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.
--
*Plain Text* email -- it's an accessibility issue
() no proprietary attachments; no html mail
/\ <>

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%

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.
--
*Plain Text* email -- it's an accessibility issue
() no proprietary attachments; no html mail
/\ <>

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

If you want to be quick and efficient doing your own boards build a splash tank.? I built one years ago and it did may boards before I quit doing them myself.? My tank could etch two 10" x 10" boards at once but I would not build that large a tank today.?? The advantage to a splash tank is the speed of etching due to the aggressive agitation of the etchant and the minimal quantity needed.? Bubble tanks usually take a lot of etchang and the bubbles tend to ad hear to board shielding the copper from the etchant.
I built my 12" x12" x 12"? tank from 1/2" plywood but any material would work.? The plywood was coated with fiber glass and epoxy resin to resist the etchant.? But one could make a tank out of almost any plastic just as well.??? The top was built from a piece of acrylic and removable by lifting off.? The edge where the top intersected the sides was formed with a jog step in the sides so splashing etchant in the tank would not splash out the joint, no seal was used just the jog step.? The bottom of the tank was slightly sloped from the left and right sides towards the center ( Ie there was a low spot in the center of the tank).??? You should not be thinking how a kitchen dish washer? or food? blender works)? Above the acrylic top I mounted a small fractional junk box AC motor coupled to 1/4" shaft that extended to the bottom of the tank.? There was a small acrylic block used as a lower bearing block epoxied to the bottom center of the tank.? A small strip of stainless steel was fitted to the bottom of the shaft (saw a slit in the shaft) possibly 1" x .5" in size to be the dasher.??? It only took enough etchant to cover about half of the dasher strip to sling etchant on all sides of the box.?? To hold the boards I used? a piece of acrylic that would slip down into the chamber, held by some guides against the left and right wall.??? I only had a board holder (two of them) on each end of the chamber.?? The boards were mounted to the acrylic pieces wedged by some small rubber suction cups.? The suction cups were easy to move around for different size boards and held the boards by their edges. Note: only one side of a board at a time could be etched, once the first side was etched the acrylic piece was lifted up and the boards flipped over to do the back side.??? With fresh (ammonium persulfate) etchant a board would etch in less than a minute and never tool longer than 5 minutes. ? Quick etching gives less undercutting of the traces.

I don't think stainless steel would work with copper chloride based etchants so one would need to use another material for the rod and dasher.

Now I just use JLC pcb? -- just can't justify the time, effort and mess against their quality, deliver and price.
Craig

You most likely need a hand piece to test the Metcal.? I believe some of the power supply models have open circuit shut down capability.? So if you don't see any RF at the connector that is not definitive for being defective.??? The hand hand piece with the element is really an inductive heating element that regulates the temp by the curie point of the alloy used for the actual tip.? I never opened up? one of the element tips but it should contain an inductive heating coil around the heat conductive alloy.?? IIRC there is a resonant cap located in the body of the hand piece that forms a series LC resonant circuit with the heating coil in the heating element.??? I guess the idea is as the temp approaches the curie point of the material in the core of the inductor, the LC resonant point shifts off? resonance reducing the absorbed energy, thus regulating the temperature.? As you start to solder the tip cools, returns to resonances and absorbs more energy.? They respond very fast.

I purchased a special stand for the hand piece which has a sponge, and tip storage but it also contains some ferrite material around the hole for hand piece.? The ferrite upsets the resonant point so the tip standby temp is lowered when not in use, extending tip life. ? I do notice a slight delay before the tip gets to soldering temp with this stand over the old one but it's not significant.?

After market tips and Metcal clones are available from a company called Thermaltronics.? thermaltronics.com ? Tips are in the $11 to $22 range.
Be aware there are different temp ranges available for each style tip??? 325-358c (type 600)?? 350-398C (type 700)?? 420-475c (type 800)

I normally use 63/37? tin/lead , hate the lead free stuff.?? So my old 600 types work fine? just need to get a couple higher temp ones for the lead free boards
Craig

_._,_._,

---

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

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

Actually in "chemistry lab terminology" they are called fretted glass filters. Generally, they are 1-3" dia funnel sort of like devices with a fretted glass disk down near the bottom. For filtering I assume they are available with various pore sizes, they will also work for generating very small bubbles.

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

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