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Article
Publication date: 24 August 2010

A.J. Cobley, D.J. Comeskey, L. Paniwnyk and T.J. Mason

The purpose of this paper is to investigate if copper nanoparticles could be utilized for two types of through hole plating in printed circuit boards, namely: as a catalytic…

Abstract

Purpose

The purpose of this paper is to investigate if copper nanoparticles could be utilized for two types of through hole plating in printed circuit boards, namely: as a catalytic material to initiate the electroless copper deposition process; and as a “conductive” layer which is coherent and conductive enough to allow “direct” electroplating of the through hole. The employment of nanoparticles means that an effective method of dispersion is required and this paper studies the use of mechanical agitation and ultrasound for this purpose.

Design/methodology/approach

The paper utilized drilled, copper clad FR4 laminate. The through holes were functionalized using a commercially available “conditioner” before being immersed in a solution of copper nanoparticles which were dispersed using either a magnetic stirrer or ultrasound (40 kHz). When the copper nanoparticles were utilized as a catalytic material for electroless copper plating, the efficacy of the technique was assessed using a standard “backlight” test which allowed the plating coverage of the through holes to be determined. As a control, a standard palladium catalysed electroless copper process was employed. The morphology of the electroless copper deposits was also analysed using scanning electron microscopy. In the “direct plate” approach, after immersion in the copper nanoparticle dispersion, the through holes were electroplated at 3 Adm−2 for 15 min, sectioned and examined using an optical microscope. The distance that the copper electroplate had penetrated down the through hole was then determined.

Findings

The paper has shown that copper nanoparticles can be used as a catalytic material for electroless copper plating. The coverage of the electroless copper in the through hole improves as the copper nanoparticle concentration increases and, at the highest copper nanoparticle concentrations employed, good, but not complete, electroless copper coverage is obtained. Dispersion of the copper nanoparticles using ultrasound is critical to the process. Ultrasonically dispersed copper nanoparticles achieve some limited success as a conductive layer for “direct” electroplating with some penetration of the electroplated deposit into the through hole. However, if mechanical agitation is employed to mix the nanoparticles, no through hole plating obtaines.

Originality/value

The paper has demonstrated the “proof of concept” that copper nanoparticles can be utilized to catalyse the electroless copper process, as well as their potential to replace costly palladium‐based activators. The paper also illustrates the potential for copper nanoparticles to be used as a “direct plate process” and the necessity for using ultrasound for their dispersion in either process.

Details

Circuit World, vol. 36 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 September 2001

A.J. Cobley and D.R. Gabe

Significant reductions in the cycle time for the desmear, “making holes conductive” and imaging stages of the printed circuit board manufacturing process have been achieved by the…

1283

Abstract

Significant reductions in the cycle time for the desmear, “making holes conductive” and imaging stages of the printed circuit board manufacturing process have been achieved by the use of horizontal conveyorised techniques. If these savings in time are to be fully realised, it is also necessary to have a high‐speed acid copper electroplating process that, by implication, must be capable of operating at very high current densities. This paper outlines the fundamental electrochemical principles of acid copper electroplating and explains how these impact on high speed electroplating in terms of the electrolyte chemistry, the construction of the plating cell and the method in which the current is delivered (i.e. DC or pulse).

Details

Circuit World, vol. 27 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 29 July 2014

Jing Wang, Miao Wu and Chengqiang Cui

The purpose of this paper is to present a clear picture of the key factors of blind via and through hole filling in electroplating, e.g. shape of via or hole, electroplating

1098

Abstract

Purpose

The purpose of this paper is to present a clear picture of the key factors of blind via and through hole filling in electroplating, e.g. shape of via or hole, electroplating solution, process, as well as the developments of mechanisms and models.

Design/methodology/approach

First, the paper details the development trends and challenges of via filling. Then the research status of mechanisms, electroplating solutions, including base solution and additives, numerical model and mass transfer is described. Finally, through hole filling is briefly reviewed.

Findings

To achieve excellent via filling performance, the characteristics of the via or hole, the ratio of acid/copper, selection of additives and factors of mass transfer are comprehensively considered in terms of optimization of the electroplating process. It is beneficial to design vias with appropriate aspect ratios, to strengthen the adsorption of the accelerator in the via bottom, to inhibit the increase of surface copper thickness and to form butterfly-shaped copper in the centre of through holes. Optimized process parameters should be taken into consideration in superfilling.

Originality/value

The paper reviews different sets of additives, mechanisms and superfilling models for state-of-the-art via filling and the developments of filling for through holes.

