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60 SMT007 MAGAZINE I FEBRUARY 2020 Suzuki: Right. And for better planarity, Taiyo has developed a dry-film solder resist that isn't liquid anymore. Dan Feinberg: Is the primary volume that your customers use still screen print? Suzuki: That is correct. Feinberg: They screen the prod- uct to apply the image. Do you sell photo-definable solder mask that's liquid or dry film? Suzuki: Most of our customers still use liquid photo-definable solder mask. Feinberg: Is the developer you use solvent or aqueous? Suzuki: It's aqueous. Feinberg: Very good. Chemi- cally, there's not much differ- ence between the liquid and dry film. It's a case of how it is applied and the way it's man- ufactured. As far as the thick- ness of the dry film, what is the average thickness that you sell? Suzuki: The standard thickness is 10–35 microns in thickness. The direction- type materials are used only for the IC packag- ing area right now, where the form factor is a much thinner, and the wiring is thinner. Feinberg: And you need a higher resolution. Suzuki: Exactly. Feinberg: What kind of definition can you get as far as lines and spaces with your average dry film, which is probably mid-range? Suzuki: Our definition and resolution are defined by the opening size. With the dry film resolution solder resist, the opening sizes are typically 50–80 microns. Resolution wise, there's not a big difference between the liquid and dry film types as long, as you're not going to look at something less than 50 microns. You don't see a big difference between the liquid and dry film in terms of the variation. Feinberg: Do those that use your dry film use it for tenting over holes? Suzuki: So far, nobody has used it for tenting. Similar to liquid, the dry film can flow in between the lines, but the biggest differ- ence is the planarity of the sur- face after the coating, or in the case of the dry film, it's lamina- tion. In the case of the liquid, the conformity of the coating covers the surface of the cop- per wiring. The surface has a good roughness, but with the lamination, there is a pressing process that planarizes the sur- face. Feinberg: Do you apply the dry film solder mask with a hot roll laminator? Suzuki: Some use hot roll lami- nators, but many are using vac- uum laminators. Feinberg: You apply it in sheet form and then laminate it on with a press laminator. Suzuki: Yes. Feinberg: You also have a lot of sales in Japan. Does your product have a decent market share in China? Suzuki: Most of our dry solder resist is sold in Japan, Taiwan, and Korea. We've started pro- moting it in China right now, but the packag- ing market is mainly dominated by those three major areas.

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