Blog - Advint Incorporated

Posts About fundamentals

In the fast-paced world of modern electronics, the ability to create intricate circuitry on an increasingly miniature scale is paramount. At the heart of this technological marvel lies a process known as copper electrodeposition – a sophisticated technique that forms the backbone of printed circuit board (PCB) manufacturing and advanced microelectronics. But what truly elevates this process from mere metal plating to a precise science is the delicate dance of molecular additives, with polyethylene glycol (PEG) and polypropylene glycol (PPG) taking center stage as crucial suppressor molecules.


The Molecular Choreography of Copper Electrodeposition

Copper electrodeposition might sound straightforward – the process of depositing copper onto a surface using electricity – but its intricacies are far more complex. The real magic happens at the nanoscale, where PEG and PPG molecules interact with the copper surface in a carefully orchestrated performance that controls the rate and quality of copper deposition.


PEG: The Prima Ballerina of Suppressors

Polyethylene glycol, or PEG, is a hydrophilic polymer that plays a starring role in this molecular ballet. Its performance, however, is heavily dependent on a supporting cast – chloride ions. The relationship between PEG and chloride is so crucial that without chloride, PEG simply refuses to take the stage (or in scientific terms, adsorb to the copper surface).


When chloride ions are present, they facilitate a remarkable transformation. PEG molecules form a complex bridge structure on the copper surface, known as the PEG-Cu(I)-Cl− bridge. This intricate formation sees PEG's oxygen atoms complexing with Cu(I) ions, which are in turn stabilized by the adsorbed chloride. The result? A robust suppression layer that acts as a barrier, controlling the reduction of copper ions at the electrode surface with exquisite precision.


PPG: The Contrasting Performer

Enter polypropylene glycol, or PPG – a more hydrophobic counterpart to PEG. PPG's performance is distinctly different, adding depth and nuance to the molecular show. Its adsorption kinetics are slower, and it reaches surface saturation at a reduced rate compared to its PEG counterpart. Intriguingly, PPG causes a more negative suppression potential, hinting at a unique mechanism of action that complements PEG's performance.


The Chloride Ion: More Than Just a Supporting Actor

The role of chloride ions in this molecular performance cannot be overstated. Far from being mere spectators, chloride ions are essential facilitators that influence every aspect of the suppressor molecules' behavior:

  • They are crucial for PEG adsorption, creating favorable conditions for these molecules to attach to the surface.
  • Chloride ions help form the stable PEG-Cu(I)-Cl- complex, a key element in the suppression mechanism.
  • They stabilize Cu(I) ions on the surface, promoting interaction with PEG's oxygen atoms.
  • Chloride ions occupy high-energy adsorption sites, complementing PEG's preference for lower-energy sites and contributing to a more effective suppression layer.
  • They significantly influence the adsorption-desorption dynamics of PEG, shifting the equilibrium strongly towards the adsorbed state.

This chloride-induced shift in equilibrium is not merely a kinetic effect but a fundamental change in the thermodynamic stability of adsorbed PEG. The result is enhanced surface coverage, conformational changes in PEG molecules (notably an increase in gauche conformation of C-O bonds), and the formation of a more stable and effective suppressor layer.

Copper Electroplating

Spectroscopic Insights: Peeking Behind the Curtain

To truly appreciate the complexity of this molecular performance, researchers have employed advanced spectroscopic techniques, offering unprecedented insights into the behavior of these suppressor molecules:


Raman Spectroscopy:

Both normal and surface-enhanced Raman spectroscopy (SERS) have revealed significant spectral shifts in PEG's C-H stretching and bending regions upon surface adsorption. These shifts indicate conformational changes as PEG molecules adapt to their new role on the copper surface. PPG, true to its distinct character, shows less pronounced spectral changes, reflecting its reduced conformational flexibility.


Electrochemical Quartz Crystal Microbalance (QCM): 

This sophisticated gravimetric technique has allowed researchers to quantify the adsorption process with remarkable precision. QCM studies have confirmed that PEG adsorption occurs only in the presence of chloride ions, while PPG can adsorb with or without chloride. Fascinatingly, PPG forms a denser surface layer (0.598 μg/cm²) compared to PEG (0.336 μg/cm²), highlighting how molecular structure influences adsorption behavior.


The Gauche Effect: A Twist in the Tale

Computational studies have added another layer of understanding to this molecular narrative. The observed spectroscopic trends are associated with an increased gauche character in the polymer backbone upon adsorption. This conformational change is not merely a curiosity but plays a pivotal role in the suppression mechanism, influencing the packing density and stability of the adsorbed layer.


Implications for Electrodeposition Kinetics

The distinct behaviors of PEG and PPG have profound implications for copper electrodeposition:

  • Suppression Strength: PEG typically exhibits stronger suppression due to its more stable adsorption layer, while PPG's weaker suppression may allow for more dynamic control of deposition rates.
  • Desorption Kinetics: PPG is more readily desorbed by anti-suppressors like bis(3-sulfopropyl) disulfide (SPS), potentially allowing for more rapid modulation of local deposition rates.
  • Fill Performance: The differences in adsorption behavior can be exploited to optimize the filling of high-aspect-ratio features, such as trenches and vias, in damascene processes crucial for advanced microchip fabrication.

Challenges and Future Directions

While PEG and PPG have revolutionized copper electrodeposition, challenges remain. The stability of these suppressor molecules under operating conditions is a key concern. Studies have shown that PEG-PPG copolymers can undergo degradation during the electrodeposition process, potentially impacting the consistency and quality of the deposited copper film over time.


Looking to the future, researchers are focusing on several promising avenues:

  1. Developing novel suppressor molecules with tailored hydrophobicity and molecular structures to further fine-tune the deposition process.
  2. Implementing in-situ spectroscopic monitoring for real-time process control, allowing for unprecedented precision in electrodeposition.
  3. Advancing molecular modeling techniques to predict suppressor behavior and guide additive design, potentially leading to breakthroughs in suppressor technology.

