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Awareness of Ultra HDI is growing, and a significant share of the market is looking into designing with these ultra-fine features. Why do you feel that this new technology is important to the industry?
There is constant pressure to reduce geometries in electronics. The resulting reduction in package sizes, increased ball count, and pin pitch, coupled with reduced transistor technology, places unprecedented demands on the PCB. The required trace widths and spacings are pushing beyond 1.0 mil, and traditional fabrication techniques do not provide a cost-effective solution.
Once you pass the 0.5 mm pin pitch, UHDI presents a very attractive solution to routing density and signal integrity challenges. Signal integrity also poses significant challenges, and UHDI, coupled with additive manufacturing techniques, can provide a method to create small, controlled impedance transmission lines in unconventional ways. Imagine, single-layer 50-ohm routing. DDR5 and PAM4 can be easily tamed.
What key information points are critical to shortening the cycle for adoption - to more quickly begin taking advantage of the benefits of ultra HDI?
The most important issue is what I call "dielectric awareness." It is critical to understand which dielectric the signal energy begins, the required path through the board stack and the destination dielectric. With that understanding, next is knowing how to use these extremely small structures to create the required boundaries (waveguide walls) to contain the signals in all three dimensions as they travel through the board.
It is easy to just connect the signals, but much more difficult to manage the spaces, especially in the Z axis. Each pad-stack used for a signal must be accompanied by a matching pad-stack that connects the ground layers. When properly addressed, these fundamental issues will result in greater success in using this technology, and I believe that successful designs are the key to adopting this technology.
Understanding the difference in thermal performance poses another key issue. These structures are extremely small compared to traditional drill technologies, and creating structures that can help dissipate the heat these new ICs create may be the biggest challenge. Learn to embrace thermal modeling. Your product's life will depend on it.
As a Design expert that has navigated through multiple waves of technology advancements, what advice to you have for those who are looking at learning new techniques?
Focus on the science. EM field theory may seem daunting, but the energy is governed by simple rules, and the EM fields always follow those rules. If you understand that energy moves in the spaces and use your PCB design to create those spaces, you can take advantage of all new advances in IC and PCB fabrication technology. The geometries involved in the newer devices present simple problems. The structures are reduced, and the impact on the signals is ratiometric.
No advanced math is needed, just a belief in geometry and spaces, and you will be able to face any challenge, from the most advanced network server design to high-power automotive electric inverters.
Ralph Morrison always said,
"Buildings have walls and halls.
People travel in the halls, not the walls.
Circuits have traces and spaces.
Energy and signals travel in the spaces, not the traces."
It's all about the space!
What are your outside interests - the hobbies that help you reboot?
It goes without saying that I love spicy food. Thai, Indian, Mexican, bring on the heat! My wife Renee and I have 7 children and 12 grandchildren between us, so family gatherings are a challenge, and I am usually the chief BBQ cook. Those are always a pleasant distraction. I also collect rocks and minerals, primarily focusing on beautiful crystals. I have a large citrine geode on my desk as a constant companion, and one of my favorite trips was to Herkimer, NY, to mine Herkimer Diamonds. I have quite a nice pile of those. I hope to take some of my grandchildren to the Badlands of North Dakota to look for dinosaur bones, as several of them share my interest in fossils. My wife and I love to dance, and do so when we can. Nothing quite as elegant as ballroom dancing, but we do alright because she is such a good dancer. OK, I admit it; I am an avid Pokémon GO player. I have gotten to level 43, and like most players, I need friends from Sandstorm and River (hint, hint). My nickname, of course, is FieldWizard.
In that vein, I really love spreading the knowledge I gained from working with Ralph Morrison, and I do everything I can to continue his legacy. PCB design reviews provide an excellent platform for teaching this valuable perspective, as well as presenting at seminars whenever possible. It's All About the Space!
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