Details

Circuit World, vol. 40 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 August 2016

Jia Liu, Jida Chen, Zhu Zhang, Jiali Yang, Wei He and Shijin Chen

The purpose of this paper is to introduce a new copper electroplating formula which is able to fill blind microvias (BVHs) and through holes (THs) at one process through a direct…

Abstract

Purpose

The purpose of this paper is to introduce a new copper electroplating formula which is able to fill blind microvias (BVHs) and through holes (THs) at one process through a direct current (DC) plating method.

Design/methodology/approach

Test boards of printed circuit board (PCB) fragments with BVHs and THs for filling plating are designed. The filling plating is conducted in a DC plating device, and the filling processes and influence factors on filling effect of BVHs and THs are investigated. Dimple depths, surface copper thickness, thermal shock and thermal cycle test are applied to characterize filling effect and reliability. In addition, to overcome thickness, increase of copper on board surface during filling plating of BVHs and THs, a simple process called pattern plating, is put forwarded; a four-layered PCB with surface copper thickness less than 12 μm is successfully produced.

Findings

The filling plating with the new copper electroplating formula is potential to replace the conventional filling process of BVHs and THs of PCB and, most importantly, the problem of thickness increase of copper on board surface after filling process is overcome if a pattern plating process is applied.

Research limitations/implications

The dimple depth of BVHs and THs after filling plating is not small enough, though it meets the requirements, and the smallest diameter and largest depth of holes studied are 75 and 200 μm, respectively. Hence, the possibility for filling holes of much more small in diameter and large in depth with the plating formula should be further studied.

Originality/value

The paper introduces a new copper electroplating formula which achieves BVHs and THs filling at one process through a DC plating method. It overall reduces production processes and improved reliability of products resulting in production cost saving and production efficiency improvement.

Details

Circuit World, vol. 42 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 December 2003

A.J. Cobley and D.R. Gabe

Despite the fact that insoluble anodes are becoming more utilized in acid copper electroplating for printed circuit board manufacture, little work has been published on the impact…

Abstract

Despite the fact that insoluble anodes are becoming more utilized in acid copper electroplating for printed circuit board manufacture, little work has been published on the impact of using such anodes on the process control of the baths or their effect on the electroplated deposit. In this study, two electroplating tanks were set up, which were identical in all aspects except that one tank used the traditional phosphorized soluble anodes, whilst the other employed insoluble anodes. Incorporating insoluble anodes into the electroplating tank caused a large increase in brightener consumption rate and the mechanical properties of the electroplate and the throwing power tended to be somewhat inferior to when soluble copper anodes were employed. This was thought to be due to the problems of controlling the brightener concentration at optimum levels rather than to any deterioration in the electrolyte, attributable to, for example, by‐product build‐up.

Details

Circuit World, vol. 29 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 17 May 2013

Ping Zhu, Liang You Wang, Guang Ren Qian, Tie Hua Cao and Ming Zhou

The purpose of this paper is to investigate the electrodeposition of copper coatings directly onto AZ31 magnesium alloy, considered as a substrate of electroplating nickel. The…

Abstract

Purpose

The purpose of this paper is to investigate the electrodeposition of copper coatings directly onto AZ31 magnesium alloy, considered as a substrate of electroplating nickel. The additive, pH, complexing agent, current density, time, and temperature of electrolytic bath were studied to understand electrodepositing copper coating on AZ31 magnesium alloy.

Design/methodology/approach

Electrodeposition of copper was carried out in an aqueous solution containing copper hydroxide, citrate, and fluorine ion, which avoids the replacement or corrosion of the magnesium alloy. The morphology, structure, and interface of the electrodeposited copper coating were investigated by a scanning electron microscope (SEM).

Findings

The copper coating was dense, and there was good adhesion of the copper coating on the AZ31 magnesium alloy. This suggests that successful deposition of copper using an electroplating process could decrease the cost of coating AZ31 magnesium alloy.

Practical implications

This paper will be helpful for the development of coating on magnesium alloy using electroplating processes.

Originality/value

Copper hydroxide and citrate were the main compositions of the electrolyte, combined with sodium poly dipropyl (SP) and polyethylene glycol (PEG) as brightening agents and can be used to electrodeposit copper directly onto AZ31 magnesium alloy.

Details

Anti-Corrosion Methods and Materials, vol. 60 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 16 August 2019

Zhihua Tao, Guanting Liu, Yuanxun Li and Hua Su

The adsorption and acceleration behavior of 3-mercaptopropyl sulfonate (MPS) were investigated by electrochemical tests for microvia filling by copper electroplating.