Conclusion: The Future of Molecular Engineering in Electronics

As we continue to push the boundaries of electronic miniaturization and performance, the insights gained from studying these suppressor molecules will be invaluable. The intricate dance of PEG, PPG, and chloride ions on copper surfaces is more than just a fascinating scientific phenomenon – it's the key to unlocking the next generation of microelectronics.

By mastering this molecular ballet, we're not just improving a manufacturing process; we're paving the way for smaller, faster, and more efficient electronic devices that will shape our technological future.

From smartphones to supercomputers, the invisible performance of these molecular actors plays a crucial role in the devices we rely on every day.

As research in this field progresses, we can expect to see even more sophisticated control over the copper electrodeposition process, leading to advancements in electronics that we can scarcely imagine today. The molecular dance of PEG and PPG is just the beginning – a prelude to a future where molecular engineering drives the next great leaps in electronic technology.

add a comment
Subscribe to this Blog Like on Facebook Tweet this! Share on LinkedIn

In the world of metallurgy and manufacturing, there's an invisible enemy that can turn the strongest metals brittle and cause catastrophic failures without warning. This nemesis is hydrogen embrittlement, a phenomenon that has kept engineers, metallurgists, and heat treatment specialists on their toes for decades. Today, we're diving deep into this critical issue that affects industries ranging from aerospace to everyday manufacturing.


What is Hydrogen Embrittlement?

Hydrogen embrittlement (HE) occurs when hydrogen atoms infiltrate a metal's structure, reducing its ductility and load-bearing capacity. Imagine a mighty steel beam suddenly snapping like a twig - that's the devastating potential of HE.

This process requires three key ingredients:

  1. A susceptible material (often high-strength steels, titanium alloys, or aluminum alloys)
  2. An environment that allows hydrogen to attack
  3. The presence of stress (either internal or applied)

When two of these factors align, failure becomes not just possible, but inevitable.


The Sneaky Sources of Hydrogen

Hydrogen can be a master of disguise, infiltrating metals through various means:

  • Heat treating atmospheres
  • Breakdown of organic lubricants
  • Steelmaking processes (e.g., electric arc melting of damp scrap)
  • Welding with damp electrodes
  • High-pressure hydrogen gas environments
  • Grinding in wet conditions
  • Electrochemical surface treatments (etching, pickling, plating)

Particularly problematic are acid cleaning and high-current electroplating processes, which are incredibly efficient at producing hydrogen.

Electroplating hydrogen embrittlement

The Science Behind the Breakdown

Hydrogen embrittlement isn't a single process, but rather a collection of mechanisms that can lead to metal failure:

  • Hydrogen-induced cracking: Hydrogen atoms weaken the bonds between metal atoms, leading to crack initiation and growth.
  • Hydrogen-enhanced localized plasticity (HELP): Hydrogen increases dislocation mobility, causing localized deformation and facilitating crack propagation.
  • Pressure-induced embrittlement: Hydrogen accumulates at voids or inclusions, increasing internal pressure and leading to micro void coalescence and fracture.

Detection: A Challenging Endeavor

Identifying hydrogen embrittlement, especially at low concentrations, can be like finding a needle in a haystack.

However, some methods have proven effective:

  • Simple bend tests to check for ductility loss
  • Metallographic techniques to examine near-surface areas and grain boundaries
  • Non-destructive testing (NDT) methods like ultrasonic testing and X-ray diffraction
  • Hydrogen concentration measurements using thermal desorption spectroscopy (TDS)

Prevention: The Best Medicine

When it comes to hydrogen embrittlement, an ounce of prevention truly is worth a pound of cure. Here are some strategies to keep HE at bay:

  • Reduce hydrogen exposure and material susceptibility
  • Implement mandatory baking after plating processes
  • Utilize test methods to identify susceptible materials
  • Opt for lower-strength steels when possible
  • Avoid acid cleaning
  • Employ low-hydrogen plating techniques
  • Minimize residual and applied stress
  • Apply surface treatments or coatings to prevent hydrogen ingress
  • Perform stress relief heat treatments

The Hydrogen Bake-Out: A Powerful Solution

One particularly effective method for combating hydrogen embrittlement is the hydrogen bake-out process. This involves heating the component to allow hydrogen to diffuse out of the metal. The effectiveness of this method depends on factors like temperature, time, and concentration gradient.


Industry Impact: It's Not Just Rocket Science

While aerospace applications have seen some of the most severe hydrogen embrittlement issues, it's crucial to remember that, as one expert put it, "it doesn't have to fly in order to die." 


HE affects a wide range of industries and components:


  • Aerospace: Landing gear components and other critical parts
  • Automotive: High-strength steel components used for lightweighting
  • Construction: Fasteners and structural elements in bridges and buildings
  • Nuclear industry: Various critical components

The Future of Fighting Hydrogen Embrittlement

As we continue to push the boundaries of material strength and performance, understanding and mitigating hydrogen embrittlement becomes increasingly critical. Research into new alloys, improved surface treatments, and advanced detection methods is ongoing.


Conclusion: Vigilance is Key

Hydrogen embrittlement remains a significant challenge in the world of metals. By implementing proper prevention strategies and remaining vigilant, we can reduce the risk of unexpected failures and ensure the integrity of our metal components. Remember, when it comes to hydrogen embrittlement, what you can't see can hurt you - so stay informed, stay prepared, and keep your metals safe from this invisible threat.

add a comment
Subscribe to this Blog Like on Facebook Tweet this! Share on LinkedIn

Recent research has unveiled groundbreaking advancements in electrodeposition techniques for bismuth and tin, offering innovative insights that could transform metal coating technologies. These studies provide crucial information on optimizing electroplating processes, enhancing coating uniformity, and understanding the impact of various factors on deposit properties.


Bismuth Electrodeposition from Perchloric Acid Solutions

A pioneering study on bismuth electrodeposition from perchloric acid solutions has revealed several key findings:


Bismuth perchlorate solutions exhibit exceptional stability, resisting hydrolysis and precipitation even when diluted.

Optimal deposition conditions were achieved at room temperature using a current density of 3.1 A/dm², resulting in smooth, finely crystalline cathode deposits free of rough edges.

