Oh, my Lord! I've etched a board!

[David]

With apologies to any REAL poets out there...   :oops:  :oops:

Oh, my Lord!  I've etched a board!
But though I feel great, the quality is not first-rate.
My etchant was somewhat too strong,
Or my board was bathed too long.

Peroxide and acid muriatic,
Not the norm - but please, no static;
In DIY fashion, I used what I had,
For a first attempt, it ain't too bad.

My victory should be sweet,
But I have traces incomplete;
If you could help me, you have my thanks -
Gentlemen, how can I fill in the blanks?

[niftydog]

several ways, depending on how large the gaps are.

If you're handy with a small tipped soldering iron, you can solder skinny lengths of wire from broken track to broken track. Shield braiding wires are very skinny and work well for this.

If it's a very small gap, just whack a blob of solder across the break.

You can also buy "conductive ink pens" that you can draw the tracks onto a pcb. I've never used them so I can't vouch for their quality.

Or, if it's only one or two connections, insulated wire soldered from pin to pin on the underside is also a great way. Just bypass the broken track entirely with a bit of wire!

You can even get track repair kits and glue a new track to the board, but these are expensive and incredibly fiddly.

[David]

That's nifty, Nifty!  Good to know!  I wasn't sure that could actually work.

I've got a roll of that wire the ROG crew are so fond of using on their perfboards.  I guess I'll just cut myself a few pieces of that - and hold my breath while I solder them.

[guitarmonky55]

i just went through the learning process of etching a board, and found the key is to etch the board fast so as to not allow the etchant to eat away at whatever you are using as your resistant.  I used sharpie, and it even ate trhough some 5 layers of sharpie when i left it be.  the best way i found is to get 2 containters, boil some water in the larger one and then place the etchant in the smaller, place this containter into the larger.  hold this container down a little into the water so that the heat is all around it and then swirl the etchant around for about 7-8 minutes, the copper will melt away and you get a perfectly etched board.  honestly i suggest you make a new board if its not too terribly complicated and you have more board left over, i botched 2 and got it spot on the 3rd one.

[David]

i just went through the learning process of etching a board, and found the key is to etch the board fast so as to not allow the etchant to eat away at whatever you are using as your resistant.  I used sharpie, and it even ate trhough some 5 layers of sharpie when i left it be.  the best way i found is to get 2 containters, boil some water in the larger one and then place the etchant in the smaller, place this containter into the larger.  hold this container down a little into the water so that the heat is all around it and then swirl the etchant around for about 7-8 minutes, the copper will melt away and you get a perfectly etched board.  honestly i suggest you make a new board if its not too terribly complicated and you have more board left over, i botched 2 and got it spot on the 3rd one.

Good advice.  Trouble is, I was using muriatic acid and peroxide.  I'm not using that indoors!  I was outside and the temp was only about 50 degrees F.  I might not have gotten the ratio right.  One example I read said 4:1.  Another said 1:1.  I think I did a cup of peroxide to half a cup of muriatic acid.

Actually, I'm not sure I want to go this route again.  I think I may try the ammonium persulphate next time.

[Paul Marossy]

Oh my, what is this world coming to?! Today it's PCBs, what is it going to be tommorrow?!  :lol:

The quality of the etch is somewhat dependent on the PCB material itself. I once bought a blank PCB from RadioShack, and that stuff wouldn't etch worth a crap! It took nine years to get it to etch, and then it wasn't very good. As niftydog says, you can solder little jumpers to fix things up. Been there, done that.

[toneman]

pcb *has* 2B clean clean clean.
copperoxide is not only an electrical insulator, but is also a
resistive layer--an etchant resist.
David, I've never heard of using MuraticAcid.
(that's hydrochloricacid,same as "pool acid" 4 the not-so-chem able)
--used for keeping swimming pools clean.
Also etches concrete B4 U paint or epoxy it.
Did U use regualar hydrogenperoxide?  
That's stuff from RiteAid is really really weak(something like 6% solution).
The HyPer i use at work is 30%  !!
GMonk,  hot ferricchloride etches fastest.
Try to heat it up well B4 U etch.
The indirect water bath U mention is good, but that stuff will
stain everything and the fumes will rust away metal screens.
I mix mine up from dry powder.  Called "anhydrous"--"without water".
The mixing is exothermic---gives off heat.
I always seem 2 want to etch when it's cold outside.
I use a 100Watt aquarium heater & an aquarium air pump 4 the bubbler.
Getting ready to do several projects worth this TurkeyDay weekend.
stayetched
tone

[Michael Allen]

David, I also roll with the muriatic and hydrogen peroxide. It's so cheap that I just can't bother to use anything else.

