Received from Dave at 3/24/2019 02:25 AM UTC:

I have a bottle of FeCI from RatShack I bought 15 years or more ago still unopened. Read all kinds of stories about that stuff. Being I am a noob just starting I read all the comments and I may try different methods so this is just another note in my toolbox.

I don't like ferric chloride (FeCl3) because the solution is too dark to observe the progress of the etching and it doesn't change color appreciably as it becomes spent so you don't know it's spent until it doesn't work. That and it makes for stains that are very hard to remove.

That said, if none of that bothers you, it works just fine for etching copper and it can be rejuvenated by bubbling air thru it. Etch and rejuvenate enough and you'll need to add a bit of HCl too. I guess you'll know when adding a bit of HCl is necessary when it won't etch copper properly even after extensive rejuvenation. The color of the solution prevents seeing when it isn't properly rejuvenated so you can't tell when to add HCl until you're disappointed in the results.

I see people saying ferric chloride is "sludgy." If it's sludgy it's probably badly spent and/or overconcentrated from repeated use and repeated rejuvenation. sludgy solution just needs rejuvenating with bubbled air (or H2O2) and probably a bit of HCl also. And some water if too heavily loaded with copper. Properly maintained solution won't be sludgy. The thing is... at this point you're also etching with the cupric chloride the solution also contains... so just start out with cupric chloride and have a solution that's nicer to work with and easier to see if it needs rejuvenation.

Jim H

If you want to try ferric chloride you really should consider using citric acid with it - the so called "Edinburgh Etch" You can read about it here:

It really does make a significant difference. Citric acid is quite safe and readily obtainable form Amazon if not locally.

?

Craig

On Sat, Mar 23, 2019 at 08:12 PM, Jim Higgins wrote:

Received from Dave at 3/24/2019 02:25 AM UTC:

I have a bottle of FeCI from RatShack I bought 15 years or more ago still
unopened. Read all kinds of stories about that stuff. Being I am a noob just
starting I read all the comments and I may try different methods so this is
just another note in my toolbox.

I don't like ferric chloride (FeCl3) because the solution is too dark to
observe the progress of the etching and it doesn't change color appreciably
as it becomes spent so you don't know it's spent until it doesn't work. That
and it makes for stains that are very hard to remove.

That said, if none of that bothers you, it works just fine for etching copper
and it can be rejuvenated by bubbling air thru it. Etch and rejuvenate enough
and you'll need to add a bit of HCl too. I guess you'll know when adding a
bit of HCl is necessary when it won't etch copper properly even after
extensive rejuvenation. The color of the solution prevents seeing when it
isn't properly rejuvenated so you can't tell when to add HCl until you're
disappointed in the results.

I see people saying ferric chloride is "sludgy." If it's sludgy it's probably
badly spent and/or overconcentrated from repeated use and repeated
rejuvenation. sludgy solution just needs rejuvenating with bubbled air (or
H2O2) and probably a bit of HCl also. And some water if too heavily loaded
with copper. Properly maintained solution won't be sludgy. The thing is... at
this point you're also etching with the cupric chloride the solution also
contains... so just start out with cupric chloride and have a solution that's
nicer to work with and easier to see if it needs rejuvenation.

Jim H

What etchant do you pump with it? Do you completely submerge it?

?

Craig

All aquarium water pumps are magnetically driven, as is the one I posted.? I have two.? Care to guess what I've used them for?

?

Aeration without isolating it is not a good idea.? Or use it outside.

?

A bubble tank will put enchant in the air.

?

All aquarium water pumps are magnetically driven, as is the one I posted.? I have two.? Care to guess what I've used them for?

?

Aeration without isolating it is not a good idea.? Or use it outside.

?

A bubble tank will put enchant in the air.

?

Flow rates of peristaltic pumps are usually quiet small. Although they can be designed to pump at higher rates - the peristaltic pumps used during heart bypass surgery pump at about 2.5 liters per minute.

The pump linked to in an earlier message is a submersible pump, meaning you put it in the fluid you are pumping. Usually they don't have an inlet port that you can connect tubing to. Even if it did, or if you could modify it to have one it would not last long without being submerged or having some other extra cooling as they rely on the surrounding fluid for cooling.