The ideal bath composition was determined to be 40 g/L of bismuth oxide and 104 g/L of perchloric acid, ensuring efficient deposition.

Cathodic current efficiency approached 100%, indicating minimal energy waste during the deposition process.

The deposited bismuth contained trace amounts (0.4-0.5%) of perchlorate, suggesting the need for further purification in certain applications.

While addition agents such as glue and cresol slightly improved the deposits, they were not essential for achieving satisfactory results. This method shows promise for specialized applications in electrical and magnetic devices. However, the brittleness and tarnishing tendency of the deposited bismuth currently limit its broader commercial use.


Enhancing Coating Uniformity in High-Speed Tin Plating

Another crucial study focused on improving coating homogeneity in high-speed tin electroplating:

Both 3D and simplified 2D models were developed to analyze factors affecting coating uniformity, such as electrolyte potential distribution, tin ion concentration, gas evolution, and current distribution.

The primary challenge identified was the "edge effect," resulting in thicker coatings at the cathode edges, posing significant challenges in achieving consistent coatings.

Adjusting anode sizes or arrangements proved insufficient. However, auxiliary devices like insulating bars and auxiliary cathodes showed potential in mitigating the edge effect.

Although auxiliary cathodes nearly eliminated the edge effect, they introduced drawbacks such as increased current and tin wastage.

The simulation results correlated well with actual production data, particularly for high coating masses, though discrepancies were noted at lower coating masses.

These findings provide valuable strategies for enhancing coating uniformity in high-speed electroplating processes, applicable beyond tin plating.


Impact of Additives and Current Density on Tin Deposits

Further research explored the effects of organic plating additives and current density on the properties of electroplated tin deposits:

Increasing the concentration of organic plating additives raised the carbon content in tin deposits from 5 wt% to 8 wt%.

Higher current densities caused the tin oxide film to reach donor density saturation at lower additive concentrations, suggesting a role in the decomposition of organic additives and subsequent carbon incorporation.

Depth profile analysis revealed that carbon was consistently incorporated throughout the deposit, not just sporadically.

The native tin oxide layer exhibited n-type semiconductor characteristics, crucial for understanding its potential applications in electronic devices.

These studies highlight the complexities of electrodeposition processes and pave the way for future innovations in electroplating technologies. By optimizing bath compositions, current densities, and additive concentrations, researchers can develop more efficient and effective electroplating methods for bismuth, tin, and potentially other metals, opening new possibilities in coating technologies and electronic applications.



The research on bismuth from perchloric acid solutions offers a reliable method for specialized applications, while the high-speed tin plating study provides strategies for achieving uniform coatings.

Both investigations underscore the critical influence of additives and current density on the properties of electrodeposited metals, setting the stage for future advancements in electroplating technologies.

add a comment
Subscribe to this Blog Like on Facebook Tweet this! Share on LinkedIn


Chromium plating is a widely used technique for coating metal surfaces with a layer of chromium. It provides several benefits, such as corrosion resistance, improved hardness and wear resistance, and aesthetic appeal. However, chromium plating can also pose significant environmental challenges because of the toxic nature of chromium compounds. To win the environmental challenges of chromium plating, here are some strategies you can follow:


Use alternative plating methods 

One way to reduce the environmental impact of chromium plating is to explore alternative plating methods that do not use chromium compounds. For example, electroless nickel plating or electroplating with non-chromium-based solutions can provide similar benefits without the toxic effects of chromium.


Optimize process parameters

Another way to reduce the environmental impact of chromium plating is to optimize the process parameters. This can include using lower concentrations of chromium compounds, reducing plating time, or adjusting the temperature and pH of the plating solution.


Implement a closed-loop system 

Implementing a closed-loop system can reduce the amount of chromium discharged into the environment. A closed-loop system recirculates the plating solution, rather than disposing of it after each use, reducing the amount of waste generated.


Use a chemical recovery system

A chemical recovery system can help to recover the chromium from the plating solution and recycle it for future use. This reduces the amount of chromium needed for the plating process and minimizes the amount of waste generated.


Proper waste management 

Proper waste management is essential to minimize the environmental impact of chromium plating. All waste generated during the plating process should be collected, treated, and disposed of appropriately, following local environmental regulations.


In conclusion, winning the environmental challenges of chromium plating requires a combination of strategies, such as using alternative plating methods, optimizing process parameters, implementing closed-loop and chemical recovery systems, and proper waste management. By following these strategies, we can ensure that chromium plating is a sustainable and environmentally friendly process.


Hexavalent chromium, also known as chromium (VI), is a toxic and carcinogenic substance that has been widely used in the metal finishing industry for hard and decorative plating processes since the 1920s. The exceptional physical characteristics of chromium plating make it a preferred choice in many applications, but the hazardous nature of hexavalent chromium has led to increased environmental and health concerns.


The US Environmental Protection Agency (EPA) has classified hexavalent chromium as a hazardous substance and has established regulations to limit its discharge into the environment. The Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) program in the European Union has also listed chromium trioxide, a common source of hexavalent chromium in plating solutions, as a hazardous chemical and has implemented strict regulations on its use.


Because of these regulations, the metal finishing industry has been working to develop alternative plating methods and to improve the sustainability of chromium plating processes. This includes the use of closed-loop systems, chemical recovery systems, and the development of non-chromium-based plating solutions.


It is important to continue to monitor and regulate the use of hexavalent chromium to minimize its impact on the environment and public health.

Chromium plating has been widely used in various industries for decades due to its exceptional physical characteristics such as corrosion and wear resistance, and aesthetic appeal. In the aerospace industry, hard chromium is commonly used for its durability and ability to withstand extreme environments. The automotive sector primarily uses decorative chromium plating, while other industries use both decorative and hard chromium plating.


Chromium plating- Advint Incorporated


Chromium is the only element among groups 4, 5, and 6 of the periodic table that can be plated using an aqueous solution. Ionic liquids can deposit most of the transition elements, but they are not widely used in industrial applications. Aqueous hexavalent chromium deposits have exceptional tribological and corrosion resistance properties, although not all formulations possess these properties.


