PCB routing

Hi i would like to know anyone about PCB routing experience with Altera/Xilinx FBGA. My aim is to know if which is easier to route, and w/c one has lower layer count for 676-Ball

Thanks.

Reply to
yy7d6
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dear sir/madam

I am a pcb designer > Hi i would like to know anyone about PCB routing experience with

Reply to
mostafa

Don't know about them.....

If they both have 676 balls with the same dimensional spacing and size and you apply the same PCB layout design rules to them then they will be 'Exactly' the same.

Your mission, should you accept it, is to 'think' about how you might play with your internals, and externals, to iterate the final solution. Do not, under any circumstances, give it to a PCB monkey. Do the job yourself.

I assume that since you know about beginning sentences with capital letters the word 'iterate' will not be a problem.

I think it might be called Engineering.

DNA

Reply to
Genome

Figure that you can get the outer two rows of balls out on layer 1, and the next two rows on layer 2, and one more row per layer after that. Then you need a ground plane and probably two power planes. The Alterx/Xilinx thing depends on the details.

We did a Xilinx FG456 on an 8-layer board, with 6 rows deep of signal balls all around. I could post pics.

John

Reply to
John Larkin

Layer count is going to be about the same for both. They both use a full grid approach, rather than leaving the centre zone clear.

I've put both of them down on different boards and from a PCB layout perspective there's not really any difference between them. The biggest single thing is being able to route the signals you need to the external balls, but if you need all of them (otherwise you wouldn't be in a 676) then figure 8 layers at a minimum.

I had (on both those designs) 16 layers for other reasons, so layer count was not an issue for me.

In any case, for both devices, use non-SMD (solder mask defined) pads.

Cheers

PeteS

Reply to
PeteS

Genome, Application Notes tells that Xilinx 676 BGA was routed with 6-layers, while the competing 672 BGA was routed in 10-layers, have you tried any of these? Just want to make sure.

Reply to
yy7d6

Thanks can you show some?

Reply to
yy7d6

Hi PeteS, I have a gerber of an Altera 672-ball 8-layers, but Xilinx Applications notes says that their 676-ball can be routed with 6-layers.

Reply to
yy7d6

Can you see posts to a.b.s.e.? I could post there.

John

Reply to
John Larkin

On 03/09/2006 the venerable yy7d6 etched in runes:

To misquote Archimedes.

"Give me tracks thin enough and vias small enough and I'll do it in two layers."

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John B
Reply to
John B

Application notes are the greatest lies in the electronics universe, and can be the greatest truths.

What was being routed? What were the signal definitions? What impedance controls were required? What power? There are so many variables even for a single device that it's not possible to say how many layers are required without knowing the specifics of a design.

Cheers

PeteS

Reply to
PeteS

With tracks thin enough, you could get all the signals out on one layer, with no vias. For my FG456, about 2 mil design rules would do it, but I'd still want power and ground planes with vias.

John

Reply to
John Larkin

Xilinx has an application note on suggested routing. In fact, the Xilinx PCB routing application note is informative for people doing BGA PCBs. I doubt that you will be using all the I/O pins, so you can adjust your number of layers accordingly. The Xilinx parts have most of the power/ground pins near the center. I would assume that the Altera part is similar which means that the number of layers and routing strategy will be similar. If the Altera part has a significant number of power pins towards the outside, that can cause routing problems.

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Mark
Reply to
qrk

Did you use blind vias on the pads, or vias "between" the BGA pads? I know it costs extra to have blind/buried vias, but also it could allow you to use fewer layers possibly. Do you guys autoroute or manually route? Thanks!

cheers, Jamie

Reply to
Jamie Morken

We use dogbones, undrilled pads for the bga balls with a very short trace to a thru via, for all pads except the two outer rows, which are the undrilled pads alone.

We mostly manually route, since autorouters usually make a bigger mess than they're worth. But we do assign all the fpga pins to make routing easy, with minimum crossovers. I usually let my layout guy assign the fpga pins.

John

Reply to
John Larkin

South Africa of all places.

In looking around I found a reference on Digg that claims they are making Copper Indium Gallium Diselenide (CIGS). The breakthrough doesn't produce that much more power for the same area just (supposedly) a much lower cost for the Solar Panel. A factor of 4-5 is quoted in the second reference.

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Reply to
Robert

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AFAIK these panels are still at the 'lab' stage.

If they perform as advertised it will indeed be a major breakthrough. Since they're using Germanium I'd be concerned over their ability to take much in the way of high temperatures though.

Graham

Reply to
Eeyore

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Don't bother. Doing the math (50 watt panel costing $70 to build, $100 retail), show the panel makes about $1 of electricity a year, the cost of borrowing the money, at least $7.

And that doent include the cost of installation, maintenance, batteries, inverters, etc.

Reply to
Ancient_Hacker

"Eeyore" wrote in message news: snipped-for-privacy@REMOVETHIS.hotmail.com...

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Germanium?

I see a bunch of materials quoted but no Germanium.

Perhaps you meant the Gallium?

Quoting: "As it uses no silicon, costs are dramatically lower. It makes use of normal window glass as a substrate, with - and this is where it gets complex - molybdenum applied as back contact, followed by the core component, being a compound semiconductor comprising five elements - copper, indium, gallium, selenium and sulphide, replacing the silicon - with cadmium sulphide as a buffer layer, followed by an intrinsic zinc oxide layer and, finally, a conductive zinc-oxide layer."

They mentioned a Production Plant (verified) of 25MW. That's certainly small compared to a commercial generation plant but I don't know if it's still in the "Lab" stage. If you can believe what they say.

Robert

Reply to
Robert

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Since they quote a cost of 4 to 5 times larger for imported Solar Panels, and say there is a thriving Solar Industry using them, I certainly think the new panel will make a lot of changes in the current Industry. No one ever said they were a replacement for the Power Grid in First World Countries. And that's if you can believe what they say.

Robert

Reply to
Robert

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