What are the maximum g forces an FPGA could operate under? E.g. an FPGA sitting in a car wheel, where the car is travelling at 100 km/hr experiences approx 400g due to the centripetal acceleration. (assuming a 15" diameter wheel). Can anyone point to products or applications where this is done already? (I know tyre pressure sensors are coming..but these are not FPGAs) What would the mass of your typical FPGA package/silicon be? Say a 256 ball BGA(e.g. FT256 or similar). Force = mass x acceleration so I guess you could work out the force on the solder balls etc etc. I know vibration probably is an issue also - but at least that can be mitigated to some extent with the mechanical design of our product ,e..g vibration damping etc. However, the centripetal force is another matter - its always there whenever the wheel is rotating. (and grows with the square of the cars velocity).
Can an FPGA be operated reliably in a car wheel?
Started by ●May 7, 2006
Reply by ●May 7, 20062006-05-07
>...FPGA...in a car wheel...100km/hr...approx 400g... >...15" diameter wheel...Your figures seem correct, close to the outside of the wheel. The first thing you should think about is how not to have the FPGA there. Maybe you need sensors or outputs in the wheel itself, but do you really have to process the information there? Take a look inside a VCR to see how high-bandwith signals are communicated with the spinning heads. If you can't avoid it, keep the circuit close to the axis, so the acceleration is less.
Reply by ●May 7, 20062006-05-07
> Your figures seem correct, close to the outside of the wheel.Thanks for pointing that out Mike, my physics were obviously a bit lacking. Redone the calculations and I see that I now get 108 g if the FPGA is located at 50mm from the axis of rotation. I need a minimum area for the electronics so a 50 mm radius gives me that. Still, the question remains is 100g too much for an FPGA? How much g could it take reliably? I know 100g is way too much for a human and I know that some MEMS accelerometers spec up to 10,000 g for the absolute max rating (measurement up to 250g max I have seen so far). Regards Andrew MikeShepherd564@btinternet.com wrote:> >...FPGA...in a car wheel...100km/hr...approx 400g... > >...15" diameter wheel... > > Your figures seem correct, close to the outside of the wheel. > > The first thing you should think about is how not to have the FPGA > there. Maybe you need sensors or outputs in the wheel itself, but do > you really have to process the information there? Take a look inside > a VCR to see how high-bandwith signals are communicated with the > spinning heads. > > If you can't avoid it, keep the circuit close to the axis, so the > acceleration is less.
Reply by ●May 8, 20062006-05-08
Ever since WW II, >60 years ago, electronic circuits have been used in artillery shells. I have seen a whole TV camera and transmitter housed in the tip of a 155 mm shell. Those accelerations upon firing are much higher than 400g. Plastic-encapsulated conventional commercial-grade ICs are actually extremely rugged, since everything is completely encapsulated in plastic, the silicon or the wires have nowhere to go. Modern BGA packages do not even have bonding wires... I will look for acceleration test data in our reliability reports. I am sure the G-loads are not your problem. Temperature may be... Peter Alfke, Xilinx
Reply by ●May 8, 20062006-05-08
Ever since WW II, >60 years ago, electronic circuits have been used in artillery shells. I have seen a whole TV camera and transmitter housed in the tip of a 155 mm shell. Those accelerations upon firing are much higher than 400g. Plastic-encapsulated conventional commercial-grade ICs are actually extremely rugged, since everything is completely encapsulated in plastic, the silicon or the wires have nowhere to go. Modern BGA packages do not even have bonding wires... I will look for acceleration test data in our reliability reports. I am sure the G-loads are not your problem. Temperature may be... Peter Alfke, Xilinx
Reply by ●May 8, 20062006-05-08
Andrew FPGA wrote:> What are the maximum g forces an FPGA could operate under? > E.g. an FPGA sitting in a car wheel, where the car is travelling at 100 > km/hr experiences approx 400g due to the centripetal acceleration. > (assuming a 15" diameter wheel). > Can anyone point to products or applications where this is done > already? (I know tyre pressure sensors are coming..but these are not > FPGAs) > > What would the mass of your typical FPGA package/silicon be? Say a 256 > ball BGA(e.g. FT256 or similar). Force = mass x acceleration so I guess > you could work out the force on the solder balls etc etc. > > I know vibration probably is an issue also - but at least that can be > mitigated to some extent with the mechanical design of our product > ,e..g vibration damping etc. However, the centripetal force is another > matter - its always there whenever the wheel is rotating. (and grows > with the square of the cars velocity).By getting as close to bare die as is reasonable (chip scale packaging comes to mind) you can reduce the mass to the point where forces are inconsequential. When hybrid microelectronics started with all the teeny tiny assemblies using bare die, printed resistors, and other space saving techniques, it was to house electronics in artillery shells. Those were only fired over the ocean in WW II for fear the enemy might get hold of an unexploded shell and discover the tiny electronics. Work toward a smallest mass solution and you'll probably have an easy time of it. At least you don't have to worry about the electrons bunching up to one side of the chip!
