Printed Circuit Boards

SK8 4 U

Hi all...

What is the new technology for desinging and laying out printed circuit boards?· When I was really into it, it was a time consuming and very messy procedure, which involved designing and laying out the board with tape and sticky symbols, transfering that design to film, photosenthesizing the copper clad board with a really nasty and·gloppy substance, transfering the image to the board with a high power UV light that constantly burned my eyes and hands, then etching the board with chromic acid...the end product was servicable but not pretty.·I know that there must be a better way now (it has been about 25 years or so) to make PCBs now using computers.· Any ideals would be most welcome!


Thanks in advance

Joe
KB0TXC


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Cats are the creator's method of demonstrating to mankind that man is not the supreme being.

Paul Baker

Am I understanding that you want to create the boards yourself? Many people who do thier own boards use someting like this product http://www.allelectronics.com/cgi-bin/category.cgi?category=445&item=TEK-5&type=store·which is basically iron on transfer using copy toner as your resist.

If you want to have them done professionally, many people on the forums use www.expresspcb.com·which has a deal for 3 boards 2.5" x 3.8" for $51. They have a proprietary layout program for designing boards availible for free download on their website. These boards still have a prototype feel to them because they do not have a soldermask or silkscreen.

When I have time to wait for a board, I like to use www.sparkfun.com. They have a PCB production service for $2.50/sq in. no minimum size and has soldermask and silkscreen and can accomodate trace pitches small enough for 0.85 mm pin spacing surface mount parts. The turn around time is 10-18 days because they aggregate several customer orders and have an asian PCB manufacturer do the production. They require Gerber files.

When I do not have time to wait or I have surface mount parts with 0.50 mm pin spacing I use www.33each.com which offers 3 boards up to 60 sq. inches apeice for $99·(discounts are availible for students) and has soldermask and silkscreen. They also have in-house designers to check over your design to make sure your not making any production mistakes such as placing soldermask over pins. They too require Gerber files but will do translation from other formats such as OrCAD for you. Their turn around for this service is 5 business days, faster times are availible by using thier regular service (for more cost of course).

To create designs using Gerber file formating, I use EaglePCB from www.cadsoft.de. Thier free version does all the things the professional version does except the board size is limited to 4·x·3.2·inches and two layers.

Post Edited (Paul Baker) : 4/20/2005 2:53:50 PM GMT

Paul Baker

Ah and most people use Ferric chloride as the etchant nowadays, its less toxic than chomic acid and has a much longer shelf life when in anhydrous form. Again allelectronics sell 1/4 lb bags (makes 1 pint solution, enough to etch·200 sq in) for $4 here http://www.allelectronics.com/cgi-bin/category.cgi?category=445&item=ER-3&type=store·or you can pickup a PCB kit from radioshack that contains a small bottle of liquid Ferric cloride (and ignore thier Sharpie photoresist instructions, it produces useable boards in a pinch but because its near impossible to apply a uniform coat of the ink you'll end up with a fair amount of pitting).

Photosensitized boards are not really used that much any more, you just clean your board, apply the resist, etch, rinse, disolve the resist and rinse again.

Post Edited (Paul Baker) : 4/20/2005 3:32:23 PM GMT

Jon Williams

Places like ExpressPCB offer such good service at low prices that I wouldn't even consider making a board at home anymore -- but that's just me; I have a lot of things on my plate and the last thing I want to do is etch a board.

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Jon Williams
Applications Engineer, Parallax
Dallas, TX· USA

Chris Savage

·· I too, use ExpressPCB for prototyping.· The boards have always been great, and you can't beat the prices when you consider free software that's very easy to use and you can add components too.

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Chris Savage
Parallax Tech Support
csavage@parallax.com

StarMan

Does ExpressPCB output a gerber file?· Can you get boards made elsewhere if you want to scale up to higher production?

Chris Isaacson

Forrest

You can use inkjet photopaper in a laser printer/copier to transfer an image to copper clad laminate by ironing it on the board - see www.fullnet.com/u/tomg/gooteepc.htm

I've used this method to make a few boards and it works fine, though it's somewhat time consuming because you'll need to use a toothbrush to remove the photopaper before you can start etching. If you're in a hurry, Radio Shack still sells copper clad laminate (4.5 x 6.125 in for $4.29) and a pint of ferric chloride ethchant for $4.29. If you have the time - you can find copper clad laminate for much less online - I picked-up a 4 x 8 in x .026 inch thick piece for $.95 at www.goldmine-elec-products.com/home.asp

If you want more information - or want to learn how to design and build your own printer and etcher then check out groups.yahoo.com/group/Homebrew_PCBs/

SK8 4 U

Hi again...

