Author Topic: Board too big to fab cheaply? (6x8")  (Read 4732 times)

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Offline justanothercanuckTopic starter

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Board too big to fab cheaply? (6x8")
« on: December 28, 2012, 11:41:40 am »
I've been working on a PCB in kicad, and I've started to think about how I'm going to get it fabbed.

The board is quite large, 6x8" in size, 4 layers, comprised of all through-hole components.  I could convert the passives to SMT so save some space, but it wouldn't save a lot, and I think it would disrupt the look of the board, and the premise of the project...  and there are some components I just can't convert, because they're ~30 years old.

I had a look at a few sites listed on the wiki for board fabbing, but they all seem to want $300+ to build my board, let alone place parts on it...  Seems like a lot considering you can buy a PC motherboard for less than $100.

Am I really stuck paying these crazy prices?

Thanks
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Offline mariush

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Re: Board too big to fab cheaply? (6x8")
« Reply #1 on: December 28, 2012, 12:12:24 pm »
Eurocircuits will do 1 for 150 euro (including shipping)

If you want more boards, like 10 or more, it's much cheaper... about 35 euro + vat for each board.

Play with the calculator here if you want: http://be.eurocircuits.com/basic/ecbasket/order.aspx?lang=en

 

Offline AndyC_772

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Re: Board too big to fab cheaply? (6x8")
« Reply #2 on: December 28, 2012, 12:34:14 pm »
6x8 isn't big by any means. Bear in mind it's the PC motherboard that's ridiculously priced for what it is, because they're produced in enormous quantities. Any one-off PCB is going to be expensive purely because of the tooling cost.

Offline justanothercanuckTopic starter

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Re: Board too big to fab cheaply? (6x8")
« Reply #3 on: December 28, 2012, 01:00:20 pm »
Really?  I don't mind being the one that's crazy, but I figured oldschool tech would be cheaper...  :scared:
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Online mikeselectricstuff

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Re: Board too big to fab cheaply? (6x8")
« Reply #4 on: December 28, 2012, 01:06:30 pm »
Does it really need to be 4 layer? Going to 2 layer (even if you need finer track/space) will save a lot of cost.
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Offline TheWelly888

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Re: Board too big to fab cheaply? (6x8")
« Reply #5 on: December 28, 2012, 03:12:07 pm »
....and I think it would disrupt the look of the board, and the premise of the project...  and there are some components I just can't convert, because they're ~30 years old.
I get the impression that the appearance of the finished board is important? If you want a certain colour for the substrate then you have no choice but to pay more....
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Offline mariush

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Re: Board too big to fab cheaply? (6x8")
« Reply #6 on: December 28, 2012, 03:20:35 pm »
Another idea... perhaps it would be cheaper to make the board a two layer one and use additional small pcbs that mount vertically to make room on the big board... kind of like how power supplies use small dc-dc converters on separate boards:

like you see in this picture : http://www.techpowerup.com/reviews/Silverstone/ST45SF-G/images/in_VRMs3.jpg

Not sure if there'd be a problem with the additional resistance of the connectors and trace lengths when connecting the pcbs together though.
 

Offline justanothercanuckTopic starter

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Re: Board too big to fab cheaply? (6x8")
« Reply #7 on: December 29, 2012, 07:57:17 am »
I guess I can spill the beans a little...  I'm trying to build a 70s/80s microcomputer from scratch...  I'm hoping to keep it as classic looking as possible...

Anywho, I can move the power supply to its own board, and move the memory/IO logic chips to a riser board, but the main board (containing the MPU, ROM, and half the RAM) still remains. 

And it leaves out how I would interconnect all these PCB fragments.  I was tinkering with the idea of making a backplane that other boards would connect to (UART/serial, the other half of the RAM, video, sound, maybe DMA... FDC...  I'm getting ahead of myself here), but the only connection method I could think of that would provide adequate contacts is a PCI connector.

I'm not that keen on slimming the board down to 2 layers... because of the busses running down both sides of the chips, running power lines might not be possible...  I suppose theoretically I could move the busses to a single side, but I'm pretty sure I would still wind up using both layers for signal traces, which makes running power and ground planes a pain.

But I'll keep thinking about it...  I really want to see this project to the end, I was just hoping it would be cheaper so others could also build one of their own.
« Last Edit: December 29, 2012, 07:59:35 am by justanothercanuck »
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Offline free_electron

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Re: Board too big to fab cheaply? (6x8")
« Reply #8 on: December 29, 2012, 03:46:58 pm »
fab it at iteadstudio. it'll be cheap.
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Offline peter.mitchell

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Re: Board too big to fab cheaply? (6x8")
« Reply #9 on: December 23, 2013, 02:41:43 pm »
Just wondering, did this ever get completed, if so, do you have pics?
 


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