3 ms·
A couple of factors. 1) The yield rates for spaceflight-qualified chips is very, very low. Like 1%-5% or so. The chips are inspected when they come out of fab,
by GlenTheMachine 8y ago
A couple of factors.
1) The yield rates for spaceflight-qualified chips is very, very low. Like 1%-5% or so. The chips are inspected when they come out of fab, and only the most perfect ones are given a spaceflight certification. The rest of the chips are used for other, less stringent applications (test boards, or military/embedded applications).
2) Spaceflight parts have significant paper trails. For metal parts, they are traced from the moment a lot of material comes out of the mill, and every time it is touched or changes hands thereafter that fact is recorded. Same thing with chips. Every chip has a "traveler" associated with it that records when it was manufactured, how it was stored, etc. Keeping those records costs a surprising amount of money. Handling the parts so the paper trail can be kept costs even more. You have to organize your logistics train such that every part is individually trackable. That reduces efficiency and adds cost.
3) Relatively low economies of scale.
- hinkley 8y agoCommercial aircraft also track provenance very carefully. I wonder how much the two systems have informed each other over the years. You would never want a part involved in a stress test to be reused, and you certainly don't want test parts anywhere near a production craft. This isn't like IT where you can cannibalize parts from a QA box to put into a production server.
- rocketperson7 8y agoHaving worked on mission critical commercial aircraft electronics, I can assure you every part is stress tested before it goes on a plane. Both after its first made and every time its in for service. Supposedly there has been research done showing that stress testing does not adversely affect reliability, at least at this quality level Also, the paper trail is quite literally paper. Its kinda amazing how slow the aviation industry is to adopt new things
- hinkley 8y agoIt's possible I'm mucking up the jargon, but isn't stress testing electronics what most of us might call "burn-in"? I definitely want the flight control computer burnt in before I sit on the airplane. I was thinking more of physical components, like an aluminum bracket, and you don't want a part with metal fatigue being installed as new.
- rocketperson7 8y agoCorrect, thermal testing. Not vibration