Copper Filling in Non-Through Holes Using Composite Polymer Additive
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Solution Overview
Problem
The existing electroplating methods for filling copper in non-through holes on substrates require a complex formulation and control of multiple additives to maintain consistent plating layer properties, making it difficult to achieve both high conductivity and smooth surface finishes.
Innovation Solution
A method using an acidic copper plating bath with a water-soluble copper salt, sulfuric acid, and a polymer additive that acts as both a brightener and leveler, such as a copolymer of diallylmethylamine addition salt and sulfur dioxide, to fill non-through holes efficiently, reducing the number of additives needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple additives (brightener, carrier, leveler, chloride ion) are used in the plating bath to achieve both bottom filling and outer surface control, then the plating layer properties and plugging property can be improved, but the formulation complexity and concentration control difficulty increase significantly
Solution Approach 1:
The patent combines multiple additives (brightener, carrier, leveler) into a single copolymer additive comprising polyethylene glycol, polypropylene glycol, and poly(N-vinyl-N-methylimidazolium chloride). This integration simplifies the plating bath formulation from multiple separate chemicals to one composite additive, reducing formulation complexity while maintaining the dual functionality of promoting bottom filling and controlling outer surface plating thickness
Solution Approach 2:
The copolymer additive performs multiple functions simultaneously: it acts as a brightener to promote copper deposition at the bottom of non-through holes, as a carrier to control plating rate, and as a leveler to prevent excessive plating on outer surfaces. This multi-functionality eliminates the need for separate additives and their complex concentration coordination
2Reliability
If multiple additives are co-present in the plating bath to achieve desired plating effects, then both bottom filling and surface smoothness can be improved, but the concentration control becomes troublesome and maintenance of constant plating properties becomes difficult
Solution Approach 1:
By merging multiple additives into one copolymer formulation, the patent reduces the number of concentration parameters from four (brightener, carrier, leveler, chloride ion) to one (copolymer concentration). This simplifies operation and maintenance while ensuring consistent plating properties through single-point control
3Ease of manufacture
If a plating bath with fewer additives is used to simplify formulation, then the ease of operation and formulation simplicity improve, but the ability to maintain constant plating layer properties and plugging property may deteriorate
Solution Approach 1:
The patent employs a composite additive material (copolymer) that integrates the functional properties of multiple separate chemicals. This composite structure maintains plating consistency through its designed molecular composition while simplifying the overall formulation to fewer components
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
This approach allows for effective copper filling in non-through holes with easier control of additive concentrations, resulting in a well-filled substrate with sufficient bottom portion plating and minimal surface plating, enhancing the filling form and efficiency.
Implementation Method 1
This invention relates to a copper filling-up method, and more specifically it relates to a method for filling copper in a non-through hole on a substrate that has been treated for rendering it conductive. (1) a method of filling copper in a non-through hole on a substrate that has been treated to render it conductive, which comprises plating said substrate in an acidic copper plating bath
Data Source
AI summary
A method of filling copper in a non-through hole on a substrate that has been treated to render it conductive, which comprises plating said substrate in an acidic copper plating bath comprising a water-soluble copper salt, sulfuric acid and a filling additive that is a polymer having the activities of both of a brightener and a leveler.