I need to make a very simple but large trace PCB. For a machine tool I'm building.

For a signal generating type PCB I would use toner transfer. But this is basically some straight bars on a board. Is it possible to use tape(clear Mylar packing tape) for resist when etching?

I'll be using Ferric Chloride to etch with. Anyone ever used tape for resist?

Thank you, Cary

 

Some of the discussion in the thread might be interesting - http://forum.allaboutcircuits.com/showthread.php?t=12474

 

Tape will work. You may consider getting stripping tape available at hobby shops, auto places, stationary and drafting stores, etc. Tape, particularly dry-transfer (i.e., rub on) was used quite commonly in the early days. Even a water-resistant marker can be used.

John

 

If it is very simple, you could use the "Large" sharpie marker to block out what you don't want etched.

Another option if the board is VERY Simple is to use a Dremel tool with a router bit, and cut away the unwanted copper rather than etching the board. Care must be taken not to cut too deep, but still make a wide enough insulator for the voltage you are working with. Some people use cuts as small as those made by an X-Acto knife for low voltage circuits.

 

Thank you all for the replies!

beenthere, thanks I always "search the forum archives" before posting. Some times theres some thing close but rather than bringing up an older post I start my own.

John, do you mean "pin stripe" tape? That was my first thought, but didn't think it would work.

Thatoneguy, I've read that a "Sharpie" works but didn't think the film would be thick enough on it's own. I know it works to fill in toner transfer.

Cary

 

Cary,

Yes, I meant pin stripe tape. It is pretty decent. The model stuff is like PVC electrical tape and is quite flexible. Some brands have several sizes on a single spool. The auto stuff probably would also work, but it may not be as flexible.

People complain about ferric chloride as being caustic. It does release a little hydrochloric acid vapor (muriatic acid) and stains everything. Despite that reputation, though, if something is water proof, it will probably be OK for the short time that the board is in the etching solution. The PVC/electrical tape/fine-line auto masking tape (blue= flexible; green= semi-flexible) and similar will probably give a fairly clean line. I have no experience with auto body decorative tape, but suspect it may not give quite the same sharpness as the softer tapes.

If you have never used ferric chloride before, be very careful around stainless steel sinks. It will etch/dull the surface instantly.

John

 

I never got really good results using a Sharpie with ferric chloride. Staedtler Lumocolor pens work much better; they're basically for overhead projection type work.

 

I never got really good results using a Sharpie with ferric chloride. Staedtler Lumocolor pens work much better; they're basically for overhead projection type work.

I usually use 2-3 "layers", letting it dry between, so the surface is solid black with no streaks of lighter color. If you scribble too much on a later layer, it all dissolves again, so it is kind of a pain.

 

There are many Sharpie markers. The one that is working very well is the industrial one. It is written on the marker: SHARPIE INDUSTRIAL SUPER PERMANENT INK and the item number is 13601. It has a fine point and it can make a trace of about 1 millimeter. Before it was also available with an extra fine point but unfortunately they dont make it anymore.

 

When I started as a teen making PCB I used sharpie's with good results. Any paint that can resist water will probably work though.

 

It were all crepe tape, rubdown transfers and Decon Dalo etch-resistant pens when I were a lad. The pens are still available, though I hope improved upon since I used them as they had 2 modes - dry and scratchy, and haemorrhage.

Why not use some nice pre-preg board and a photopositive? It's possible to get great results with a standard inkjet/laser print onto acetate, you only need a bit of old glass (greenhouse glass is best) and a few minutes in the sunshine. If the latter is not available, tanning lamps work well. But not "black light" mercury bulbs, wrong part of the UV spectrum I guess.

If you really want to use tape then anything waterproof will do. Press it down well so the acid doesn't seep in underneath.

 

Why not use some nice pre-preg board and a photopositive? It's possible to get great results with a standard inkjet/laser print onto acetate, you only need a bit of old glass (greenhouse glass is best) and a few minutes in the sunshine. If the latter is not available, tanning lamps work well. But not "black light" mercury bulbs, wrong part of the UV spectrum I guess.

Or a 100 watt incandescent lamp will work (light bulb) just have to have it close (4" to 6") for about 15 to 20 minutes.....

The industrial marker will also work if available, just have to make sure you do not have light spots and make sure it is dry if you have to go over it again....

Radio Shack used to sell rub on etch resist stencils, I am not sure if they still do, I know they still carry the ferric chloride....

But for a real simple, one of a kind PCB, I would draw your circuit on it with a sharpie (mirror image of course) and "etch" it with a dremmel type tool, a LOT faster than etching with solutions and peeling paper with toner transfer method (I have used all methods, until I finally made my own home made CNC PCB mill/drill, actually when I made the CNC, I hand etched all the pcb's for it ) ... If you have a steady hand the outcome should be pretty good....


My .02

 

Thanks to everyone for the replies. Now all I have to do is do it.

Cary

 

But for a real simple, one of a kind PCB, I would draw your circuit on it with a sharpie (mirror image of course) and "etch" it with a dremmel type tool, a LOT faster than etching with solutions and peeling paper with toner transfer method (I have used all methods, until I finally made my own home made CNC PCB mill/drill, actually when I made the CNC, I hand etched all the pcb's for it ) ... If you have a steady hand the outcome should be pretty good....


My .02

Hi, what type of cutter did you use in the Dremmel? A ball shaped burr?

thanks for your reply, Cary

 

I need to make a very simple but large trace PCB. For a machine tool I'm building.

For a signal generating type PCB I would use toner transfer. But this is basically some straight bars on a board. Is it possible to use tape(clear Mylar packing tape) for resist when etching?

I'll be using Ferric Chloride to etch with. Anyone ever used tape for resist?

Thank you, Cary

I don't know how wide the trace is, but I have covered the copper side of the board with strips of masking tape. Then used a glass bottle to roll back and forth over the tape to make sure it is on good. Then a drew some lines with a pencil where I wanted the traces. Used a straight edge and an xacto knife(pen knife) to cut the tape. Pulled the tape off where I wanted to etch.
I also drawn on the bare board where I want the copper removed, cut the lines with the same knife, used a hot flat bladed soldering iron to heat the area to be removed and as the heat broke the bond between the copper and the board pulled off the copper. The generally on works for narrow strips that have to be removed. This method makes sense as if you take a regular PCB and heat the traces to much they will start to lift off the board.

 

I use paint marker pens (not pernament marker), like shown below
,

 

Dalo pens work quite well and last for years. Some sharpies work good, but you have to draw real slow to get a thick enough layer of ink.

For thick power traces (1/4" and up) and ground planes I use some quick drying nail varnish, the little brush means it can be applied quickly to larger areas. It's also a very reliable coating when etching. But you need nail varnish remover or acetone to get it off.

 

Hi, what type of cutter did you use in the Dremmel? A ball shaped burr?

thanks for your reply, Cary

I actually used a PCB milling bit, I get packs of them (refurbished 20 for $4.99!! at Harbor Freight)


but one of those small ball shaped burr's would work.....

 

We had a thread a long while back about home made CNC machines. Something I'll want to play with till I die I suspect. They were used in a similar manner (if not identical).

 

Oh I would love to build myself a CNC PCB drill. It's going to be my next project for definate. Not going to be a while though, still very engrossed in my current project.

Maybe we could start a new thread for people who want to build one? Not just the electronics, but the mechanics too.