Tin Electroplating Suppressing Agent for Smooth Deposit Morphology
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Solution Overview
Problem
The electronics industry faces challenges in achieving uniform and smooth tin or tin alloy electroplating deposits with low roughness, particularly for features in the micrometer scale, as existing solutions often result in rough surfaces and voids, which affect the coplanarity and connection density of solder bumps on copper pillars.
Innovation Solution
An aqueous composition comprising tin ions and specific suppressing agents, such as polyamine-based compounds with polyoxyalkylene groups, is used to inhibit dendrite growth and achieve smoother surfaces and improved coplanarity, suitable for features ranging from 500 nm to 500 μm in aperture size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional tin electroplating baths are used, then the plating process is simple and cost-effective, but the deposit surface is rough and contains voids
Solution Approach 1:
The patent modifies the chemical composition parameters of the plating bath by introducing specific suppressing agents with defined molecular structures (formula I) containing polyoxyalkylene groups. This changes the electrochemical parameters of the plating process to achieve smoother surfaces while maintaining cost-effectiveness through controlled additive usage.
Solution Approach 2:
The suppressing agents act as intermediary substances between the electroplating bath and the substrate. These agents mediate the electrochemical reactions to inhibit dendrite growth and void formation, resulting in smoother deposits without fundamentally changing the overall plating process simplicity.
2Manufacturing precision
If known electroplating baths are used for small amounts of solder, then the process is straightforward, but uniformity of deposit height is difficult to achieve
Solution Approach 1:
The suppressing agents provide local quality control by selectively influencing the electroplating reaction at different locations on the substrate. This ensures uniform deposit height across all features including small amounts of solder, while maintaining overall processing efficiency through a single bath composition.
3Shape
If conventional plating compositions are used, then the formulation is simple, but the deposit morphology is poor with high roughness
Solution Approach 1:
The patent employs composite additive formulations combining suppressing agents with specific molecular structures (formula I) containing polyoxyalkylene groups. This composite approach improves deposit morphology by synergistically acting on multiple aspects of crystal growth and surface formation, while the formulation remains manageable in complexity.
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 described composition effectively fills recessed features with smooth, uniform tin or tin alloy deposits, reducing surface roughness and void formation, thereby enhancing the coplanarity and connection density of solder bumps.
Implementation Method 1
The invention relates to tin or tin alloy electroplating compositions comprising a suppressing agent
Implementation Method 2
suppressing agent... to inhibit dendrite growth and achieve smoother surfaces
Data Source
AI summary
Described herein is an aqueous composition including tin ions and at least one compound of formula IwhereX1, X2 are independently selected from a linear or branched C1-C12 alkanediyl,R11 is a monovalent group of formula —(O—CH2—CHR41)m—OR42,R12, R13, R14 are independently selected from H, R11, and R40;R15 is selected from H, R11, R40 and —X4—N(R21)2,X4 is a divalent group selected from (a) a linear or branched C1 to C12 alkanediyl, and (b) formula —(O—CH2—CHR41)o—,R21 is selected from R11 and R40,R40 is a linear or branched C1-C20 alkyl,R41 is selected from H and a linear or branched C1 to C5 alkyl,R42 is selected from H and a linear or branched C1-C20 alkyl,n is an integer of from 1 to 6,m is an integer of from 2 to 250, ando is an integer of from 1 to 250.