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PostPosted: Thu Jun 18, 2015 1:17 pm 
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Does anyone know of a PCB maker that can handle very large 2 layer boards cost effectively in small quantities?
Yeah, I am asking for a lot in this day and age, but perhaps there is a "mom and pop" outfit with old equipment still kicking around?

I would like a board as large as 12" x 12", and only want 2 layers.
Will probably only order 2 boards to start with.

Any suggestions for a PCB house that can offer a board of this size for less than $200 would be great.

Thanks,
Brad


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PostPosted: Thu Jun 18, 2015 2:18 pm 
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I think the large size is going to keep you from getting the cost down anywhere near that low. Years ago I did however once or twice use PCB Express (not to be confused with Express PCB) for a small lot of small boards and got the entire order under $100. http://www.sunstone.com/ Their maximum size is larger than that, and they use industry-standard gerber files, unlike Express PCB which locks you into their CAD and their file type so once you've designed your board you can't go anywhere else. Do consider going to more layers though, which, besides being able to perform much better if properly laid out (with a true ground plane, not copper pours), might also make a dramatic reduction in the number of square inches needed to get it all routed, and the cost may not be any higher.

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PostPosted: Thu Jun 18, 2015 7:00 pm 
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If you would order it at OSHpark.com, it might cost you 144 x $5 = $720 but that includes shipping and you get 3 boards.

===Jac


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PostPosted: Thu Jun 18, 2015 7:06 pm 
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Yeah, big $$$ for copper real estate!

I might just stick to my original, tried and tested plan... perf board and P2P soldering.
Worked for a 40 chip design I did years ago.

Funny, for under $200, I can just keep the thing on a breadboard!
But since I have a nice oak cabinet design with a glass front, I want a slightly more compact layout than my 28" x 14" breadboard!

No big deal, I have never been afraid of a little hands on work.

Brad


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PostPosted: Fri Jun 19, 2015 4:54 am 
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Oneironaut wrote:
Yeah, big $$$ for copper real estate!

I might just stick to my original, tried and tested plan... perf board and P2P soldering.
Worked for a 40 chip design I did years ago.

Funny, for under $200, I can just keep the thing on a breadboard!
But since I have a nice oak cabinet design with a glass front, I want a slightly more compact layout than my 28" x 14" breadboard!

No big deal, I have never been afraid of a little hands on work.

Brad

Just for grins, I looked up what it would cost for Express PCB to make a two-layer, 12 × 12 (inch) PCB and ship it to Ontario. It came out to about 401 USD. The same board as four-layer would be about 530 USD. Both costs include shipping, and you get two boards for the price.

As Garth noted, a four-layer board will most likely make it possible to shrink the design, since you don't have to use up real estate in order to route Vcc and Gnd traces. Plus you'll get better noise immunity and avoid ground bounce problems. When I designed POC V1.0, I tried a layout using a two-layer board, since I wanted to go with a cheaper way. It ended up being less difficult to do it on a four-layer board, and I saw an area reduction of about 15 percent over the two-layer equivalent.

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PostPosted: Fri Jun 19, 2015 6:48 am 
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BigDumbDinosaur wrote:
As Garth noted, a four-layer board will most likely make it possible to shrink the design, since you don't have to use up real estate in order to route Vcc and Gnd traces. Plus you'll get better noise immunity and avoid ground bounce problems. When I designed POC V1.0, I tried a layout using a two-layer board, since I wanted to go with a cheaper way. It ended up being less difficult to do it on a four-layer board, and I saw an area reduction of about 15 percent over the two-layer equivalent.

I'm thinkin' an even greater reduction. The ground plane is the most important, and you get most of the effect of a Vcc plane if Vcc pins (connected by traces) are bypassed to ground immediately close to the pin, leaving a third layer available to help route signals. Now with that, you can make the board even smaller, further shortening connections and also reducing cost.

Don't be afraid to go down to the minimum trace & space width, whether .006" or whatever they allow without charging extra. Fine traces are not any more delicate than wide ones. If their characteristic impedance as transmission lines mattered, it would still be lower than you want anyway, so widening them won't be helpful in that respect. Obviously if their their resistance is too high for a high DC current on a Vcc trace, that's a separate issue; but with the bypassing at Vcc pins, you don't have to be concerned about their AC behavior. (At a 20°C rise in temperature, an 0.008" trace of 1oz copper, ie, 0.0014" thick, can carry a half Amp. From the trace's cross-sectional area and its length, you can calculate the voltage drop for a given amount of current and see if it's ok.) And again, getting traces closer together allows making the whole board smaller and traces shorter, which is good.

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PostPosted: Sat Jun 20, 2015 5:46 am 
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Oneironaut wrote:
Does anyone know of a PCB maker that can handle very large 2 layer boards cost effectively in small quantities?

I would like a board as large as 12" x 12", and only want 2 layers.

