Copper Hole Filling via Flash-Plating and Additive-Free Baths
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Solution Overview
Problem
The existing methods for filling holes in component carriers with copper often result in irregular growth patterns leading to cracks and voids, which compromise the quality and functionality of electronic assemblies, especially at high frequencies, and are inefficient due to the reliance on chemical additives that may not reach all areas effectively.
Innovation Solution
A method involving a two-step process where a thin layer of electrically conductive material is formed on the hole surfaces using electro-less plating, followed by flash-plating with a copper ion bath concentration of 60 g/L to 70 g/L, eliminating the need for chemical additives and ensuring a uniform copper fill without cracks or voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electro-plating is used to fill holes in component carriers, then copper material grows from walls and bottom structure, but irregular growing patterns cause gaps and failures in the center of filled holes
Solution Approach 1:
The patent changes the copper ion concentration parameter in the plating bath from conventional levels to a specific range of 60-70 g/L. This parameter change transforms the plating process into flash-plating, which achieves uniform copper deposition without the irregular growth patterns that cause center gaps and failures. The high copper ion concentration enables rapid, controlled filling that maintains uniformity throughout the hole.
2Manufacturing precision
If chemical additives are used to support regular growth of copper material, then gap formation may be reduced, but additives are brought into and out of the hole without providing sufficient influence on copper material growth
Solution Approach 1:
The patent extracts and eliminates chemical additives from the plating process. Instead of relying on additives that are washed in and out of the hole without sufficient effect, the invention uses a clean plating bath with controlled copper ion concentration (60-70 g/L). This extraction of harmful or ineffective elements achieves uniform copper growth without the need for chemical additives.
Solution Approach 2:
The patent changes the fundamental parameter of copper ion concentration to 60-70 g/L, which enables flash-plating to occur. This parameter change makes chemical additives unnecessary, as the high copper ion concentration alone drives uniform, rapid deposition that fills holes evenly without requiring external chemical agents.
3Manufacturing precision
If copper ion concentration in plating bath is increased to 60 g/L to 70 g/L for flash-plating, then uniform copper fill is achieved without gaps, but the process requires precise control of plating parameters
Solution Approach 1:
The patent establishes a specific copper ion concentration range of 60-70 g/L that enables flash-plating. Within this parameter range, the process achieves uniform deposition automatically. The parameter change creates a self-regulating effect where the high copper ion concentration drives rapid, uniform filling without requiring complex external control mechanisms.
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 significantly improves the quality and reliability of copper-filled holes, enhancing signal transduction and reducing manufacturing costs while being environmentally friendly by avoiding the use of supplementary chemical additives.
Implementation Method 1
a layer of an electrically conductive material is formed on the surfaces of walls, which physically delimit the hole, by means of electro-less plating
Implementation Method 2
the layer of electrically conductive material is covered and an unfilled volume of the hole is filled with copper material by means of flash-plating as an electro-plating process
Data Source
Figure 1a~1d
Figure 2
Figure 3a~3b
AI summary
A method of filling a hole (120) formed in a component carrier (100) with copper (110). The method comprises i) forming a layer of an electrically conductive material (111) covering at least part of a surface (131) of a wall (130), wherein the wall (130) delimits the hole (120), and subsequently ii) covering at least partially the layer (111) and filling at least partially an unfilled volume (121) of the hole (120) with copper (110) using a plating process including a bath. Hereby, the bath comprises a concentration of a copper ion, in particular Cu2+, in a range between 50 g/L and 75 g/L, in particular in a range between 60 g/L and 70 g/L.