A Focus on Ultra HDI

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John Johnson is relatively new to American Standard Circuits, but definitely not new to the technology. In fact, he was hired to focus on business development for ultra-high-density interconnects. John explains more about the process and where it's taking ASC.

John, how do you define ultra-high density?

I define it as ultra-fine lines, small microvias, sub-4-mils; layer count can vary depending on what the needs are. It can be stacked microvias, multiple stacks up to four, maybe a little bit greater than four—any layer type of technologies.

What's the ASC technology roadmap to UHDI? What do you have and what do you still need? What are the customers asking for?

American Standard became a licensee of Averatek's technology—which is the A-SAP™ process—about a year and a half ago. During that time, ASC has been getting up to speed and running the technology, looking at business, and bringing in commercial opportunities.

Before joining American Standard, I worked for Averatek and had multiple years of experience with the technology; I spent time working on installations at a variety of printed circuit board manufacturing sites. When I came here, it was natural to get that process to the next level. We're now building a lot of test vehicles, prototypes, commercial orders that are quickturns with smaller requirements.

Now we are looking at adding ultra-fine vias. We've done some copper filling on 4-mil diameter through-holes as well.

ASC has been using outside sources for laser. But as we get into this, it's beneficial to have our own laser in-house, so we've recently put in a purchase order to get a brand-new laser drill. We have quite a bit of capital acquisition right now. We've refreshed our strip/etch/strip line (SES), and our inner layer etch/strip line with vacuum etching technology.

Of all these changes, which ones are directly related to UHDI? An additive process is critical to get those sorts of dimensions in a laser drill. Which pieces are necessary to support getting to UHDI?

In a sense, they all are necessary to getting there. We have been getting into other aspects where you have embedded capacitors and resistors. We’ve been working quite closely with the folks at Quantic in terms of the Ticer materials and the OhmegaPly® materials as well.

It all must come together because ultra HDI needs many different aspects. The Averatek process that we're using as our vehicle to get to ultra-fine lines is the cornerstone. But you can't do fine lines without ultra-fine vias. We've added copper filling ability for our microvias and we've been upgrading our plating lines. We're moving to insoluble anode technology with special brighteners and levelers to control the plating distribution better from surface to the via; there are many pieces that make ultra HDI.

To read the rest of this interview, which appeared in the May 2023 issue of PCB007 Magazine, click here.