I agree...I do not have the time or inclination to actually etch a board...I would much rather get a professionally made board with solder mask and screen printing. You have to remember that the last time that I actually made a PCB was 25 years ago, and as I said before, that was a real nasty process.

I have one question though, and I am afraid that it shows my ignorance...what is a Gerber file? I am going to look at the companies that were mentioned above, and hopefully get going on this. One other question...does one input the circuit diagram and the software design the layout or do you design the layout yourself and the software simply makes it look good and bring the spacings and such to spec?

Thanks again for taking time to answer some very basic questions!

all the best

joe

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Cats are the creator's method of demonstrating to mankind that man is not the supreme being.

Jon Williams

No, but ExpressPCB also offers production service with full silkscreen, etc.· I spoke with them once about taking the design elsewhere, and their position at the time was that they would sell you the gerber files and you could do with them as you please (in a way, that's like paying a license to use their design software).

StarMan said...

Does ExpressPCB output a gerber file?· Can you get boards made elsewhere if you want to scale up to higher production?

Chris Isaacson

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Jon Williams
Applications Engineer, Parallax
Dallas, TX· USA

Chris Savage

StarMan said...
Does ExpressPCB output a gerber file?· Can you get boards made elsewhere if you want to scale up to higher production?
Chris Isaacson

Chris,

·· No, ExpressPCB doesn't output to a gerber file directly.· It uses a proprietary format.· I don't know if they still do it, but it seems like you used to be able to buy the gerber file from them.· They do however offer decent prices on higher capacity production runs, so you don't necessarily need to go elsewhere.

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Chris Savage
Parallax Tech Support
csavage@parallax.com

Paul Baker

Codecat said...
Hi again...

I have one question though, and I am afraid that it shows my ignorance...what is a Gerber file? I am going to look at the companies that were mentioned above, and hopefully get going on this. One other question...does one input the circuit diagram and the software design the layout or do you design the layout yourself and the software simply makes it look good and bring the spacings and such to spec?

Gerber is a file format to describe a PCB layout, it is considered the industry standard. Like mentioned above, expresspcb's software does not provide files in this format. Both expresspcb's software and EaglePCB offer schematic and board layout in thier packages. To my knowledge expresspcb's software requires you to provide the linkage between the two, EaglePCB does automatic linking, EaglePCB also has autorouting. Both packages permit you to define new parts (schematically and board layout). People say expresspcb's software is easier to create new parts, but Ive never had problems·defining parts in·EaglePCB.·I, simply·as a matter of taste, do not use expresspcb. Getting boards of comperable quality (including soldermask and silkscreen) makes expresspcb not attractive at all pricewise. Thier 10 day service for production quality boards is $233 + ($0.27 * NumberOfBoards * BoardAreaInSquareInches) + ($0.50 * NumberOfBoards) - QuantityDiscount + Shipping. This comes out to over 2.5 times the cost of using 33each.com for the exact same board. Plus you cannot send the layout files to any other company (without paying for a translation service). With EaglePCB and Gerber files I can take my board to any major PCB fab company, lets just say I don't like feeling locked into one vendor unless I feel that I can get quality support at all times and at a competitive price (I am not saying expresspcb does not have quality support, on the contrary Ive heard nothing but glowing remarks, but in my mind expresspcb is not "medium scale friendly", thier price points are good for proto-work and large·volume work but really nails you in the mid-range).

Post Edited (Paul Baker) : 4/20/2005 6:11:06 PM GMT

Bean

I've been happy with pcbexpress.com (not expresspcb.com, I haven't tried them). Althought you do have to provide gerber files. They have a deal for 4 board for $100 (with solder mask and marking). They say the boards must be 3.375 x 2.875, but when I provided a board layer, they always have cut them to my board size. They are very good quality boards.

I have also used pcbpro.com for production board (same company as pcbexpress). The pricing was good, but the boards weren't quite the same quality as the 4 for $100 boards. Of course they were only $2.50 each for 150 boards 1.5"x2.0", so I has happy. The main problem I had was that the solder mask had "drip" marks on some of the boards. Doesn't hurt anything...Just doesn't look too good.

Bean.

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"A problem well defined, is a problem·half solved."
·

Steve Joblin

If you have Eagle CAD (you can download a free demo version), you can use the folks at SparkFun (http://www.sparkfun.com) to get a PC board made for the rediculous low price of just $2.50/sq in.

dkemppai

Bean said...
I've been happy with pcbexpress.com (not expresspcb.com, I haven't tried them). Althought you do have to provide gerber files. They have a deal for 4 board for $100 (with solder mask and marking). They say the boards must be 3.375 x 2.875, but when I provided a board layer, they always have cut them to my board size. They are very good quality boards.

