BTU International’s advanced thermal processing equipment and expertise are used in the manufacture of solar cells and nuclear fuel as well as the production of printed circuit board assemblies and semiconductor packaging. We recently had a chance to speak with Mr. van Maaren, vice president of marketing communications, about BTU’s in-line process systems.

Dr. Jan-Paul van Maaren

Jan-Paul, why should customers who are looking for best-in-class advanced thermal processing equipment and processes consider BTU International?
Well, thermal processing is what we do. If you are facing a challenge, process-wise, chances are that we’ve seen it before. We have more than 60 years of experience and over 10,000 tools shipped. We are set up for collaboration and partnership with our customers. Our USA headquarters, near Boston, is our engineering center with advanced modeling and analysis capabilities and a fully appointed solar applications lab. We also have maintained our skill set in custom manufacturing here in the US. Additionally, we have a factory and solar applications laboratory in Shanghai, China, and over 30 service locations worldwide. Manufacturing in Shanghai can reduce our delivery time to the rapidly growing Asian market by as much as six weeks. We are uniquely positioned to work with a customer through the initial development of their processes to the worldwide deployment of high-volume manufacturing.

We understand that BTU’s strength is high-volume in-line processing. What does it mean to be ‘in-line’ and how is this relevant to the photovoltaics industry today?
Being in-line refers to continuous processing, where the process conditions are kept constant, and the product is moved through the process chamber, typically exposing the product to varying temperature and atmospheric conditions as it travels through the different zones. Many of our continuous systems use conveyor belts or powered rollers. We also offer specialty conveyors for unique situations like extremely high temperatures or atmospheres with reactive gasses. In-line processing is particularly relevant to the photovoltaics industry today. If you look at the history of other high-tech industries like electronics, as the industry ramped up and entered into a phase where its business model was based on cost competitiveness, in-line processing has been one of the key enabling technologies. As a company with more than 60 years of experience, we’ve been a part of that transition numerous times.

Do you find that the industry has been switching over to in-line processing rather than traditional batch processing? Why do you think this is? What benefits does in-line offer over batch processing?
In photovoltaics, in-line processing is dominant in certain areas, such as metallization firing, but still is emerging in others. We see the adoption of in-line processing accelerating in emerging areas such as diffusion and thin-film. Certainly, cost is a huge driver in the change, but other factors are pushing it along, including increasing production volumes and the availability of process data for in-line processes. There are many benefits of in-line processing: wafer breakage is dramatically reduced, process times are slashed and productivity is increased. All of this really boils down to reducing manufacturing costs, but what’s exciting is that it is not just a drop in the bucket, but an incredible savings over time. For example, an independent analysis of our Meridian™ in-line diffusion system showed a 12-cent per wafer savings over batch, a savings of a whopping three-quarters of the cost for that process step. I believe that in silicon photovoltaics, game-changing technologies are needed to keep pace with new lower cost alternatives, and in-line can do it. CapEx per watt is becoming an important metric for many of our solar customers. In-line atmospheric processing is extremely attractive when compared to batch vacuum processing from a capital expenditure perspective. Many of our customers are astounded by the types of atmosphere control our continuous atmospheric systems can offer, down to 2 ppm oxygen in nitrogen or other novel gases.

BTU factory

Are there any disadvantages of going in-line?
Any time you are considering changing a process of record there are disadvantages. We certainly recognize that there are some risks. Today, there is even more pressure to minimize risk as our customers are ramping up their factories so rapidly and, in some cases, are driving to start production in less than a year. However, the driving force in this industry is ultimately lowering the cost per watt and the cost savings offered by processes like in-line diffusion are too compelling to ignore. To date, we have received more than 2 GW in customer commitments for in-line diffusion equipment. We are working with world-class research institutes to optimize our processes and generate cell efficiency datWe also maintain fully appointed solar process labs in both the US, near Boston, and at our Shanghai, China, facility. Our process engineers are working with many of our key customers as they make the switch to in-line.

How do BTU’s in-line process systems maintain process performance?
BTU’s in-line systems are known worldwide as process leaders for thermal uniformity. Additionally, we have numerous techniques for atmosphere control, including our patented gas-barrier technology that allows us to offer the lowest oxygen levels in the industry. Inherently, an in-line system has advantages over batch for process control, in that by design, the process is held constant. Over the years, BTU has developed solutions that allow the system to respond to varying product loads, eliminating the need for the dummy loads that are used by batch systems. Another area in which we have significant expertise is multi-lane systems. We’ve shipped hundreds of dual-lane systems into the electronics assembly and semiconductor packaging markets where they were qualified and monitored through rigorous standards by our customers. Needless to say, we’ve learned a lot over the years and are applying that to our dual-lane solar metallization firing equipment. We don’t rely on side heaters or other “Band Aid” approaches to thermal uniformity in our systems.

What does the future of in-line processing look like for photovoltaics?
Well, not surprisingly, we think the future is pretty bright. The opportunity to save manufacturing costs while maintaining process efficiencies for silicon photovoltaics is too great to ignore and, frankly, will become a necessity as prices continue to drop. We’re developing in-line processes for some of the most advanced PV processes, so it’s safe to say that we think it’s here to stay.

Is BTU experiencing increased interest in the alternative energy industry? In addition to the BTU products already in the solar market, will you be introducing anything new this year?
Yes, our alternative energy business, which includes products for nuclear fuel sintering, has been experiencing rapid growth during the last few years. In fact, it more than doubled in 2010. We expect that to continue with a very strong contribution from the solar segment. Last year, we had two major product introductions with our Meridian™ in-line diffusion system and the Tritan™ Metallization Drying and Firing System. As mentioned earlier, these products are cost of ownership leaders and provide excellent process performance. This year, we are expanding our solar business in other areas and partnering with key customers. We have targeted specific processes that not only save costs, but also increase cell efficiencies.

Thank you, Jan-Paul.
Trevor Galbraith

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