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The purpose of this paper is to study the effect of the electropolishing time of stencil manufacturing parameters and solder‐mask definition methods of PCB pad design parameters on the performance of solder paste stencil printing process for the assembly of 01005 chip components.

During the study, two types of stencils were manufactured for the evaluations: electroformed stencils and electropolished laser‐cut stencils. The electroformed stencils were manufactured using the standard electroforming process and their use in the paste printing process was compared against the use of an electropolished laser‐cut stencil. The electropolishing performance of the laser‐cut stencil was evaluated twice at the following intervals: 100 s and 200 s. The performance of the laser‐cut stencil was also evaluated without electropolishing. An optimized process was established after the polished stencil apertures of the laser‐cut stencil were inspected. The performance evaluations were made by visually inspecting the quality of the post‐surface finishing for the aperture wall and the quality of that post‐surface finishing was further checked using a scanning electron microscope. A test board was used in a series of designed experiments to evaluate the solder paste printing process.

The results demonstrated that the length of the electropolishing time had a significant effect on the small stencil's aperture quality and the solder paste's stencil printing performance. In this study, the most effective electropolishing time was 100 s for a stencil thickness of 0.08 mm. The deposited solder paste thickness was significantly better for the enhanced laser‐cut stencil with electropolishing compared to the conventional electroformed stencils. In this printing‐focused work, print paste thickness measurements were also found to vary across different solder‐mask definition methods of printed circuit board pad designs with no change in the size of the stencil aperture. The highest paste value transfer consistently occurred with solder‐mask‐defined pads, when an electropolished laser‐cut stencil was used.

Due to important improvements in the quality of the electropolished laser‐cut stencil, and based on the results of this experiment, the electropolished laser‐cut stencil is strongly recommended for the solder paste printing of fine‐pitch and miniature components, especially in comparison to the typical laser‐cut stencil. The advantages of implementing a 01005 chip component mass production assembly process include excellent solder paste release, increased solder volume, good manufacture‐ability, fast turnaround time, and greater cost saving opportunities.

The rate of copper dissolution in the presence of phosphoric acid‐alcohol mixtures was studied by measuring the limiting current density which represents that the rate of electropolishing is decreased by increasing phosphoric acid concentration, electrode height, and mole fraction of alcohol. Thermodynamic parameters are calculated. The rotating disk electrode is being used as a tool to study the influence of organic solvent addition on the rate of electropolishing of copper. Different reaction conditions such as temperature, speed of rotation of copper disk, the physical properties of solution are studied to obtain a dimensionless correlation between all these parameters. The data can be correlated by the following equations: Sh = 1.835 (Sc)^0.33 (Re)^0.36 (for ethylene glycol) Sh = 1.25 (Sc)^0.33 (Re)^0.5 (for glycerol) It is obvious that the exponent in the two cases denotes a laminar flow mechanism.

Introduction Much work has been done on the phenomenon of electropolishing since it was discovered by Jaquat. Most of this work was directed towards the elucidation of the polishing mechanism as well as establishing conditions for polishing of different metals and alloys. Studies on the polishing mechanism have revealed that electropolishing is a diffusion‐controlled process, which takes place at the limiting current, and electropolishing can therefore be treated quantitatively using the theory of mass transfer to the cathodic deposition of metal and metal powder. Some work has been done on the study of electropolishing under forced convection mass transfer conditions. A notable recent investigation involving copper and copper‐based alloys in a stirred cell is due to the study of Gabe and strongly suggests a diffusion‐limited mechanism at low temperature. Fouad et al. studied mass transfer under free convection in the electropolishing of vertical copper electrodes in phosphoric acid.

Reports on the determination of rates of electropolishing of copper by measuring the limiting current of anodic dissolution of copper in phosphoric acid and in (water‐acetone) ‐phosphoric acid mixtures. Notes that the rate of electropolishing is decreased in (water‐acetone) ‐phosphoric acid mixtures and that the percentage inhibition of dissolution depends on the mole fraction of acetone, and its dielectric constant. Concludes with calculation of the thermodynamic parameters of activation.

Electropolishing or, to give it its more precise title, electrochemical polishing, has now become an accepted finishing aid in the aerospace industry. Few processes offer the highly advantageous technical characteristics achieved by a treatment once derogatively referred to as “reverse plating”.

Quite often in everyday service ‘stainless’ steels stain and ‘rustless’ alloys rust. In particular, the straight chrome/iron nickel‐free alloys have frequently exhibited early signs of severe tarnishing in service. Electrolytic polishing enhances the corrosion resistance of certain metals by forming very thin passive films—probably oxides—on these surfaces. This applies mainly to ferritic stainless alloys but also to some of the austenitic steels, to aluminium, brasses and to certain carbon steels. This article considers the nature and properties of the films and discusses practical applications.