Chromium plating is commonly used on high-strength steels and nickel alloys, and a Wood's nickel strike is often used to prepare the surface for plating. The chromium deposit exists in the alpha phase and is crystalline, with limited compounds or components and occlusion of hydrogen and carbon, which can lead to the development of internal deposit stress.


The low cathode current efficiency of the electrolyte used for chromium plating allows for greater tribological properties because of the presence of hydride and carbide compounds. However, these compounds can also develop intrinsic stress in the deposit and affect its deformation properties.


Despite its extensive applications and good properties, chromium plating poses significant environmental challenges due to the toxic nature of hexavalent chromium. As mentioned earlier, the US EPA and REACH have established regulations to limit its discharge into the environment, and the metal finishing industry has been working to develop more sustainable plating processes. It is essential to continue to monitor and regulate the use of chromium plating to minimize its impact on the environment and public health.


The original hexavalent chromium plating formula was developed by accident in the early 1900s and it comprised of chromium trioxide and sulfuric acid. The researcher who developed the formula initially assumed that chromium trioxide was a trivalent salt, but this was later corrected by another scientist.

Since then, alternative methods of hexavalent chromium plating have been developed to address environmental and health concerns. Trivalent chromium plating, cobalt alloy deposits, and electroless nickel deposits with phosphorus or boron alloys are some of the substitute methods that have been developed and continue to be researched.



In recent years, there has also been increased interest in high-temperature and room-temperature ionic liquids for depositing metals such as trivalent chromium, niobium, aluminum, and molybdenum. These alternative methods offer the potential for more sustainable and environmentally friendly plating processes. However, more research is needed to develop and optimize these methods for industrial use.


Yes, trivalent chromium plating is an alternative to hexavalent chromium plating and can produce similar decorative deposits. However, there can be variations in deposit characteristics, particularly on hard chromium applications where macrocracks can develop after baking.

Comparing the microstructure on transverse sections can be a useful practice in analyzing macrocracks.

Electroless nickel deposits with boron alloys can offer some tribological properties, but they may not offer comparable wear and corrosion resistance properties of hard hexavalent chromium plating. Similarly, while ionic liquid methods, particularly room temperature ionic liquid electrolysis, offer potential advantages, they are still emerging technologies and require further development.

Vapor deposition methods, including chemical vapor deposition (CVD), can also be used as alternatives to hexavalent chromium plating. CVD can be applied to several transition metals, including tantalum (Ta) and niobium (Nb). However, these methods may require specialized equipment and expertise.

Thermal spray coating is a versatile and diverse alternative to hexavalent chromium plating, with several methods available in the market, including oxyfuel wire (OFW) spray, electric arc wire (EAW) spray, oxyfuel powder (OFP) spray, plasma arc (PA) powder spray, and high velocity oxyfuel (HVOF) powder spray.

Thermal spray coating can offer a range of properties, including corrosion resistance, wear resistance, and thermal barrier properties, depending on the coating material and method used.


The choice of an alternative to hexavalent hard chromium plating process depends on various factors, such as the application demand, cost, and the required physical characteristics. Trivalent chromium plating, vapour deposition, and thermal spray methodologies are viable alternatives to consider. However, each method has its advantages and limitations, and the final decision must be based on the specific needs of the application.

Subscribe to this Blog Like on Facebook Tweet this! Share on LinkedIn

Students from USA, Middle East, and Asia had rated 100% satisfaction with Advint’s Online Industrial Electroplating Training course.

We feel good about the progress made in placing Advint’s online training as the best and unrivaled source in the global industry.

Go To Training Page


We write this paper to explain why this study is the most comprehensive and all-encompassing course in the market and why early career professionals, both novice and ardent, see value and rate highly.

  1. The course explains electrochemistry, processing, physical characterization, engineering, automation, methodology, and management.
  2. We use Adobe Illustrator graphics to explain electrolysis.
  3. Covers basic and advanced concepts.
  4. Written and instructed by practiced manufacturing professional with over thirty years of experience.
  5. We give access to students a 172-page E-book and present with over 350 pages of high-quality MS PowerPoint slides.
  6. We used one word instead of two for succinct communication, where possible.
  7. The course is interactive and engaging, and not limited by time.
  8. It is not driven by revenue, but value.

We offer custom training courses to aerospace and automotive operating staff on an as need basis.


Click the PDF link to refer to recent endorsements, and breakdown of students by region and qualification.




Our course content drives the growth. The value we offer and the students’ recognition makes us improve the content and presentation at every opportunity. It will be an amiss, if we don’t mention about our plating training participants. Advint is fortunate to have the most dedicated people attend the course with an intent of making a difference. We owe high approval rate to them!


Of course, higher satisfaction increases our responsibility. The responsibility to make the next cohort of students experience better. We commit Advint to do just that!


Behind the scenes, work is in progress to offer new cohort of student’s latest digital technology experience.

Overall, Advint’s Online Industrial Electroplating Training course is on the path to become the premium source of education in the global industry.


add a comment
Subscribe to this Blog Like on Facebook Tweet this! Share on LinkedIn

The metal finishing industry plates hard and decorative hexavalent chromium processes from 1920s. It is an acknowledged industry standard and preferred choice because of its exceptional physical characteristics. US Environmental Protection Agency (EPA) and Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) had listed chromium trioxide as a hazardous chemical because of its carcinogenic property.



Many aerospace components use hard chromium, the automotive sector primarily uses decorative and other sectors use both decorative and hard chromium plating deposits. A deposit thicker than 1.2 micron are functional (hard) and any lesser are decorative. The industry favors chromium because of its oxidation resistance properties. Among groups 4, 5, and 6 elements of periodic table we plate only chromium using an aqueous solution. Ionic liquids can deposit most of the transition elements. Aqueous hexavalent Cr deposit has exceptional tribological and corrosion resistance (not all formulations) properties. We plate the deposit on high strength steels and nickel alloys (with Wood’s nickel strike). This deposit exists in alpha phase, is crystalline and forms limited compounds or components with occlusion of hydrogen and carbon developing internal deposit stress (refer ASM Handbook for more information). The electrolytes’ low cathode current efficiency allows greater tribological properties. This is because the deposit has hydride and carbide compounds. These hydrides and carbides develop deposit intrinsic stress and effect deformation property of the deposit (Hooke’s law describes elastic properties of materials or deposit).


