Custom Professional PCB's > Make 'em or buy 'em?

**2k1Toaster** · 02-07-2007, 03:19 PM

Hi. I am starting a project that I think will require a nice looking PCB board. I have seen some very nice looking boards for small projects, and I was just wondering how you got them?!

I know about the laser toner and iron method, but I haven't really heard of good results with small traces (surface mount components 0.65mm).

I looked at a few sites that you can just give them your design and they send you a board, but they are expensive for small runs. I found most were $20-$25 per board!

The one that I have looked at the most was http://www.pcbexpress.com/products/prices.php#1pricing because of their $51 for 3 boards deal.

I also looked at some big manufacturers with prices as low as 6.7 cents a board! Woohoo! Unitl I looked at the minimum order quantity of 60,000 units!

I don't have $4000 to spend up front on boards. And I highly doubt, I will ever sell close to 60000 units, but we can dream eh?

So if you have made a PCB before, or have had one made for you, how did you do it, or who did you use? What was the per unit cost?

Reason I ask is $20 for the board on a small project is just a killer money waster, and that could ground the entire project right there. Until now I just use a maze of wires beneath the board!

**durwood** · 02-08-2007, 03:18 PM

What about something like this? It will fit into a standard socket.

http://www.futurlec.com/SMD_Adapters.shtml

How many surface mount components do you have for those boards you are making? I know it wouldn't look as clean but just trying to help.

**jcdillin** · 02-08-2007, 04:04 PM

All my boards I use the photosenstive method. It's pretty cheap to get into and doesnt really require much stuff to purchase initially.

What I usually do is prototype the design with my homebrew PCB method and then if it goes far enough I can always send it out to a board house to make.

http://www.batchpcb.com/index.php is a service i've heard is pretty good and since it's ran by the sparkfun guys it's even better.

As far as the photosenstive method all you need is some blacklights, the photosensitve board and some sodium hydroxide to develop them. Then you can just etch using whatever method works best for you.

Here is a board I made with that method.

**MatrixPC** · 02-08-2007, 04:49 PM

I has very good luck with lazer toner and iron method when doing the Sproggy PSU (I know you already mention about that).

http://www.mp3car.com/vbulletin/show...2&postcount=43

**evandude** · 02-08-2007, 04:57 PM

From my personal experience, I routinely use 10mil (0.254mm) wide traces and track spacings on my homemade PCB's with no trouble. I'm fairly confident that I could even go slightly finer than that if needed, because of how great my PCB's come out with 10 mil traces. I use the toner transfer method with press-n-peel blue. I don't have a great tutorial of my own on it, but the closest I've found to my method is: http://aliben.wordpress.com/2006/12/02/41/

It's really cheap, once you actually have the supplies and tools. I have a dremel and (QUALITY) drill press attachment for it, an assortment of carbide drill bits I've collected from ebay over the years, a small laser printer, a cheap iron, a miniature table saw with 4-1/2" carbide-tipped blade (for cleanly cutting boards), and a small etching tank setup with an aquarium heater and air bubbler. You can get away without the saw and proper etching tank, but clearly the process is a lot cheaper to get started with if you already have any of the other items on hand.
As for actual board costs, Press-n-Peel is about 1-2 cents a square inch (well worth it IMO for the time savings vs. using photo/magazine/etc paper and having to soak/scrub it off), you can get blank PCB for on the order of just a few cents a square inch if you hit up ebay, and etching solution is relatively affordable, though I don't have a per-square-inch figure for it.

Just for reference, here are a few old pictures of mine:
http://eegeek.net/electronics/pnpb_transferred.jpg (pattern transferred, high-res)
http://eegeek.net/electronics/pnpb_transferred2.jpg (pattern transferred, size comparison)
http://eegeek.net/electronics/pnpb_etched.jpg (a board, after etching)
notice that the polishing marks are still visible on the copper - it's completely unetched - which is not always the case when using paper for the transfer.

**SnyperBob** · 02-08-2007, 05:08 PM

Originally Posted by evandude

From my personal experience, I routinely use 10mil (0.254mm) wide traces and track spacings on my homemade PCB's with no trouble. I'm fairly confident that I could even go slightly finer than that if needed, because of how great my PCB's come out with 10 mil traces. I use the toner transfer method with press-n-peel blue. I don't have a great tutorial of my own on it, but the closest I've found to my method is: http://aliben.wordpress.com/2006/12/02/41/

Nice tutorial. In the comments of the above link, they say that it's not a good idea to wash the acid down your copper drain. Here in the US, most newer homes have PVC plastic drains (slop sink/laundry tub)- would it be ok to wash it down those drains?

I'm guessing if you dilute it by running lots of water, there shouldn't be a problem? Does anyone have insight on this?

Thanks

**evandude** · 02-08-2007, 05:27 PM

Originally Posted by SnyperBob

Nice tutorial. In the comments of the above link, they say that it's not a good idea to wash the acid down your copper drain. Here in the US, most newer homes have PVC plastic drains (slop sink/laundry tub)- would it be ok to wash it down those drains?

I think the biggest issue there is not in the risk of damaging your plumbing, but in damaging the environment. Etching solution isn't exactly furiously reactive to copper - otherwise the boards would etch in mere seconds. So, once it's down the drain and diluted with a significant amount of water, I wouldn't expect it to have much effect on plumbing anyway. But, there are legal limits on how much copper (such as the copper-based chemicals in used etchant) can go down your drain. I don't know the exact number but I recall it being on the order of parts per million - meaning you would have to dilute your etchant in an incredibly large amount of water (probably more than you use in your house in a year...) to meet that regulation.

In other words, I doubt many (if any) hobbyists are meeting these kinds of regulations, and short of paying out the nose to have it disposed of at some kind of industrial chemical place, I'm sure the "dilute it as much as you can when you flush it" method is probably the most feasible.

In regards to jcdillin's post, yeah, the photoresist method is a great one - it's really the best method of all as far as performance, and even with press-n-peel I can't get that much precision. The only problem is the cost of the sensitized boards - if you feel it's a reasonable price then it could be a great method for you. For me, the appeal of being able to buy lots of regular blank PCB on ebay for mere pennies a square inch, and a big pack of PnP that will last me for years, is too great.
The photoresist method is also great if you plan to make a lot of the same board - you print one pattern and just reuse it, instead of printing off new iron-on patterns for each one. Consistent, reliable, accurate, etc...

**bbalazs** · 02-08-2007, 05:31 PM

Another vote for photosensitive method.

There are factory made photosensitive PCBs, you do not need to bother with that spray or so. They aren't expensive either.
I use two VERY clean glass plates, sandwitching the PCB and laserprinted layer. I remove the black shield just at the last moment.
Four elastic clips fix them. My lamp is an old ex-street lamp, without outer coat. A heater serves as serial resistor (do not forget in Europe there is 230V).
I dissolve certain portion of NaOH in distilled water and develop.
I use hot FeCl3 + HCl to finalise the masterpiece

My best up to now was to lead two wires between adjacent pins of a standard SMD ic.

**jcdillin** · 02-09-2007, 09:28 AM

Yup I buy my photosenstive board from digikey and mouser, which the best i've found so far is the MG Chemicals brand.

Also I don't use FeCL3 anymore since I got tired of it staining everything in sight. I use 3 to 1 mixture of hydrogen peroxide and muriatic acid which does a great job and creates it's own heat.

But I have to agree with evandude on the cost factor since a typical 4x6" presensitized copper clad board runs about $3.45 in singles it can get up there. But since you can buy all the chemicals to develop and etch at home depot it really brings the cost down.