PCB printing and transfering - Page 1
Forum section: electronics / projects

author: expertmax1
author_rank: Contributor
timestamp: April 25, 2013, 12:20:33 am
content: Hi !I would like to make my own little PCB, but I don't know where to start.I've already made my .pcb file using ExpressPCB which you can find here :http://www.mediafire.com/?1m8ad81dkqd0ag8So what are my options ? I am willing to spend up to 20$ for this project. Is it worth to send my project to a PCB printing company or I should do the infamous acid bath and everything ?Thanks y'all !Here is an image for people who like previews :

author: minibutmany
author_rank: Regular Contributor
timestamp: April 25, 2013, 12:37:09 am
content: I am pretty sure that express PCB files only work through their service, which is not ideal considering the price is not great(http://www.seeedstudio.com/depot/fusion-pcb-service-p-835.htmlThese guys are really cheap, but i dont know what the quality is like). I doubt you want to redo your board for another service, but there are much better ones out there. I say go for the home-etched, for simple one sided boards it is much more practical. Lots of people have tutorials and you get to use your board that day.

author: expertmax1
author_rank: Contributor
timestamp: April 25, 2013, 12:57:31 am
content: Is it possible to home-etch my own boards with ExpressPCB ?Took me like a full 3h of work to achieve my goal !

author: sleemanj
author_rank: Super Contributor
timestamp: April 25, 2013, 01:04:58 am
content: Quote from: expertmax1 on April 25, 2013, 12:57:31 amOk, you're board there is very simple. Even if you can't export from ExpressPCB for something DIY suitable, you could always just load your image into your favourite graphics program and trace over the top to produce something suitable for your etching purposes.In fact, you could just get an etch resist pen and manually draw it directly onto the copper, then etch, for a one-off.

author: kizzap
author_rank: Unknown
timestamp: April 25, 2013, 03:48:31 am
content: It looks like a nice simple circuit, if you want, I can draw up a board in Eagle for you and send you a copy of the Gerbers you would need to send to oshpark or seeed or where-ever you want to send it.let me know if you would be interested.-kizzap

author: Rerouter
author_rank: Super Contributor
timestamp: April 25, 2013, 03:55:01 am
content: you can export to bitmap or even print only the copper layer, its what i do,

author: cwalex
author_rank: Frequent Contributor
timestamp: April 25, 2013, 05:51:35 am
content: With itead and seeed studio pricing it would be better to just get them to make the board from gerbers that you supply. Itead will send you 10qty 5x5cm boards for $10 + $4 shipping, it's a no brainer. The quality is good in my experience but I'm not an expert on PCB quality.If you don't decide to take up kizzup's generous offer you could spend some time to learn diptrace (free version will be fine for your design) and draw your design in diptrace then generate the gerbers you need. Youtube has lots of tutorials and the time spent to learn a real software package will be worth it in the long run if you intend to make more boards in the future.There is also eagle cad and kicad that you could use without costing any money and there are plenty of tutorials on youtube and the interwebs to learn how to use them but I think diptrace is probably regarded as the best compromise of features and user interface but lots of opinions are out there regarding PCB software and many will disagree. The choice is yours and you can try them all out and settle for the one you find the easiest/best for your needs.Good luck with your project and more importantly have fun with itOh, BTW the shipping from itead is pretty slow, can be as long as 4 weeks so you have to have a little patience. I believe seeed has similar shipping times for the cheap shipping options but I have never used seeed so I cant speak from personal experience.

author: poorchava
author_rank: Super Contributor
timestamp: April 25, 2013, 06:31:25 am
content: There are also other companies like iTead:http://elecrow.com/<-- tried recently, very pleased with customer service, yet waiting for the PCBshttp://www.elecfreaks.com<-- haven't tried themseeedstudio.com<-- they are the contract manufacturer behind all the stuff from hackaday (like buspirate)On the other hand they probably use the same fab house anyway. For example one of them (i dunno which one, elecrow or elecfreaks) has the eagle DRC rule file even still named something like seeed_DRC.zipAs for the board: this one can be pretty much done with a dremel or something. Or a perfboard. And please ditch the Express PCB. This software absolutely sucks. You can do better PCBs in CorelDraw. Look athttp://www.diptrace.com/.

author: Skimask
author_rank: Super Contributor
timestamp: April 25, 2013, 08:28:33 am
content: Quote from: poorchava on April 25, 2013, 06:31:25 amI bought the load of "free" PCBs from them.http://www.elecfreaks.com/store/products_all.html?disp_order=3(hope the link works)The circular and "star" shaped PCBs aren't what I'd call 100% user-friendly, but for the price, the boards were just what I needed.Even though the boards were "free", they still cost about $19 S&H to the USA. Came out to about $.28 per adapter board.

author: expertmax1
author_rank: Contributor
timestamp: April 25, 2013, 11:57:40 pm
content: Today I've bought all my parts for etching.Ferric Chloride 7$Light-sensitive PCB board 6$Scalpel 2$100% acetone 4$Glass container & lid 3$Forgot to buy :Freaking small drill bits 5$-ishPrinting acetates 10$Let's hope that everything goes well and that I won't have no issues cutting out the board.Thanks y'all fo' helping mey 'out!