Abstract

Purpose

The adsorption and acceleration behavior of 3-mercaptopropyl sulfonate (MPS) were investigated by electrochemical tests for microvia filling by copper electroplating.

Design/methodology/approach

The synergistic effects of one suppressor of propylene oxide ethylene oxide propylene oxide named PEP and MPS as the accelerator during copper electroplating were also investigated by electrochemical methods such as electrochemical impedance spectroscopy cyclic voltammetric stripping (CVS) and Galvanostatic measurements (GMs).

Findings

The research results suggest that the adsorption of MPS onto the Cu-RDE metal surface was a spontaneous process and the adsorbing of MPS on cathode was proposed to physical-chemistry adsorption in the plating formula. There was no potential difference (i.e. ?? = 0) of GMs until MPS was injected into the plating solution suggest that copper deposition is not diffusion-controlled in the presence of PEP–Cl–JGB.

Originality/value

A new composition of plating bath was found to be effective to perform bottom-up copper filling of microvias in the fabrication of PCB in electronic industries. The adsorption of MPS into the Cu-RDE metal surface was a spontaneous process and the adsorbing of MPS on cathode was studied by EIS and the results proposed to physical-chemistry adsorption in the plating formula. An optimal plating solution composed of CuSO4, H2SO4, chloride ions, PEP, MPS and JGB was obtained, and the microvia could be fully filled using the plating formula.

Article
Publication date: 1 March 1989

L. Zakraysek

Multilayer printed wiring boards make use of electrodeposited copper from two sources. Copper for conductor traces comes from foil manufacturers through thin laminate suppliers…

Abstract

Multilayer printed wiring boards make use of electrodeposited copper from two sources. Copper for conductor traces comes from foil manufacturers through thin laminate suppliers. Copper plating for layer interconnection is performed in an in‐house PTH process. Each source makes use of plating chemicals that are obtained from industry suppliers, but production requirements inherent in foil manufacture or in PTH processing can cause variations that occasionally result in copper deposits that exhibit poor hot strength. In a PWMLB, this can result in corner cracks, barrel cracks and inner layer cracks because some of the copper deposits will be susceptible to fissuring under thermal stress conditions. The phenomenon of hot fissuring is caused by the presence of co‐deposited impurities that degrade the hot strength of the deposit due to easy grain boundary separation at elevated temperatures. Stresses imposed by a solder float test, by soldering or by thermal cycling are then sufficient to cause microcracking in a copper plate that is in this condition. In this paper, the author describes how changes in the quality of copper plate can be monitored with a hot rupture mechanical test method. By testing plated copper samples before board fabrication, it is possible to detect and evaluate harmful effects such as fissuring before the electroplated copper is used in a PWMLB assembly.

Details

Circuit World, vol. 15 no. 4
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 12 August 2021

Zhihong Sun and Jing Wang

The purpose of this paper is to solve the issue of via filling and pattern plating simultaneously by concentration optimization of accelerator and leveler in the electroplating

Abstract

Purpose

The purpose of this paper is to solve the issue of via filling and pattern plating simultaneously by concentration optimization of accelerator and leveler in the electroplating bath.

Design/methodology/approach

This paper designs a series of experiments to verify the performance of pattern plating with the via filling plating formula. Then the compositions of electroplating solution are optimized to achieve via filling and pattern plating simultaneously. Finally, the mechanism of co-plating for via and line is discussed in brief.

Findings

To achieve excellent performance for via filling and pattern plating simultaneously, proportion of additives are comprehensively considered in optimization of electroplating process. Effects of additives on the via filling and pattern plating should be taken into consideration, especially in achieving flat lines.

Originality/value

This paper discusses the different effects of accelerator and leveler on the via filling and the pattern plating, respectively. The process of co-plating for the via and the line is presented. The superfilling of via and the flat line are simultaneously obtained with the optimized via filling formula.

Details

Circuit World, vol. 49 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 December 1998

Peter Moran

In order for system designers to make full use of the successive generations of semiconductor devices it is becoming increasingly necessary to choose interconnection systems that…

Abstract

In order for system designers to make full use of the successive generations of semiconductor devices it is becoming increasingly necessary to choose interconnection systems that are tailored to the application. As this trend becomes more pronounced, the limitations of traditional methods of constructing boards onto which electronic components can be assembled are becoming more obvious. In this paper the application of selective electroplating, a technique that has been in use for many years but has not previously been fully exploited, is discussed. It is shown by examining a number of case studies that with a small amount of innovation this basic technique can be extended to meet the needs of a number of application areas while still operating within the normal processing windows of the materials.

Details

Microelectronics International, vol. 15 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

1 – 10 of 933