exists an etch resistant pen from corner drugstore/office supply ?

Yup..I used black vinyl tape too. The vinyl for labels, decals and stickers work good too. :) But no more... I use dryfilm photoresist now (in a darkroom).

My chemistry is not good.. I'm wondering if there is a chemical that can make a copper oxide layer that either Ammonium P or Ferric C won't react?? Instead of an ink pen..How about a oxidizing pen?

D from BC

Do it before you do your nails, otherwise you'd have to let them dry first. ;-)

Cheers! Rich

[snip]

A few years ago I bought my wife a Stika vinyl cutter, for her Girl Scout signs AND for masking sand-blasted "etched" glass objects.

I've been tempted to try making a PCB mask the same way.

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

| 1962 | America: Land of the Free, Because of the Brave

Tim, I get medicore results with Sharpies. The ink holds off the echant, but warm FeCl eventually works through an starts etching underneath. How 'bout for you?

Ditto for the Staedtler Lumicolorp 'red' pens, though these appear marginally better--haven't rigorously tested.

Both Lumicolor and Sharpie are much more resistant if baked over my stove's pilot light first--about 60c for ten to a zillion minutes (depending on when I remember to retrieve).

An official "etch resist pen" from Radio Shack--thirty years old and still going strong--is best of all (it uses lacquer), but even it benefits from the heat treatment. DigiKey & Allied(?) still offer these.

My last quickie board was experimental: spray acrylic on board, draw land pattern with marker (for a guide), then scratch isolation lines between (through the acrylic). Pretty decent: super quick, excellent resolution, and etches very quickly.

Cheers, James Arthur

When I can't see the copper under the ink, it works out fine for me. I have a "Bic 4x4 Grip" marker here, which inevitably makes a thin purple mark. Where it's thinnest -- and it of course varies like wood grain -- I get scratches in the track.

I don't use warm FeCl3, and my chemistry may be different. I made mine (of course!), by dissolving rust and whatnot iron compounds in muriatic acid. It's a dark brown solution with a curiously fruity smell accompanying the acid fumes. That may be due to chlorine and acid reacting with the plastic container, I don't know.

I don't remember what weight my PCB is, but it's probably the usual -- what, 2 ounce? It takes about 20 minutes with room temperature solution and intermittent stirring.

I've had consistent results ranging from blow dry mere minutes before etch, to day old ink. I haven't tried heat-curing it, but I don't see any reason to.

Interesting. Should work nice with RF, too, if you ground all the floating sections. Not a good idea around HV though!

Tim

-- Deep Fryer: A very philosophical monk. Website @

I bought one of those many years ago as well, and except for the "etch resist" logo or whatever it was imprinted on the side, it was indistinguishable from a Sharpie.

Admittedly, the ink may have had some exotic additives, but it looked and smelled and worked just like a Sharpie.

And it resisted the FeCl3 quite well, thank you. I etched the board in a glass baking dish out in the sun on the asphalt driveway. :-)

Cheers! Rich

As long as the etchant doesn't undercut the adhesive, I don't see why not.

Cheers! Rich

That's the main defect I get with Sharpies. If quickly retrieved the traces are weakened, but not wrecked.

Hmmm. I have had okay results with Sharpies on occasion, but suppose I've changed some important process variable.

Fresh warm (50-60c-ish) etchant does my boards in > Both Lumicolor and Sharpie are much more resistant if baked over my

*No* floating sections, not on that board (a small, isolated DC-DC floating supply for use in another project) anyway.

I don't do a whole bunch of boards, but it sure is nice to be able to whip one out when needed.

Thanks for the feedback--

James Arthur

I half-wondered if Sharpie changed their formula, since they quit working well for me, but your and Tim's testimony suggest it's me somehow.

I have directly compared smells and Sharpie is definitely not the same. The lacquer pen smells distinctly 'solventy'; the Sharpie doesn't.

Ahh uh'preciate's the info Rich,

Best, James Arthur

After I do my nails. Too thin to use on them if I do it before...... :-)

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The Sharpie site has links to MSDS for each product they sell some of the markers have different formulation thn other. and sharpie apparently has a line of paint markers as well which i did not see at my local store.

as for Sharpie resist., i just tried the Black fine point Sharpie on my board using the muriatic + peroxide etchant and the sharpie did resist that etch . i made sure the line was heavy with no copper glimmer showing through

my etching + agitating was working faster on edges and not in middle or between the small traces so ... i...

decided to speed up (**even out**) the process by using a medium sized CRAYOLA 3135 paint brush made with plastic handle and {rat or cat hair bristles ? } (very soft). I swished it over the the board and traces where the reaction was moving slowly and this sped things up quite alot.

but then i ripped off some traces trying to tin the board with a weller 40Watt bazooka (it was my first DIY board) boo hoo

robb

Heh, my 40W iron (essentially the same model as Radioshack's 30W iron, but with a bigger tip and element) gets painfully hot, so I put a 50 ohm resistor in series with it. It's still awfully hot, but not to the same degree at least. At any rate, phenolic boards tend to delaminate and old ones even pop as the track heats up. FR4 seems to be just fine around this kind of heat though.

Get some real PCB stock. :-)

Tim

-- Deep Fryer: A very philosophical monk. Website @

I've heard that "paint markers" (e.g. white uniball px203) are excellent, but haven't seen or tried them.

Jim Thompson wrote some time ago that "Liquid Embroidery" pens from craft and fabric stores have an asphalt-based ink that makes great resist, but fine lines are difficult.

Hey, put a 1n4007 diode in series with that iron. It'll still get plenty hot enough to solder with, and it won't chew up tips or traces. Mine's installed in an in-cord switch, along with a neon indicator bulb.

(view in Courier font)

/ / SW ~ >---+-------o o--------+-----. | | | | | | | .-----. | \\ | | | | / Soldering '--|-|) (|-|--/\\/\\/--' \\ Iron | | / '-----' | NE-2 | ~ >------------------------------'

The neon bulb lights for "low / idle." Flick the switch for "high" when you need to solder something heavy. A very useful accessory that you'll really enjoy.

Cheers, James Arthur

[snip] [snip]

Excellent memory, or excellent filing system?

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

| 1962 | America: Land of the Free, Because of the Brave

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D from BC

I have a Weller SP-23, 25 watt, and it got so hot that I cut the cord and put in an SPST switch with a diode across it - when I open the switch, it puts the diode in series. At one time, I thought that that would make it consume half the power, but a couple of years ago, someone explained to me that it actually only decreases it to .707, something to do with RMS.

But it makes the iron a nice comfortable soldering temp. for small stuff.

Cheers! Rich

They are, mostly, one and the same, but to be quite sure of faithfully preserving your particulars, I confirmed the facts before posting.

Cheers, James Arthur

I have the RS iron that has the switch and diode in the handle. Very portable.

I also used the diode and switch in a Minibox long ago.. Also the lamp dimmer model.

greg