Palladium Plating Solution Bath Stability
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Solution Overview
Problem
Palladium plating solutions face challenges with low bath stability and short lifespan, leading to insufficient deposition properties, particularly when using aminocarboxylic acid as a complexing agent or sodium hypophosphite/boron hydride as a reducing agent, which results in a hard and weak palladium film.
Innovation Solution
A palladium plating solution comprising an aqueous palladium compound, a complexing agent with an ethylenediamine or propylenediamine skeleton, formic acid or formate, and a sulfur compound with two or more sulfide groups, which improves bath stability without compromising deposition properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If aminocarboxylic acid is used as a complexing agent, then bath stability is improved, but deposition property decreases
Solution Approach 1:
The patent combines ethylenediamine or propylenediamine skeleton compound with formic acid/formate and sulfur compound (having 2+ sulfide groups) to create a synergistic system. This combination achieves both bath stability and good deposition properties, resolving the contradiction where aminocarboxylic acid alone provided stability but poor deposition.
Solution Approach 2:
The patent changes the chemical parameters by specifying exact concentration ranges: complexing agent (0.5-25 g/L), formic acid/formate (10-100 g/L), and sulfur compound (0.01-50 mg/L). These optimized parameters enable simultaneous achievement of bath stability and deposition quality.
2Stability of the object's composition
If sodium hypophosphite or sodium boron hydride is used as a reducing agent, then bath stability is improved, but film quality deteriorates due to phosphorus or boron codeposition
Solution Approach 1:
The patent extracts and removes phosphorus and boron from the reducing agent system. Instead of using sodium hypophosphite or sodium boron hydride, it employs formic acid or formate as the reducing agent, eliminating the source of harmful codeposition while maintaining bath stability through the sulfur compound-containing system.
Solution Approach 2:
The patent converts the harmful effect of phosphorus/boron codeposition into a benefit by using formic acid/formate reduction, which produces hydrogen gas instead of phosphorus/boron deposits. The sulfur compound (with 2+ sulfide groups) then provides the necessary bath stability without compromising film quality.
3Stability of the object's composition
If conventional sulfur compound is used, then bath stability is improved, but deposition property decreases
Solution Approach 1:
The patent applies local quality by specifying that the sulfur compound must have a particular molecular structure (2 or more sulfide groups in specific positions) and concentration range (0.01-50 mg/L). This localized optimization ensures that the sulfur compound provides bath stability only when structurally and concentration-appropriately configured, avoiding negative impact on deposition.
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 significantly enhances bath stability while maintaining deposition speed and film quality, preventing bath decomposition and ensuring a stable palladium plating process.
Implementation Method 1
one or more complexing agent containing a compound having at least an ethylenediamine or a propylenediamine skeleton
Implementation Method 2
a formic acid or a formate
Implementation Method 3
a sulfur compound, wherein the palladium plating solution is having two or more sulfide groups in a molecule of the sulfur compound
Data Source
AI summary
The purpose of the present invention is to provide a palladium plating solution and a plating method for improving a bath stability of a palladium plating, without decreasing a deposition property of the palladium plating. A palladium plating solution for improving a bath stability, without decreasing a deposition property, comprising: an aqueous palladium compound: one or more complexing agent containing a compound having at least an ethylenediamine or a propylenediamine skeleton; a formic acid or a formate; and a sulfur compound, wherein the palladium plating solution is having two or more sulfide groups in a molecule of the sulfur compound.