PCB's - Iron Transfer Method

goom

Senior Member
#1
I've been making PCB's for some time using iron-on transfer from a laser print on paper. I bought some glossy paper recently in the US, and have just tried it.
It works perfectly. NO imperfections, NO smearing, EASY to remove with a bit of soap and water, NO furry redidue across the bare copper.
The paper is:
Color laser paper, gloss white . heavyweight
Source: Staples item# 633215
Size: 8.5" x 11"
Quantity: 300 sheets per package
Price: I think I paid about $7.00

I use 1 part murialic (hydrochloric) acid to 2 parts 3% hydrogen peroxide as an etchant. Fast and very cheap, but demands a little more respect than ferric chloride.

Hope this helps someone.
 
#2
Isnt it bad to mix an acid and an oxidizer? I have not etched my own boards yet ,Most of what I make is on proto boards. Do I just have to mix the acid and H202 slowly or do I have to do anything else to it? Also , What do you use on it to keep the chemicals from burning off the part you want to stay? Thanks.
 
#3
Be very careful with gloss papers in laser printers. The gloss surface is usually plasticised, with a melting temperature way below the fusing temperature used in laser printers/photo copiers. Result, the plasticised paper wound around and fused to the heated fusing roller and a ruined machine. See my homepage at http://www.users.on.net/~endsodds. But I like the etchant ....:)
 

goom

Senior Member
#4
The paper is supposedly "for laser printers only", so I guess that it should not be a problem with melting in the fuser.

I just throw the acid and H2O2 together in a glass dish. Nothing seems to happen when I do so (no fizzing, bubbling, fuming). It does seem to warm up a little, but that is all to the good for the etching.
 

goom

Senior Member
#5
I print the PCB design using a cheap black & white laser printer, with the quality set to "dark". I use Visio to draw the PCB (and the schematic). I have even embedded 6 point text (using a mirror font), and it printed and etched perfectly.
Then clean the copper-clad board VERY thoroughly. I use fine steel wool followed by swabbing with laquer thinner, then methyl hydrate (may be overkill). Keep your fingers off the freshly cleaned board.
With the laser print face down on the copper, rub the paper with a household iron set to maximum temperature. Keep going, with quite heavy pressure, until you get a reasonably uniform bleed through of the black toner onto the unprinted side of the paper.
Soak the paper with warm water and a bit of soap for a minute or so. The paper can be easily rubbed off with your fingers or an old tothbrush, leaving the toner well adhered to the copper. Check for defects and touch-up with a permanent marker (with this paper I needed NO touch-ups).
Use laquer thinner to remove the toner after etching. I then centerpunch and drill the holes, swab with acid flux, tin with a soldering iron, then scrub with soap and water. All ready now to populate with your components.
 
#6
A comment and a question. I also use Visio to draw the board. I have found if I have the holes marked in the pads a little larger than required (eg 1.0 to 1.2mm), they etch out, creating a natural "centrepunch" for steadying the drill bit. - I should say I'm currently using Press-n-Peel, not paper.

The font I use in StraitBack (KCAB.TTF) - its not ideal for PCBs, a bit chunky, but its the best I can find. What font do you use?
 
#7
I'm the same as Pete. I draft using Protel Autotrax, and use their printing package to produce an .eps file (mirror image) which I then print on to clay based paper. I draft with 34 thou holes (0.85mm) or slightly larger for items like trimpots, 1N4004's etc, and after etching, have perfectly centred hole targets in the copper for the drill (and an NC drilling table all prepared).
 

goom

Senior Member
#8
I use PRMirror as a mirrored font in visio. You can download it at:
http://www.searchfreefonts.com/search/?q=prmirror

I have also developed some templates for common components (for schematics) and PCB pads and DIP footprints. Send me a private message if you would like me to email it (and the font if necessary).

I use 0.02" holes. I do centerpunch each hole before drilling.
 
#9
Protective equipment

The muratic acid / peroxide etchant does have some advantqges over Ferric Chloride, it is less expensive, and clear which makes it easier to monitor the etching. Unfortunately, it is much more agressive and dangerous to the skin and eyes.

The Muriatic Acid will eat though clothing and skin. Acid burns are one of the most painful burns that you can have. Even the mist or tiny droplets can cause painful rashes. And yes, I am talking from experience. :(

So protective equipment, goggles and gloves are a must.

Also keep a box of Baking Soda (Sodium Bicarbonate) handy to neutralize any spills and have ready to put on your skin. It is also useful to wipe down the work area. Any little bit of foaming shows where the acid spilled. It is amazing to see where the droplets end up.

Baking Soda can also be used to neutralize the etch before diposing it. The etch does also work very well on copper and brass plumbing. I ususually dilute the etch before neutralizing and add the Baking Soda very slowly to reduce the amount foaming.

Be safe!

Myc (retired Industrial Chemist)
 
#10
PCB Cad software

Everyone has their "favorite" software to draw pcbs. After trying quite a few, finally settled on DIPTRACE and have using it for a number of years. It is easy to learn and the free version will do boards with up to 250 pins. There are a jumber of printing options, including mirroring and reverse, as well as gerber outputs and isolation milling. Not bad for a free package.

Here is a link to the website: www.diptrace.com

I use DIPTRACE along with a custom library of parts that I created to make my pcbs using the Toner Transfer process. I'll make the same offer as Goom, send me a private email and I'll send a copy of the library.
 
#11
I've recently read about a chap who has had much success using magazine paper to do the toner transfer... the image seems to transfer better and faster, and the paper is much much easier to remove when you go to soak it off... I think he recommends "Us" magazine as the best... Lots of great discussion about making your own PCB's are at Yahoo's Homebrew PCB forum at http://tech.groups.yahoo.com/group/Homebrew_PCBs/
 
#12
Talking of PCB,s I use the INKJET print direct to copper method,
No paper needed , Just print with an Epson Printer , Bake the ink
to make it Etch proof , then etch with Ferric Chloride, clean the
ink off with acetone, then drill the board , ready to populate.

Here is a small Example before cleaning with the ink still on the traces.

Kym
 
#13
Just print with an Epson Printer , Bake the ink to make it Etch proof
kym, Can you point us to more info on this? (Or give more of your experiences) Does the printer have to be modified?

...I'm all for making life easier for myself ;o) Although I seem to have only recently gotten on top of the PnP method.
 
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