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Topic: PCB fabrication forum (Read 3953 times) previous topic - next topic

Lima7

Hi,

This might be a little-off topic, but does anyone know where to go to discuss PCB fabrication? I've reached the stage in my project where I want to move from a breadboard to my own PCB. I've made my own pcbs in the past using the photoresist/UV light/etching process and I've just started again using the laserjet toner-transfer method.

I've got some questions and issues to discuss, but the few forums I can find seem to be very infrequently visited.

I guess a lot of arduino users also build their own boards? Where do you go to discuss pcb fabrication issues.

Cheers

pwillard

I think General Electronics is probably going to be your best bet.  What questions do you have?   I make my own boards at home all the time.

tkbyd

I'm NOT saying "don't discuss it here"... but you might find Good Stuff already in the achives at...

http://forum.sparkfun.com/viewforum.php?f=16

or at the BatchPCB.com site... whether you end up using them or not. I'm a hobbyist/ beginner in that area, and have pretty well decided that I will use BatchPCB when it comes time to do my first that way.

A nice feature of BatchPCB is that IF you wish, they will keep your design "on file", and other people can order "copies" of your masterpiece.

If you want more of my "one eyed king" thoughts on PCB fabrication, they are at....

http://www.arunet.co.uk/tkboyd/ele1bp.htm


Lima7

Thanks for the suggestions guys, I've since discovered that there's a yahoo group forum called 'Homebrew_PCBs' which seems pretty active.

xl97

I have done some 'home brew' etching myself.. (actually just whipped one out last night in like 15 minutes)..  using toner transfer/iron method..

works great in a pinch.

I would like to branch out and take a step in the more professional world of this using Eagle.. to sendoff to PCB fab houses..

but even with all the tuts.. its a big learning curve if you are not familiar with this stuff.  (IMHO of course)

That being said.. I had a friend design something in Eagle for me/us.. and we used BatchPCB for it..

they turned out great IMHO.. and I think they had some restrictions on trace widths..etc  things looked and worked good..and the prices and hard to beat.


I wish there was a place for people here to take on small freelance jobs..  (Id like to get a schematic designed) ;)




Njay

#5
Nov 07, 2011, 05:11 pm Last Edit: Nov 07, 2011, 05:17 pm by Njay Reason: 1
I do some PCBs at home using the tone transfer method. The main "secrets" are:

1) The right paper - glossy and thin, I use a 120g HP photo paper
2) Board very well clean - and that means scrubbed, with very thin sand paper or steel wool, and then washed (I use water and soap, scrubbing to remove all dirt from sanding) *and* immediately very well dried (so that no residues are left on the board after drying). Don't over-sand at the edges, because the copper gets thinner and rounder and the toner won't adhere well (I use my PCB area to the limits).

The toner adheres amazingly well, I can even scrub the board with a brush that it won't come off easily (I have to sand again to remove it after it's etched).

I use a cheap 2KW cloth iron, set to 50-75%, and press hard for ~1 minute, then pass the iron's tip all over the board and tracks to make sure they are all well pressed (while still hot).

Then, before drilling, I pass a special varnish for protection. It's a spray can you can buy at any electronics store for this purpose, it protects and works like a flux.

Then there are some design tricks to ease your work and to ensure success. Don't go below 0,25 mm trace width. Don't go below 0,2 trace to trace spacing. Doesn't mean you can't do "better", but it requires more expertise.
I also use a trick on holes. I set them all to 0,5mm, because at this diameter they work like a "drill guide" which makes you drilling holes more accurately.

xl97

Some tips: (for home brew/etching pcb fabrication)..

1.) after iron/transfer of toner..  I use cold water to 'rinse/rub away the glossy photo paper.. (leaving only the toner on the copper clad board behind)

2.) You can use nail polish remover to remove toner after etching..  works like a charm and there is no sanding involved.



Njay

I also leave the board on water after ironing. I leave it there for some time and the paper comes off almost by itself (one of the advantages of the HP paper I mentioned).

Personally I prefer sanding over nail polish remover; I try to avoid using chemicals as much as I can.

