Taiyo America’s Yuya Suzuki, marketing manager for IC packaging materials, talks with Nolan Johnson and Dan Feinberg about the challenges with soldering due to shrinking components and how Taiyo’s R&D work around smaller filler sizes and increased planarity has been preparing them for the future of solder mask.

Nolan Johnson: Shrinking components and smaller feature sizes are creating a need for increased precision in all aspects of the component attachment processes. For Taiyo and its products, what research and development work are you doing to meet these tighter tolerances that are increasingly showing up in stencils and solder paste application?

Yuya Suzuki: Screen printing is the major process for coating or caulking the photoresist. But as the thickness control and tolerance are going to be smaller, some people—especially in the IC packaging area, where they already had a similar issue 10 years ago—lean toward spray coating or other methods. At that point, the viscosity of the photoresist was still compatible with new coating processes. Another way Taiyo needed to tailor our solder resist ink was by changing the filler size. The thickness of the solder resist that can be coatable on top of a circuit board is defined by the filler size, so we are moving toward the smaller filler size, usually tens of micrometers. That is the first step we have taken to accommodate such requirements.

Johnson: What effect do these changes produce that can improve yield?

Suzuki: By changing the filler size, we can guarantee that we can accommodate the inner coating capability. It allows the customer to have better thickness tolerance and better reliability for assembly.

Johnson: Is the trend toward thinner coatings?

Suzuki: Yes.

Johnson: Because it’s thinner and going to be more planar.

Suzuki: Right. And for better planarity, Taiyo has developed a dry-film solder resist that isn’t liquid anymore.

To read this entire interview, which appeared in the February 2020 issue of SMT007 Magazine, click here.