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At the recent NEPCON China, I sat down with Eric Gu, application manager at Nordson Asymtek China, to talk about the challenges and innovations in solder paste dispensing, and factors to consider when using solder paste dispensers.
Stephen Las Marias: Eric, what are the greatest challenges that manufacturers have when it comes to soldering?
Eric Gu: Before, we were normally using screen printing for the solder paste process. But nowadays, products such as mobile phones, cameras or smart watches have become smaller and thinner. Therefore, the PCBs inside these products have become smaller and smaller, including the chips, the packages, and the components. So the current printing process would be limited by this trend. Also, printing will be limited by the gap. If the components are tall, we cannot do printing. So, it will require solder paste dispensing. That’s where we are. We have a needle valve for solder pasting. And also, when dispensing solder paste, you know, there are some alloys in solder paste that may cause needle clogging during dispensing. We have an extensive experience on solving these kinds of issue. We have very high level of success in solder paste dispensing.
Las Marias: Definitely the shrinking components are a big factor. But as we go smaller, the solder pastes being dispensed definitely are also becoming dot sized. What is the impact of the material in the solder on this trend?
Gu: Yes. The component is becoming smaller. It will only require to dispense a very small dot and hold a very narrow line, which is a key challenge. Another challenge is that material inside the solder paste can cause needle clogging.
Las Marias: So what innovations are happening to help customers address that issue?
Gu: Actually, we are using needle dispensing instead of jetting, but I know there are maybe one or two vendors here that are using solder jetting. Of course, solder jetting is much faster than solder-based needle dispensing. But you know, the key limitation of solder-based jetting is that we cannot use many types of solder pastes. Solder pastes have many types—type 1 through type 6. The smaller the solder particle, the more expensive the paste. For instance, a type 6 solder paste is maybe 10 or 15 times more expensive than type 5 solder paste. For solder paste jetting, maybe we can only use type 5 or type 6. But for our needle dispensing, we can use everything from type 1 to type 6—this is one advantage of needle dispensing.
Editor's Note: This article originally appeared in the June 2016 issue of SMT Magazine.