Aircraft Transparency Bus Bar Junction
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Solution Overview
Problem
Conventional bus bar systems for vehicle transparencies face issues due to thickness differences between conductive coatings and bus bars, leading to thin, weak, or discontinuous coatings at the film/bus bar junction, resulting in non-uniform current transfer and potential arcing that can damage the substrate.
Innovation Solution
A bus bar system featuring a non-conductive substrate with conductive bus bars and coatings, where an isotropically conductive adhesive is applied over the film/bus bar junction, optionally with a conductive metallic foil, to ensure consistent electrical contact and mechanical protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional bus bars with large thickness difference (1:200 to 1:400) are used, then the bus bar structure is simple and easy to manufacture, but the conductive coating at the film/bus bar junction becomes thin, weak, or discontinuous leading to non-uniform current transfer and potential arcing
Solution Approach 1:
A transition layer with intermediate thickness is introduced between the thick bus bar and the thin conductive coating. This transition layer serves as a mediator that gradually reduces the thickness discontinuity, allowing the coating to be deposited uniformly without the extreme 1:200 to 1:400 thickness ratio. The transition layer prevents coating discontinuities and arcing while maintaining manufacturing simplicity.
Solution Approach 2:
The thickness parameter of the bus bar structure is modified by introducing a transition layer with intermediate thickness values. This changes the thickness gradient from extreme (1:200 to 1:400) to more gradual, enabling uniform coating deposition while maintaining the overall bus bar functionality and ease of manufacture.
2Ease of manufacture
If the conductive coating is made thinner to match the bus bar thickness ratio, then manufacturing is easier, but the coating becomes weak and discontinuous at the junction
Solution Approach 1:
The transition layer acts as an intermediary structure that supports the thin conductive coating at the junction area. By providing this intermediate thickness layer, the thin coating gains mechanical support and continuity without requiring increased coating thickness elsewhere, thus maintaining ease of manufacture while improving junction strength.
Solution Approach 2:
The bus bar structure is transformed into a composite system consisting of the bus bar, transition layer, and conductive coating. This composite structure allows each layer to have optimized properties - the bus bar provides structural support, the transition layer provides thickness transition and coating support, and the thin coating provides electrical functionality - achieving both ease of manufacture and junction strength.
3Reliability
If the conductive coating is made thicker to ensure continuity, then coating strength improves, but the thickness difference with bus bar increases to 1:200 to 1:400 making manufacturing more difficult
Solution Approach 1:
Rather than making the coating thicker, a transition layer is introduced as an intermediary that addresses the thickness mismatch problem. This approach maintains the thin coating properties for electrical functionality while providing the necessary thickness transition to prevent discontinuities, avoiding the extreme 1:200 to 1:400 thickness ratio complexity.
4Device complexity
If conventional bus bar systems are used, then the system is simple, but arcing and substrate damage can occur due to non-uniform current transfer
Solution Approach 1:
The transition layer serves as a protective intermediary that prevents harmful arcing and current non-uniformity. By providing a gradual thickness transition, it ensures uniform current distribution across the junction area, eliminating the conditions that lead to arcing and substrate damage while adding minimal complexity to the overall system.
Solution Approach 2:
The transition layer provides beforehand cushioning by pre-establishing a favorable thickness gradient at the junction area. This preparatory structure prevents the occurrence of harmful effects (arcing, non-uniform current transfer) before they can happen during operation, rather than attempting to address them after they occur.
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 solution enhances the durability and conductivity of the film/bus bar junction, reducing the risk of arcing and damage, while providing a rapid and flexible application method that bridges gaps and provides additional mechanical and chemical protection.
Implementation Method 1
An electrically conductive adhesive, e.g., an isotropically conductive adhesive, such as an isotropically conductive tape or film, is located over at least a portion of the film/bus bar junction
Data Source
Figure 1~3
Figure 4
AI summary
A bus bar system includes a non-conductive substrate having a major surface. At least one conductive bus bar is formed over at least a portion of the major surface. A conductive coating is formed over at least a portion of the bus bar and the major surface. An electrically conductive adhesive, such as an isotropically conductive tape or film, is applied over at least a portion of the film/bus bar junction. The system can optionally include a conductive metallic foil adhered to the isotropically conductive adhesive.