author: ecat
author_rank: Frequent Contributor
timestamp: April 26, 2013, 12:13:07 am
content: I assume you have the exposure of the light sensitive board worked out.Before you begin you should make the PCB tracks wider where possible, and on this board that's everywhere. I'd make them at least as wide as the pads they connect to.1) You'll have more success transferring wide tracks than skinny little ones.2) You'll have more success etching wide tracks than skinny little ones.3) Wide tracks give you more margin for alignment when drilling.

author: hlavac
author_rank: Frequent Contributor
timestamp: April 26, 2013, 10:48:06 am
content: Quote from: expertmax1 on April 25, 2013, 11:57:40 pmDeveloper for the light sensitive PCB? (You can make it by dissolving 10g of NaOH per 1L of water)

author: expertmax1
author_rank: Contributor
timestamp: April 27, 2013, 02:39:03 pm
content: I thought I could just use FeCl3.

author: poorchava
author_rank: Super Contributor
timestamp: April 27, 2013, 02:42:43 pm
content: Quote from: hlavac on April 26, 2013, 10:48:06 amI have found that around 7g/l works better. More room for error. Perhaps that's because I'm using 99.8% pure NaOH (bought on auction @ 1.50€ / kg). Might be also the fact that I'm using spray photoresist (Positiv 20).Quote from: expertmax1 on April 27, 2013, 02:39:03 pmYou need to develop photoresist after exposure. Developer will remove the lacquer where it was exposed to UV (positive resist) or where it was not exposed (negative resist). Most of commercially available presensitized laminates and spray-on resists are positive. Dry film is usually negative.Btw. Ferric Chloride is nasty. It's hard to see etching progress and it leaves unremovable brown stains on everything. And it underetches quite a lot. HCl+peroxide is the best. If you have hard time getting hydrochloric acid, then you can try Sodium Persulfate - it's the industry standard etching agent, but requires heating to ~50*C and agitation (air pump) to work well.My pcb fabrication technique goes like that:-drill and mill the pcb on a cnc machine (if you don't have cnc the you'lll drill and cut pcb later)-polish with fine (1000grit) sandpaper and/or abrasive cleaning powder-de-grease with acetone/isopropyl/paint thinne-prepare a photomask on transparency or semi-transparent drafting paper-spray thin layer of photoresist on the board and leave for 10minutes to dry. Repeat for the other side if going for 2-layer design.-put into and oven @60 *C for 20 minutes.-expose to uv (I'm using 36W nail extensions curing machine, that I bought used for ~4€). Timing has to be determined experimentally. It's 3 minutes in my case. Expose both sides if going for 2-layer design-repare solution of 7g of NaOH in 1 liter of water. I just make about 10l in one go and then store it in plastic container.-rub the board gently with a used toothbrush or something similar to help the developer react with lacquer-when you think it's done, then put it into teching agent for a second and pull out. If you can see oxidation everywhere it should be, then go on with exthing. If not then develop a little bit more. Looking at the pcb at sharp angle also makes it easier to see if development of photoresist is complete or not.-etch in 2 quantities of 3% peroxide mixed with 1 quantity of hydrochloric acid.-agitate-in 5 minutes your pcb should be ready.

author: Hardcorefs
author_rank: Regular Contributor
timestamp: April 28, 2013, 04:42:44 am
content: Quote from: expertmax1 on April 25, 2013, 12:20:33 amHi,Just before you start:1. Make the tracks atleast 4 times wider than they are2. make the holes for the pads twice as small3. Make the pads bigger.You will note that when you use 'photo resist', the results are not as good as many people make out, mainly because light can leak round the edge of the transfers, so it is a good Idea to make the tracks as thick as possible.as regards photo-resist and developer1. CHECK that the developer is DILUTED, some shops sell it undiluted, recently I have a beautiful developed result for about 10 seconds, then I saw in Chinese that the developer was needed as 1:4 parts water2. Make sure that the 'film" is as thick (opaque as possible), most laser printers DO NOT produce solid black.... it just looks like that.3. make sure you place a piece of glass over the film to flatten it down to the PCB, or you WILL get light leakage.4. Warm the ferric chloride to about 50 deg C and continually agitate the PCB, with a new batch etching time should be 4 min.

author: hlavac
author_rank: Frequent Contributor
timestamp: April 28, 2013, 02:33:10 pm
content: Quote from: expertmax1 on April 27, 2013, 02:39:03 pmNo, FeCl3 is etchant. Developer is what you use to rinse off the exposed photoresist before etching.It washes away parts that have been exposed to UV light but leaves parts that were covered by your mask.Etchant simply eats away any copper it can get to, it does not care about the photosensitivity.

author: hlavac
author_rank: Frequent Contributor
timestamp: April 28, 2013, 02:42:09 pm
content: One more tip, you will want to place the printed out mask with printed side facing the PCB to get sharp edges, which means you need to print the top side mirrored as you would do with toner transfer method.