Acid Copper Plating Bath Additive System for Elevated Temperature Operation
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Solution Overview
Problem
Existing copper electroplating solutions are not effective at elevated temperatures, leading to dull, rough copper deposits and reliability issues, particularly in hot climates where cooling systems are needed to maintain optimal plating conditions.
Innovation Solution
An acid copper plating bath with an organic additive system comprising a heterocyclic nitrogen compound as a leveler, a high molecular weight polymer as a suppressor, and a divalent sulfur compound as a brightener, allowing copper electroplating at elevated temperatures without the need for cooling systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional copper electroplating solutions are used at elevated temperatures, then plating speed increases, but deposit quality deteriorates (dull, rough layers) and reliability decreases
Solution Approach 1:
The patent modifies the chemical parameters of the plating solution by introducing specific organic additives (polyether suppressor, heterocyclic leveler, sulfur-containing brightener) that enable the system to operate effectively at elevated temperatures (80-100°F) while maintaining deposit quality. This represents a parameter change in the solution composition to accommodate higher temperature operation.
2Device complexity
If conventional plating solutions are used at elevated temperatures, then cooling systems are eliminated, but deposit morphology deteriorates (dull, rough layers)
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating temperature-stable organic additives that maintain their functionality at elevated temperatures, thereby eliminating the need for cooling systems while preserving smooth, bright deposit morphology.
Solution Approach 2:
The patent uses a composite additive system combining multiple functional components: polyether suppressor, heterocyclic leveler, and sulfur-containing brightener. This composite approach synergistically addresses both the temperature stability and deposit quality requirements, allowing operation without cooling systems.
3Productivity
If conventional brighteners are used at elevated temperatures, then plating can proceed, but brightener effectiveness is lost due to chemical changes
Solution Approach 1:
The patent selects brighteners with specific chemical structures (sulfur-containing compounds) that exhibit thermal stability in the 80-100°F range. These compounds maintain their electrochemical activity and brightening effectiveness at elevated temperatures where conventional brighteners would undergo detrimental chemical changes.
4Productivity
If conventional suppressor and leveler combinations are used at elevated temperatures, then plating can continue, but rough, dull deposits form especially inside through holes
Solution Approach 1:
The patent employs a specifically formulated composite system where polyether suppressors, heterocyclic levelers, and sulfur-containing brighteners work synergistically. This combination maintains uniform suppression and leveling effects at elevated temperatures, preventing the formation of rough, dull deposits in through holes while allowing continuous plating operation.
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 deposition of bright, smooth, and ductile copper layers at elevated temperatures, maintaining thermal and mechanical integrity, and eliminating the need for cooling systems, as demonstrated by successful plating of printed circuit boards with no corner or barrel cracks during solder shock tests.
Implementation Method 1
the suppressors (or inhibitors) adsorb at the cathode surface uniformly, increasing the deposition over-potential
Implementation Method 2
electrolytic copper plating solutions are used... copper is electroplated over selected portions of the surface
Data Source
AI summary
An aqueous acidic copper electroplating composition containing an improved additive system for use at elevated temperatures. The improved additive system comprises (a) a suppressor comprising at least one high molecular weight polymer; (b) a brightener comprising at least one divalent sulfur compound; and (c) a leveler comprising a heterocyclic nitrogen compound. The improved electroplating composition is usable for plating through holes in printed circuit boards.