Extensive applications and good properties make environmental directions a challenge to meet. Before we get deeper, let us get a historical perspective.



Around 1910, a researcher accidentally developed the original hexavalent chromium plating formula comprising chromium trioxide and sulfuric acid. He assumed chromium trioxide was a trivalent salt until another scientist corrected the misinterpretation within two years.  



From that time substitute methods such as trivalent chromium plating, cobalt alloy deposits, electroless Ni deposits with P or B alloys were developed and are a focus of continuing research. High temperature and room temperature ionic liquids for deposits such as trivalent chromium, niobium, aluminum, molybdenum is in study.


Alternate Choices

Chromium Plating

Trivalent Chromium Plating

Decorative trivalent and hexavalent deposits have similar properties because of the thickness limit and electrolysis mechanisms of the respective electrolytes. Electrolysis mechanisms change as electrolysis progresses and the deposit characteristics vary with thickness. There are scientific papers on this phenomenon. On hard Cr applications major variation is on macro-cracks, which develops after baking. When analyzing macro-cracks, a seldom adhered to practice is to compare the microstructure on transverse sections. Refer to ASTM E3 – Microstructure and Properties for more information. A few applications use nickel undercoat to negate the effect of macro-cracks.


Other Electrolytic Methods

A few specialists recommend electroless Ni-P, electroless Co – P and electroless Co as substitutes to hexavalent hard chromium plating deposit. But the author of this paper doesn’t consider these as dependable alternatives. Only electroless Ni-B (mid boron) deposit possesses tribological properties, but it doesn’t offer comparable wear and corrosion resistance properties of hard hexavalent Cr plating deposit.


Ionic Liquid Methods

Room temperature ionic liquid electrolysis is an effective alternate. Aluminum deposit offers many unique advantages. However, it is still an emerging technology.


Vapour Deposition Methods

There are two types of vapour deposition methods – physical vapour deposition (PVD) and chemical vapour deposition (CVD). We can apply CVD on several transition metals. Of particular interest to this topic are CVD deposits of Ta and Nb.


Thermal Spray Coating

On economy, versatility and diversity of options, the thermal spray coating processes is the best alternate to hexavalent Cr plating method. There are five different methods available in the market – oxyfuel wire (OFW) spray, electric arc wire (EAW) spray, oxyfuel powder (OFP) spray, plasma arc (PA) powder spray, and high velocity oxyfuel (HVOF) powder spray. Refer to ASM Handbook Volume 18 for more information on this subject. However, on many applications the line-of-sight characteristic will limit the thermal spray method. There is continuous research in this field, and recently a few companies have taken the processes to a new level.



Bottom line, trivalent chromium plating, vapour deposition, and thermal spray methodologies are operative substitutes to hexavalent hard chromium plating process. Application demand, cost and the required physical characteristics determine the value of a specific method.


add a comment
Subscribe to this Blog Like on Facebook Tweet this! Share on LinkedIn

Acknowledgement of the influential in electroplating develops our learning of the fundamentals, and it improves our research.

There are thousands of contributors who served the electroplating industry and academia for over a century.

Who tops your list?

What did they do?

Why is it important?

What did we learn?

This short paper lists 8 innovators, two focused on electrochemistry and the rest on industrial plating (electrolytic, autocatalytic, ionic & aqueous). Their contributions enabled our understanding, improved our applications, and helped us to advance the technology.


Let us see who they are, when and what did they offer to the field and its benefits.


Michael Faraday

During 1832 Faraday published a paper relating the quantity of electricity with the amount of metal liberated at the electrodes resulting in two laws. When we think of electroplating, Faraday’s laws are probably the first to come to our mind. Mastering a process or shining at customer satisfaction does not end without due consideration of an electrolyte’s current efficiency and the feasibility of a deposit.


Walther Nernst

Nernst equation is the fundamental equation of electrochemistry and for the electrode processes. An ardent electroplating researcher shall begin and ensure a thorough understanding of Nernst equation and its concept. We can plate several transition metals, post transition metals, and metalloids. Some using aqueous electrolytes and room temperature ionic liquids, and most using high temperature ionic liquids. A modest approach to choose the electrolyte and the element for the deposition process is to comprehend Nernst equation and its concept. An interstitial or interatomic alloy electrodeposit choice is no exception to this subject.


Abner Brenner

Brenner conducted many studies on electroplating deposits. We conspicuously recognize for his preliminary contributions on electroless nickel plating invention around 1946. Though he got black non-adherent dendrites in the initial testing, his research allowed significant growth in electroless Ni-P and Ni-B deposition processes, and plating on plastics.


Richard Hull

Hull cell device is common in most electroplating laboratories. Most platers gain Hull cell testing skills or aspire to become good at it! Hull around 1930s invented a testing cell and derived a formula to calculate the effective current density of an electrolyte. Hull cell unit and its formula is quite easy to use! Is the design of the unit and its formula an ordinary achievement?


Oliver Watts

Professor Watts reported on 1931 his work on nickel plating bath comprising nickel sulfate, nickel chloride and boric acid at a higher temperature. Many used nickel-plating electrolyte using the same inorganic constituents at room temperature or at 120ºF. Watts was the first to report the benefits of thick and uniform deposit at 145ºF and 160ºF. Since then we began calling this electrolyte a Watts nickel plating solution.


Donald Wood

Wood was an expert in cyanide silver plating, and that is what he did for most of his career. We know him for his invention of chloride-based nickel strike bath during early 1940s. The Wood’s nickel strike formulation enabled the global industry to plate on all ferrous, nickel, titanium and aluminum alloys.


