Novel, Simple, and Green Citrate-Based Copper Electronic Electroplating Bath in Microvia Void-Free Filling for Printed Circuit Board Application

Abstract

In this work, a novel, simple, and green citrate-based copper electronic electroplating bath with the characteristics of weak corrosion, low copper ion concentration, and simple composition is developed in microvia void-free filling for printed circuit board application. Succinimide (SM), regarded as a leveler, is the core component of the bath. The action mechanisms of SM on microvia void-free copper filling are carefully expounded. UV–vis spectroscopy and theoretical calculations demonstrate that only the [Cu2(Cit)2]2– coordination ion exists in the bath containing SM at pH 9.0. Linear sweep voltammetry and in situ Fourier transform infrared spectroscopy combined with X-ray photoelectron spectroscopy experiments illustrate that SM can inhibit the electroreduction of the [Cu2(Cit)2]2– coordination ion and promote the electroreduction of intermediate Cu(I) to Cu(0), resulting in the improvement of coating quality. Galvanostatic measurements reveal that the reduction of the [Cu2(Cit)2]2– coordination ion is electrochemically controlled, and SM is diffusion-controlled. The leveler properties of SM (diffusion control and inhibition of [Cu2(Cit)2]2– coordination ion electroreduction) promote copper in bottom-up growing and void-free filling of microvias.

Eco-Friendly Electrowinning for Metals Recovery from Waste Electrical and Electronic Equipment (WEEE)

“…Citric acid-based solutions are very promising for metal leaching and electrowinning due to its biodegradability. Citrate ions form stable complexes with many metals and it is widely used for metal and alloy electrodeposition, including electrowinning of metals after treatment of WEEE (e.g., Cu [32], Ni [33], Sn [34], Pb and Zn [35], Sn-Zn [36], Cu-Sn [37], FeCoNiCr [38]). The agents facilitating metals leaching are EDTA [39] and H 2 O 2 [40], which can also be used for electrowinning.…”

Investigation of a Single-Component Additive for Bottom-Up Superfilling of the High-Aspect-Ratio TSV by Theoretical and Experimental Studies

“…Through-silicon via (TSV) is a key technology for advanced three-dimensional integration, as TSV can provide extremely short vertical interconnects that significantly improve interconnect density and operational performance. , Among the TSV manufacturing processes, TSV Cu filling emerges as a critical technology for providing reliable electrical interconnect. However, achieving defect-free electroplating Cu filling for TSVs is a huge challenge due to the extremely uneven current density distribution between the via opening and bottom, as well as the difficulty of copper ion transfer . As the aspect ratio increases, filling the bottom of the TSV becomes progressively arduous, leading to filling defects such as voids and seams.…”

“…However, achieving defect-free electroplating Cu filling for TSVs is a huge challenge due to the extremely uneven current density distribution between the via opening and bottom, as well as the difficulty of copper ion transfer. 3 As the aspect ratio increases, filling the bottom of the TSV becomes progressively arduous, leading to filling defects such as voids and seams. The filling defects would severely impact electrical conductivity and compromise the overall reliability of interconnects.…”

Synthesis of Quinacridone Derivatives and Their Application as High Performance Levelers in Electroplating

“…20,21 However, limitations such as planarity issues affecting adsorption performance and incomplete understanding of underlying mechanisms highlight the need for further research in this area. 22,23 The unique structure of the quinacridone molecule, characterized by a conjugated five-membered ring and strong electronegative groups like the carbonyl and sp 2 hybridized N atoms, makes it highly suitable for electrode surface adsorption and effective charge dispersion. [24][25][26] This inherent potential motivated the present study to synthesize a series of quinacridone aromatic heterocyclic quaternary ammonium salts from 2,9 dichloroquinacridone, and these compounds were analyzed and tested to explore their properties in terms of electroplating.…”