The Chemical Connection

June 24, 2025

The Chemical Connection: Through-glass Vias in Glass Substrates

This month’s theme is vias and how best to ensure via quality and reliability. I don’t have much expertise in this process area or much to contribute that most of you don’t already know. However, I’ve recently become peripherally involved in a via technology that may be of more than academic interest to some of us. It entails putting vias in a material not usually associated with PCB manufacturing: through-glass vias (TGVs) in glass substrates.

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June 04, 2025

The Chemical Connection: Reducing Defects in Circuit Board Production

We all agree that in any manufacturing process, reducing defects in your product induced during manufacture (aka increasing yields) is a good thing. Doing so, however, can be a source of contention and frustration. I don’t pretend to be an expert in this field, because most of my work involves feasibility studies for new concepts or testing improvements made to existing equipment. High yields were usually not a factor; it’s simply about having enough data to prove or disprove a concept or seeing whether improvements to equipment design actually work. However, here are some observations I made visiting quality shops where high production at high yields was important.

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April 28, 2025

The Chemical Connection: Common Misconceptions in Wet Processing

Initially, I thought an April Fool’s column would be fun this month. I could highlight some of the crazier ideas and misconceptions I’ve witnessed over the years from potential customers and we could all have a good laugh. For example, there was a first-time buyer of a ferric chloride etcher (with no regeneration system) who was astonished to learn that he had to put fresh etchant in the system occasionally to maintain production.

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March 31, 2025

The Chemical Connection: Surface Finishes for PCBs

Writing about surface finishes brings a feeling of nostalgia. You see, one of my first jobs in the industry was providing technical support for surface cleaning processes and finishes to enhance dry film adhesion to copper surfaces. I’d like to take this opportunity to revisit the basics, indulge in my nostalgia, and perhaps provide some insight into why we do things the way we do them in the here and now.

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February 25, 2025

The Chemical Connection: Earthquakes, Astronauts, and Aquatics—A Lighter Look at the Past

IPC will host its 25th IPC APEX EXPO with the theme “Reimage the Possibilities,” in Anaheim, California, next month. It will also mark the 68th anniversary of IPC’s founding. This year’s event brings up many memories of IPC APEX EXPO’s past and former National Electronics Packaging Conferences (NEPCONs). In this column, I would like to share some of the lighter moments from my almost 50 years of exposition experiences—especially those in Anaheim.

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January 23, 2025

The Chemical Connection: Better Fabs Attract a Better Workforce

Workforce problems are almost as great an issue in PCB manufacturing today as the product quality and reliability of the increasingly complex circuit boards now in demand. I believe they are directly related. A quality workforce makes it easier to produce a quality product. Unfortunately, as an industry, we have not done a good job of attracting quality young people for today’s production requirements.

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January 13, 2025

The Chemical Connection: Can Changing Spray Nozzles Improve My Etch Quality?

Whenever the need to improve etch quality due to tightening customer specifications arises, the inevitable question asked early on is, “Will going to a different type of nozzle or nozzle flow rate make my etch quality better?” Unfortunately, the answer is most likely, “Probably not.” (Sorry, folks.) So, why not?

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December 04, 2024

The Chemical Connection: Getting the Best from Your Cupric Chloride Etchant

Over the past several months, we have received a lot of questions from our customers about cupric chloride etching—mostly about how to improve etch quality, but also about process problems. Most of them were easily dealt with, but the questions arose because the people involved in running the etching process were not aware of the finer nuances involved in using cupric chloride as the primary etchant. (They don’t have courses on etching in most colleges and trade schools.) I thought this might be a good time to summarize some things I have learned in my 50 years of experience with cupric chloride etching and clear up some of the confusion.

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October 29, 2024

The Chemical Connection: Troubleshooting PCB Process Problems

As a supplier of PCB wet processing equipment, we inevitably find ourselves involved in helping customers solve sudden process problems that may or may not be caused by equipment malfunctions. For the most part, equipment problems are relatively easy to identify and repair: sensors for chemistry and equipment control, clogged nozzles and filters, leaks in the plumbing, etc. But what happens when the equipment checks out and the problem is still there?

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October 07, 2024

The Chemical Connection: How We Deal With a Technology Roadmap

Ideally, we would all be aware of what future technology demands will be, at least for the near future, and take steps to be prepared to meet those demands. For most of us, however, while we may be aware of what’s coming in terms of production requirements, we usually don’t do much to get ready for them until we’re forced to by the market. We generally don’t have the time or personnel to spend on detailed planning or money to purchase any new equipment before it’s needed. So, how do most of us deal with it?

