical connectivity, thus protecting the overall system reliability during the manufacturing process.
3Length of stationary object
If vias are used to connect touch electrodes to flex circuits on the same side, then the border and thickness are reduced, but the manufacturing complexity increases
Solution Approach 1:
The adhesive layer with conductive particles serves multiple functions simultaneously: it provides mechanical bonding between layers, establishes electrical conductive pathways, and protects the via structures. This multi-functionality reduces the need for additional separate via filling materials or bonding layers, thereby simplifying the overall manufacturing process despite the introduction of via structures.
Solution Approach 2:
The patent merges the via formation, conductive pathway creation, and bonding processes into a single integrated step using the adhesive with conductive particles. The vias are formed through the substrate, and the same adhesive material that fills and bonds the vias also provides the conductive connection. This merging of functions reduces the number of manufacturing steps and decreases the overall structural complexity.
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 reduces the border and thickness of the touch screen, enhances durability and reliability by minimizing adhesive compression, and improves manufacturing yield by avoiding damage to flex circuits and conductive connections.
Implementation Method 1
the adhesive can include conductive particles that can enable the via filling material to directly contact a conductive connection of the flex circuit
Data Source
AI summary
A touch screen (500) can include electrodes (520, 540) (e.g., first and second touch electrodes, reference electrodes) on opposite sides (e.g., top and bottom) of a substrate (510). In some examples, vias (618, 638) can be used to couple the touch electrodes (520, 540) to conductive connections (518, 538) of flex circuits (502, 522) such that the connections (604, 624) to the flex circuits (502, 522) can be on the same side of the substrate (510) even if the touch electrodes (520, 540) are on opposite sides of the substrate (510). The conductive filling material of the via (618) can make direct contact with the conductive connections (604, 624) of the flex circuits (502, 522), for example.