Sign in to follow this  
Followers 0
Aghaster

PCB Manufacturing

10 posts in this topic

Hi,

I would like to build OpenPCD and OpenPICC, two open hardware projects to which all specifications are given on openpcd.org. The full list of components is available, so I will order them from Digikey. However, a pre-made PCB for OpenPICC is not available from the shop of the OpenPICC project, so I need to make it. The PCB files are in gerber format, so I need to find a PCB manufacturer that accepts that file format. I've never done that kind of stuff before, and I do not know which PCB manufacturer would be the best. There's a pre-made PCB for OpenPCD available in the OpenPCD shop, but I might as well make it be manufactured at the same time as the PCB for OpenPICC and save a little bit of money. Does anybody know a good PCB manufacturer with good prices for what I need? Everything is available on www.openpcd.org if you want to know more about the dimensions of the PCB I need. Thanks a lot :P

PS: I'm asking because there are literally tons of them online and I frankly have no idea which ones are good.

0

Share this post


Link to post
Share on other sites

Depending on the pitch of the smallest component's leads, you may be able to make the PCB yourself. I etch my own boards using LaserJet toner transfer -- you print the mirror of your traces on inkjet photo paper, then iron it on to copper clad board. The paper is dissolved off using warm soapy water. What's left is the re-melted toner, which acts as a resist for the etching acid. I've only used ferric chloride, but ammonium persulfate is supposed to give sharper traces. Using this method, I've produced PCBs with .01" traces spaced .01" apart, using 0805 surface mount components.

0

Share this post


Link to post
Share on other sites
Depending on the pitch of the smallest component's leads, you may be able to make the PCB yourself. I etch my own boards using LaserJet toner transfer -- you print the mirror of your traces on inkjet photo paper, then iron it on to copper clad board. The paper is dissolved off using warm soapy water. What's left is the re-melted toner, which acts as a resist for the etching acid. I've only used ferric chloride, but ammonium persulfate is supposed to give sharper traces. Using this method, I've produced PCBs with .01" traces spaced .01" apart, using 0805 surface mount components.

Would that also work with double layer PCBs? I've heard the trick you've just said from a friend, but he said it would only be doable for single layer PCBs. From what I've seen on openpcd.org OpenPCD and OpenPICC are using double layers.

0

Share this post


Link to post
Share on other sites

Etching your own is difficult. It is possible to etch single-sided PCBs for through-hole components yourself, but you run into trouble once you start getting into surface mount and double-sided PCBs. First, surface mount is very delicate. You have to perfect the etchant you use (which means you'll need to find the right concentration of hydrochloric acid, the best etchant you can get readily) and the technique in order to get an even etch. Not to mention getting toner transfer right. Also, having to etch both sides of the board at once without being able to see one side, and not having proper vias really throws a monkey wrench at you. If you want to etch your own, this isn't a good first project at any rate.

Look to Asia. You can get boards from places like Futurlec for a pretty good price. Though, as with all boards, ordering just one is quite expensive. I suggest finding some other people who want this board, order 10 or so and split the cost.

0

Share this post


Link to post
Share on other sites

Hydrochloric acid as an etchant? I doubt this would work very well, as copper is not readily attacked by HCl, at least not by HCl alone. Ferric chloride isn't the greatest stuff around, but it'll work for most hobby etching. I've heard ammonium persulfate gives much sharper traces, but I've never needed it.

Toner transfer isn't that hard to perfect -- I make surface mount and through-hole boards in my dorm room with nothing more than a block of wood, an old clothes iron, and some plastic dishes for soaking/etching. It /does/ take some time to get down, but once you've figured out how to transfer the toner to the copper, you'll find the benefits of being able to etch your own boards at home for very little cost to be worth it.

As for double-sided boards, yes, you can do them -- I have. There's two good ways to do it: you can coat one side of the board with something that resists your etchant (like varnish or wax) and remove it later, or you can drill alignment holes in the raw copper clad boards, by which you align your front and back toner sheets. I prefer alignment holes, since it means not having to etch the board twice (for the other method, you coat one side in your resist, actually etch the other side, then remove the resist, coat the etched side, and etch the previously un-etched side). For the projects I've done, four alignment holes in the corners of the board have been sufficient.

I'd at least give the toner transfer method a try. Costs are minimal, especially if you already have a laser printer. I didn't, so I picked up a HP LaserJet 4 at our university's surplus auction for $2.50. Even a printer as old as the LaserJet 4 is high enough resolution for .01 pitch components. You can, of course, print your board pattern on regular paper, and then photocopy it onto inkjet photo paper for transfer, but you'll probably lose resolution in the process.

In any case, the most crucial part in toner transfer, especially for fine pitch work, is finding a good photo paper to use. You want something that won't let the toner granules fall into the weave, but doesn't contain a plastic coating that will melt when you iron it. I've been successful with Staples house-brand matte paper.

0

Share this post


Link to post
Share on other sites

Two companies I have seen recommended are BatchPCB (Haven't heard of outside of the following article) and PCB-Pool(Seen advertised in a magazine (Nuts and Volts)). There is a write-up on a site called HackADay which talks about creating the gerber files, and they are both mentioned there. The writeup from HackADay is here. The reason that I mention these two companies is that they take designs from multiple people and collect them together, so one person doesn't have to buy the whole plate. You just pay by the square inch, and the turn-around times are ok for non critical things.

I will also plug the toner transfer method, as I have had very good luck making boards that way for quite a few years now, and have also done double sided boards with no problems. My only advice for making your own boards is get some micro drill bits (Harbor Freight sells them fairly cheap) to drill holes for through hole components and use a drill press as these bits break very easily. Second, use a carbide grit blade to cut the PCB material. It will eat normal blades very quickly. (Normal jigsaw blades might last 2 to 3 inches)

Overall, if the board has some tiny traces and is rather complicated, you might be better off just ordering it. If you see yourself trying to make boards in the future though, it might be worth wile to learn the toner transfer method.

If you have any questions about either route let me know.

-Light

0

Share this post


Link to post
Share on other sites

BatchPCB looks like a nice one, I definitely keep that one in mind. However, I decided I would probably not build OpenPCD + OpenPICC after receiving some advice. Proxmark III is a better RFID sniffer, but it is even harder to solder. I really want to eventually be able to build something like that, but I know I need to practice on smaller projects before that. Does anybody has ideas on what I could do to learn and practice my soldering skills for very tiny components?

0

Share this post


Link to post
Share on other sites
BatchPCB looks like a nice one, I definitely keep that one in mind. However, I decided I would probably not build OpenPCD + OpenPICC after receiving some advice. Proxmark III is a better RFID sniffer, but it is even harder to solder. I really want to eventually be able to build something like that, but I know I need to practice on smaller projects before that. Does anybody has ideas on what I could do to learn and practice my soldering skills for very tiny components?

you can get some really small solder like .015 diameter and just build stuff on pcbs and just bend the leads so everything is really close toghter instead of spread out and just make random circuits

0

Share this post


Link to post
Share on other sites

I've dealt with 4pcb, they are pretty reliable and makes good quality boards.

0

Share this post


Link to post
Share on other sites

Speaking of online manufacturing... can anyone recommend a machine shop that is online? Preferably one that can do plastic prototyping (3d printing) as well as typical machine shop stuff (CNC/CAD-CAM Machining, Milling, etc..)

And yes, I've seen eMachineShop. Their CAD program sucks balls...

Edited by jfalcon
0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0