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August 27, 2024

The Chemical Connection: Chemical and Equipment Control of High-density Circuits, Part 2

In my June column, I discussed how much control was needed for high-density circuits rather than what was thought necessary. I concentrated on cupric chloride and alkaline etch issues and equipment, since the etching step in the circuit board manufacturing process is one of the most critical areas where small changes in etchant parameters can have a large effect on the final product. The intention was to continue in the July issue with less critical process steps, such as developing and stripping. However, I got distracted by a specific control issue for alkaline etch, specifically controlling your alkaline etch process when you’re not etching a lot of copper. So, this month, I’m picking up where I left off in June.

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August 07, 2024

The Chemical Connection: Controlling an Alkaline Etch Bath With Low Copper Loading

This month, I wanted to continue my discussion on how much process control is actually needed for high-density circuit production. However, in the last month, I have been called on to help with a specific process control problem: how to control an alkaline etch bath when you’re not etching much copper. This problem has been cropping up more frequently as smaller shops (and a few larger ones) concentrate on low-volume, high-value plated through-hole panels such as prototypes, resistor cores, etc.

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July 02, 2024

The Chemical Connection: Chemical and Equipment Control of High-density Circuits

As line and space requirements and specifications get increasingly tighter, it is obvious that at some point you must consider tightening the controls on the chemical and equipment parameters (temperature, specific gravity, conveyor speed, etc.) of your production lines to meet those requirements. For the purposes of this discussion let’s consider line and space requirements of 75 µm (0.003") or less with tolerances of ±5% as the tipping point for serious consideration of tighter chemistry and equipment control.

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June 03, 2024

The Chemical Connection: Can the Limits of Subtractive Etching Be Extended?

Subtractive etching has been the technology of choice since the era of PCBs began in the mid-1950s. I can remember TV ads for one manufacturer that claimed their TV sets were of much higher quality claiming, “We use wires to make the connections for our television sets, not cheap printed circuit boards.” Imagine that.

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May 02, 2024

The Chemical Connection: Reducing Etch System Water Usage, Part 2

In my last column, I reviewed some relatively simple ways to reduce water usage in existing etch systems: cutting down cooling coil water flow, adding chillers to replace plant water for cooling, lowering flow rate nozzles for rinses, etc. This month, I’ll continue with more ways to control water usage in your etcher. Most of these are not easily retrofittable to existing equipment but should be given serious consideration when new equipment is contemplated. With the right combination of add-ons, it is possible to bring the amount of water used in an etch system to almost zero.

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April 05, 2024

The Chemical Connection: Reducing Etch System Water Usage, Part 1

Water conservation has become an important component of the overall system design for most manufacturing operations today. Changing climate conditions and increasing populations are beginning to strain the freshwater supplies in many areas of the country. As a result, as equipment suppliers, we see an increasing number of requests for options that reduce water usage in proposed wet processing systems. Etching systems tend to use more water because of the need for close temperature control to maintain steady etch rates and the rinsing requirements for complete removal of corrosive etchants from the surface of the product before the next process step. This column contains some simple suggestions for reducing water usage in etch systems that won’t strain the budget too much.

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February 28, 2024

The Chemical Connection: An Exhibitor’s View of IPC APEX EXPO

When I learned that this issue would be dedicated to optimizing the bare board fabricator’s experience at the IPC APEX EXPO 2024, I thought it would be an easy column to write. With more than 40 of these shows under my belt, I didn’t think it would be too difficult to come up with a list of dos and don’ts to make your visit to an exhibitor’s booth worthwhile. So, what can you do to make your visit even more useful?

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February 16, 2024

The Chemical Connection: Getting to Know Your Vendor

After working for a capital equipment supplier for almost 50 years, I’ve found that the most important part of getting to know your vendor is good communication among all parties. While contact between fabricators of a constantly changing product line and the designers of those products may occur daily or weekly, conversations between you and your equipment supplier may be years apart. That lengthy gap often means that previous contacts may have been promoted, retired, or moved on to other opportunities. You may have also migrated to a new supplier with whom you have little or no history. In either case, you will be interacting with someone you are unfamiliar with (as they are with you). Therefore, it is essential for both sides to communicate clearly so expectations will align.

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December 28, 2023

The Chemical Connection: The High Cost of Etcher Non-maintenance

We all understand that day-to-day maintenance and long-term preventive maintenance of etching equipment is a good thing. However, the pressing need to get product out the door in the face of tough production schedules can sometimes cause us to delay necessary maintenance for long periods of time. In some cases, we become fixated on short-term production and forget about long-term stability.