I would like to find a small magnetically coupled pump with chemically inert parts at a reasonable price to use for an etching setup. The ones I have seen recommended for this use run around $200 or more which is more than I want to spend just to experiment with. If anyone has I suggestion please post your recommendation.

?

Craig

?

I have a bottle of FeCI from RatShack I bought 15 years or more ago still unopened. Read all kinds of stories about that stuff. Being I am a noob just starting I read all the comments and I may try different methods so this is just another note in my toolbox.

Thanks

I hafe to add my experience with aerating etching solutions.? I had a tank using ammonium persulfate.? I etched in a closet in my carport.? After a dozen or so, i looked and the heads of all the nails were missing.? Aerosolizing etchant is not a good idea and it can grt anywhere.? I use HCl + H2O2 + H20.? Ru;er gloves, rubbing the boards and 5 to 10 minutes later im done.? It takes me less than 1/4 cup of etchant to do a board.? HCl is cheap at Lowe's and 35% H2O2 is readily available from Amazon.

I never liked FeCl.? Too thick and the sludge buildup kept the etchant away from the board.

I woufd suggest a water pump over aeration.? I have also seen bubbles protect the copper from the etchant.

Sent from my T-Mobile 4G LTE Tablet

-------- Original message --------

From: Harvey White <madyn@...>

Date: 3/23/19 2:08 PM (GMT-06:00)

To: [email protected]

Subject: Re: [homebrewpcbs] Bubble Tank DIY Plans

On Sat, 23 Mar 2019 14:33:48 -0400, you wrote:

>High concentrations of H2O2 result in VERY exothermic reactions. Etching takes place in seconds. Lots of heat. Lots of acrid fumes. Do outside or with a good hood. Have water available to put your board in to stop the etching. I did a lot with those high mixtures but decided it wasn't worth the problems and went back to 3% peroxide. I usually use a sponge with a small quantity of etchant. Takes a minute or two but is very controllable and uses only a fraction of the volume, making disposal much easier. I don't make a lot of boards, so it's not worth keeping vats of chemicals around.

The "top up the solution" is meant to add enough H2O2 to restore the
solution to good operation, but NOT to replace a lot of water.? You
want to maintain the overall concentration.? The goal (I think) is to
maintain the same concentration you get with 3%, but not end up
diluting the overall mixture.? You do lose some to evaporation, etc.

Harvey


>
>
>Mark
>
>
>At 12:32 PM 3/23/2019, you wrote:
>Noted.
>
>
>Thanks,
>
>
>Dave
>
>
>On 3/22/2019 7:40 PM, Harvey White wrote:
>On Fri, 22 Mar 2019 20:31:31 -0400, you wrote:
>
>
>I found Sally Beauty Supply to be a good source for H2O2. I recall the
>"volume" rating is a bit more than 3x the concentration, so "30 Volume"
>H2O2 is 10% concentration.Do be careful, since the drugstore concentration is far less than the
>various products available in beauty supply stores.
>
>
>I'd think that the best use is as follows:
>
>
>1) build the etchant with drugstore H2O2 and HCL.
>
>
>2) when desired, top up the mixture with beauty supply H2O2, but in
>far less quantity than needed for the initial mixture.
>
>
>YMMV
>
>
>
>
>Harvey

Received from Dave at 3/24/2019 02:25 AM UTC:

I have a bottle of FeCI from RatShack I bought 15 years or more ago still
unopened. Read all kinds of stories about that stuff. Being I am a noob just
starting I read all the comments and I may try different methods so this is
just another note in my toolbox.

I don't like ferric chloride (FeCl3) because the solution is too dark to
observe the progress of the etching and it doesn't change color appreciably
as it becomes spent so you don't know it's spent until it doesn't work. That
and it makes for stains that are very hard to remove.

That said, if none of that bothers you, it works just fine for etching copper
and it can be rejuvenated by bubbling air thru it. Etch and rejuvenate enough
and you'll need to add a bit of HCl too. I guess you'll know when adding a
bit of HCl is necessary when it won't etch copper properly even after
extensive rejuvenation. The color of the solution prevents seeing when it
isn't properly rejuvenated so you can't tell when to add HCl until you're
disappointed in the results.