I used to measure out 1 cup for 1 cup, but now I just add a bit off HCL, then mix put in the board, then add some H2O2 until I see green preciptate forming under the board. Then I just mix around the bowl.

Agitation is key. Heat also helps to accelerate the reation. Try using a hair blowdryer, I've used one with good results.

FWIW, my Radio Shack PCB doesn't etch very well at all. But it gets the job done!

[David]

Ummm, Michael?  You're doing this in the house?  My workbench is about 6 feet from the furnace.  When I opened the bottle of muriatic acid, I saw something like steam coming off.  I assume this is vapor that contained free hydrogen.  Somehow, I don't think I should have free hydrogen gas close to my furnace...

While I can get around the furnace issue by shutting it off during etching, the other concern is the odor.  Is there any?  Also, you said you poured your muriatic into something.  Into what - an empty container, or water?

[Paul Perry (Frostwave)]

When I opened the bottle of muriatic acid, I saw something like steam coming off.  I assume this is vapor that contained free hydrogen.  

I don't think so, what is given off (don't breathe it!) is hydrochloric acid gas, which forms visible acid solution droplets with the water in humid air.
As poisons go, hydrochloric acid is corrosive, but it isn't deadly in the way that say cyanide is (after all, there is hydrochloric acid in your stomach). But don't drink it, it is a particularly agonising death as your throat corrodes.

[David]

OK, Paul, I feel better about the lack of so-called free hydrogen.  Now the next question is, I understand that hydrochloric acid gas is corrosive.  Is it explosive as well?

Also, should the muriatic/peroxide mixture be warmed, or will that introduce other problems?  I'm thinking that my missing trace issue happened because I left the board in too long to remove some copper that was bridging traces.  Looks like maybe I need to etch the whole thing faster.

Any ideas?
And thanks!

[David]

...  was also a failure!

Dagnabit, it looked so good, but I didn't etch long enough!
<Sigh>

[smashinator]

so dissappointed
no replies in poem form
you guys sure blew it

[Paul Perry (Frostwave)]

, I understand that hydrochloric acid gas is corrosive.  Is it explosive as well?
Also, should the muriatic/peroxide mixture be warmed, or will that introduce other problems?  

Hydrochloric acid certainly isn't explosive. Rather the opposite.
As for heating it, I wouldn't like to, because that might drive off more hydrochloric acid gas.  As for the hydrogen peroxide, that is a pretty reactive & unstable chemical (it was the oxidising fuel in the German rockets in WW2) and, there is a lot of scope for confusion when you buy it, because it is sold in a lot of different concentrations, sometimes described by how much oxygen it generates, sometimes by the % of peroxide in the solution.

Note I havn't ever used peroxide & hydrochloric myself, but here is someone who has: http://www.ocmodshop.com/default.aspx?a=203

[Michael Allen]

David, the gas is chlorine gas which you don't want to inhale. It's disgusting and you'll certainly know when you get some in your lungs.

As far as heating goes, I don't really do it. Here's my process:

I use a miracle whip (or other small plastic bowl) and put in a bit (don't need too much or you're just wasting it) of HCL. Then I put my board in, followed by an estimate of equal amount of H2O2. The ratio all depends on your concentrations, so if the board isn't really etching, add some more.  You're reducing the Cu, so you want enough oxygen in there to facilitate the reaction. Now that the board is etching I put on some plastic gloves and use my index finger to make swirling motions, or back and forth motions in the solution above the board. Usually I can see the copper swirling off. This agitation really helps the process.