Bean.

I'm surprised that no one knows about Eprotos. https://www.eprotos.com/qorder.asp

You provide gerber, and order is online, credit card only. The web page is a little screwey, but
5 peices, 5 days turn,Specs: FR4, 0.062",1 Oz Cu., SMT pitch minimum 0.025", smallest hole 0.015", all Plated holes, smallest trace/space 0.007", Green LPI Mask, White Silkscreen, Individual boards.

Most of the time they send more than the 5 peices, usually 7 to 9 boards for $75 for the lot.
Cheapest I've found.

-Dan
·

Phil Pilgrim

For layout, I use CADint:

www.cadint.com (U.S.)
www.cadint.se (Elsewhere)

The user interface takes some getting used to, but once you get over the hump it leaves the others in the dust productivity-wise.

For proto PCBs, I highly recommend Alberta Printed Circuits:

www.apcircuits.com

They have two-day turns and rock-bottom prices for two-sided PTH boards without soldermask or silkscreen.

In dealing with a proto house, the first thing you want to ask them is their definition of a "board". Most will not allow you to panelize more than one copy or one design on a single "board" without charging extra. Fortunately, APCircuits doesn't employ any Panelization Police, realizing (rightly) that their business is drilling holes and etching copper by the square inch -- not scrutinizing their customers' designs. I refuse to deal with any board houses who charge extra for panelized submissions.

For soldering surface mount boards, I use solder paste from DigiKey that's sold in a syringe. (Can't remember the brand.) The boards are then reflow soldered in a Panasonic NB-G100P infrared toaster oven. It works great, but -- even with the time and temp control -- you've gotta keep your eye on the board while it's in there!

SK8 4 U

Hi Phil...

When you wrote that you use a toaster oven to reflow your solder, it reminded me of when I would have to use that glopy photosensetiser on the copper clad...once we had it spread on the board, we would let it dry for an hour (in the dark of course), then put it on a cake cooling rack (small one) inside of an electric fry skillet over night to cure. The skillet was supposed to be set on the lowest setting, but sometimes a prankster would turn it all the way up, and if someone didn't check it when placing their board in there, the next morning they would really have a toasted board!

All the best,

Joe
KB0TXC

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Cats are the creator's method of demonstrating to mankind that man is not the supreme being.

bobledoux

Try this site. He uses ExpressPCB software to provide the masters for boards etched at home.

http://robotroom.com/PCB.html

Dave Paton

Eagle (v4.1...so much better than the last 3 revisions) and the nice guys at Advanced Circuits (4pcb.com, 33each.com) are my personal favorite way to get things done. Of course, I deal with big and very compex boards, so I use the full version of Eagle (which my boss paid for) but at home and on the weekends, I use the freeware version and love it. It's really to generate gerbers, and it has great integration betweent he schematic capture and board layout sections. It's very hard to screw up a board if the schematic is right.
My $0.02, being a progrssional at this stuff

-dave

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This is not a sig. This is a duck. Quack.

Bean

Phil Pilgrim (PhiPi) said...
In dealing with a proto house, the first thing you want to ask them is their definition of a "board". Most will not allow you to panelize more than one copy or one design on a single "board" without charging extra. Fortunately, APCircuits doesn't employ any Panelization Police, realizing (rightly) that their business is drilling holes and etching copper by the square inch -- not scrutinizing their customers' designs. I refuse to deal with any board houses who charge extra for panelized submissions.

Phil,
· I have to agree. The board houses incure no extra expense for a multi-up board (against a board of similar size with the same # of holes). So I don't see how they can justify the extra charge. I would be like an extra charge for buying 4 of the same candy bar. It makes no sense.
Bean.


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"SX-Video Display Module" Available Now.

www.sxvm.com

"A problem well defined, is a problem·half solved."
·

MacGeek117

Bean, ExpressPcb is very good to. you should try ExpressSch, to.
bugg

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Ryan Clarke

I have used http://www.expresspcb.com/ and had very good luck with them. (Good quality)- They have a 'miniboard' service for just over $50 bucks....

You might want to check out the Al Williams book "Build Your Own Printed Circuit Board" (ISBN 0-07-142783-X) - great source of info, and teaches you basics of Eagle CAD.

Ryan

inaki

Are there any comparable service to those mentioned in this thread in Europe ?

I know lots of professional pcb services here but I am thinking on something suitable for small series.

Harry Stoner

Try Olimex, www.olimex.com. Low prices, low shipping costs and good turnaround. There service is good for me in Canada because they ship via the post office for US$9, as opposed to many of the other places that might charge $20 or more for Fedex/UPS shipping. Board prices themselves are low.

Harry