Any suggestions for a PCB house that can offer a board of this size for less than $200 would be great.


http://smart-prototyping.com/PCB-Prototyping.html seem to offer just that: 300x300mm for US$199 for 5x 2 layers boards. I've just used them for my project at https://github.com/neilstockbridge/6502-computer/tree/master/R1. The boards are not quite as beautiful as OSH Park boards but are stunning compared to anything I can achieve at home. I would recommend their DHL option for delivery since Swiss Post lost my first shipment. SP re-spun the boards at no cost.


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PostPosted: Sat Jun 20, 2015 2:56 pm 
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Thanks, that one is on my list for sure.

Brad

unclouded wrote:
Oneironaut wrote:
Does anyone know of a PCB maker that can handle very large 2 layer boards cost effectively in small quantities?

I would like a board as large as 12" x 12", and only want 2 layers.

Any suggestions for a PCB house that can offer a board of this size for less than $200 would be great.


http://smart-prototyping.com/PCB-Prototyping.html seem to offer just that: 300x300mm for US$199 for 5x 2 layers boards. I've just used them for my project at https://github.com/neilstockbridge/6502-computer/tree/master/R1. The boards are not quite as beautiful as OSH Park boards but are stunning compared to anything I can achieve at home. I would recommend their DHL option for delivery since Swiss Post lost my first shipment. SP re-spun the boards at no cost.


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PostPosted: Sun Jun 21, 2015 5:41 pm 
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I have used ExpressPCB for more than 350 jobs over the last 20+ years, with the gerber data being obtained for mass production by other companies.

When I was at the Microchip Master's conference in 2014 I learned that someone had reverse engineered the ExpressPCB format. The Robot Room's (http://www.robotroom.com) "Copper Connection" PCB program can load ExpressPCB files and output gerber data. Why is this important? Because it costs $60 everytime to get the gerber data from the ExpressPCB company. I paid that fee on over 300 jobs before finding this out. Do the math. The Copper Connection program requires a $50 fee to unlock it's ability to handle ExpressPCB files directly and output the gerber data... that's less than the cost of a single time getting the gerber data from the ExpressPCB company! Also, you can manipulate the ExpressPCB file once loaded to add graphics, move/change traces, etc. just like it was originally created using the Copper Connection program (which is quite nice). So, you can do things like change the hole sizes for vias, tint the vias, etc. before outputting the final gerber data for mass production.

PCB Unlimited (http://www.pcbunlimited.com) has the best pricing for PCB's that I have seen, especially their offshore options. In your case, 10 of the 12"x12" boards with a 6 day turn cost would be $287.10 including shipping! I have only used PCB Unlimited for 4 layer boards, and their quality is great.


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PostPosted: Mon Jun 22, 2015 1:39 am 
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JimDrew wrote:
When I was at the Microchip Master's conference in 2014 I learned that someone had reverse engineered the ExpressPCB format. The Robot Room's (http://www.robotroom.com) "Copper Connection" PCB program can load ExpressPCB files and output gerber data.

I just now tried visiting that site to no avail. The FQDN is apparently valid, but no server seems to be answering the call.

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PostPosted: Mon Jun 22, 2015 3:54 am 
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(Works for me right now. To see if a problem is local or global, use http://downforeveryoneorjustme.com/)


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PostPosted: Mon Jun 22, 2015 4:54 am 
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BigEd wrote:
(Works for me right now. To see if a problem is local or global, use http://downforeveryoneorjustme.com/)

It appears to be a problem with improperly configured DNS. The URL robotroom.com points to the IP address 72.167.131.23, which makes it an A record. The URL www.robotroom.com shows up in DNS as a CNAME record, not an A record as it should. I can reach the site via the robotroom.com URL only.

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PostPosted: Mon Jun 22, 2015 4:50 pm 
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Both methods (www and without) work for me. Must be something with your ISP.


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PostPosted: Mon Jun 22, 2015 6:13 pm 
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BigDumbDinosaur wrote:
BigEd wrote:
(Works for me right now. To see if a problem is local or global, use http://downforeveryoneorjustme.com/)

It appears to be a problem with improperly configured DNS. The URL robotroom.com points to the IP address 72.167.131.23, which makes it an A record. The URL www.robotroom.com shows up in DNS as a CNAME record, not an A record as it should. I can reach the site via the robotroom.com URL only.


I think this is exactly the way it is supposed to be: the cname record makes www.robotroom.com an alias for robotroom.com (or robotroom.com the canonical name for www.robotroom.com).


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PostPosted: Tue Jun 23, 2015 5:11 am 
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rwiker wrote:
BigDumbDinosaur wrote:
BigEd wrote:
(Works for me right now. To see if a problem is local or global, use http://downforeveryoneorjustme.com/)

It appears to be a problem with improperly configured DNS. The URL robotroom.com points to the IP address 72.167.131.23, which makes it an A record. The URL www.robotroom.com shows up in DNS as a CNAME record, not an A record as it should. I can reach the site via the robotroom.com URL only.


I think this is exactly the way it is supposed to be: the cname record makes http://www.robotroom.com an alias for robotroom.com (or robotroom.com the canonical name for http://www.robotroom.com).

It should be the other way around. 'A' records are supposed to point to specific machines.

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