There's nothing special about the process or my methods. Just make sure you agitate, don't breath in the HCL, and try not to spill it because you can stain stuff if not corrode it. I've got some good splotches on my concrete driveway!

Good luck

[David]

Interesting...  you're using only enough etchant to do the job, thus reducing gas production -- clever!  Hey, I think I can make this work.  I would have had board #2 done successfully if I had just left it in the cussed etchant a little longer.

Hmmm...  I might just have time to pull off another attempt tonight!   :twisted:  :twisted:

[toneman]

Michael is correct,
the "gas" is Clorine gas, not hydrogen.
Hydrogen is odorless & colorless.
&, of course, U know, it *ignites*.

Paul, Thank U!!! for that link.
I'm aware of other acids used to etch metal and glass,
but never encountered info on ordinary muratic acid & HydrogenPeroxide
used expressly 4 etching pcbs.   The article mentions the 10% HCL,
which is ordinary "pool acid", but doesn't mention the concentration
of H2O2(HydrogenPeroxide)...10%?? that's the stuff U can buy anywhere.
My medicine cabinet has a bottle of 10% solution.
Although both methods, FeCL3 & HCL + H2O2 are corrosive & stain
and *both* should B done outdoors, the "new" method has advantages
of being cheap and easily available.
Also, both techniques work best above 80degF.  
I heat my FeCL3 with a 100W aquarium heater; it's about 14inches long.
I "rejuvinate" my FeCl3 with a little HCL.
I'm looking into actualy removing the copper with a power supply
and 2 electrodes to "plate" out the copper.  I have yet to determine
the polarity, but I will use 2 stainless steel electrodes and a current
limited/adjustable power supply...trying soon.
I will definitely try HCL + H2O2 after this next round with FeCL.
Thanx!! for the great NFO.
stayetched(safely)
tone

[Paul Perry (Frostwave)]

There would be a problem trying to plate the copper off a board electrolytically.
1. all seperate bits of copper would have to be connected to the supply.
2. what happens as the last bits of copper go? maybe the bits near the connections go first, leaving islands.

And while I'm here, being over 50, I'll give some advice I wouldn't have listened to as a kid: remember you can die from mixing household chemicals. One notorious case was a guy cleaning a toilet who put in normal bleach (calcium hypochlorite) and then added hydrochloric acid (whihc is very good for removing rust stains). Generated enough free chlorine gas to kill him (confined space).
Not every toilet caretaker gets a half page in a forensic toxicology text.
Could you have etched a board in that toilet? Very likely...

[David]

Hmmm...  maybe it's a good thing last night's board failed too.  I think I may confine etching to the garage -- with the door open.

[toneman]

Paul,
I'm not talking about "deplating" the pdb.
I'm talking about taking the copper out of the saturated solution,
*after* the pcbs have been etched and the FeCL3 is no longer active.
Now, I use a cup of HCL to 2gal of  (used)FeCL3 & bubble for 24hrs.
Afterwards, the FeCL3 is able to etch more boards, but all the copper
stays in the solution,  The HCL adds more CL ions to solution allowing
it to attach to more copper, to etch more boards.  I've been doing this
for over 25yrs.  It's not perfect, and the solution gets thicker, that's
why I'm thinking of extracting the copper electrically.  After all, when
U etch, U are creating a "difference of potential" with the solution &
the copper.  There *IS* a voltage being generated.  Reverse that voltage
with a power supply & U can take the copper *out* of solution.
I've read about this a long long time ago, but only just recently got a
power supply that will do 30V @ 30A with adjustabe current limiting.
I've even read of using SulfruicAcid(battery acid) and H2O2 to etch pcbs.
Maybe in the spring, I will give all these ideas a try........(?)
David, better to do etching outside.  The funes will attack any&all
metal parts in your garage.   Even using a fan.   My indoor attempts
rusted the knobs on the washermachine, the doorknobs, and eventually
rusted away the metal window screens.  
..... Though, I was doing 50-100 pcbs.
Time 4 some breakfast, & to continue 2 prepare circuits 4 etching soon.
StayActivated
tone