HDI: Born in the USA and Making a Comeback

Reading time ( words)

There is no denying that high-density interconnect (HDI) has been around a long time—over 25 years, believe it or not. From almost the moment of its conception in the U.S., the technology was adopted by and used almost exclusively in Asia. It was a puzzlement—and a frustration—as to why the quick move to Asia, and why the U.S. did not pick up on this technology and start making these boards. However, Taiwan, et al., were making most of the consumer products such as cellphones and camcorders, and HDI helped pack the necessary computing power into these devices.

But HDI is back! In this month’s reader survey, we learned that while half of the respondents have less than 25% of their production in HDI boards, for some 28% it accounts for more than half their business, and a for a third of those, HDI is their main technology (Question 1). In addition, 30% of all respondents expected their percentage of HDI work to grow to at least 25% and 45% expected it to represent more than half their business (Question 2).

According to our respondents, the three main industry segments using HDI were telecommunications, automotive and consumer electronics. We then asked about market trends: What market trends are driving your HDI work? Obviously, a multi-answer question, but note that many of the answers have to do with density on the board (Question 3).

Now, think back 25 years and you realize that fine features on a PCB were certainly not the same as they are now, and neither were the chip packages being used. Drilling, imaging and other PCB processes have made significant advances as you can imagine. And today’s densely-packed semiconductor packages are making HDI a necessity for many types of boards for many more applications—think electronics in cars, medical electronics and your incredible smartphone—all making use of components with many, many more I/Os and finer pitches (imagine what Moore’s Law has done in 25 years!). How to fit all those connections into a finite area on a PCB? So, it’s with all this in mind that we delve into this month’s issue on HDI, which is not for the faint of heart or the light reader!

Of course, we can’t talk about HDI without first hearing from the acknowledged “Father of HDI,” Happy Holden. And Happy has put together our intro article on the subject. He provides the proverbial wakeup we need to move all the faster into it. He points out concerns and obstacles and what needs to be done to overcome them.



Continuing in this theme, Mike Carano, RBP Chemical Technology, discusses in his col umn the practical competencies needed by a PCB fabricator to be a successful manufacturer of HDI boards. Consultant Vern Solberg continues with a more design-focused view—or perhaps explanation—of the rather recent surge in HDI. He not only thoroughly explains the need for HDI based on the increased package density, but also discusses both imaging and via formation.

This is a heavy-duty column for the PCB manufacturer, but definitely something you should read. As usual, we pulled together some experts who could intelligently explain some of this to us, as well as our readers. Our group consisted of Finisar’s Steve Bird, APCT’s Tony Torres, and several technologists from MC Assembly: Steve Jervey, Mike Smyth and Paul Petty. We learned a great deal about the latest technology, manufacturing challenges and strategies for design, fabrication and assembly—and you will too.

OK, let’s take a break and talk about something else. Elmatica’s Andreas Lydersen makes the case for a common PCB language called CircuitData. This open source standard was conceived to help prevent insufficient and erroneous article specifications that occur far too often between designer and manufacturer, often due to the many ways to describe even simple items like solder mask. This project sounds like a very good idea and one you should consider participating in.

Next, Tara Dunn, Omni PCB, writes about FlexFactor, a NextFlex program to help grow the next generation of advanced manufacturing workforce. She starts by listing several interesting electronics-based products that have been conceived by high school students and goes on to describe the four-week program and some of its encouraging results.

IPC’s John Mitchell also writes along these lines, covering the nationally recognized Manufacturing Day, which occurs on the first Friday in October. This day gives manufacturing companies the opportunity to present their company to their communities by inviting businesspeople, students, teachers and other community members, into their companies. It serves as a perfect venue to inform on career options in manufacturing, including the electronics industry.

OK, everyone. This issue is definitely required reading, so get on it. You need this technology and you need to read about it here. Next month we’ve got a hot one for you: an issue devoted to thermal management. We want you to learn and thrive in our industry and we’re doing our best to help you do that. If you haven’t already put yourself on our waiting list, what are you waiting for? Subscribe now and get a leg up on your competition. Move!

Patricia Goldman is managing editor of The PCB Magazine. To contact Goldman, click here.

This article originally appeared in the November 2017 issue of The PCB Magazine, click here.


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