John Cardone on Designing Flex for Spacecraft

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If you watched footage of the Mars rover driving all over the red planet, you’re familiar with some of John Cardone’s handiwork. He’s been designing rigid, flex, and rigid-flex circuitry for spacecraft since he joined JPL in the early ‘80s, and he’s worked on some of the more ground-breaking flex circuits along the way. Now John runs his own design service bureau, JMC Design Services, and he continues to design circuitry for things that blast off. I caught up with John recently and asked him to give us the straight scoop on designing boards for spacecraft.

Andy Shaughnessy: John, give us a little bit of background about yourself, and how you got into PCB design.

John Cardone: My first engineering jobs were with Raypak, where I designed hydronic de-icing systems (which looked very much like film heaters on a larger scale), and then Medical Communication & Instrumentation (which coincided with my start at Cal State, Northridge), where I designed my first electronic enclosure, PWBs and flex cable, all on the drafting and light tables with pencil and red/blue tape from Bishop Graphics.

The product I redesigned at MCI (later Biocom Inc.) was a medical communicator, the Biophone 3502, which was a feature of the old ‘70s TV series "Emergency." You can see the old unit by clicking here. It had miles of wire, stack pole switches, and a gutted Motorola radio behind the front panel. The attached pdf is of the manual for the replacement radio. The second pdf is a copier scan that shows only a portion of the panel flex cable (focal length issue). I took this with me on my CSUN job fair interview with JPL, and as it happens not too many other students had comparable show-and-tell items.

After graduating from CSUN I went to JPL as a mechanical design engineer. At that time JPL was just getting into CAD design and they had three seats of Computer Vision Cadds3 that were kept in a dimly lit closet. My first task (after listening to Cadds3 training tapes, and reading the manuals) was to layout a two-layer PWB used in a PAP smear analyzer. From there I worked in a support role for most of the flight projects that came through our mechanical design group from Galileo on. The drafting tables were slowly replaced by more CAD stations; we transitioned through software revisions, flirted with ProE (until the designer revolt), and settled on Unigraphics NX and Solidworks. PWB design moved from Computervision to Protel, Mentor and Altium. My work focused on electro-mechanical design. This might include light structure, electronic enclosures, schematic capture, PWB design (rigid, flex, rigid-flex), and cabling.

Shaughnessy: Tell us about JMC Design Services, and what led you to start your own company?

Cardone: I worked at JPL from 1983-2005. At that time factors all converged to allow my family to make the move to Grenada where we have a small ranch, for the purpose of raising horses. If I could have done that and stayed at JPL I would have, but it's 650 miles away. The next best thing was to contract to them as a remote associate, and this I've been doing for JPL and a number of other clients since 2005.

Shaughnessy: So you were at JPL for 22 years, when they were just getting into EDA tools. What were some of the biggest challenges you faced (technical, bureaucratic, etc.) during that time?

Cardone: When I started at JPL in the design room, they were just getting started in MCAD with CV CADDS3. JPL is a matrix organization, and I am not certain of the state of EDA tools in the sections with an EE focus. It may have been very rudimentary as I do recall creating many schematics and PWBs for the Galileo S/C.

CV was a unique platform because it did it all. You could create an electronics enclosure, add a PWB to it, link the PWB to a schematic net-list from a schematic created in CV, and then place and route the PWB. CV is still being used in the ship-building industry because it is very adept at large assemblies. It was later purchased by ProE, hence its decline and JPL's search for a replacement. I believe that the fact it was being used at the time of my start at JPL fostered my inclination to cross the boundaries that typically exist between mechanical, electrical, systems, thermal, etc. On the MER (Mars Exploration Rover) project I was a member of the mechanical, systems, and electrical engineering teams.

At JPL these were few bureaucratic challenges. It's a marvelous place, and more of a campus environment than a commercial engineering firm. The one challenge I felt is that the vast majority of funding is tied to a specific project, so we could not be a Bell Labs where you have the luxury of playing around until you hit on something. An axiom is that technology used on flight projects must have a high TRL (technology readiness level), and how do you get a high TRL? By being demonstrated on a flight project, of course!

To read this entire article, which appeared in the September 2016 issue of The Printed Circuit Design Magazine, click here.


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