Issue link: https://iconnect007.uberflip.com/i/994883
34 DESIGN007 MAGAZINE I JUNE 2018 I could foresee that in the future, we should extend that capability to do DC Power Deliv- ery network analysis across multiple boards and through connectors. That will take a fair bit of work and take us some time, and I'm not promising that that's what we are going to do, but I could foresee that we would endeavor to do that because power supplies in a multi- board assembly are critical. Sending power and having ground returns appropriately assigned to pins on connectors in multi-board assemblies is critical to even the AC function of the design. Shaughnessy: How do designers figure out the cutoff, or the break-even point, for going the multi-board route? It seems like there would be a lot of trade-offs. Jordan: Has anyone ever tried to draw a Venn diagram with all of the trade-offs with PCBs? I think it's impossible. You'd have so many bub - bles and some of them would never overlap, so you couldn't actually find that happy medium. At the same time, I can understand why a tool you have developed for yourself would work, but also be complex. I think there's promise there. If one can make some assumptions about the kind of product that you're designing or what its target industry or position is, in the broader sys - tem, then there are certain lists of assumptions can be made about some of those trade-offs; and that can simplify the decision making. Shaughnessy: So, how would you sum up what we've discussed regarding multi-board design? Jordan: There are really three elements to this. One is design for proper function and that involves the latest in signal integrity, power integrity, pin assignments on connectors, and making sure you have proper return path designs so that you don't get electromagnetic radiation problems. Coupled with that, we as an industry still need to solve that problem of making sure everything works together as an integrated bun - dle of boards versus just the individual modules. The second thing is the 3D assembly and making sure all the parts fit, and that's associ- ated with the bill of materials as well. Design for assembly is an exponentially more complex thing when you're dealing with multi-board systems, because you've got to assemble the individual parts but also the overall system, and I think our industry could improve or aug- ment our existing DFA practices. I think IPC could help with this to define DFA guidelines for multi-board assemblies so that contract manufacturers can do final module integration and test—design for excellence, basically. And the third thing is integration of the design practice into the broader organization. PCB design is so complex that it's very easy to fall into the fissure of that narrow space of only considering the boards; it's very important to consider the broader implications: We're designing a multi-board system, and it's part