Interview—Ralph Hoeckle, ZESTRON— High Precision Cleaning

ZESTRON have been developing customized solutions for precision cleaning applications for more than 30 years. At SMT/HYBRID/PACKAGING, held last month in Nuremberg, Germany, editor-in-chief Trevor Galbraith had the pleasure of speaking with ZESTRON Europe’s managing director, Ralph Hoeckle about the state of the cleaning market today, ZESTRON’s technical centers and how they can help companies with their cleaning processes, conformal coating issues, and more.

Ralph Hoeckle, ZESTRON

With the increasing requirements for cleaning of power modules and electronics, how do you see the cleaning market today?
The European market is quite interesting. As ZESTRON has been lucky to be pretty much the first party in the cleaning industry over here, we have had the chance to really drive and develop the market. ZESTRON was a driving force in changing the market from solvent-based cleaning in the past to water-based solutions nowadays. In principal, I would say that the market is still very much driven by no-clean Who ever does not want to clean, does not do it, especially when cost restrictions are an issue. However, more and more people see the benefit of cleaning, specifically in the high-end field, and we see this tendency growing.

So it’s growing because of reliability requirements?
Exactly. It is reliability, quality & warranty requirements, especially in the automotive, EMS, medical and industrial business, and all these industries have high-end components. With no-clean technologies, they are unable to meet their quality requirements, they cannot supply the quality they are asked for by their customers, so they tend to look into cleaning more and more. Today, cleaning becomes even more important because, due to the low-cost idea driving the market, there are lower cost components from Asia, which tend to be more sensitive against material compatibility issues. Fortunately, we were able to develop a pH-neutral defluxing agent two years ago, which is excellent in this regard.

In your opinion, what are the important factors that customers should be looking for when they’re developing a cleaning process?
In some cases, customers consider the cleaning process just as a machine and a chemical. However, what the customer needs in the long run is a stable, total cleaning solution. Of course, the cleaning process consists of the machine and the chemical; however, the analytics – the process monitoring – is extremely important, as are the internal components, such as the recovery system, water treatment or cost-saving peripheral devices. At the end of the day the user does not want to talk to five different parties; he wants one answer from one party. That is what ZESTRON principally stands for: to provide knowledge on all cleaning requirements and questions in the market.

What kind of support do you offer customers?
Customers, typically being engineers, look for cleaning equipment in the first place, because the cleaning machine is hardware and they can touch it. This is one of the key factors at Zestron: we give the customer a wide choice of cleaning machines at our five Technical Centers around the world. Just the Technical Center in Germany alone features 25 cleaning machines for different requirements. Customers can test these machines with their own substrates and finally we conduct the cleanliness analysis directly after the trials. Thus, customers visit us and after just one day they basically go home with a good idea on suitable processes. There are a lot of choices, and we have the machines from all leading equipment manufacturers available. So we try to help customers cut them down to those processes which would best meet their individual needs.

So how far do you take that when you’re working with customers in cleaning trials at your tech center? Do you help with qualifications?
Yes, we know the qualification standards in the market, such as IPC or MIL standards. When the customer defines a cleaning process for the first time, he usually needs assistance. The questions are how to clean the parts, to monitor the cleaning process and to analyze the cleanliness results, and we provide the total information package.

Most people try to avoid cleaning because it’s a cost. What would be your answer to this? How would you address people who literally just want to cut the cost and avoid cleaning?
Honestly, if I had the responsibility of manufacturing boards, the first thing I would ask my team is, “Do we really have to clean?” And if they say no, I would make the decision not to clean.

But, as discussed before, there are cases where the quality requirements make cleaning inevitable, and then customers want to know how to do it in the most cost-efficient way.

We have seen that in the past, for example in defluxing. Removing flux residues is only one part of the equation. If you clean the flux residue, you clean the board substrate at the same time. That means you remove fingerprints, dust or other contaminations in the same process, so there are side benefits. Additionally, we recently published a study that we did with a customer who had found that, he could save significantly on his conformal coating costs by cleaning beforehand. Firstly, it increases the product reliability. Secondly, due to the cleanliness level achieved, he could reduce the layer of conformal coating, saving a significant amount of money on materials. He actually paid for the cleaning process by saving the conformal coating cost.

Are there actually people out there who conformally coat without cleaning?
Yes, there are. While conformal coating people know that cleaning improves the coatability and adhesion, they still claim, depending on the requirements of the substrate that you could coat on no-clean paste residues. In class I or class II substrates, which might be coated for cosmetic reasons, this might be okay, but for higher-end products, it would create issues. That are the cases where customers clean prior to coating, but in principle every customer tries to avoid cleaning in the first place.

A lot of the cleaning and coating has been used in the automotive and military markets. It seems to be opening up a little bit now in Asia for cosmetic reasons. How do you specifically see the European market in terms of cleaning applications? Is it still really on cleaning high-reliability devices?
The high volume, low-mix substrates are long gone, i.e there is no mobile phone manufacturing in Europe anymore. Today, it is really high mix/low volume, and that creates a higher demand for batch cleaning versus inline cleaning, compared to the US. It is just a different market. You can draw a line around Europe on a map, but there still are Italy, France, Germany, Belgium etc. and each market has different requirements, different concepts, and also a different language. As a supplier, you need to address the European market—but based on the single market’s requirements, and they can be very, very different.

Tell me, what technology trends are you seeing happening in cleaning?
As mentioned before, the movement from solvent-based to water-based has more or less been closed. There are still a couple of solvent processes around, I would say even in Europe. But most of them are water-based. As mentioned before, what we have seen is that the quality of some materials is decreasing due to cost pressure, such as for sockets or connectors. This makes substrates more sensitive against material compatibility issues. We saw that very early and we asked our R&D to develop the pH-neutral product range. This is the trend we are seeing in defluxing, and customers really like those products. We now have the second generation of pH-neutral defluxing products, which have been quite successful in the market. They feature very strong material compatibility and yet they provide the same good cleaning performance, which was only provided by alkaline cleaners in the past.

What specific new developments are we going to see from ZESTRON?
I do not want to talk too much about things that will happen at Productronica, but there will be a couple of new products coming out for defluxing, stencil cleaning and potentially also for lower-end applications. In general, our main focus is on the high-end side and we strive to offer customers full cleaning solutions for every application.

—Trevor Galbraith

Watch the complete interview on Global SMT at http://globalsmt.net/global-smt-tv/