Behaving passively!

-November 08, 2013

During the summer, my family and I travelled to Northern Ireland for a short vacation to visit my parents and extended family. One sunny day, we decided to go the beach to get some negative ions and let the children play in the sea. En route, I mentioned to my wife that we would be taking a short detour. Naturally, my wife became very curious and asked many questions:

"Are we going to stop-off at Maud's famous ice-cream shop and indulge in some Pooh-Bear or Guinness ice-cream?"

"Are we going to stop off at the local distillery for a little tipple?"

"Are we going to the nearby Giant's Causeway – a UNESCO world heritage site?"

"Are we going to drive the beautiful Antrim coastal road and then stop somewhere for lunch?"

"None of the above," I said, "We have been invited to tour the local multi-layer ceramic factory!" At this point in my post, it's best that I move on and not share my wife's reaction, but let's just say it was anything but passive!

My tour of AVX's multi-layer ceramic factory at Coleraine was impressive and incredibly insightful: this was the first time I got to see all the manufacturing stages necessary to produce a qualified, space-grade component. Starting from an initial sheet of ceramic, it was a real education to see the casting, printing, stacking, laminating, dicing, burning-out, firing, polishing, plating, terminating and packaging processes that are required to produce a Hi-Rel, space-grade, passive component. Each day, the factory can potentially make up to 50 to 70 million ceramic capacitors, which is a staggering and impressive number for a low-volume industry such as ours.

It's very easy to become mesmerised by the latest advances in space microelectronics, however, passive components account for almost 80% of all electronic parts used on a spacecraft. These are used to filter, de-couple, terminate, condition, connect and configure the main signal processing and power supply functions. One of our recent payload PCBs contained almost 10,000 components - nearly all passive!

Recent innovations by AVX will offer the space industry flexible capacitors to accommodate PCB bending during assembly as well as 0402-sized, surface-mount parts. Physically smaller capacitors present a lower intrinsic inductance making them more suitable for high-frequency de-coupling. Presidio is now starting to offer buried electrode, thick-film gold parts with extended values.

ESA recently hosted its first international symposium on passives to discuss the latest advances and understand the needs of the space community: http://www.congrexprojects.com/13a04.

It's great to see suppliers of microwave, space-grade passives and connectors offering S-parameter and SPICE simulation models to assist high-frequency and RF design. Last month I presented some work on Post-Layout vs. Schematic that uses such models to ensure high-frequency analog and digital designs are right-first-time before committing to an expensive PCB build. The latest EDA tools allow you to predict the input/output match, the TDR response, and in-band flatness of a complete mixed-signal front/back-end accounting for trace, pad and via parasitics.

Are you facing any reliability issues or procurement challenges when sourcing space-grade passives? What are your views on solderless interconnect?

I would like to take this opportunity to thank AVX for their time and hospitality during my tour of their impressive manufacturing plant in Coleraine. I learned a lot and encourage everyone to make similar visits to appreciate the effort required to produce and deliver a space-grade component. I'd also like to apologise to my wife and children for delaying our trip to the beach!

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