Tweaking PCB pics for Press-N-Peel?

[CJ Miller]

I have been looking forward to making my first PCBs for some time. A few things cinched it lately - I didn't think that I had PNP or a clothes iron, but it seems that I do. And I definately have board layouts which I'd love to try etching. I am as n00b, though, so my first PCBs are other people's work. This way I get to hopefully try some cool old projects I've heard about, and the troubleshooting process should be much simpler.

My wife has Photoshop, so I used it to panel the art for an 8"x10" copper board, which I then plan on cutting into module-sized pieces. I have found my way around well enough to figure out a few things like positive/negative, contrast, rotation, size, pixel density, and layers. But now that I am printing it out on paper to test, I am nervous about the quality of the lines. Way too many jaggy edges.

Any tips from some of you more-experienced people who have done this sort of thing? Since these are just lines in black, I am hoping that there is some kind of edge detection which can be done to make them crisp - or even convert them into vectors. Then my laserjet should be able to make a nice printing of these. As things are, I'm afraid I should hold off until I get better edges on here. I would be grateful for any advice here.

[andrewF]

I set the printer to blurt ink at 1200dpi, a lot of printing software is different so best to explore yours and do plenty of test prints before the P&P.

could you post an image to show the jagged edges?

Btw - i don't use P&P anymore, $33 for 6 sheets in Australia.
now its ceramic based matte photo paper - $15 for 100 sheets!
bit more hassle to remove the paper after ironing - long soak in water. Otherwise just as good.

good description here - http://www.users.on.net/~endsodds/pcb.htm

[CJ Miller]

Hi Andrew! I will try to post some comparisons later. I've been messing around and now it is far past my bedtime! And thanks for the tip about that paper, I want to learn more.

What I've done is open one of the pictures in Illustrator. It turns out that there are raster>vector features here which sound like what I want. But I don't know what the parameters mean or how they work yet. And to compound matters, I don't know how Illustrators tools work. The vector process completely improves the lines, but the pads become less defined. I tried using "tools" to draw circles and rectangles for the pads. They looked perfect - except that they always have a border around them! So my new pads aren't connected. I'll figure something out later, but I need to sleep now...zzz

[Luka]

andrew your are awesome
i was just about to buy PnP

cheers

[fluxmonkey]

http://www.electro-music.com/forum/viewtopic.php?highlight=peel&t=21654

[Peake]

I've just started at this using Photoshop as well, truly the most difficult method, I'm told. The pencil becomes a line tool, you can of course change the trace widths, and using a thin width plus the IIRC shift plus mouse click, add or undo the thickness of traces (using white or black tone). Save multiple edits as you flatten the layers so that you can then connect new pads, etc.

I hope to move to something easier, and recommend it to you as well.

[CJ Miller]

That was a lot of sleep, I needed it. Now I am back on the case for a few hours.

bbob - Thanks for reminding me of this thread you linked. I am particularly amazed by the direct etchant printing! I have seen many discussions about materials and techniques, but I started this thread because I usually see no mention of preparing the graphics files themselves for printing. This is an aspect of synth diy which I hadn't thought much about before.

Peake - It seems that there are many capable applications for making one's own PCB layouts. I would never try making a new layout in Photoshop nor Illustrator, if I could help it. My concern here is taking jpegs and other such graphic files of PCB art and cleaning them up prior to printing. These types of graphics apps do seem ideally suited to this sort of task. The problem is mainly my lack of familiarity with the tools.

[CJ Miller]

[fluxmonkey]

I do a lot of PCB artwork cleanup in photoshop, altho i've learned some tricks it can be either tedious or meditative. various tools i often use:

i edit at 300dpi; increase the resolution of the original file if necessary.

sharpen filters, including unsharp mask and sharpen edges.

select the white bg with the magic wand... antialiasing on and some tweaking of antialias value can help, plus select contigious only so you don't select the component holes. once you have a good selection, use the stroke command to smooth edges or enlarge traces.

create a library of good (not fuzzy) elements like IC sockets and component donuts. in a separate file, overlay the crisp elements on top of the fuzzy originals.

i've even gone so far as to redraw the entire pcb artwork on separate layers (one for components, one for traces) and turning the original image layer off. really not that much work for most sdiy-size schemos.

bbob

[andrewF]

One problem with p&p, is trying to feed the stuff into your laser printer - the best technique, at least it has never failed for me ....I think Fonik posted it?...print out your pcb image (just one pcb at a time, not the whole collection) on a normal sheet of paper. cut out a piece of p&p big enough to cover the image with 1/4inch to spare on each side. scotch-tape the p&p cutout over the image, I just do the top and bottom, and feed the paper back into your printer. voila!

In the thread, bbob linked to, check out the last post on page two from Randaleem. He describes how to use the print program 'scale printing' function to get a correct sized print.

To find the scaling amount, enlarge the PCB image as much as possible in photoshop. turn on the grid function, move the image so you can measure the spacing between two IC pins. The pins for PDIP chips should be 2.54mm, from centre to centre (Have a look at the last page of any IC datasheet for dimensions). so if, for example, you measure 4.50mm between two pins in Photoshop, calculate the % to scale by using 2.54/4.50 = 56.44%.
In Print Options, 56.44% in 'scale'.
It doesn't have to be precisely accurate, near enough=good enough.
Plus all the usual tweaks to get as much ink as possible onto your blue P&P!

[scriptstyle]

if you want a good vector image with minimal work out of a web based image(pdf, jpeg) this is what i do:

1. open image with illustrator
2. select image and go to >object >live trace > tracing options
3. select the preveiw box and change things like blur% and corner angle untill you have what you are looking for
4. when done with that you will be able to go back to object > expand and you should be all good.

hope this helps i use photoshop alot too, but this seems to be the quick and easy solution for most situations for me.

garret

[asafnetzer]

If using cs2 / cs3 version of photoshop, try this method when scaling.
Choose the right layer, goto layer --> smart objects --> convert to smart object.
Then use the free transform tool to scale that layer, being in smart object mode it should remain crisp.
Ofcourse if drawing a new circuit design you should go with Illustrator if possible, you could construct a bank of pads, lines...

Best regards,
Asaf

[CJ Miller]

Ok, I'm getting there!

Thanks much for relating your experiences, everyone. I was surprised that this info was missing from the searches I was doing before. Hopefully people will find this helpful.

On my setup, print scales just fine, so no worries there. As for feeding press-n-peel through my printer... haven't tried it yet. My printer has a front feed tray for envelopes and such, pnp might just go through.

Andrews comments about pin spacing got me thinking. Comparing prints on paper of stuff it turns out that some of my freehand traces of DIP spacing were a bit off. All it takes is for two pins to be a little off, especially in opposite directions, for things to be problematic. So I tried setting the grid meausurement defaults to DIP spacing, and then I use the move tool to position the whole image until pins are centered on some grid, and trace away. Works great and they print spot-on.

Peakes tip about the pencil tool is something which I was just finding out. I guessed that pen was what I was looking for, but pencil was what was required. A few things I found: Drawing while pressing the shift key constrains to drawing straight horizontal or vertical. And for angles, all I needed to do was draw the straight line up to where the angle goes, release the shift key, move the cursor to the far point of the angle, and then shift-click. The pencil then draws a straight line between any two points, which is very handy.

I was looking into Illustrator and livetrace, but at first my results were very flaky! The far-out traces looked very cool though. Asafnetzer was mentioning first converting the image into a "smart object" before tracing. Sounds good but I don't know what it means/does yet. Will definately look further into this soon.

[fonik]