Donald Cook

Even if you are well read in the industry, you might not have heard about Dr. Donald Cook! Cook coined the term ‘metaliding’. Metal finishing industry did not see the effects of his research. But if I didn’t mention his name with others, it would be amiss as he is alike Nernst and Brenner. No one would have worked on more transition elements and diffused into others than him! His knowledge in electrochemistry and chemistry of halides was impeccable, and he distinguished the ins and outs of transition metals of group 3 to 11 of the periodic table. But his only focus was in high temperature ionic liquids.


Seymour Senderoff

We know Dr. Senderoff for his invention of spiral contractometer used in hard hexavalent chromium and nickel sulfamate plating applications to detect internal stress in the deposit. He worked for Dr. Brenner for several years and later focused on high temperature ionic liquid tantalum plating. It was my source of pride to continue on his research and improvise his formulation.


electroplating leaders


So, what is the learning?

Recognizing these pioneers and their work must transcend awareness and dwell on a deeper understanding of their explanations and research outputs.

Faraday and Nernst focussed on the fundamental of electrochemistry. Cook and Senderoff concentrated mostly on high temperature ionic liquid electrolysis (plating and diffusion). Brenner, Hull, Watts and Wood dedicated their research on commercial electrolysis. Nevertheless, all played a revolutionary role in electroplating applications.


Here are the examples of teachings from a few of these pioneers’ work:

Nernst’s invention allowed us to relate electrode potential, valency of the metal ion and current. Hull’s work brought to light Tafel’s, Butler’s and Volmer’s work. Wood’s invention signified electromotive force (emf) series and distinguished strike, flash plating, and plating. Cook’s and Senderoff’s developments emphasized the importance of eutectic temperature, phase diagram, liquidus temperature of salts, fluxing effect and ionic conductivity of electrolytes.


Hope you find this paper valuable and you dig deeper on these matters!

Post your comments and write about who tops your list.


add a comment
Subscribe to this Blog Like on Facebook Tweet this! Share on LinkedIn

A recently published paper by a senior staff on a leading American magazine was unclear about the electroplating terms, like covering and throwing powers. Many times, we see vague interpretation and wrong distinction on these terms.


Advint’s online electroplating training and E-book offers right definition, explanation of identical terms and concepts. So, I’ll abstain from offering an elucidation here and write on the effects and recommendations.


The supplementary purpose of this paper is to emphasize the importance of correct interpretation of underlying electrolysis mechanism, terms, concepts of electrochemistry and electroplating fundamentals.


The confusion on these terms occurs when one draws a literary meaning on these words, reads leading technical magazines and science journals, and listens to veterans in this field.


Dr. Samuel Glasstone’s An Introduction to Electrochemistry delivers the clearest definition of throwing power of an electrodeposition process.

To correctly understand the terms, deeply observe acid chloride zinc or Watts nickel plating and cyanide copper or cyanide silver plating processes. Careful analysis of these electrolytes using a Hull cell will make clearness of these terms.


Handbooks and electroplating books frequently cannot document and analyze all developments, and now and then it misconstrues the depth of progress in the metal finishing field.


Confidentiality and hidden knowledge within the industry is the reason for such limitations. This limits awareness of all electrolyte properties and their formulations options with benefits. Many large organization’s operating procedures and practices also deter the best ability of a process.

We recommend you to question, test and re-consider critical attributes and formulations, including the references of Advint’s e-book guide to get a model electroplating routine.


Why is it imperative to comprehend properly?

Choosing a suitable electrolyte and maintaining the concentration of anions and organics will enable us to:

  1. improve product quality
  2. improve deposition thickness with due consideration for product geometry
  3. meet functional and customer criterions
  4. improve process control
  5. reduce cost associated with rework and under or over thicknesses
  6. minimize or eliminate problem solving time
  7. correctly comprehend fundamental electrolysis mechanisms

How can you learn the correct terms?

Advint’s virtual course E-book syllabus covers relevant electroplating terms and concepts.

We recommend referring authentic resources, test yourself by analyzing electrolysis and deposition mechanisms on various electrolyte formulations and metal deposits.


To the Point

In this short paper, we discussed why right construal of a plating term is important. We reviewed how to access the pertinent information and the reasons for confusions. A diligent comprehension of the terms will help advance the metal finishing capability to what it’s worth.


add a comment
Subscribe to this Blog Like on Facebook Tweet this! Share on LinkedIn

Managing time with a data-driven approach offers incredible value in process management and customer service on electroplating and anodizing applications. Analytical data, awareness of chemicals and deposit properties with a historical context add value to engineers and aspiring scientists in the metal finishing field.


Spot and quick tests offer incredible insights for the metal finishing processes. What is a spot test? Are these tests reliable?


High temperature oxidation resistance is a valuable elemental and deposit property. What does it mean? Which elements possess this property? We will review the value of this physical property.


Surface and metal finishing offer a variety of options such as plating, anodizing, coloring of metals and electropolishing. Plating on several substrates such as plastic, steel, stainless steel, Invar, Kovar, nickel, aluminum, and titanium alloys are common. Elements like gold, silver, nickel, chromium, zinc and cadmium are plated. We choose the deposit based on consideration for cost, corrosion resistance and tribology properties.


Other than plating, we can electropolish and anodize metals such as stainless alloys. Applicators anodize on aluminum, magnesium, titanium, niobium, tantalum, etc.


Anodising is an electrolytic process in which we make an Al alloy anodic with a metal cathode on an acidic electrolyte. There are three classes of coating. We anodize with and without sealing.


This short paper explains which element to choose as deposit or substrate. It lists spot and quick tests available in the market. Review brightener chemistry and history. Discuss inhibitors, chemicals used for coloring metals and chromium conversion coatings.


Spot Tests

Several wet and instrumental analyses methods are used to conduct qualitative and quantitative analysis of elements. The advantage of these methods are accuracy and data reliability. But these test methods are time consuming and some are expensive. When you need a quick feedback, consider conducting spot tests on deposits and effluents. The sensitivity of spot test reaction can be at ppm levels. Elements such as aluminum, stannous tin, gold, silver, iron, nickel, palladium, lead, zinc, cadmium, chromium and copper can be tested. Many of these tests can take less than 5 minutes.

We can detect heavy metals, hexavalent ions and cyanide content in the effluent. You can distinguish between cadmium or zinc plating deposits using spot tests.