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September 25, 2023

The Chemical Connection: Don’t Just Blame the Etcher

If your HDI or UHDI production process is quality challenged, don’t assume your etcher is to blame. Many factors impact the quality of the final product, so assess broadly, and you may find that the “the devil is in the details.” Generally, the first place most people can get good product specification measurement is at the end of the etching process, It’s natural and easy to blame quality shortcomings on the etcher. By all means, look at your etcher and invest some time trying to improve its performance but don’t stop there. Other factors may be affecting the etch uniformity.

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July 12, 2023

The Chemical Connection: Solutions for Better Etch Uniformity

In my very first column, “Etch Uniformity and The Puddle Problem,” I wrote about a phenomenon in the PCB etching process called the “puddle effect,” which causes large PCB panels to have varying etch quality across the board, typically on the top side. This variation exists because as you are spraying etchant onto the top of a panel, you begin to accumulate spent etchant. It creates a layer that inhibits the fresh etchant from reaching the board’s copper surface that needs to be etched.

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June 12, 2023

The Chemical Connection: The Challenges of Thin Material Transport

In wet processing, the transport of thin materials and substrates (less than 1 mil in thickness) can be a rather tricky process. These materials are vital in manufacturing flexible circuits, but often this flexibility adds new challenges. Most of these materials are easily damaged, and in some cases require well-trained personnel to handle them. You would think that this could be easily remedied with conveyorized equipment, but it is not entirely the case. Transporting thin materials through a conveyor aids the process to a degree, but once you get to the wet-processing stages—cleaning, developing, etching, and stripping—there are risks for error if you do not have the right tools or equipment.

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May 10, 2023

The Chemical Connection: Engaging the Next Generation

If you work for a company that employs people of a younger generation, you may have a lot of questions. Many people tell me that there is often a major disconnect between the young workforce, comprising Millennials and Gen Zers, and the established workforce made up of Baby Boomers and Gen Xers. If you are among the more seasoned crowd, it may be useful to gain some insights into the perspective of younger generations. The better you understand how they think and what they need, the more likely you can keep them happy in their jobs.

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April 13, 2023

The Chemical Connection: Chemical Control for Wet Processes

As I’ve mentioned in previous columns, etching can be the most complex process in the wet processing stages because there are many factors that contribute to your etch rate. Without keeping these contributing factors steady, your etch rate will vary and, therefore, so will your product quality. If you are looking to implement an automated approach to maintaining your etch chemistry, here are the basic concepts you will need to understand.

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March 13, 2023

The Chemical Connection: Wet Process Start-up Considerations

Are you considering starting your own PCB fabrication process? Do you have a solid game plan? If you are new to managing a PCB shop, the first thing to know is that wet processing is essential in making PCBs. Wet processing steps, such as cleaning, developing, etching, and stripping, are among the many steps in the PCB fabrication process that require thorough planning. When you are just starting to get involved in this industry, keeping track of all this can feel overwhelming. Here are a few considerations and base essentials to aid you in starting up the wet processes for your new facility.

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February 13, 2023

The Chemical Connection: The Subtractive Vision

The November issue of PCB007 included a fair amount of discussion on the growing need for ultra-high density interconnects (UHDI). UHDI is an area replete with manufacturing challenges due not only to the feature sizes this technology requires (< 50 micron or < 2 mils), but also the lack of familiarity U.S. manufacturers have with this technology. In an interview with Calumet’s Todd Brassard and Meredith LaBeau, they stated that the U.S. is roughly 30 years behind the curve in manufacturing UHDI, which is likely the result of companies offshoring UHDI manufacturing for many years. How can we catch back up?

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January 11, 2023

The Chemical Connection: Basics of Cupric Chloride Etchant

Cupric chloride (CuCl2) is an etchant that has capabilities that make it a great application in PCB manufacturing. Maintaining CuCl2 is relatively forgiving in comparison to alkaline etchant because there are only a handful of parameters you need to monitor. If CuCl2 seems like it would be an appealing etchant to use for your PCB etch process, here are some basic parameters that are key to understanding how to maintain it.

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December 06, 2022

The Chemical Connection: Cupric Chloride Regeneration Options

Cupric chloride (CuCl2), if you recall my column “Etchants of the Industry: Cupric vs. Alkaline,” is the second most used etchant in PCB etching next to alkaline etchant. It holds many benefits such as simple maintenance, easy wastewater treatment, reduced cost of etching, and efficient regeneration. Many times, I have discussed how critical it is to implement regeneration because it allows you to maintain a consistent etch quality and reduces the cost of etching. What makes cupric’s etch regeneration simple is that it is a matter of what you choose to use.

