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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.

Insoluble anodes have long been used as an alternative to the preferred soluble types, primarily for their practicality and without great attention to their efficacy. However, since about 1970 so‐called catalytic anodes, typified by platinised titanium, have been increasingly used for electrochemical processes without too much attention to possible side‐effects. The purpose of this paper is, therefore, to review the types of commercially available catalytic anodes and their electrochemical properties, particularly with respect to acid copper electroplating.

Commercially available catalytic anodes were obtained from various anode suppliers and their electrochemical properties and behaviour with respect to acid copper electroplating were studied.

While the oxidising capability of catalytic anodes is undisputed, it can lead to oxidation of organic species in electroplating solutions. This in turn can lead to loss of control and additional costs for additives in electrodeposition. This study has addressed the issue and the paper attempts to set down some data‐based rules for the selection process. It also discusses some ways of optimising the choice of anode for acid copper processing of printed circuit‐related processes.

The paper determines the benefits and problems associated with the utilization of catalytic anodes in acid copper electroplating baths and, in particular, their effect on brightener consumption. It describes the factors affecting this phenomenon and describes a novel method for overcoming it.

The purpose of this paper is to develop an optimised sonochemical surface modification process which could be operated at low temperature and which uses non‐hazardous chemistry with short treatment times. A range of sonochemical parameters such as ultrasonic intensity/power and process temperature were investigated.

A 20 kHz ultrasonic probe was used as the ultrasonic source. Ultrasound was applied through deionised water (DI) to sonochemically surface modify a high Tg epoxy laminate material (Isola 370 HR). The efficiency of the sonochemical surface modification process was determined by weight loss, roughness, adhesion and scanning electron microscopy (SEM).

This study has confirmed that ultrasound has the ability to surface modify a high Tg epoxy substrate material (Isola 370 HR). Weight loss and roughness values were increased by using an optimised ultrasonic process compared to control samples which were processed under “silent” conditions. Adhesion testing showed an improvement in the adhesion level between the surface and the subsequently electroless plated copper.

Surface modification of high Tg materials generally utilizes wet chemical methods. These processes involve using hazardous chemicals, high temperatures, require high volumes of water for rinsing and need relatively long immersion times. This research has shown that by optimising ultrasonic parameters, surface modification can be brought about in deionised water (DI) at low temperature.

Previous studies have proven that, under optimised ultrasonic conditions, a range of materials used in electronic manufacturing can be sonochemically surface modified using benign solutions at low temperature. The purpose of this paper is to focus on a specific process, namely, the desmearing of through holes in printed circuit boards (PCB). The objective was to determine whether the introduction of low frequency ultrasound (20 kHz) to the “etch” stage of a standard “swell and etch” desmear system could enable reduced temperature processing and the use of less chemistry in the permanganate solution.

The study was divided into three main stages. In the first “screening” phase, the effect of ultrasound in the etch solution was studied by measuring the weight loss after desmear on a PCB laminate material (Isola 370HR). Factors such as etch temperature and concentration of permanganate (including permanganate‐free) were varied. In stage 2, confirmatory runs were carried out on the most promising conditions from the screening work and through holes in a four‐layer multi‐layer board (MLB) were assessed for smear removal using a scanning electron microscope (SEM). Finally, a four‐layer MLB was desmeared through the most promising ultrasonic process and then metallized at a PCB manufacturer. Thermal shock testing was subsequently carried out and sections from the board assessed for inter‐connection defects (ICDs).

The initial screening study indicated that, whenever ultrasound was used in the etch stage of the desmear process, significantly higher weight loss was achieved compared to a standard “silent” process. This effect was most pronounced when permanganate was removed from the etch solution and, in this situation, weight loss could be an order of magnitude higher than the silent equivalent. Further testing on through holes suggested that smear‐free inner‐layers could only be guaranteed if permanganate was present in the etch solution but that ultrasound again improved smear removal. Final testing under semi‐production conditions confirmed that, if ultrasound was employed in the etch part of the desmear process, then a reduction in processing temperature from 85°C to 60°C could be achieved and the permanganate concentration halved (65 to 33 g/L) whilst still achieving ICD‐free boards.