Here is a list of some organic chemicals used for spot tests:

Diphenyl carbazone

Dimethyl glyoxime

Tri-ammonium aurine-tricarboxylate

Nitro-bruciquinone hydrate

p-Dimethylamino benzylidene rhodamine

diphenyl thiocarbozone


(1-2-Hydroxy-5-sulpho-phenyl)-3 phenyl-5-(2-carboxy-phenyl)-formzan) sodium salt


Refer to Chem Spider for further information on any chemicals.


For further information on spot tests, read the book - Analysis of Metal Finishing Effluents and Effluent Treatment Solutions. This is a book written by Duncan MacArthur, Fred Stevens, and G. W. Fischer.



Did you know tobacco and licorice were one of the earlier brighteners used? Several decades ago, or even a century back, the use of brighteners or additives were very limited. Even the awareness of organic brightener science did not exit. Like many inventions, use of organic chemicals as a brightener was an accident. Tobacco was one of earlier recorded chemical used as additive. More than a century ago a plating operator who had the habit of chewing tobacco drooled the juice onto a plating solution during electroplating. Later noticed that a plated lot had a brighter appearance. Further investigation revealed the brightness influence of tobacco on plating deposit.

People used licorice during earlier days. It had a presence in the industry for some time and even now to an extent. Licorice extract is a carbohydrate and its chemical name is glycyrrhizin. They used it as an additive.


The additive was prepared by weighing a known quantity of licorice root and steep in a boiling water until colour saturation occurred. For 100 L plating solution, 100 grams of root was steeped in 0.5 L of boiling water.

Pickling and acid activation are a very common process at a steel mill, metal foundry, and a metal finishing processing plant. Conditional on activation and deposition bonding requirements, a substrate such as copper alloys or steel alloys would require activation under strongly acidic conditions. Use of strong acids such as hydrochloric acid, sulfuric acid and hydrofluoric acid can etch the substrates.


We commonly use sodium fluoride as an inhibitor. On picking applications, industry used antimony trioxide as an inhibitor.


Copper alloys such as brass tarnish in the presence of oxygen from atmosphere. Brass plated deposit do the same. An organic coating can prevent tarnish. Benzotriazole coating forms a thin layer in an immersion process, and the layer protects copper alloys from tarnish.


Brass plating is an alloy deposition process. The electromotive force potential of copper and zinc makes cyanide brass plating one of the most complex electrolytic processes. Attainment of a consistent and durable colour is tricky. Proper use of current density with an excellent choice of rectifier (IGBT or SCR) with an organic coating ensures great cosmetic appeal with durability.

We can also colour brass. One such colour is blue. An immersion process at high temperature in the presence of sodium sulphite and lead acetate colours brass substrates. Other than brass, we can colour stainless steel alloys using dichromate salts.


Yellow chromate on zinc deposit is one of the popular choices. We recognize the yellow chromate for brilliance of colour and corrosion protection. There is a subtle colour difference different between hexavalent and trivalent chromates. Chromates sometimes leaves iridescent finish. A protective coating similar to benzotriazole layer reduces iridescent streaks.  One can get a reddish tone on the yellow chromate formulation. Use of a sulfate ions and nitric acid offers a reddish yellow chromate finish.


Occasionally people refer to chromate or chromium plating as chroming. Chroming is a colloquial speech term and we prefer you avoid using informal terms to avoid confusion and for use of clear language communication. Hexavalent Cr and (cyanide) cadmium is listed by Registration Evaluation Authorization and Restriction of Chemicals (REACH). We now replace cadmium plating with zinc / nickel alloy. Sacrificial protection of cadmium under saline conditions are inimitable.


Deposit Properties

Observing electromotive force series of elements and their potentials (negative or positive / active or noble) suggests evidences on fascinating deposit, material or electrolyte properties. We are referring to properties such as high temperature oxidation resistance and conductivity.

Pilling and Bedworth conducted a seminal work on high temperature oxidation.

Chromium, tantalum, zirconium and gold possess exceptional high temperature oxidation resistance properties. What is high temperature oxidation resistance?

The volume of oxide is greater or lesser than the parent metal, it produces or cannot produce an effective protective property.

What does a reference to protective property mean? It refers to the formation of an oxide layer, such as tantalum oxide, chromium oxide and zirconium oxide on the metal or the deposit. The refractory metals offer oxidation resistance up to ~ 600ºF. Oxidation and healing property are the principal reason hexavalent hard chromium plated components had gained wide popularity. Many applications of aerospace and automotive industries require components to posses tribological properties at a higher temperature. Wear, lubrication, and friction are such examples. The oxides can re-form and withstand high temperatures during these mechanical transformations. Tantalum, zirconium, niobium, and chromium metals are a few among the best to possess such a property. Other than oxidation properties, these elements are susceptible to corrosion resistance from acids, alkalis, organic media and other reagents. We measure high temperature oxidation in ratio and Pilling - Bedworth (PB) ratio of corrosion resistant metals range between 0 and 4. Higher the number better the corrosion resistance. PB ratio is the ratio of the metal oxide volume divided by the metal volume. Chromium PB ratio is 2. All chromium electroplating deposits do not have the same corrosion resistance properties. Corrosion resistance of decorative Cr plating is because of nickel undercoat. Most hard chromium deposit do not have any corrosion resistance. However, a few formulations containing fluoride ions in the electrolyte possess high corrosion resistance. Some hard-hexavalent Cr deposits pass 500 hours of neutral salt spray test (NSST). We mainly attribute the variations to formulation, processing, and process control.


Other than refractory metals, precious metals such as gold plating deposit possess high temperature oxidation resistance. Industry uses gold plated components on space applications because of high temperature oxidation resistance, conductivity, high surface stability, high resistance to tarnish, and chemical corrosion. Both trivalent and monovalent salts are used to deposit gold from electrolytes. Precious metals like gold, silver and palladium can be plated on several substrates such as stainless steel, Kovar, Inconel, magnesium, aluminum and titanium alloys efficaciously.


