Issue link: https://iconnect007.uberflip.com/i/1174596
OCTOBER 2019 I DESIGN007 MAGAZINE 17 additive process on top of that. We did a flash etch but didn't have to have an etch protection. We used a liquid crystal display capability, but the sheets could be three meters by three meters. Hartley: And that may be the long-term future, but I doubt that's the immediate future. Creeden: Something that's challenging now is BGA package design where you see the silicon chip on these little BGA transposer boards that then mount on a standard PCB circuit. Hartley: That's right. Creeden: And you see some thin substrates where it's a one-millimeter board, but it has 18–32 layers; it's traversing down with these semi-additive processes that Happy was refer- ring to where it's the 1-mil line. And when you go below 25 microns, you enter into a whole new world that typically has to be additive to get the profile and resolution of the line; it's a different material. One of the other things I see is the need for any type of buried capacitance (BC) materials. You no longer have the luxu- ry to put decoupling capacitors on the bottom side of a package design; you have to put them on the top side at best, and when they're out- side of the chip, they're more ineffective. Hartley: My prediction is that you're going to see a lot of them in the IC packages themselves in the future—not on the die, but in the pack- age. I'm sure higher-end ICs these days can't operate at the speeds they need to from decou- pling on the board; they must have on-die and on-package capacitance to even operate at all. They're building a lot of capacitance into the die of most processors now so that they will function, but they're also putting as much as they can on the substrate, interposer, and die mounts too. And I bet that you'll find a lot of this varied capacitance technology in the inter- posers in future designs. Creeden: Another thing I see is that there's a strong push for education, which has always been a passion of mine. Now, people are tak- ing a Band-Aid approach to education. They think that if they give you a little snippet here and there, that will solve the problem, but there's no easy answer. Hartley: No, there isn't. Their companies won't let them go long enough to learn what they need to in one fell swoop. Creeden: Hear, hear. Matties: Another challenge is finding places to learn about PCB design Hartley: There are some, but not a lot; you're right. Matties: Then, what path of training do you take? There are so many disciplines that you need to focus on. For example, do they want to work on high-speed or printed electronics, or do they need a combination of both? Creeden: Well, you hit the nail on the head there; it's the nuance of PCB knowledge. For instance, what I know and apply on a high- speed digital board is not the same thing I'm going to apply on a low-loss, radio-frequency (RF) circuit. The rules don't apply in all three of those technologies. Matties: In terms of landscape, one thing that we've been talking about and hearing about for years is the need for more collaboration from