Still Struggling with my 1st PCB toner transfer

[JohnnyB60]

As I mentioned in another thread I tried my hand for the first time at making my own PCB using the toner transfer technique. My first transfer didn’t come out very well and I’m getting ready to try it again, but after looking at the imprint on this board and I’m worried that the tracks may be too small for etching. Will the etching solution eat at the edges and undercut the tracks if it is too thin?

I made some the tracks a little larger in the software and had to move things around to allow more clearance, but I may run out of space on my 8x10 board. The PCB Artist program has the minim clearance set to 0.01” which seems way too small for etching, but then I’ve never done this before.

On my first try I used the default track width of 0.025” and I’m thinking of changing it to 0.08”.

This is a close up of just a small section of what I got for my first try with what needs to be fixed. So anyway I’m open to suggestions. Should I redo it with larger tracks and pads or just use a sharpie to fix it?
**broken link removed** I know the 8x10” board is too large for 1st time, but the expense of adding headers, connectors, and ribbon cable went outside my budget for this project. Also the addition of headers took up even more space. Anyway I found a neat idea of using a dowel for larger board at the pulsarProFx web site

 

[3v0]

Traces should be nearly the same size when etched as on the artwork. The min size is based on the current they need to handle. They can most always be made larger.

Again I would urge you to share the PCB files here. I expect we can make it smaller.

 

[JohnnyB60]

Oh thanks for the move, I did know this section was here.

 

[JohnnyB60]

The min size is based on the current they need to handle. They can most always be made larger..

From my breadboard test I have a maxim current of 6.5 milliamps so I don’t think that is a problem. It’s the etching itself that I’m worried about.

It just occurred to me that I do have another board that I could cut off a small piece to practice on. Then I can actually see for myself what the end result would be.

Also I bought Ferric Chloride for my etching just in case that makes a difference.

 

[ronv]

That is not to bad for the process. You can't get the board to clean for this method. I use cleanser (comet or the like) and alcohol and get fair results. Set the copier to dark.

 

[JohnnyB60]

That is not to bad for the process. You can't get the board to clean for this method. I use cleanser (comet or the like) and alcohol and get fair results. Set the copier to dark.

Thanks, you brought up a good point that I was wondering about. When I did this I was in a hurry and I might not have cleaned the board very well. I used a Scotch Sanding pad and cleaned it with Acetone. The 1st wipe with the Acetone was loaded with dirt, then the second time looked clean, but maybe I should have gone farther.

As far as darkening the print, I haven’t figured out how to do that with the PCB Artist program, but I’ll look again for a setting.

 

[JohnnyB60]

I printed out a sample of the board with the enlarged tracks just to see what it looks like and I hate it. It looks stupid.

So, I decided to go back to the default settings and break the board down into smaller boards, but instead of using headers and plugs, I’m going to just solder ribbon cable directly to the individual boards. I remember working on an old VCR that had the boards laid out this way and the boards folded over to stack on top of each other. I kind of like the idea of keeping the overall size small so that it will fit into a smaller box.

 

[JohnnyB60]

Cutting Copper Clad Circuit board

What can I use to make a CLEAN STRAIGHT CUT on Copper Clad circuit board?

I have a couple of saws only I would like it to be straight and clean. I also have a vinyl tile cutter that looks like a paper cutter, but I’m not so sure it would cut my 1/16” thick board. Anybody ever use a table saw?


Ok, I ended up using a band saw and filing it clean. It wasn't too bad, so now I just need to print out a sheet of toner.

 

[JohnnyB60]

I use cleanser (comet or the like) and alcohol and get fair results.

Do you use water to remove the cleanser and then clean it with alcohol?

 

[bobledoux]

I use a table saw with carbide blade to cut board.

A clean board is critical for good toner adhesion. I start by filing cut edges so there is no burr. I've found Tarnx is a good cleaner. But I follow it with comet cleanser rubbed using the fingers in a damp mixture. This is washed off and followed by a wipe of acetone. At this point no fingers touch the board surface.

I never had good luck using a laundry iron. My cheap laminator works good. I pass the board through multiple times until the board is too hot to hold.

I use the widest traces my application allows. For through hole tenth of an inch spacing I often go .050 trace width. For SOIC I drop this down to .020. I have passed two fine traces between adjacent through holes but try to avoid it.

 

[3v0]

At least for you first few PCBs forget you pride and print the stupid looking PCB with wide traces. It may save you having to do it over!

People can have problems with the edges of the PCB not being flat due to cutting. Not just burs but maybe some degree of warp from the cutter. Pays to check.

If anything goes wrong it seems to be on the traces nearest the edge of the PCB. I often use a wide dimension line around the edge of the board as a sacrificial goat.

