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80 SMT Magazine • June 2016 you will sacrifice on throughput. They are slow- er. Imagine, printing will take one dot (stroke) whereas dispensing will take thousands of dots. So the cycle time is different. It's a very different process. Although solder paste dispensing has a better edge over getting these finer pitches done. Las Marias: What are the key factors to consider when selecting a solder paste printing solution? Sim: Typically, the customer will look at the ma- chine accuracy—that's always the first thing— because accuracy is the key, especially for tight- er tolerances and finer pitches. If the machine is not accurate, you just cannot move on. The second thing is throughput. Las Marias: What is the impact of solder pastes on printing? Sim: Different customers will use different pastes. Paste characteristic is typically defined by their viscosity and paste type. Printing a high-viscosity paste and low-viscosity paste are totally different. Different paste types, which means the solder ball size will be bigger in some, and smaller in others will also greatly im- pact the printing. There's a general guideline for printing—and not all pastes can be printed into fine lines. There has to be tradeoffs. Las Marias: Do you think your innovations in solder paste printers address your custom- ers' problems today? Sim: I would think so be- cause our products are the next generation printers in the market. We have been in this industry for a very long time, and as such I would say that our technology is very far ahead. The key factors that will affect customers' processes are machine capa- bilities, in particular, the ma- chine accuracy and through- put. More than 10 years ago, we came out with the MPM Accela, and this machine was the most accurate at that time. Accuracy is ±12.5 microns at Six Sigma with Cpk greater or equal to 2.0. A Six Sigma process is one which expect to have not more than 3.4 defects features per mil- lion opportunities, thus it is critical to achieve it. That's the consistency and repeatability of the printer, which is why we put a very detailed specification on it. At that time, we believe that the system could print all the way down to 0201 component size. We know that devices will be- come small, but we are not sure how far. Today, we are kind of hitting the edge. We can still see smaller components now, but the next generation of components, about 03015 and smaller, means that we have to develop a new technology. Over the past two years, we have been de- veloping a printer that will work for the next 10 years. That's where our new MPM Edison came out. From 12.5 microns down to eight microns. It's a big change. If you think about it, we don't build printers for the next two years. We build them for the next 10 years. So whatever the component type is today, we have to think 10 years ahead and what they will be like. Accuracy is a big thing. Customers have to Adam Sim IMPROVING THE SOLDER PASTE PRINTING CYCLE TIMES

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