Palladium or Platinum Tetraammine Baths for Cleaner Electroplating
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Solution Overview
Problem
Existing electroplating solutions suffer from contamination and reduced plating rates due to the buildup of non-volatile anions such as phosphate, borate, and alkali metals, which degrade bath performance and coating quality.
Innovation Solution
An electroplating solution comprising tetraammine metal ions (M(NH3)4]2+, where M is Pt or Pd, with organic anions like bicarbonate or carbonate that decompose under alkaline electroplating conditions, minimizing the presence of alkali metals, phosphorus, and boron compounds to prevent buildup and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If non-volatile anions (phosphate, borate, alkali metals) are used in electroplating solutions, then bath stability is improved, but contamination of coating and reduced plating rate occur due to anion buildup
Solution Approach 1:
The patent changes the chemical nature of anions from non-volatile (phosphate, borate) to volatile (bicarbonate, carbonate, formate, acetate). This parameter change allows anions to decompose into volatile products that escape from the bath, preventing buildup and contamination while maintaining bath stability through controlled decomposition
Solution Approach 2:
The patent extracts harmful non-volatile anions from the electroplating solution and replaces them with volatile anions that decompose into gaseous products. This extraction eliminates the contamination problem by removing anions that would otherwise accumulate and deposit on coated surfaces
2Productivity
If non-volatile anions are used in electroplating solutions, then initial plating performance is maintained, but plating rate decreases over time due to anion accumulation
Solution Approach 1:
The patent changes anion volatility parameters to enable decomposition into volatile products. This allows the bath to maintain stable composition over extended periods as volatile anions continuously decompose and are replaced, extending bath lifetime while sustaining plating rates without anion accumulation
Solution Approach 2:
The patent introduces dynamic equilibrium where volatile anions continuously decompose and are replenished. This dynamic system prevents static accumulation of anions, maintaining consistent plating rates over longer bath lifetimes compared to systems with stable non-volatile anions
3Manufacturing precision
If volatile anions that decompose under plating conditions are used, then anion buildup is prevented and coating purity is improved, but bath composition stability may be affected
Solution Approach 1:
The patent selects volatile anions (bicarbonate, carbonate, formate, acetate) whose decomposition parameters are controlled to occur at rates compatible with plating operations. This balances coating purity improvement through volatile product formation with maintenance of adequate bath composition stability for consistent plating
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 maintains high plating rates and reduces coating defects by ensuring that anions decompose into volatile products, thereby extending bath lifetime and improving plating efficiency.
Implementation Method 1
organic anions like bicarbonate or carbonate that decompose under alkaline electroplating conditions
Implementation Method 2
Electroplating is a well-known technique for applying coatings of platinum and other platinum group metals onto conductive substrates
Data Source
AI summary
Aqueous electroplating solution for alkaline electroplating, comprising: [M(NH3)4]2+ ions, wherein M is selected from the group consisting of Pd or Pt; and organic anions selected from the group consisting of bicarbonate, carbonate, or a mixture thereof; wherein the following species, if present, are present in the following amounts: alkali metals in an amount of less than 5 g/L; compounds comprising phosphorus in an amount of less than 5 g/L; compounds comprising boron in an amount of less than 5 g/L. The invention also relates to an electroplating bath comprising the electroplating solution, and a method of forming a metal layer on a substrate by electroplating using the electroplating solution.