Linxian Ji, Chong Wang, Shouxu Wang, Kai Zhu, Wei He and Dingjun Xiao
The uniformity of electrodeposition is the key to successful application of pattern plating because the quality of electrodeposited copper layer has a huge impact on the…
Abstract
Purpose
The uniformity of electrodeposition is the key to successful application of pattern plating because the quality of electrodeposited copper layer has a huge impact on the performance of printed circuit boards (PCBs). The multi-physics coupling technology was used to accurately analyze and forecast the characteristics of electrochemical system. Further, an optimized plating bath was used to achieve a uniform electrodeposition.
Design/methodology/approach
A multi-physics coupling numerical simulation based on the finite element method was used to optimize electrodeposition conditions in pattern plating process. The influences of geometric and electrochemical factors on uniformity of current distribution and electrodeposited layer thickness were discussed by multi-physics coupling.
Findings
The model results showed that the distance between cathode and anode and the insulating shield had a great impact on uniformity of electrodeposition. By numerical simulation, it had been proved that using an auxiliary cathode was an effective and simple way to improve uniformity of electrodeposition due to redistributing of the current. This helped to achieve more uniform surface of the copper patterns by preventing the edge effect and the roughness of the copper layer was reduced to 1 per cent in the secondary current distribution model.
Research limitations/implications
The research is still in progress with the development of high-performance computers.
Practical implications
A multi-physics coupling platform is an excellent tool for quickly and cheaply studying the process behaviors under a variety of operating conditions.
Social implications
The numerical simulation method has laid the foundation for the design and improvement of the plating bath.
Originality/value
By multi-physics coupling technology, we built a bridge between theoretical and experimental study for control of uniformity of pattern plating in PCB manufacturing. This method can help optimize the design of plating bath and uniformity of pattern plating in PCB manufacturing.
Details
Keywords
Linxian Ji, Chong Wang, Shouxu Wang, Wei He, Dingjun Xiao and Ze Tan
The purpose of this paper is to optimize experimental parameters and gain further insights into the plating process in the fabrication of high-density interconnections of printed…
Abstract
Purpose
The purpose of this paper is to optimize experimental parameters and gain further insights into the plating process in the fabrication of high-density interconnections of printed circuit boards (PCBs) by the rotating disc electrode (RDE) model. Via metallization by copper electrodeposition for interconnection of PCBs has become increasingly important. In this metallization technique, copper is directly filled into the vias using special additives. To investigate electrochemical reaction mechanisms of electrodeposition in aqueous solutions, using experiments on an RDE is common practice.
Design/methodology/approach
An electrochemical model is presented to describe the kinetics of copper electrodeposition on an RDE, which builds a bridge between the theoretical and experimental study for non-uniform copper electrodeposition in PCB manufacturing. Comsol Multiphysics, a multiphysics simulation platform, is invited to modeling flow field and potential distribution based on a two-dimensional (2D) axisymmetric physical modeling. The flow pattern in the electrolyte is determined by the 2D Navier–Stokes equations. Primary, secondary and tertiary current distributions are performed by the finite element method of multiphysics coupling.
Findings
The ion concentration gradient near the cathode and the thickness of the diffusion layer under different rotating velocities are achieved by the finite element method of multiphysics coupling. The calculated concentration and boundary layer thicknesses agree well with those from the theoretical Levich equation. The effect of fluid flow on the current distribution over the electrode surface is also investigated in this model. The results reveal the impact of flow parameters on the current density distribution and thickness of plating layer, which are most concerned in the production of PCBs.
Originality/value
By RDE electrochemical model, we build a bridge between the theoretical and experimental study for control of uniformity of plating layer by concentration boundary layer in PCB manufacturing. By means of a multiphysics coupling platform, we can accurately analyze and forecast the characteristic of the entire electrochemical system. These results reveal theoretical connections of current density distribution and plating thickness, with controlled parameters in the plating process to further help us comprehensively understand the mechanism of copper electrodeposition.
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Keywords
Jianhui Lin, Chong Wang, Yuanming Chen, Wei He, Dingjun Xiao and Ze Tan
The purpose of this paper was to present a simple and convenient technology to produce the electronic-grade CuO. The prepared electronic-grade CuO fully meets the demands of…
Abstract
Purpose
The purpose of this paper was to present a simple and convenient technology to produce the electronic-grade CuO. The prepared electronic-grade CuO fully meets the demands of industrial production of high density interconnect (HDI).
Design/methodology/approach
A new method termed as open-circuit potential-time technology is proposed to measure the dissolution time of CuO in plating solution. X-ray diffraction (XRD) scanning electron microscopy (SEM) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) were used to characterize the prepared CuO. Solder shock and reflow tests were carried out to examine the Cu deposits.
Findings
All aspects of the prepared CuO meet the demands of printed circuit board (PCB) industry.
Originality/value
A simple and convenient technology was presented to produce the electronic-grade CuO. A new method was proposed to determine the dissolution time of CuO in plating solution.
Details
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Fang Wang, Shiting Lin, Xiaoyu Liu, Chunyan Jiang and Jianing Li
The former residences of historical figures are typical landscape elements of historic districts, which are characterised by the styles of these residences and spiritual…
Abstract
Purpose
The former residences of historical figures are typical landscape elements of historic districts, which are characterised by the styles of these residences and spiritual historical figures cultures. The purpose of this paper is to determine how the former residences respond once the historical figures living there have passed.
Design/methodology/approach
The history of human culture and progression of urban construction – which are submerged in societal transformation – is recorded for old Beijing city. Narrative space theory is used and methods such as a content analysis, map overlay and the Geographic Information System are employed to analyse the selected 300 former residences of historical figures in old Beijing city.
Findings
The results are as follows: the political setting played a key role in the evolution process, three political narrative areas in the inner city and one cultural narrative area in the outer city form the narrative spatial structure of the former residences of historical figures, “government construction” and “resident construction” are the main reasons for the loss and destruction of narrative spaces and ordinary life is an important channel for showcasing the history of former residences. The narrative spaces of these residences carry double histories, namely, the development of human history and of city construction.
Originality/value
Different from former studies that focus on the preservation of the single historical building, this study explores the integral logic of historic buildings in the whole city through narrative space theory to get a combination of culture and space.