Nolan’s Notes: UHDI—Raising Awareness and Interesting Questions

It was over lunch on the second day of the recent IPC Symposium on Advanced Packaging when I asked a question that triggered an interesting discussion about advanced packaging and ultra high density interconnect (UHDI). While these two technologies are distinct, they are also symbiotic; it takes both to make either one successful. As the symposium delivered on its agenda, the inter-relationship between these two technologies became crystal clear.

UHDI is the fabrication technology necessary if you want to manufacture the interposer subcomponents so critical to connecting the semiconductor chips to the enveloping package. For the history of semiconductors, each component package contained one and only one chip. Advanced packaging uses sophisticated techniques to include and connect multiple chips inside one package. This allows for a more modular approach to building up the finished product.

But how do the chips get connected inside? Interposers—super small fanout or interconnect features. Interposers provide the interim fanout steps from nanometer-scale IC pads to the ultimate goal of BGA solder balls leading to the outside world. Interposers work a lot like a PCB, but their feature sizes are in the micron range—much smaller than most PCB shops can fabricate, and much larger than current semiconductor facilities can build. Ironically, the advanced packaging component that fills the gap needs to be built with a technology that is right in the middle of the fabrication gap. It is within this fabrication gap that UHDI resides: To make the interposers necessary to deploy advanced packaging, UHDI fabrication is necessary; advanced packaging is the “killer application” that makes UHDI a financially feasible investment for a fabricator. There, in a nutshell, is the symbiosis.

Our technical editor, Happy Holden, “father of HDI,” is well-quoted saying that HDI took a long time to be adopted, in part because it took a long time for the cost vs. capability evaluation to flip. Until cellphones, there just hadn’t been a “killer application” for HDI that pushed it out of its niche status. It seems safe to say that UHDI will grow out of its niche status and into a major technology supporting the semiconductor industry’s appetite for advanced packaging.

Ah, but there’s a piece missing from this puzzle, upon which my lunchtime question centered. I asked, “Which mid-career engineer is more likely to pivot their career into UHDI for substrates—PCB fabricators or IC manufacturers?” Our conversation kicked this conundrum around for much longer than I expected. So, what was the outcome?

On the one hand, PCB fabs seem the most likely to understand the interposer game, but they will need a facility that resembles the semiconductor fabs of 25 or 30 years ago. That’s a big step up for most of them. Will they be able to pick up the necessary expertise?

That’s precisely the challenge for the semiconductor engineer. Moving to UHDI feature sizes is a big step backward from current semiconductor feature sizes. While the semiconductor engineers would have the experience, would they also find it lacking in challenge? The upshot: Even when we build out packaging capabilities, where will the skilled staffing come from? Suddenly, and once again, the industry’s gaze turns to the academic community to educate talent, and to employers to remain competitive with hiring packages. But that’s an entirely different conversation.

In this issue of PCB007 Magazine, we pull out the microscope and peer down into the UHDI niche in the marketplace. Calumet’s Todd Brassard and Meredith LaBeau discuss UHDI and the give-and-take that comes with helping define a new market niche in their interview, while Sunny Patel at Candor Industries sheds light on the operational side of ramping up UHDI skill sets and facilities. Jan Pederson shares his industry-wide perspective on supply and demand for UHDI as well. As features get smaller, drilling and cutting capabilities must also become more precise; in a group discussion with the MKS/ESI team, they share their work to deliver laser systems for UHDI applications. Of course, we bring you columns from IPC’s Dr. John Mitchell, Gardien's Todd Kolmodin, Chemcut’s Christopher Bonsell, Paige Fiet in her IPCEF role, Travis Kelly representing PCBAA, and our very own Happy Holden.

There is still a lot to work through in UDHI; there are many more questions than answers at this moment. But what is clear is that we will be embracing this technology, adding these capabilities, whether we want to or not. Semiconductor advancements will require it.

As always, our mission is to help move the conversation forward in the industry. To that end, we appreciate your feedback and suggestions identifying the most important topics. To be honest, yours are among our favorite emails to receive. Please keep in touch.

This column originally appears in the November 2022 issue of PCB007 Magazine.



Nolan’s Notes: UHDI—Raising Awareness and Interesting Questions


It was over lunch on the second day of the recent IPC Symposium on Advanced Packaging when I asked a question that triggered an interesting discussion about advanced packaging and ultra high density interconnect. While these two technologies are distinct, they are also symbiotic; it takes both to make either successful. As the symposium delivered on its agenda, the inter-relationship between those two technologies became crystal clear.

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Nolan’s Notes: The Conveyor Belt Effect


How many times have you watched a conveyor belt in a movie played out for comedic effect? It’s a familiar trope: The belt starts out slowly, then increases its speed, until chaos ensues. Think “I Love Lucy,” “Star Wars,” and Charlie Chaplin in “City Lights.” These are perfect metaphors for this issue on workflow management, where planning your workflow on the manufacturing floor in these challenging times sometimes feels like being just one step away from disaster—or safety.

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Nolan’s Notes: Have Passport, Will Travel


Technical conferences, expos, symposia, and trade gatherings of all kinds are back and in a big way. Maybe it’s just because we’ve been quiet for a while, followed by a year of careful, tentative restarts to the event schedules, but this upcoming year’s calendar of events seems to be full steam ahead. I’m excited to get back into the convention centers and hotel ballrooms; that is where some of our best news and reporting originates. That comes at a price, however, as my travel schedule looks pretty brutal between now and Thanksgiving. Just between you and me, while it may feel brutal to my workload, I’m ready to dust off my passport, see some airports, and wear thin some shoe leather.

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Nolan’s Notes: New Era Manufacturing


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Nolan’s Notes: Light at the End of the Tunnel


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Nolan’s Notes: Supply ‘Pain’ Management


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Nolan’s Notes: The Shifting Supply Chain—An Argument for Investment


The gears of the economy worked like clockwork for quite a long time, at least in North America, Europe, and Asia. Overall, that smooth operation is no longer the case, for several reasons. It’s as if the watchmaker has upended the clockworks onto the worktable and is rearranging the mechanism to work differently—to tell a different time, if you will. In the overall economy, there are bearish signs (9.1% inflation year-over-year in the U.S. in mid-July). But in electronics manufacturing, the market looks quite bullish on the demand side. This month’s cover reflects that dynamic—a bullish industry within what seems to be an emerging bearish economy.

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Nolan's Notes: Data Security—It’s Incumbent Upon You


In May 2022, the news broke in Portland, Oregon that the city government had suffered a “cybersecurity breach” and lost $1.4 million in city funds. As reported by numerous news sources, a city-issued press release stated that “preliminary evidence indicates that an unauthorized, outside entity gained access to a City of Portland email account to conduct illegal activity.” Incidents like these are more common than we realize, and must be addressed in our industry as well.

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Nolan’s Notes: What’s the Point of Collaborating?


When we first started planning this issue, we used the word “partnership” in our working title. Partnership certainly is one way to collaborate. Creating close working relationships with manufacturing specialists who can extend your capabilities for your customers is one obvious way to collaborate. But there are others, for example, collaboration can also look like proactive communication with customers as well as vendors.

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Nolan’s Notes: Where Are the Golden Eggs?


We all went through the simultaneous transitions in our industry in the last three years. To be clear, I’m referring to supply chain issues due to the pandemic, manufacturing channel resiliency, parts shortages, people shortages, governmental investment in infrastructure, and above all, a huge demand for manufacturing capacity. All that demand, all those hurdles, and the all the constraints can leave one a little dizzy. The reality is that we’ll feel both short- and long-term impacts from these trends.

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