CrossRoads

"I wish there was a place for people here to take on small freelance jobs..  (Id like to get a schematic designed) "

I could do that for you XL97. I am working a couple of designs right now even.
I've used iteadstudio to build a couple of batches of cards for me, and others have used them for cards I designed as well.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

xl97

Thanks..  (I'll PM you.. (but something tells me you aint cheap!)  LOL

Yeah I just found iteadstudio myself..  (seems cheap! and look like quality boards from pics at least)

actually read article where it was linked to.. when finding a local hacker/maker space in my city!  (WOOT!.. first meeting for me is tomorrow)


CrossRoads

Maybe not cheap, but quite efficient  XD
Will watch for your PM.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Lima7

Quote
What questions do you have?   I make my own boards at home all the time

Ok, here's the issue, I'm using the toner transfer process, after ironing most of the toner seems to transfer ok, so I dunk the board in hot water and start removing the paper. Most of the paper comes off ok, but it seem that the paper fibres actually attached to the toner prefer to stick to the toner rather than wash off. I'm using a toothbrush to remove the paper, but anything more than a gentle scrubbing and the toner comes off the board, if I don't scrub then a few tiny paper fibres remain sticking to the toner and the tracks end up blurred. First question, why is the toner not sticking very well to the board - is the iron not hot enough, am I not pressing hard enough, or not pressing for long enough? Second question, is there any paper where the fibres don't end up sticking to the toner? I seem to have gone through most of the staples product line, but to no avail. I've also tried a couple of glossy 'photo quality' papers but when I use these the paper seems to melt and stick to the pcb along with the toner! (if I turn the temperature down the toner doesn't transfer). I've also tried one of the press 'n' peel systems http://www.maplin.co.uk/press-n-peel-pcb-transfersystem-13464?c=froogle&u=13464&t=module but these seem to be only slightly better and at £20 for 5 sheets it ain't cheap!
Before starting I clean the boards with an abasive block, then accetone, then dry them. I'm having so little luck with the toner transfer process, I'm thinking of biting the bullet and buying/making a UV light box instead.

Cheers

xl97

hi..heres my .02 cents on it. =)


1.) I use COLD water.. (not sure if it makes a difference..but in my minds eye.. I do NOT want to heat/warm up the toner again.. I want it to adhere to the copper clad board)

2.) I too get the 'residue' after you peel off the paper.....  gentle finger rubbing will get rid of 95% of it..   run under water...  peel/rub..  then let sit in cup of water for a few..come back and re-run with finger..   (rinse/repeat).. do this a few times.. and most everythign outside of the 'junk' between FINE traces will be removed.    I was never sure if the etchant would be retarded by the left over residue or if it would dissolve it away (like the copper)...  but I some times take an exacto knife and run between the traces lightly.. just to be sure.. you can see the white residue/fog being removed after.

3.) I iron HOT.. very hot in fact...  Im not sure at what temp you get the copper separating from the board..but it hasnt happened to me yet..  (only sanding my toner off has left me with errors/problems)

and I keep pressure on it.. while moving back and forth

you should ALWAYS USE A GLOSSY PHOTO PAPER!..  the paper WILL stick to the PCB....but once you get it wet.. it will fall off/apart from the pcb..  and you rub the remaining off.



on the flip side.. it cant urt (and would be fun) to make a UV box!..

stencils can be re-used.. and from what I gather.. great results can also be had from these.

(I think I saw a nice one posted on Instructables or hackaday or something)

Njay

I think xl97 mostly said it all. I keep pressing hard on the iron (almost with my weight) for 1m to 1m30s, not moving the iron. Then I use the iron's tip to pass hard all over the board, with special emphasis on the toner zones while everything is still hot for another 2m or so. And that's it. Then let the board+paper sink in water for 10-15m and then scrub lightly with finger, dip in water, scrub, etc until it all comes off. Those fibers being left is because of the paper. It happened to me when I used normal paper, but not with this HP glossy paper. As I said my iron is 2KW, and I set it to 0.5 to 0.75%. I also can scrub it with a toothbrush-like tool and the toner won't come off easily (only comes off easily on parts that didn't get enough heat/pressure, but that doesn't happen to me anymore). Print with maximum darkness. I don't have the paper ref with me, maybe it's not produced anymore I bought it some 3years ago, it's HP 120g/m^2 photo paper for laser printers, comes in a package of 200 A4 sheets; anyways being a thin paper is part of the "secret", try any 120g/m^2 or less you can find.

cyclegadget


Maybe not cheap, but quite efficient  XD
Will watch for your PM.


CrossRoads helped me with a couple designs. I made the designs in Eagle, he checked my work and gave me great tips. He will work with you I am sure.

  I made my order to Itead a little while back I need to find out where it is. I am still waiting for the boards I ordered. They haven't charged me yet as far as I know.
Good links: Eagle tutorial= http://www.youtube.com/playlist?list=PLDE1858BD83D19C70
General Arduion tutorials = http://tronixstuff.wordpress.com
http://www.gammon.com.au/forum/bbshowpost.php?bbtopic_id=123

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