Flexible Wiring Substrate Connection Protection
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Solution Overview
Problem
The connection between mounting and extension substrates in electro-optical devices, such as liquid crystal display devices, lacks sufficient moisture resistance and insulation reliability, especially in harsh environments like high-temperature and high-humidity conditions.
Innovation Solution
The use of a protective film that covers the connection portion between the substrates, providing enhanced moisture resistance and insulation properties, and an adhesive layer to ensure proper adhesion and prevent moisture intrusion, while also shortening the flexible wiring substrates to reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If substrates are connected by an ACF or similar connection method, then the substrates can be electrically connected, but the connection portion lacks sufficient moisture resistance and insulation reliability
Solution Approach 1:
A protective film is disposed to cover the connection portion between the mounting substrate and extension substrate. This protective film provides moisture resistance and insulation protection to the connection area, preventing harmful factors like moisture from affecting the electrical connection while maintaining the flexibility needed for the substrate structure.
Solution Approach 2:
The protective film acts as an intermediary layer between the electrical connection portion and the external environment. It mediates the protection needs by providing both moisture barrier and insulation properties without interfering with the electrical function of the ACF connection, thus resolving the contradiction between electrical connectivity and environmental protection.
2Reliability
If a protective film is added to cover the connection portion, then moisture resistance and insulation reliability are improved, but the device complexity increases
Solution Approach 1:
The protective film is implemented as a thin film structure that covers the connection portion without adding significant bulk or complexity to the overall device structure. This approach provides the necessary moisture resistance and insulation while maintaining a relatively simple and compact device design.
3Ease of manufacture
If the flexible wiring substrate is shortened to reduce cost, then the cost is reduced, but the connection portion becomes more vulnerable to moisture and environmental factors
Solution Approach 1:
The protective film provides the necessary environmental protection for the connection portion, allowing the flexible wiring substrate to be shortened for cost reduction without compromising the reliability of the connection. The protective film compensates for the increased vulnerability that would result from the shortened substrate design.
Data Source
AI summary
An electro-optical device includes a first drive IC and a second drive IC which are respectively mounted on a first flexible wiring substrate and a second flexible wiring substrate in a first mounting substrate and a second mounting substrate (first substrate). A first extension substrate and a second extension substrate (second substrate) which are configured by a flexible wiring substrate are connected to end portions of the first mounting substrate and the second mounting substrate, and a first protective film and a second protective film are attached to both surfaces in connection portions. The first protective film and the second protective film extend to positions covering the first drive IC and the second drive IC.