The paper indicates the feasibility of using ultrasound to reduce temperatures and chemical concentrations used in the permanganate etch solution, whilst still producing through holes with no ICDs.

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.

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.

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.

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.

To build on the results detailed in the previous paper where it was shown that sonochemical surface modification could be achieved in water. This paper aims to look at one of the factors affecting sonochemical surface modification, namely the ultrasonic source to sample distance.

Ultrasound was applied through deionized water for the surface modification of three materials: a high Tg PCB laminate (Isola 370HR), a polyphenylene ether – polystyrene polymer (Noryl HM4025) and an acrylonitrile‐butadiene‐styrene/polycarbonate (Cycolac S705). The efficacy of the treatment was determined by weight loss, scanning electron microscopy, contact angle, roughness and tape testing after electroless copper plating.

The study confirmed, and extended the previous findings, that a range of substrates could be sonochemically surface modified in water, even though in this work the ultrasonic horn had a larger tip size and produced a different ultrasonic intensity. Although the results were material dependent, the ultrasonic source to sample distance was found to be critical. Employing a spacing of 5 mm produced samples which generally exhibited higher weight loss, roughness and significant changes in surface morphology than when a distance of 25 mm was utilized.

The paper demonstrates that sonochemical surface modification has the potential to be a much more sustainable surface modification process than those currently employed in the electronics industry. However, to achieve this outcome acoustic cavitation and factors affecting it (such as source to sample distance) must be understood so that suitable equipment can be built.

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).

The purpose of this paper is to investigate the influence of pulse plating current density on the morphology and solderability of Pb-free Sn-Cu solder coatings prepared from alkaline stannate baths.

Sn-Cu solder coatings were produced from a plating solution containing sodium stannate, copper stannate, sodium hydroxide and sorbitol additive on copper substrates. The pulse plating experiments were conducted in galvanostatic mode. The plating current density was varied from 5 to 25 mA/cm², and the morphology of the coatings was studied. The solderability of the coatings was assessed by spread ratio measurement after reflowing the solder coatings at 250°C.

The composition control of eutectic solders is always a challenge in plating. The findings show that Sn-Cu coatings prepared by pulse plating are composed of tetragonal ß-Sn structure and Cu₆Sn₅ compounds irrespective of bath composition and conditions. The final coatings were very dense and smooth with nodular morphology. It was shown that a eutectic composition can be achieved if we apply a current density of ∼15-20 mA/cm². The solderability studies suggest that solder coatings plated at and beyond 15 mA/cm² are more suitable for solder finish applications.

The work presents key issues in pulse electroplating of Sn-Cu solder coatings from an alkaline bath. Possible strategies to control the eutectic Sn-Cu composition by plating process are recommended.

The purpose of this paper is to present current state of understanding on jet electrodeposition manufacturing; to compare various experimental parameters and their implication on as deposited features; and to understand the characteristics of jet electrodeposition deposition defects and its preventive procedures through available research articles.

A systematic review has been done based on available research articles focused on jet electrodeposition and its characteristics. The review begins with a brief introduction to micro-electrodeposition and high-speed selective jet electrodeposition (HSSJED). The research and developments on how jet electrochemical manufacturing are clustered with conventional micro-electrodeposition and their developments. Furthermore, this study converges on comparative analysis on HSSJED and recent research trends in high-speed jet electrodeposition of metals, their alloys and composites and presents potential perspectives for the future research direction in the final section.

Edge defect, optimum nozzle height and controlled deposition remain major challenges in electrochemical manufacturing. On-situ deposition can be used as initial structural material for micro and nanoelectronic devices. Integration of ultrasonic, laser and acoustic source to jet electrochemical manufacturing are current trends that are promising enhanced homogeneity, controlled density and porosity with high precision manufacturing.

This paper discusses the key issue associated to high-speed jet electrodeposition process. Emphasis has been given to various electrochemical parameters and their effect on deposition. Pros and cons of variations in electrochemical parameters have been studied by comparing the available reports on experimental investigations. Defects and their preventive measures have also been discussed. This review presented a summary of past achievements and recent advancements in the field of jet electrochemical manufacturing.