Let's Make Robots!

Home Made PCB

Can someone who has experience post how to make PCBs at home? Specifically I have the following questions...

How much does it cost to get started?

Ongoing costs? Roughtly how much per PCB (assuming a size appropriate for a START HERE robot)? 

Is it "worth" making your own PCB or  just using perf board?

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Thanks, jip. That reminds me. If you want to print the component side of the board (to remind you where to stick your active components), EAGLE allows you to print the top side of the board. Print this with an inkjet printer onto a regular piece of paper and iron that onto your component side. Looks well professional.

If your PCBs don't require fine details like very thin traces or traces very close to each other you can also do it like this:

Design you PCB in Eagle, ExpressPCB, CirCad or whatever software you use (as long as it can print it). Then you attach the paper with the print to a piece of single sided copper board and tape it down really good so it sits firmly and flat against the copper. Now you drill the various holes through the paper - and through the copper board and after that you take off the paper and do the traces by hand using some waterproof marker pen (I'm not really sure if that is the right english word for that thing) - constantly checking against the paper with the print. 

When done tracing you etch the board just like BOA said using either ferric chloride og maybe something a little less messier (again I don't know the english names of these solutions). FeCl is the messiest thing you could use and it is very dark so you can't see how the etching process is coming along without having to lift the board from the solution, though it is cheap, doesn't require more than room temperature (although I think it gets better at around 30 to 40 degrees celcius) and it can be contained and reused. It takes a little while for the etching to finish, depending on how many times the solution has been used and how much copper you're going to etch away.

You can do speed-etching using HCl and NaOH but that is some serious shit and can be dangerous if not used correctly - also the result won't be as pretty as slower etching methods.

It's on my to-do list. I will post a walkthrough. Along with my getting started guide to PIC RISC assembler, building your own programmer, my outline for an opensource modular robot electronics project and ... the list goes on.

Ingredients

PCB layout program EAGLE CAD has a free version. You give it your schematic, and the autorouter creates your PCB. There is a size limit on the PCB produced by the free version. Even though it's a .DE site, it's all in English.

Your blank single sided copper clad boards are not expensive. Here are some on eBay and here are some in Farnell.

You also need ferric chloride. Pretty sure eBay is unhappy about the sale of toxic chemicals.

An etching tank. You can spend up to £500 on one if you like. Bugger that. I use an ice-cream tub. Mine is quite exotic because I added a fishtank air pump to keep the solution moving.

Press-n-peel transfer paper.

You need Scotchbrite pads and a 1mm drill bit. 

Rubber gloves or forceps (or both).

I assume you posess an electric iron. Personally, I bought a cheap one for the workshop. You'll need access to a photocopier or a laser printer. NOT an inkjet.

So, all-in-all, you can get started for about $50. You have enough material there for maybe 30 or 40 PCBs.

Method

Design your schematic, layout your components, autoroute the tracks. Print onto the blue paper. Iron onto the PCB. Peel the paper off. Cut to size. Dump it in the etching tank for 20 minutes. Scrub the excess ink off. Drill the holes.

Handle the boards with the forceps or gloves. Don't get the ferric chloride on your skin or clothes. It NEVER comes out. 

Sometimes it can be several days before I get around to populating a board. I tend to populate as I develop the software so that I can test the parts of th board as I go along. Consequently, it can be worth applying a laquer to stop the copper from oxidising. (Oxidised copper is more difficult to solder.) 

This requires equipment which is less expensive than photo sensitive boards.

Easy way or Hard way

Where do you live? If you're in the UK, Maplin have two starter kits. Cheap one and expensive one. Both are excellent value. I'm sure other companies do these, too.