Author Topic: How many layers can you get in a pcb board.  (Read 34492 times)

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Offline poorchava

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Re: How many layers can you get in a pcb board.
« Reply #25 on: August 01, 2015, 09:42:22 am »
doing a 22 right now...
I thought you work for Tesla now? From my days in automotive I can hardly recall anything with more than 8 layers... Or does Tesla do telecoms stuff too?

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Offline wkb

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Re: How many layers can you get in a pcb board.
« Reply #26 on: August 01, 2015, 07:04:55 pm »
High density boards where the norm in big compute in the late 90's a good example being Sun's E10k computer co-designed with Cray.

The centre plane had 28 layers, and the system boards had 24 layers and each weighed 30kgs!.

Being a sysadmin at the time it was a two person job to swap out a CPU!!

More info for the center plane...

"The centerplane holds the 20 address ASICs and 14 data ASICs that route information between the 16 system-board sockets. It is 27” wide x 18” tall x 141 mils thick, with 14 signal layers and 14 power layers. The net density utilization is nearly 100%. Approximately 95% of the nets were routed by hand. There are 14,000 nets, approximately two miles of wire etch, and 43,000 holes."


More detail here...

http://no.spam.ee/~tonu/starfire.pdf

regards

Tim

Very similar stuff was to be found on the big Digital Equipment AlphaServers.  We even had training courses on how to bend a pin on the backplane back into shape  :o  I never liked that concept, pins on the backplane instead of on the modules plugged into it.  DEC was not alone in doing it, I once had to fix 3x Cisco ONS DWDM system backplanes. We had borrowed them from Cisco who had used them for product trainings.  And all 3 we borrowed had pins flattened in the backplane connectors.  Argh....
 

Offline DutchGert

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Re: How many layers can you get in a pcb board.
« Reply #27 on: August 01, 2015, 11:34:16 pm »
doing a 22 right now...
I thought you work for Tesla now? From my days in automotive I can hardly recall anything with more than 8 layers... Or does Tesla do telecoms stuff too?

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Offline TSL

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Re: How many layers can you get in a pcb board.
« Reply #28 on: August 02, 2015, 07:20:43 am »

Very similar stuff was to be found on the big Digital Equipment AlphaServers.  We even had training courses on how to bend a pin on the backplane back into shape  :o  I never liked that concept, pins on the backplane instead of on the modules plugged into it.  DEC was not alone in doing it, I once had to fix 3x Cisco ONS DWDM system backplanes. We had borrowed them from Cisco who had used them for product trainings.  And all 3 we borrowed had pins flattened in the backplane connectors.  Argh....

Oh yeah, Sun did that too in the V880/890's. I remember accidentally bending pins on the back plane board after i installed a RAM upgrade on a CPU board.. Sometime the boards didn't quite align with all the pins in the back, and you had these huge levers on the front of the CPU board to apply force to the board to mate it.

On power up lots of flashing lights, pull the board and shine a torch into the cavity to see if you just did what you thought you did  :scared:

Field service where no happy!!

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Offline Muxr

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Re: How many layers can you get in a pcb board.
« Reply #29 on: September 05, 2015, 04:17:39 am »
High density boards where the norm in big compute in the late 90's a good example being Sun's E10k computer co-designed with Cray.

The centre plane had 28 layers, and the system boards had 24 layers and each weighed 30kgs!.

Being a sysadmin at the time it was a two person job to swap out a CPU!!

More info for the center plane...

"The centerplane holds the 20 address ASICs and 14 data ASICs that route information between the 16 system-board sockets. It is 27” wide x 18” tall x 141 mils thick, with 14 signal layers and 14 power layers. The net density utilization is nearly 100%. Approximately 95% of the nets were routed by hand. There are 14,000 nets, approximately two miles of wire etch, and 43,000 holes."


More detail here...

http://no.spam.ee/~tonu/starfire.pdf

regards

Tim
We had one of those [E12K] at the place I worked. It was so heavy our raised floors needed to be reinforced to hold it without the floor collapsing. Was an impressive beast.

« Last Edit: September 05, 2015, 04:22:04 am by Muxr »
 

Offline TSL

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Re: How many layers can you get in a pcb board.
« Reply #30 on: September 05, 2015, 06:00:22 am »

We had one of those [E12K] at the place I worked. It was so heavy our raised floors needed to be reinforced to hold it without the floor collapsing. Was an impressive beast.


E12 ! you mean a little one ;) The E25's we're even heavier.

The 12's weighed in at 1,982 lbs (899kg), the 25's broke a few floors at 2,514lbs (1,143kg) !!

And the big guys haven't got any lighter either.

The latest Oracle/Sun M6-32 weighs in at a whopping 3,697 lbs (1,677kg) ! as the biggest single unit they ship.



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