Partial Gold-Plating Pattern on Stainless Substrate
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Solution Overview
Problem
The existing methods for forming gold-plating patterns on stainless steel substrates face challenges such as poor adhesion, surface corrosion, and productivity issues due to differential ionization tendencies between nickel and silver/gold layers, and the need for thicker gold layers or higher current densities to prevent defects during the stripping process.
Innovation Solution
A process involving a first gold-plating layer formed over the stainless substrate using a hydrochloric acid plating solution, followed by a second gold-plating layer in a desired pattern using mask plating, and subsequent stripping of the first layer with an alkaline solution to prevent attack on the substrate, allowing for a thin-film pattern of up to 1 μm to be formed efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a copper-plating layer is formed as a first layer on a stainless substrate and a silver- or nickel-plating layer is laminated as a second layer, then pattern formation is achieved, but the passivated film on the stainless substrate shows poor adhesion to the copper-plating layer
Solution Approach 1:
A nickel-plating layer is introduced as an intermediate layer between the stainless substrate and the silver- or gold-plating layer. This nickel layer serves as a mediator that provides good adhesion to both the substrate and the final pattern layer, resolving the adhesion problem between the passivated film and copper plating.
Solution Approach 2:
The invention changes the plating parameters by using a cyanide-based plating solution with specific pH and temperature conditions to form a uniform nickel-plating layer that ensures good adhesion while enabling subsequent pattern formation.
2Ease of manufacture
If a nickel-plating layer is formed all over the surface and then a silver- or gold-plating layer is laminated in a desired pattern, but the stripping solution attacks the silver- or gold-plating layer due to differential ionization tendency, then pattern formation is achieved, but discoloration and defects occur
Solution Approach 1:
The invention uses a thick nickel-plating layer as a sacrificial disposable layer that can be completely stripped away with alkaline solutions without affecting the underlying stainless substrate or the pattern structure. This eliminates the differential ionization problem between nickel and silver/gold layers.
Solution Approach 2:
The invention changes the stripping process parameters by using alkaline stripping solutions instead of acidic ones, and controls the stripping conditions to completely remove the nickel layer without causing discoloration or defects in the final pattern.
3Reliability
If the silver- or gold-plating layer is made thicker or current density is increased to prevent defects from stripping solution attack, then defect occurrence is reduced, but thin-film pattern formation up to 1 μm becomes difficult and productivity decreases
Solution Approach 1:
The thick nickel-plating layer serves as a sacrificial layer that protects the thin silver- or gold-plating pattern during the stripping process. This allows the final pattern to be formed at optimal thin thickness (up to 1 μm) without requiring excessive thickness for defect prevention.
Solution Approach 2:
The invention extracts the problematic nickel layer from the final product by completely stripping it away after it has served its protective function during plating. This allows the use of thin silver- or gold-plating layers without suffering from the differential ionization problems that would occur if nickel remained in the final structure.
4Reliability
If the nickel-plating layer is left all over the surface to prevent stripping solution attack, then defect occurrence is reduced, but the precision of pre-formed microprocessing patterns cannot be fully utilized
Solution Approach 1:
The nickel-plating layer is completely extracted (stripped away) after serving as a protective and adhesive layer during the plating process. This removal reveals the precise microprocessing patterns on the stainless substrate without distortion or interference from the nickel layer, fully utilizing the original pattern precision.
Solution Approach 2:
The nickel-plating layer is formed in advance as a temporary protective layer that enables precise pattern formation, and then completely removed to reveal the final precise pattern. This preliminary action protects the substrate and enables precise plating without compromising the final pattern accuracy.
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
This process improves adhesion, prevents substrate attack, and enables the formation of a stable, thin gold-plating pattern with reduced gold usage, enhancing productivity and handling efficiency while maintaining substrate strength.
Implementation Method 1
forming a first gold-plating layer all over the surface of the stainless substrate using a hydrochloric acid plating solution
Implementation Method 2
forming a second gold-plating layer on a portion of the first gold-plating layer that covers the processing site in a desired pattern using mask plating
Implementation Method 3
stripping off a portion of the first gold-plating layer in an area where there is none of the second gold-plating layer using an alkaline stripping solution
Data Source
AI summary
The process of forming a partial gold-plating pattern on a stainless substrate includes a first plating step, a second plating step, and a stripping step. In the first plating step, pretreatment is applied to a stainless substrate including opposite main planes and a processing site formed of a plane different from the main planes, after which a first gold-plating layer is formed all over the surface of the stainless substrate using a hydrochloric acid plating solution. In the second plating step, mask plating is used to form a second gold-plating layer on the first gold-plating layer that covers the processing site in a desired pattern, and in the stripping step, a portion of the first gold-plating layer in an area where there is none of the second gold-plating layer is stripped off using an alkaline stripping solution.