Reply by ●May 8, 20062006-05-08
Andrew FPGA (andrew.newsgroup@gmail.com) wrote: : Still, the question remains is 100g too much for an FPGA? How much g : could it take reliably? I know 100g is way too much for a human and I : know that some MEMS accelerometers spec up to 10,000 g for the absolute : max rating (measurement up to 250g max I have seen so far). All I have is a gut feeling that the FPGA will take more gs than the PCB it's mounted on? Also consider the differential forces arising from fiting a flat PCB to a curved wheel - different areas are at different radial distances... cds
Reply by ●May 8, 20062006-05-08
On 7 May 2006 16:52:31 -0700, "Andrew FPGA" <andrew.newsgroup@gmail.com> wrote:>What are the maximum g forces an FPGA could operate under? >E.g. an FPGA sitting in a car wheel, where the car is travelling at 100 >km/hr experiences approx 400g due to the centripetal acceleration. >(assuming a 15" diameter wheel). >Can anyone point to products or applications where this is done >already? (I know tyre pressure sensors are coming..but these are not >FPGAs) > >What would the mass of your typical FPGA package/silicon be? Say a 256 >ball BGA(e.g. FT256 or similar). Force = mass x acceleration so I guess >you could work out the force on the solder balls etc etc. > >I know vibration probably is an issue also - but at least that can be >mitigated to some extent with the mechanical design of our product >,e..g vibration damping etc. However, the centripetal force is another >matter - its always there whenever the wheel is rotating. (and grows >with the square of the cars velocity).Let me guess - trying to do something like this perhaps.... http://gizmodo.com/gadgets/gadgets/pimpstar-led-car-rims-162990.php
Reply by ●May 8, 20062006-05-08
Andrew FPGA wrote:> What are the maximum g forces an FPGA could operate under? > E.g. an FPGA sitting in a car wheel, where the car is travelling at 100 > km/hr experiences approx 400g due to the centripetal acceleration. > (assuming a 15" diameter wheel). > Can anyone point to products or applications where this is done > already? (I know tyre pressure sensors are coming..but these are not > FPGAs) > > What would the mass of your typical FPGA package/silicon be? Say a 256 > ball BGA(e.g. FT256 or similar). Force = mass x acceleration so I guess > you could work out the force on the solder balls etc etc. > > I know vibration probably is an issue also - but at least that can be > mitigated to some extent with the mechanical design of our product > ,e..g vibration damping etc. However, the centripetal force is another > matter - its always there whenever the wheel is rotating. (and grows > with the square of the cars velocity). >I take you want to mount the FPGA perpendicular to the rotation axis ? Are you aware that Tin flows ? Under strain, tin flows slowly, over the days. You can see that tin wire moves by itself under gravity. So even if the pbc is able to take the force and the FPGA case takes the strain, the tin won't. Rene -- Ing.Buero R.Tschaggelar - http://www.ibrtses.com & commercial newsgroups - http://www.talkto.net
Reply by ●May 8, 20062006-05-08
Rene Tschaggelar wrote:> Andrew FPGA wrote: > > > What are the maximum g forces an FPGA could operate under? > > E.g. an FPGA sitting in a car wheel, where the car is travelling at 100 > > km/hr experiences approx 400g due to the centripetal acceleration. > > (assuming a 15" diameter wheel). > > Can anyone point to products or applications where this is done > > already? (I know tyre pressure sensors are coming..but these are not > > FPGAs) > > > > What would the mass of your typical FPGA package/silicon be? Say a 256 > > ball BGA(e.g. FT256 or similar). Force = mass x acceleration so I guess > > you could work out the force on the solder balls etc etc. > > > > I know vibration probably is an issue also - but at least that can be > > mitigated to some extent with the mechanical design of our product > > ,e..g vibration damping etc. However, the centripetal force is another > > matter - its always there whenever the wheel is rotating. (and grows > > with the square of the cars velocity). > > > > I take you want to mount the FPGA perpendicular > to the rotation axis ? Are you aware that Tin > flows ? Under strain, tin flows slowly, over > the days. You can see that tin wire moves by > itself under gravity. So even if the pbc is able > to take the force and the FPGA case takes > the strain, the tin won't. > > Rene > -- > Ing.Buero R.Tschaggelar - http://www.ibrtses.com > & commercial newsgroups - http://www.talkto.net
