Chemelec's Electro-Etching

[3v0]

I have been looking at **broken link removed** for some time but am unsure regarding what to use for a power supply. From the page.

Here I am Using a Power Supply, current limited to 4 amps, but this is anominal current.

How to get there from here.

Build a current regulated PS from scratch. Found this
but I doubt it can handle the amps.**broken link removed**

Add current regulation to the backend of a PC supply.

Something with a car battery charger.

 

[ericgibbs]

hi 3v0,
Looked thru the link, the process looks interesting, its a pity the 'sample' pcb
is so 'poor'.

I think I would go for a 24Vdc 5A supply, with the '24Vdc' output being variable from say 5V thru 24V, so that the etch rate could be controlled.

I like the 'tinning' idea, you could mask off some areas of a pcb to make
switch pad contacts, in a heavy tin finish or the 'old' gold from recycled contacts.

 

[Sceadwian]

I notice he still has problems saying electroless nickle =) It's not elctrolysis nickle. He wonders why this isn't used in mass production. In order to keep the etching consistant across the board size a large tank and anode to cathode ratio needs to be kept high. Ferric or any other direct chemical etching can be done with the boards densly packed together in much smaller tanks. There's also power to consider, he uses a current limited supply at 4 amps for that dinky board. Imagine the power requirements for mass production of large batches of boards. Doesn't really scale up well at all.

 

[3v0]

I notice he still has problems saying electroless nickle =) It's not elctrolysis nickle. ...

In time I would like to switch to the etchant that you regenerate by bubbling air through it. Forget the name just now.

In the short term Chemelec's method may be easier/cheaper then hunting up and shipping toxic chemicals.

Do you think maybe you came down a bit hard. Everyone has faults, I have a bucket full of them.

EDIT: I was thinking of
(which looks like a chemistry experiment) if I could get 90% of the way there with old battery acid I would be happy.

 

[3v0]

The process is a first stage etch. When any section of the copper becomes seperated from the electrode etching stops for that section. You use a chemical etchant to finish the board.

The unetched copper you see on the sample board should be fairly thin and not take much chemical etching to finish.

 

[Sceadwian]

Coming down hard? Not at all. What he said with electrolysis nickel would easily be interpreted as being electrolytic nickel which is nickle plating requiring current, which is what electrolysis means. What he meant was electro less nickel which is a bath which only requires immersion in the solution to deposit plating but has other problems. I wasn't coming down on it as a fault, just correcting him. It's a complete inversion of meaning not some minor little spelling error or grammatical mistake. Electro les nickel baths can be very easy for a hobbyist to set up. Electrolytic one's aren't so easy.

 

[ericgibbs]

hi 3v0
Are you using a photo resist board, UV exposure light box and etching with 'warmed' Ferric Chloride solution??

An old fish tank airator makes a good bubbler.

The tinning salts I have tried carry some fearsome hazard warnings, what are using?

 

[3v0]

I do toner transfer and etch with Sodium Persulphate. Currently I am etching indoors without a hood and the Ferric Chloride fumes were more then I wanted to deal with.

At present I am not tinning. I have a flux pen that gets the solder to stick but it is not the no-wash type so I have to scrub the board after I build it.

I purchased 2 of the tinnit packages (2 packs each) but have not tried it. Need to setup a etching area in the garage.

 

[3v0]

I agree with that. But I like chemelec and I think there is a place for him here. He is the only one I know who has instructions for building electrostatic filters and even sources some of the needed part(s). Just sort of wished that you growled a bit less loudly.

Eric:
When we first talked about it I searched for "electro less nickel bath" chemicals. Found a kit but I think the shelf life on the bath was too short to justify the cost.

 

[ericgibbs]

I did have at one time a sample of flux that was loaded with solder micro-balls.

The method for small pcb's was to wipe, with a rag, a very thin film onto the copper side of the pcb.
Solder in the components as usual, then with a medium sized solder iron, just run it along the copper tracks,
to melt the micro-balls and it tinned fairly well.

On completion the pcb track was cleaned with a solvent.

If you dont already know, you can buy a double sided pcb cleaning block, about 3inch sqr.
One face is for rough action and the other for fine smoothing.

The advantage is after you have etched and drilled the pcb the block will remove the drill burrs,
which can make it difficult to get a good joint.

 

[3v0]

I buy surplus PDB board stock from Electronic Goldmine. The drilling is done with a CNC machine. The burrs come off with the scotch brite pad I use to clean the board when I prep if for the toner transfer. It takes a bit of elbow grease to get the oxidation off these boards.

Never seen one of the cleaning blocks. I take it that it works better then the green scotch brite pads. Will look for them.

When I setup the etching/plating area in the garage I am going to include a fume hood. That should make the tinnit a bit easier to use. Till then I will do without it.

On one board I coated the traces with flux and then wiped them with solder. It worked well but took a bit of time. This allowed me to tin the entire board, clean off the flux, the solder the parts. Worked OK. Sounds not to unlike the process with the little solder balls.

I found some which looks like it may work for coating circuit boards. It says it can be soldered through.

 

[ericgibbs]

The aerosol sprays work well, the clear type is OK for indoor used pcb's and a 'red' thicker type works OK outdoors. They are both solder thru types.

You can also get tins of lacquer, that you apply with a fine brush, ideal for touching small areas. I buy the cheap packs of 'kids artists' brushes, use once and dump.

Sorry if its 'egg sucking time', dont forget to mask off the pcb connectors before you spray, use a masking tape that dosnt leave a sticky residue.

If you are interested I could find out the trade names?

The advantage of the flat cleaning block, is that you get an even pressure over the pcb and dont scour some areas more than others.

Regards

 

[3v0]

Eric
Thanks for the info. The names would be helpful. Others may be interested.

These cans are in the old KRYLON red, black, and white label. I hope the propellant has not leaked out.

 

[ericgibbs]

hi,
The heavy duty pcb spray can is:

Electrolube DCR SCC3 RED Conformal Coating.

 

[3v0]

Eric,
So far I have found a 200ml spray can for $17.38 AU.

The clear I found is marked down to $3 a can. The place has 3 or 4 more cans. If the can I purchased is still good I may buy them all.

Thanks.

 

[chemelec]

Been away on Business, But in reply to most of these posts here:

So I Don't always use the Correct Terms, Sorry about that.
I Do Know it is "Electroless" nickel.
But Brain doesn't always work as needed.

As to my article on Electro-Etching, Yes it was a Simple Setup and a Simple Board, But Most hobbiests make a lot of smaller boards and only a few large ones.
(And Trying to Photograph my actual setup was too difficult to really show how it works.)

A PWM power supply works quite good in Controlling Current for this setup.
And using one or two Car Batterys, you can get Considerable Current for even fairly large boards.

Re: My website:
I TRY HARD, and Not only do I give pretty good projects but a Lot of advice.
I also can supply most of the parts for these projects to Anyone Anywhere in the world.
And Most of my parts are sold at my Actual Cost Price.

I Also give my Home Phone Number, should anyone need help, one on one.

Presently I get about 30 emails a Day and its getting Too Difficult to keep up with it. