Electroless Gold Plating Bath Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electroless gold plating baths face challenges in forming uniform gold films with sufficient thickness in minute portions, such as terminal portions, and require a two-step process for nickel plating films, leading to inefficiencies in ENIG and ENEPIG processes.
Innovation Solution
An electroless gold plating bath comprising gold sulfite, thiosulfate as a complexing agent, ascorbic acid, and hydrazine compounds as reducing agents, which facilitates the formation of a uniform gold film with a thickness of 0.1 μm or more in a single step by improving deposition properties and adhesion in both ENIG and ENEPIG processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional electroless gold plating bath is used, then the plating process can be completed, but uniform gold deposition is insufficient in minute portions such as terminal portions
Solution Approach 1:
The patent changes the chemical parameters of the plating bath by introducing specific organic acids (oxalic acid, malonic acid, succinic acid) and controlling pH (3.5-4.5) and temperature (40-60°C) to optimize gold deposition uniformity in minute portions while maintaining overall plating quality
Solution Approach 2:
The patent uses organic acids as intermediary substances that mediate between the gold source and the substrate surface, facilitating controlled and uniform gold deposition in difficult-to-plate minute portions through chelation and surface activation
2Manufacturing precision
If conventional electroless gold plating bath is used to form thick gold film (0.1 μm or thicker) on nickel plating film, then sufficient thickness can be achieved, but two-step process is required
Solution Approach 1:
The patent merges the substitution gold plating and electroless gold plating into a single integrated bath system, allowing both functions to occur simultaneously in one step, thereby simplifying the process while achieving sufficient gold film thickness
Solution Approach 2:
The plating bath is designed with multi-functionality to perform both substitution plating (on palladium) and electroless plating (on nickel) in the same solution, eliminating the need for separate processing steps
3Ease of manufacture
If conventional electroless gold plating bath is used, then plating can proceed, but adhesion and deposition properties are insufficient
Solution Approach 1:
The patent optimizes chemical parameters including pH (3.5-4.5), temperature (40-60°C), and composition ratios of organic acids to enhance gold film adhesion and deposition properties while maintaining process simplicity
Solution Approach 2:
The plating bath uses a composite chemical system combining gold sources, organic acids, complexing agents, and stabilizers that work synergistically to improve adhesion and deposition properties
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 enables the formation of a uniform and thick gold film in a single step, enhancing deposition properties and adhesion, thus overcoming the limitations of existing two-step processes and ensuring consistent gold plating across various substrates.
Implementation Method 1
a combination of a hydrazine compound and an ascorbic acid compound as a reducing agent
Implementation Method 2
a thiosulfate as a complexing agent
Data Source
AI summary
The electroless gold plating bath includes a gold sulfate, a thiosulfate, ascorbic acid compounds, and hydrazine compounds, the hydrazine compounds being at least one selected from the group consisting of adipic dihydrazide, propionic hydrazide, hydrazine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine carbonate, hydrazine monohydrate, sebacic dihydrazide, dodecanediohydrazide, isophthalic dihydrazide, hydrazide, 3-hydro-2-naphtboic hydrazide benzophenone hydrazone, phenylhydrazine, benzylhydrazine monohydrochloride, methylhydrazine sulfate, and isopropylhydrazine hydrochloride.