This paper aims to present the way of modifying surfaces of 316L stainless steel elements that were manufactured in the selected laser melting (SLM) technology and then subjected to mechanical and electrolytic processing (electropolishing [EP]). The surface of the as-generated and commercial produced parts was modified by grinding and EP, and the results were compared. The authors also present an example of the application of EP for the final processing of a sample technological model – an initial prototype of a 316L steel implant manufactured in the SLM technology.

The analyzed properties included surface topography, roughness, resistance to corrosion, microhardness and the chemical composition of the surface before and after EP. The roughness described with the Ra, Rt and Rz was determined before and after EP of samples manufactured from 316L steel with use of traditional methods and additive technologies.

EP provides us with the opportunity to process elements with a complex structure, which would not be possible with use of other methods (such as milling or grinding). Depending on the expected final surface of elements after the SLM process, it is possible to reduce the surface roughness with the use of EP (for t = 20 min, Ra = 3.53 ± 0.37 µm and for t = 40 min, Ra = 3.23 ± 0.22 µm) or mechanical processing and EP (for t = 4 min, Ra = 0.13 ± 0.02 µm). The application of the EP method to elements made from 316L steel, in a bath consisting of sulfuric acid (VI), H2SO4 (35 Vol.%), phosphoric acid (V), H3PO4 (60.5 Vol.%) and triethanolamine 99 per cent (4.5 Vol.%), allows us to improve the surface smoothness and to obtain a value of the Ra parameter ranging from 0.11 to 0.15 µm. The application of a current density of 20 A/dm2 and a bath temperature of 55ºC results in an adequate smoothing of the surface (Ra < 0.16 µm) for both cold rolled and SLM elements after grinding. The application of EP, to both cold rolled elements and those after SLM, considerably improves the resistance to corrosion. The results of potentiodynamic corrosion resistance tests (jkor, EKA and Vp) of the 316L stainless steel samples demonstrate that the values of Vp for elements subjected to EP (commercial material: 1.3·10-4 mm/year, SLM material: 3.5·10-4 mm/year) are lower than for samples that were only ground (commercial material: 4.0·10-4 mm/year, SLM material: 9.6·10-4 mm/year). The microhardness was found to be significantly higher in elements manufactured using SLM technology than in those cold rolled and ground. The ground 316L steel samples were characterized by a microhardness of 318 HV (cold rolled) and 411 HV (SLM material), whereas the microhardness of samples subjected to EP was 230 HV (commercial material) and 375 HV (SLM material).

The 316L samples were built by SLM method. The surface of the SLM samples was modified by EP. Surface morphological changes after EP were studied using optical methods. Potentiodynamic tests enabled to notice changes in the corrosion resistance of 316L. Microhardness results after electropolished 316L stainless steel were shown. The chemical composition of 316L surface samples was presented. The smoothening of the surface amounted to Ra = 0.16 µm.

Corrosion resistance measurements were performed on AISI 316L stainless steel biomaterial samples after three types of treatments: abrasive finishing (MP), standard electropolishing (EP), and magnetoelectropolishing (MEP). The corrosion studies were carried out in Ringer's solution at a room temperature. Potentiodynamic plots obtained were the basis for the analysis of measurement accuracy and uncertainty with the statistical tests results done in Statistica 64/10 software. The results of corrosion studies indicate a significant difference in the breaking potential (Epit) values, dependent on surface treatment. The highest mean values have been obtained on samples after MEP (Epit=961 mV), much lower – after a standard electropolishing EP (Epit=525 mV), and the lowest – after the abrasive treatment MP (Epit=222 mV), all of them measured against a saturated calomel electrode SCE potential. The corrosion results obtained are well correlated with the nanoindentation measurement results (Young's modulus and nanohardness). The paper aims to discuss these issues.

The AISI 316L austenitic stainless steel samples served for the study. There were 11 (MP) and 14 (EP) samples used for each of the treatment, and 31 samples used for magnetoelectropolishing MEP. All polarization measurements were made after one hour immersion in the Ringer's solution. Statistical tests were used to treat the results obtained.

After magnetoelectropolishing MEP130, the pitting corrosion resistance is much better than that after abrasive polishing MP and/or a standard electropolishing EP130. It was proved on a big statistical sample that the pitting corrosion potential Epit after MEP130 is over 1.8 times higher than that after EP130 and over 4.3 times higher than that after MP. The results obtained are in good agreement with the nanoindentation measurement results.

This is an original study of the corrosion resistance of AISI 316L SS in Ringer's solution. The breaking potential Eb obtained is comparable with that of NiTi alloys, not reported anywhere before. The results have been well confirmed statistically (on 31 samples after MEP).

This article surveys the literature which underlines the role played by passivation of stainless steel surfaces. It also discusses the benefits of electropolishing, particularly as a contribution to improved hygiene and cleanability.