Suggestions for Etch-Resist Touch-Up

[ericcoleridge]

I usually get pretty good results transferring PCB designs using P'nP blue, and by setting my iron at 2/3 heat, and using moderate pressure for 10 to 15 minutes.

But, sometimes I still get errors that need touching up. I hate having to clean off the etch resist and starting over so if I can, I'll touch up the holes w sharpie- but frankly, it doesn't work all that well. The sharpie ink always starts breaking down before the board had fully etched, and I have to touch up traces w solder or resistor leads, etc.

Has anybody found anything else that might work better than sharpie. Some kind of paint pen maybe? Anything?

What about silver trace pens, for drawing out traces? Do those work at all?

[diablojoy]

I started to notice that problem sometimes just recently but but it wasn't
until i changed from using ferric chloride to a hydrochloric acid and hydrogen peroxide mix for etching. before i changed etching solution i did not notice a problem with using a sharpie as long as it was applied pretty thick from a newish pen.

the paint pen might have some merit as they are usually an enamel type paint so should resist very well however i do use them at work nearly everyday to touch up chips in powder coated items and they don't have the finest of tips nor the best control over the flow and they do take some time for the paint to dry
still couldn't hurt to try it out. paint pens are not that expensive

[bubzy]

i use a metallic "gold" pen when i need to make sure its going to stay, they are pretty good if a little difficult to remove after the etching process. the advantage is that the effectiveness of the pen is always the same.
sharpies are ok but i do find them to vanish 9/10 times in the etching process.

[piedwagtail]

I only use the expresspcb layout to print to paper
which is then taped to the board;
drill out the holes carefully and precisely; thoroughly clean;
join with a pen
which isn't neat from the trace side but neither is it hard for non-smt parts;
cuts out a lot of things I thought I had to do.

The place to concentrate is the concentration!
Watching the start of the etch like a hawk for signs of rapid track erosion.
There's an art to get the temperature and ferric chloride solution strength right.
I err to safety then increase also using a temperature bath.

So in answer, is it the pen or could you change the etch conditions?

[Photon]

I use enamel paint (Testors model paint) and a small brush. It works well and cleans up easily.

[inlifeindeath]

you can get an 'industrial' sharpie. they sell them at any office supply store and they work great. look just like a regular sharpie but have industrial printed on them.

[reve]

[kkissinger]

I have a couple of etch-resist pens that I purchased from Mouser.

[Peake]

Industrial Sharpie works fine for me. I recently had a Serious touch-up job to save an exposure and the Sharpie worked just right. Note however that different pens have different tendencies to output ink-- I used one with copious amounts of ink output. Etched just fine, cleaned off with pure Acentone just fine.

[LFLab]

My wife's nail polish

[Luka]

actually i found that the best touch up pens are staedler fine tip perm markers
i find it even more hardy than the pnp ink

[ericcoleridge]

I picked up a pack of industrial sharpies, tried them out last night. They worked really well.

I'm sure nail polish is resistant too, but difficult to remove, no?

[LFLab]

I use acetone to remove the toner, and that's also the main ingredient for nail polish remover.
I'd say it is somewhat harder to remove than the toner, but since it's usually only touching up and not larger areas, it's not that bad.

[kkissinger]

[LFLab]

Been meaning to check up on the exact toxicity of acetone, but I am careful when I use it, the smell is not so much of a problem I believe it's more skincontact.

[Rykhaard]

Through almost all of my PCB making in the 90's (started in about '92. Went Sharpie black in about '93. Went PnP in about '97, with Sharpie for touchup.) as well as all manual and PnP with Sharpie touchups since July 2005, I have rarely had a single problem with Sharpies.

The key here, which I relearned in this build period (since 2005) is to apply the Sharpie, in at least 2 strokes. If applied once and the colouring of it looks purplish, you don't have enough of it applied and it WILL come off very easily in the Ferric Chloride. (I haven't ever heated my 4 litre container that I bought in the Fall of 2005. It's almost at it's end now, with dozens and dozens of boards, having been made - with the air bubbles / fish tank kit.)

I'll say it again - the KEY TO IT IS, going over the repair point (or the manual layout by hand) over and over, until it looks black. Not purple. Black. That, will resist at least as long as the PnP.
Since I made sure of switching to that ensured mode of application, I've never lost a single portion of anything, that was completely black. Only surrounding Ground planes where I'd NOT gone completely black, were the portions of purple Sharpie, beginning to eat away.

For cleaning my boards? The same Superfine iron wool that I use in the first place for polishing my copper before ironing on the PnP. (Polishing and then an abrasive cleaner like 'Comet' with warm water and a piece of paper towel.) This method with a little bit of elbow put into it, cleans as well as repolishes the boards, beautifully.

Edit: and this includes, black Sharpie permanent markers (fine and extra fine tips) that I've purchased from local 'Dollar Store's.

[diablojoy]

I have always just used normal enamel paint thinners to clean up
toner just wipes off with a rag soaked in. it's not quite as bad as the acetone smell wise