Narrowed Fuse Part in Laminated Intermediate Connection Layer
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Solution Overview
Problem
Existing electronic devices with surface-mounted components, such as chip-type multilayer ceramic capacitors, face challenges in providing a sufficient fuse function to prevent burnout and firing due to limitations in fuse length and manufacturing complexity, leading to reliability issues and increased device size.
Innovation Solution
An electronic device with a laminated intermediate connection layer comprising a rigid and flexible substrate, where a narrowed fuse part is formed on the flexible substrate opposite an opening in the rigid substrate, allowing for effective current cutoff and reduced heat conduction, thereby preventing meltdown and firing, and a manufacturing method involving separate production and joining of substrates with conductive bond material applied through holes for efficient electric conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an intermediate connection layer with a fuse function is used to prevent burnout and firing, then reliability is improved, but device size increases
Solution Approach 1:
The fuse part is positioned on the flexible substrate opposite an opening in the rigid substrate, utilizing the z-dimension (depth) to achieve fuse functionality without increasing the planar footprint. This spatial arrangement allows the fuse to be effectively isolated from heat conduction paths while maintaining compact device dimensions.
Solution Approach 2:
The intermediate connection layer combines a rigid substrate and a flexible substrate with different thermal and mechanical properties. The rigid substrate provides structural support while the flexible substrate accommodates the fuse part, creating a composite structure that achieves both reliability and compactness.
2Reliability
If a sufficient length fuse is provided to ensure reliable current cutoff, then fuse function is improved, but manufacturing complexity increases
Solution Approach 1:
The fuse is segmented into a narrowed portion with reduced cross-sectional area, allowing sufficient fuse length to be achieved within a compact overall structure. This segmentation enables reliable current cutoff while maintaining simple manufacturing processes.
Solution Approach 2:
The fuse part has a localized narrowed portion with different cross-sectional dimensions compared to other conductor parts. This local quality change ensures the fuse melts at the specific narrowed section under overcurrent conditions, providing reliable current cutoff without complex manufacturing.
3Reliability
If the fuse part is positioned to reduce heat conduction and prevent firing, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The fuse part is positioned in the z-dimension (opposite the opening) rather than relying solely on planar positioning. This dimensional approach reduces heat conduction to the rigid substrate while maintaining relaxed manufacturing precision requirements in the x-y plane.
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 provides a reliable and cost-effective fuse function with favorable meltdown characteristics without increasing device size, reducing the risk of burnout and firing, and enhancing manufacturing efficiency by eliminating the need for complex bridging processes.
Implementation Method 1
when large current equal to or larger than rated current flows through the mounted electronic component and damages the electronic component, the fuse part melts down to achieve an open circuit
Implementation Method 2
heat conduction from the fuse part to the rigid substrate at meltdown can be reduced since the fuse part is formed at a position opposite the opening of the rigid substrate
Data Source
AI summary
An electronic-device having an intermediate connection layer interposed between a wiring substrate and an electronic component. The intermediate connection layer has a laminated structure including a rigid substrate and a flexible substrate. A first conductor part is formed on one principal surface of the flexible substrate, and second and third conductor parts are formed on both principal surfaces of the rigid substrate, respectively. The rigid substrate includes an opening, and the first conductor part of the flexible substrate includes a narrowed fuse part at a position opposite the opening. Windows are formed near the fuse part. The flexible substrate and the rigid substrate are electrically connected with each other via solder.