I recall you are in the US. Spend the $10 to get a pack of Pulsar paper. It takes more then $10 work of guesswork pain out of the process. You can get it from Mouser and order other electronic parts while you are there and save the extra shipping.

 

[Mosaic]

I do boards with the toner xfer down to 10 mil (.010) trace thickness. No errors, shorts or dropouts. Doublesided as well. Surface mount devices etc. With 805 smd parts acting as jumpers is normal.



0) When cutting the PCB from your stock sheet, USE AN ACRYLIC SCRIBE, carbide, hand cutting tool, along both sides of the board. A metal ruler keeps the cut dead straight. Then snap it off. No bending warping or dust. If u desire go to a sign shop and let em cut it for u.

1) u need semi decent paper, like from an Oprah or Astronomy mag. Not the super cheap mags with easily wrinkled soft paper. Don't use paper with dark pics on it

2) Setup the Laser printer for heavy print, maximum darkness, max contrast.

3) Scrub the copperclad board with dishwashing liquid and a nylon pot scrub, until its real shiny.

4) Rinse clean and pat dry with LINT FREE cloth or bounty

5) Do not handle with bare fingers, handle edges only.

6) Stick the PCB Toner pattern face down on the copper with masking tape at the edges only. These edges should not have important traces underneath.

7) Iron on by:
a) Allowing the board to come to temp without shocking it with a super hot IRON.
b) Bring iron up to hot cotton temps AFTER the board is preheated.
c) Apply Iron from different directions and press along the edge of the iron, sliding the iron completely across the board repeatedly.
d) If u get a hot air pocket on your paper, puncture with a pin and iron again.
8) I also run my boards thru a laminator 3 or 4 times at max temp after the iron on.

9) Allow board to cool before soaking in water for 15 minutes.

10) Under running water slowly peel off the soggy paper, rubbing with your thumbs to remove the sticky spots.

11) If u have a mistake use a toothpick and nail polish to repair 'opens', or an exacto blade to remove shorts.
Etch board in Dilute Nitric acid....you can see the etching process with this...better than ferric chloride and better for the environment. 3 parts water to 1 part conc. nitric. Always add acid to water. Rinse with water when done. Mix turns blue as it is used up. When nearly opaque at 2" depth...discard.

12) Keep board damp to drill, I rub water on it to prevent dry out during drilling.
Cut board to size with a Tin Snips...no sawing or dust.


13) Sand board with 220 grit wet/dry paper to remove drill burrs. Pass your fingers on it to be sure it's smooth.

14) Clean all toner off with pure Acetone (nail polish remover - no scent etc.)

15) Using a standard pencil/pen eraser scrub the board with the 'pen' eraser (blue part of a (Staedtler eraser) before soldering.

Here's a pic of my most recent board...it's double sided, using mostly 10 mil traces, the heavy traces are the power supply section. Etched but not yet cleaned of toner.

There are a few more steps if u want to align a double sided board.

Both board sides after etch. 10 mil detail, Surface mount parts, down to 603 size components. 805 size components can jumper the traces.

ImageShack: Host and Share your Photos and Videos - dscf4612v.jpg

ImageShack: Host and Share your Photos and Videos - dscf4613.jpg

 

[DirtyLude]

Don't forget to file down the edges of the copper if you've cut the board. Cut copper clad has raised edges that ruins toner transfer around the edges. File down the edges until you can't feel any catching with your finger. This might be a non-issue if your bare boards are much larger than your design. I see a lot of how to's showing people using much larger boards than their design, then cutting them down afterward. I cut my bare copper clad to be it's final size before I transfer and etch.

Damn, 3V0 already said all this.
Nevermind. Move along, please.

 

[mvs sarma]

As of now I am able to do near perfect toner transfer. After ironing, I am just able to peel off the paper.

I use DESMAT brand 175gsm KLIK id Photo paper being sold in India as a 20 sheet packet that has list price for less than $4 equivalent. Indian ebay has them even cheaper. See the link below for details.
**broken link removed**

 

[JohnnyB60]

Ok, I’m impressed and very happy to see so many replies. I have to admit that I thought this thread was dead so I started searching and reading for hours yesterday for any info I could find. Thanks everybody.

Well, like I mentioned earlier I did cut the board with my band saw and I don’t know if there was an alignment problem with the saw or if the 8x10 board wasn’t square out of the package, because the pieces that I cut were not square. I did notice that when printed it out on my first try I also printed out the board outline so that I could accurately align it on the board and it didn’t work out so well. The only reason I was concerned about it is because I wanted to print out a mirrored image of the text so that I can silkscreen the top for reference. I don’t know how else to align the top silkscreen and the bottom copper traces except by aligning the edges.

