Electrolytic Nickel Foil Surface Control for CMP-Free Thin-Film Capacitors
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Solution Overview
Problem
Conventional metal foils used in thin film-type capacitors have high surface roughness, which leads to short circuits and requires costly and time-consuming chemical-mechanical polishing (CMP) processes.
Innovation Solution
An electrolytic nickel foil with low and uniform surface roughness (Ra ≤ 0.05 μm, Rz ≤ 0.20 μm, Rt ≤ 0.50 μm) and high glossiness (60° specular gloss ≥ 200 GU) is produced through electrolytic plating using a specific electrolyte composition and process conditions, eliminating the need for a separate CMP process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional metal foil is used, then the capacitor structure can be formed, but the surface roughness is high causing short circuits and requiring additional CMP process
Solution Approach 1:
The invention performs preliminary action by pre-treating the nickel foil surface through electrolytic plating to achieve the required flatness (Ra ≤ 0.05 μm, Rz ≤ 0.20 μm) before the capacitor manufacturing process begins. This eliminates the need for subsequent CMP processes, directly resolving the technical contradiction between manufacturing precision and device complexity.
2Manufacturing precision
If CMP process is applied, then surface roughness is reduced, but process cost increases and manufacturing time is consumed
Solution Approach 1:
The electrolytic plating process is performed in advance to achieve the target surface roughness (Ra ≤ 0.05 μm, Rz ≤ 0.20 μm, Rt ≤ 0.50 μm) before capacitor assembly. This preliminary action eliminates the need for time-consuming CMP processes, directly addressing the contradiction between manufacturing precision and loss of time.
3Manufacturing precision
If CMP process is applied, then surface roughness is reduced, but process cost increases
Solution Approach 1:
The invention performs preliminary electrolytic plating to achieve the required surface roughness (Ra ≤ 0.05 μm, Rz ≤ 0.20 μm) before capacitor manufacturing. This eliminates the need for expensive CMP processes, directly resolving the technical contradiction between manufacturing precision and ease of manufacture.
4Ease of manufacture
If high surface roughness foil is used, then manufacturing is simpler, but short circuit risk increases
Solution Approach 1:
The invention performs preliminary electrolytic plating to achieve the required surface flatness (Ra ≤ 0.05 μm, Rz ≤ 0.20 μm, Rt ≤ 0.50 μm) that prevents short circuits. This maintains manufacturing simplicity while significantly improving reliability by eliminating protrusions that could cause short circuits through the dielectric layer.
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 electrolytic nickel foil achieves high smoothness and reduced risk of short circuits, enabling the manufacture of thin film-type capacitors without the need for CMP, thereby improving process efficiency and reducing costs.
Implementation Method 1
performing electrolytic plating with an electrolyte including about 400 to 600 g/L of a nickel ion precursor, about 10 to 30 g/L of a pH buffer, and about 0.5 to 2.0 g/L of a roughness controlling agent and having a pH of about 1 to 5
Data Source
AI summary
Provided is an electrolytic nickel foil including, on at least one surface thereof, a flat surface having the following surface roughness: a Ra of 0.05 μm or less, a Rz of 0.2 μm or less, and a Rt of 0.5 μm or less and a glossiness of 200 GU or more as determined by measuring a 60° specular reflection angle.