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November 11, 2022

The Chemical Connection: Closing the Innovation Gap

In Nolan Johnson’s September 2022 column, “New Era Manufacturing,” he referred to the carriage whip manufacturing businesses that met their fate by failing to adapt while other carriage businesses with more robust product applications remained standing. He said this relates to our industry in the sense that the needs of our world are evolving, that the wants and needs of PCB fabricators and their customers are bound to change. There will always be a demand for PCBs, since it is the foundation of modern technology, but market challenges are inevitable. PCB fabricators are dealing with increasing material and labor costs, all while major quick-turn-around jobs are declining. The questions we must ask are: Where do we go from here? How can PCB fabricators overcome these challenges and get an edge in the market? How can we best adapt?

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October 12, 2022

The Chemical Connection: How to Automate Your Wet Processes

Considering automating your PCB fabrication line? If you are, then you may have concerns about what it takes to implement new automation technology. The good news is that setting up your processing lines for automation is simpler than you may think. Whether you are obtaining new equipment, or you want to automate a machine that you’ve been working with for years, automating it can be as simple as tightening a few bolts and wiring a couple connections. Automating your process lines are now easier than ever thanks to low-cost, user configurable robot arms. Since most of the processes from beginning to the end of PCB manufacturing are already automated (at least in wet processing), the only areas left open for automation are the loading and unloading sections.

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September 08, 2022

The Chemical Connection: The Etch Factor

One of the biggest obstacles that PCB manufacturers face is etch factor. Etch factor is the ratio of downward etch to sideways etch. Etch factor poses challenges to PCB fabricators because it limits PCB design. It can determine how fine of a line you can etch, and it can even affect how close together you can have features. For instance, if you wanted to use cupric chloride (etch factor of 3:1) to etch a fine line (3 mils or less), you might not be capable of doing that with panels of thicker copper layers. If you try to do that, you will likely receive inconsistent results throughout your panels. Inconsistencies will arise because there is a point where the sideways etch will affect metal underneath the photoresist and etch it away.

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August 17, 2022

The Chemical Connection: Don't Sludge-Out—A Guide for Alkaline Etching

In my last column, I compared cupric chloride and alkaline cupric chloride, mentioning that alkaline etchant is the most used etchant for PCB fabrication. It is used because it provides a high etch rate, improved etch factor, and compatibility with metallic resists. Although it has some great benefits, it has the drawback of being difficult to control. The etching chemistry requires a delicate balance, and the parameters it needs to stay within are relatively tight. Not only are the margins for error small, but falling outside these parameters may have consequences.

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July 16, 2022

The Chemical Connection: Etchants of the Industry—Cupric vs. Alkaline

Chemical etching is a vital process for manufacturing PCBs. It is one of the most complex chemical processes next to plating. This is because there are many different variables that can affect your product and how efficiently it is produced. Although it is complex, etching of copper can be narrowed down to a handful of etchants that PCB manufacturers widely use. By far, the most common etchants are cupric chloride and alkaline cupric chloride, commonly referred to as “ammoniacal alkaline etchant.” There are other etchants for copper, such as ferric chloride, sodium persulfate, and alkaline ammonia sulfate, but they are not commonly used for PCB manufacturing and are often only used in “special cases.” I may touch on those other etchants a bit more in a future column, but this one will focus on cupric and alkaline.

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June 06, 2022

The Chemical Connection: How Industry 4.0 Shapes PCB Wet Processes

Earlier this year, I had the opportunity to attend IPC EXPO 2022 where I was able to network with many great people in the electronics industry and see how other businesses are connected to the work we do at Chemcut. Although that might have been my main takeaway, there was another trend that I couldn’t ignore: the fourth generation of the industrial revolution is alive and well in the industry. After being shown the many different technologies that can be leveraged to boost automation, I couldn’t help but consider how they may impact the wet processing side of PCB manufacturing. I also wonder about other forms of automation we may soon see and what those developments could mean for the industry.

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May 04, 2022

The Chemical Connection: The Case for Preventive Maintenance

Preventive maintenance (PM) is a routine maintenance performed to ensure equipment runs efficiently and won’t experience problems anytime soon. This routine maintenance can become highly important when you are running a business that relies heavily on equipment for production. Printed circuit board (PCB) shops are no exception to this because their production is dependent on many different complex machines working together. Although PM is critical, a large portion of PCB shops don’t have a PM program. Far too often, manufacturers will wait until a machine starts experiencing problems before they act.

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March 14, 2022

The Chemical Connection: Etch Uniformity and the Puddle Problem

Printed circuit board manufacturers who utilize wet processes have always strived to receive a uniform etch across their panels. Although it is one of the most common matters these manufacturers tackle, it is perhaps the least understood. This is for a few reasons, one of them being that there doesn’t seem to be an agreed upon terminology within PCB manufacturing.

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