Thin Film Capacitor Protective Layer Modulus
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Solution Overview
Problem
Conventional thin film capacitors face issues with maintaining moisture resistance due to stress-induced warping and cracking of the protective layer, especially during long-term use and mounting, which degrades their electrical connection and moisture resistance.
Innovation Solution
A thin film capacitor design with a protective layer having a Young's modulus of 2.0 GPa or smaller, combined with an insulating layer of 3.0 to 5.0 GPa, and using Ni foil as the base electrode to mitigate stress and prevent cracking, ensuring the capacitor's moisture resistance is maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the protective layer is made rigid to maintain shape, then shape stability is improved, but stress concentration and crack generation increase due to dielectric layer expansion and contraction
Solution Approach 1:
The patent changes the key parameter of the protective layer from rigidity to flexibility by specifying a Young's modulus of 2.0 GPa or smaller. This parameter change allows the protective layer to maintain shape stability while accommodating stress from dielectric layer expansion and contraction, preventing crack generation and maintaining moisture resistance.
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers with different mechanical properties: the flexible protective layer (Young's modulus ≤2.0 GPa), the dielectric layer, and the base electrode. This composite design allows each layer to contribute its specific properties, with the protective layer's flexibility compensating for stress while maintaining overall structural integrity.
2Reliability
If the protective layer is made flexible to reduce stress, then crack prevention is improved, but shape maintenance capability deteriorates
Solution Approach 1:
The patent identifies and controls the Young's modulus parameter within a specific range (≤2.0 GPa) to achieve optimal balance between flexibility for stress relief and sufficient rigidity for shape maintenance. This precise parameter control resolves the contradiction between excessive flexibility and shape stability.
3Ease of manufacture
If conventional protective layers are used, then manufacturing simplicity is maintained, but warping and cracking occur during long-term use and mounting
Solution Approach 1:
The patent changes the mechanical parameter specification of the protective layer from conventional rigid materials to flexible materials with Young's modulus ≤2.0 GPa. This parameter change maintains manufacturing simplicity while dramatically improving long-term durability by preventing warping and cracking during use and mounting processes.
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 design effectively suppresses warping and cracking, maintaining high moisture resistance and stabilizing electrical connections, even under thermal and physical stress, thereby enhancing the capacitor's reliability.
Implementation Method 1
a modulus of longitudinal elasticity (It is generally called 'Young's modulus'. Hereinafter, it is simply called 'Young's modulus'.) of the protective layer is 2.0 GPa or smaller. Therefore, by mitigating stress stored in the protective layer by flexibility of the protective layer itself, warp can be suppressed, and crack generation of the protective layer can be prevented.
Implementation Method 2
the dielectric layer is expanded and contracted when use is continued for a long period of time. Stress that generates warp in the protective layer is generated by the expansion and contraction of the dielectric layer
Implementation Method 3
It is known that the Ni foil is a material having oxidation resistance and low electric resistance
Data Source
AI summary
A thin film capacitor includes: a laminated body in which a dielectric layer and an upper electrode layer are successively laminated on a base electrode; a protective layer that covers a part of the base electrode, the dielectric layer and the upper electrode layer and includes a through-hole respectively on the base electrode and on the upper electrode layer; and terminal electrodes that are electrically connected with the base electrode and the upper electrode layer through the through-holes of the protective layer. A modulus of longitudinal elasticity (Young's modulus) of the protective layer is 0.1 GPa to 2.0 GPa.