As far as the Pulsar paper goes I wish I would have known about that weeks ago, because I’ve spent at least that long trying to figure this out and now I don’t want to wait for it to arrive. I really want to finish the etching and drilling this weekend.

I stayed late at work tonight and printed up two pages for my transfer because I don’t own a LaserJet printer. I ended up printing on two separate photo sheets because the first HP Photo sheet jammed in the printer and I only got half of it, but it will complete one board. So then I had to use Kodak Photo paper to print the second sheet because I ran out of HP paper. The Kodak Paper is backed with plastic and I don’t know how that’s going to work. If I can’t get it to work this weekend then I’m definitely ordering the Pulsar paper.

I’m very impressed with the Pulsar web site. I discovered a wealth of information on the web site including how to clean the board and they say to just use dish soap and a scotch scrub pad and wash with water. I was afraid that the water was going to cause oxidation.
And Mosaic, all I can say is WOW ! That’s perfect and I’m going to print your post as reference. Thank you.

 

[Mosaic]

Glad to share it, made lots of boards like that. If u don't plan to assemble the board right away, don't clean off the toner, the toner coat prevents oxidation.

Also I have found that having some rosin flux gel in a tub is great for doing surface mount work....The solder wire is real thin for surface mount and carries very little flux core. So i dip the solder wire tip into the flux gel b4 applying it to the board....works really well for the new lead free solders which don't flow so well.

If u care you can selectively clean the toner off the component pads alone with a q tip and acetone. Thus the traces remain coated and free of oxidation , it also prevents solder bridges from forming across pad/trace neighbours as it works like a solder mask.


To achieve alignment for double sided work or even to add new traces AFTER u have already done a transfer u need to register the patterns by using 3 or 4 pad holes which oppose each other near the board edges. I actually used unattached pads for the purpose. The holes should form either a square or a triangle shape if joined by a straight line.

1) tape the 1st toner pattern facing UP onto the board.

2) Use a large safety pin or sharp scribe to punch thru the pattern and indent the copper to create drill bit starter indents. You are pressing the 'punch' thru the 3 or 4 registration holes near the opposing edges of the pattern. Press hard to dent the copper clad.

3) Remove the toner pattern carefully.

4) Drill the hole indents with a .6 to .8 mm bit. Make sure u get the centres dead on the punched marks.

5) Now use a bobby pin (head pin) to also punch thru the registration holes on both paper patterns that u plan to align.

6) For a double sided board, place a pattern, toner down, lined up on the registration holes. Push head pins thru the aligned holes on the pattern and the board. Tape the pattern in place.

7) Turn the board over, don't let the pins fall out. The pin points are sticking up now.

8) Slide the next pattern, toner down, lining up the registration holes - onto the pin points. Settle the pattern smoothly against the board and tape the edges.

9) remove the registration pins....iron both sides...etc.


When doing this for dblsided boards...one of the patterns must be printed as a positive image and the other as a mirror image to line up and etch correctly

 

[mvs sarma]

Nice suggestion Mosaic, to use toner coat as copper protection mask, if not solder mask !!!

 

[JohnnyB60]

If u care you can selectively clean the toner off the component pads alone with a q tip and acetone. Thus the traces remain coated and free of oxidation , it also prevents solder bridges from forming across pad/trace neighbours as it works like a solder mask.

This is a great idea. I’m going to do just that, thanks.

To achieve alignment for double sided work or even to add new traces AFTER u have already done a transfer u need to register the patterns by using 3 or 4 pad holes which oppose each other near the board edges. I actually used unattached pads for the purpose. The holes should form either a square or a triangle shape if joined by a straight line.

So thats how its done. I think I might have to reprint my transfers so that I can do this. This will help a lot thanks.

 

[3v0]

There has been some good info posted to this thread. I plan to copy a few of the posts and place them in a sticky for this group.

 

[JohnnyB60]

People can have problems with the edges of the PCB not being flat due to cutting. Not just burs but maybe some degree of warp from the cutter. Pays to check..

I think this happened to me on my first attempt using the board right out of the package. I did notice the iron scraping the edge as if it were a high spot and my edges did not come out very well.

I recall you are in the US. Spend the $10 to get a pack of Pulsar paper. It takes more then $10 work of guesswork pain out of the process. You can get it from Mouser and order other electronic parts while you are there and save the extra shipping.

I went to Mouser plus a few other places and the price has gone up 50% everywhere. The shipping is also big consideration bringing it up over $22. I do have some stuff in my Jameco Shopping Cart so I’ll have to see what I can move over. I can never find everything I want at a single store.

I also noticed “Foil”, what is that used for?