Basic, REAL basic, PCB etching

[Chris Wilson]

I want to etch a fairly large single sided PCB board myself. I have never tried this, but my needs are really basic, just half inch wide, by about 1 inch long copper islands to string 15 big electrolytic caps and bleeder resistors in series on one board for smoothing a HV power supply. I am wondering if I can use either masking tape or aluminium foil adhesive tape to mask out the wanted copper lands, and etch the rest off? I could cut the required shapes from tape quite easily. Would this work for a one off board, without going to the complexity of photo resist, or other more professional methods? Thanks!

[Rerouter]

lightly sand your copper till its shiney,

get an inkline pen, it doesnt need to be perminent, draw on your design (what you want to keep) and give it a full days dry time and it should make a perfect resist for the level of accuracy you need,

[PA0PBZ]

Or if it is a real simple layout take your Dremel 

[rolycat]

I wouldn't recommend aluminium foil, since it's likely to get etched as well.

I have had good results with the 'sticky backed plastic' of Blue Peter fame - aka self-adhesive vinyl. It goes by various brand names - DC Fix is a common one.

Clean the board carefully, smooth the film down ensuring there are no air bubbles and mark and cut out the areas you want to etch. A quick, fairly clean way to do the etching is to wipe the exposed copper with a sponge soaked in warm ferric chloride, repeating until it's clear. Wear vinyl/rubber gloves, and don't use a metal container.

[David Aurora]

lightly sand your copper till its shiney,

get an inkline pen, it doesnt need to be perminent, draw on your design (what you want to keep) and give it a full days dry time and it should make a perfect resist for the level of accuracy you need,

This.

(Personally when I've done quick simple boards this way I've never even waited longer than a few minutes drying time, but YMMV)

[Psi]

Make sure the pen goes on thick, you want it look solid, no patchy bits where you can see through the ink.

[rolycat]

Etch resist pens are great for very simple small PCBs, but the OP mentioned that he wanted to etch a large board. It can get expensive and/or tedious to cover large areas with a pen.

Sticky-backed plastic is also useful to mask off the second side of double-sided photo-resist or toner transfer boards if you want to etch them one side at a time to ensure good registration of the layers.

[icon]

I wonder if frisket film would work for this kind of thing? It's designed to be easily cut with a scalpel, waterproof and not leave a residue when you peel it off. See Youtube for details.

Disclaimer: I've never actually tried it - it just seems like it would be ideal/cheap.

John

[hlavac]

Plastic sticker bits/black insulation tape will work. Cut into the the properly shaped bits, stick on the board nicely, etch, peel off afterwards.
If its a large board make sure you have enough etchant to etch all that copper away, you may need about an inch deep pond of FeCl3 to cover your board.

[Psi]

yes, i used black insulation tape to protect the bottom side copper on a pcb while etching the top.

You have to make sure the tape is pushed down firmly with zero creases or the fecl will creep under, but as long as you do that it seems to work fine. I've not tried to make tracks with it though,

[G7PSK]

Pinch the wife's nail varnish. paint what you want on the board let it dry then etch the board now you have to get your hands on the other half's nail varnish remover to clean the boards, just make sure there are no bricks in the hand bag while taking the varnish.

[Alana]

From my childhood times i remember using my mom nail polish as water and etch resistant paint for my first PCBs.
For what you described, big copper traces it may be one of the cheapest solutions.

For more complicated stuff i use Edding brand pens, especially 780 0.7mm pen. This paint is tested in both FeCl3 and Sodium persulfate (Na2S2O8) etching solutions. If you need to heat it up things get tricky but it still works.
I see you have them in UK too http://www.tigerpens.co.uk/acatalog/Edding_Paint_Marker_Pens.html

[Chris Wilson]

All done, I used some PVC tape and it worked OK, one "island" has slight feathering on one edge, but very minor. I'll get better with practice. Need to look into PCB software design applications, any recommendations for something very easy to use, very basic and works under Windows XP? Free would be nice.....

Just go to mount the bleeder resistors, but I am tired tonight, too much of the demon beer with an old pal last night has taken its toll.


Thanks very much for all the great ideas, I may try something a little more ambitious next time. Photo attached for your amusement

Cheers guys, all the best.

[Psi]

31uF at 6.7kV

That's got a big kick to it, touching it is a really bad idea.
You should really have some bleed resistors to make sure the caps self-discharge after the power is cut.

Note: top middle of your pcb pic you have a shorted cap not doing anything, did you forget to cut the mask there?
You can scrape it off with a knife or a dremel easy enough.

[Chris Wilson]

Yeah, I missed the tape on the return land, Will remove the track mechanically, thanks for spotting that! I have bleeders to go on, no worries Cheers.

[SeanB]

What bleed resistors are you using? I would go for 560k ( or close to, 470k to 1M) 1W resistors, each in a fibre sleeve and a heatshrink over that, mounted on the bottom of the board.

[Kremmen]

[...] Need to look into PCB software design applications, any recommendations for something very easy to use, very basic and works under Windows XP? Free would be nice.....
[...]

Ok since you ask; by all means check DipTrace at www.diptrace.com. There is a free version limited to 2 signal layers and max 300 pins/pads. That will get you started and if not enough, there is a reasonably priced non-profit version for max 1000 pins. In both versions planes are unlimited so designing say a 4 layer board with power and ground planes is possible.
Personally i much prefer DipTrace over the other popular free one, Eagle, and so do many others. DipTrace is a relatively full featured set, including schematic capture, PCB layout editor as well as component symbol and footprint editors. So you can easily create your own schematic symbols and the associated component footprints. I find it easy and quite intuitive.

[ptricks]

It isn't free but my favorite application for quick layouts is sprint layout.  Sprint is probably the easiest layout program I have ever used. It doesn't get hung up on making you follow its rules and just lets you create the board however you want . Need a new model , just draw it then save it , no custom editor, pin mapping, etc to worry about. It is really the only PCB program I have used that just lets you create the board without worrying about design rules, footprints and all the other stuff hobbyist don't want to deal with when creating one off designs.
http://www.abacom-online.de/uk/html/sprint-layout.html

It also works with linux under wine as well as of course all the windows versions.


Aluminum - be VERY careful what metals you introduce to an etching solution. Some metals react very violently when exposed to the wrong chemical combinations, aluminum is one of those that will melt and can even get so hot as to start a fire when exposed to something like muriatic acid , often used in the hydrogen peroxide + muriatic acid etching method.

[IanB]

Aluminum - be VERY careful what metals you introduce to an etching solution. Some metals react very violently when exposed to the wrong chemical combinations, aluminum is one of those that will melt and can even get so hot as to start a fire when exposed to something like muriatic acid , often used in the hydrogen peroxide + muriatic acid etching method.

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