I see people saying ferric chloride is "sludgy." If it's sludgy it's probably
badly spent and/or overconcentrated from repeated use and repeated
rejuvenation. sludgy solution just needs rejuvenating with bubbled air (or
H2O2) and probably a bit of HCl also. And some water if too heavily loaded
with copper. Properly maintained solution won't be sludgy. The thing is... at
this point you're also etching with the cupric chloride the solution also
contains... so just start out with cupric chloride and have a solution that's
nicer to work with and easier to see if it needs rejuvenation.

Jim H

Mark,

Yes, I am aware of the issues although I haven't made any solution yet. I was more worried about my shop equipment getting rusted. And my lungs too. But I decided I would do my etching outside and just need to properly store the etchant until I need it again. I see other people use the sponge method too so I may have to give it a try but I have plans to build a tank. And like you, I am not planning on doing a lot of boards but maybe a bunch at a time. Time will tell. My initial research showed a lot of interest in the Volume 30 stuff so I had to get some. :)

Thanks


On 3/23/2019 1:33 PM, Mark Lerman wrote:

High concentrations of H2O2 result in VERY exothermic reactions. Etching takes place in seconds. Lots of heat. Lots of acrid fumes. Do outside or with a good hood. Have water available to put your board in to stop the etching. I did a lot with those high mixtures but decided it wasn't worth the problems and went back to 3% peroxide. I usually use a sponge with a small quantity of etchant. Takes a minute or two but is very controllable and uses only a fraction of the volume, making disposal much easier. I don't make a lot of boards, so it's not worth keeping vats of chemicals around.

Mark

Mark,

? Yes, I am aware of the issues although I haven't made any solution yet. I was more worried about my shop equipment getting rusted. And my lungs too. But I decided I would do my etching outside and just need to properly store the etchant until I need it again. I see other people use the sponge method too so I may have to give it a try but I have plans to build a tank. And like you, I am not planning on doing a lot of boards but maybe a bunch at a time. Time will tell. My initial research showed a lot of interest in the Volume 30 stuff so I had to get some. :)

Thanks

As Harvey said, it is to put the Oxygen back into the etchant without diluting it too much. It is much easier to dilute 30% H2O2 than it is to concentrate the 3% solution. Adding sufficient O2 with the 3% stuff adds a lot of water that is not necessary for the chemistry. Using the 30% H2O2, you can add as much or as little water as necessary to keep the chemistry where it belongs.

The goal is controlled etching, and too much water defeats that.

(I'm not a fan of bubbling to put the O2 back in - too much drag-out into the atmosphere.)

Donald.
--
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On 2019-03-23 3:24 p.m., Jim Higgins wrote:

Received from Harvey White at 3/23/2019 07:08 PM UTC:

On Sat, 23 Mar 2019 14:33:48 -0400, Mark wrote:

High concentrations of H2O2 result in VERY exothermic reactions. Etching takes place in seconds. Lots of heat. Lots of acrid fumes. Do outside or with a good hood. Have water available to put your board in to stop the etching. I did a lot with those high mixtures but decided it wasn't worth the problems and went back to 3% peroxide. I usually use a sponge with a small quantity of etchant. Takes a minute or two but is very controllable and uses only a fraction of the volume, making disposal much easier. I don't make a lot of boards, so it's not worth keeping vats of chemicals around.

The "top up the solution" is meant to add enough H2O2 to restore the solution to good operation, but NOT to replace a lot of water. You want to maintain the overall concentration. The goal (I think) is to maintain the same concentration you get with 3%, but not end up diluting the overall mixture. You do lose some to evaporation, etc.
Harvey

I absolutely don't understand the desire some have to complete etching in "seconds." As Mark says above, "it wasn't worth the problems."

And Harvey is right... if you regenerate with H2O2 (and you'll also need some HCl eventually) you may find the volume of your solution growing and growing. OTOH, if you regenerate with bubbling, and some HCl eventually same as with H2O2 regeneration, you may actually find you have to maintain the etchant volume by adding water due to water loss from evaporation while bubbling. That's if you turn on the bubbler and forget about it.

Jim H

Beauty Salon H202 is 30 "VOLUME"? not 30%? its more like 12%