Besides lightweight, the stubborn oxide layer makes aluminum and titanium alloys indispensable in our daily lives.


Previous paragraph mentioned about the conductivity of deposit. What about electrolyte conductivity? Change of ion activities with concentration affects electrolyte conductivity. Understanding interionic attraction theory of electrolytes are essential to improve conductivity.



Whether you are an engineer or a research scientist, understanding element and deposit properties, electrolyte capabilities and limitations, and vitality of unique chemicals are important. A process design engineer with a good understanding on these characteristics can design products with superior corrosion and tribological properties. The matters covered in this paper such as high temperature oxidation resistance can help a designer identify suitable metal as substrate and a deposit.


We identify some chemicals listed in this paper as hazardous or carcinogen per Registration Evaluation Authorization and Restriction of Chemicals (REACH). REACH is a European Union regulation. You can also find additional information on carcinogens by visiting the website of National Institute of Environmental Health Sciences (NIEHS) under the National Toxicology Program (NTP). Observing regulatory compliance and identifying risk mitigation plan will drive an organization’s governance.


REACH, quality demand, and customer requirement will call for a transformed focus on a few facets such as colouring of metals, plating solution additives, chromium conversion coating and anodizing. An ardent electroplating specialist must consider all the services, test methods and fundamental concepts.  

A leader must prepare electroplating companies to manage complex processes. An agile metal finishing organization aiming to survive even under adverse conditions shall be data driven, ensure speed of business is appreciable, work faster, and inculcate easy-to-use test methods. We know many that plating companies who are not data driven do not grow or adapt to developing changes.


Spot testing of effluent, electrolyte or deposit is an under used method, and will help gather data with speed and ease. Other quick tests like pH measurement, specific gravity, litmus, refractometer, and profilometer are all easy and inexpensive. This do not mean volumetric and instrumental analysis offer less value. Both methods are vital for many electroplating operations. The choice depends on their technical ability, product testing requirements and financial capability. The examples of these instruments are atomic absorption spectroscopy, scanning electron microscopy, induced couple plasma (ICP), x-ray diffraction, x-ray fluorescence and electron microprobe analysis. We use these units for elemental analysis at lower concentration with a top-level accuracy. XRD and EPMA can detect light elements such as lithium, oxygen and carbon with an outstanding repeatability and reproducibility.  

We deliberated chemicals, methods, properties, and data driven approach. Cognizance of these matters without a long-term analysis and reaction plan is not noteworthy!  Consider use of run chart, control chart and Process Development and Control (PDC) tools with a visual dashboard.

Readers can find a value on other short papers written on this page previously. Please read articles on electrode potential, IGBT and SCR power supplies, current distribution, throwing power, periodic table, Time Change Management (TCM), Process Development & Control (PDC) tools, and communication. A complex electrolysis process requires a multidimensional approach on disciplines such as science, mathematics, technology and management. There are many vital aspects involved in this field such as automation, process control, business development methodologies, and so on. Fundamentals, laws, equations, and concepts govern electrolysis. Though not needed on a day-to-day basis, these are important to be aware and apply. Discipline, observation, data, patterns, and behaviors are critical for one to succeed at a higher level. Though there will be a scientific explanation for all outputs, one needs to treat the work as art! This is imperative because of our limitations – time and knowledge. Hence, at Advint we offer on guidance on subjects related to laboratory practices, equipment engineering, automation, productivity, lean, statistical process control (SPC) tools, and management. Advint’s virtual Electroplating Training explains all these subjects comprehensively. 


view all comments (2) add a comment
Subscribe to this Blog Like on Facebook Tweet this! Share on LinkedIn

Formulating cleaners such as alkaline soak cleaner and electro cleaner are imperative, though not as significant and lucrative as formulating plating baths containing primary and secondary brightener systems.

Unlike quite a few decades ago, current cleaner formulations contain methodically investigated inorganic and organic ingredients which are effective and comply with the environmental regulations. 

Different sectors and industries use solvent, alkaline soak and electro cleaners uniquely. Does the industrial practice catch up with scientific advancement? Good formulations are available! Did the market seize the opportunity? 

This blog highlights the value of a good cleaner, identifies a simple step in choosing a cleaner, and list a few potential ingredients and their properties. 

A carefully chosen cleaner can remove organic residues from the substrate thoroughly. Decrease the cleaning time and (or) improve cleanliness. Cut cost by increasing the cleaner life and minimize environmental impact.


Go over a material safety data sheet (MSDS) to select a cleaner, however, a proprietary chemical supplier could throw a curve ball. Section 2 of an MSDS must contain hazardous ingredient listed with Chemical Abstracts Service (CAS) registry number and the concentration. The reader can find specific CAS related information on this link. 


formulating electroplating cleaners


Before considering the inorganic and organic ingredients, process owner must know their processes and supply chain well. Knowing and considering the substrate(s) and their corrosion properties in most cases are explicit. Sometimes information is hidden and implicit on aspects such as oils, lubricants, and kinds of paraffin used. Application time, heat treatment (if applicable) and their intricate factors on some instances might not be clear. Source and purity of water, properties such as temporary and permanent hardness are vital for the makeup of cleaner solution and rinsing.

Alkalinity, buffer, water softening, chelation, and surface tension are a few important solution properties to observe. The process owner should assess the presence and concentrations of sodium hydroxide, carbonate, phosphate, silicate, amines, and surfactants and relate to the application (s). A surfactant can be anionic, non-ionic and (or) amphoteric. It changes the surface tension and wettability of the solution.


Briefly put, irrespective of reasons and justifications, focussing on cleaners and improving the cleaning performance is worth the effort and not a hard nut to crack using the listed suggestions. 

add a comment
Subscribe to this Blog Like on Facebook Tweet this! Share on LinkedIn


Venkat Raja
July 22, 2024
show Venkat's posts
Charles G Graham
July 7, 2024
show Charles G's posts

Latest Posts

Show All Recent Posts



Everything Electroplating Quality Cleaner Communications Electroless plating Periodic table Rectifier High Temperature Oxidation Spot Tests Aluminum Anodizing Filtration fundamentals Hydrogen Embrittlement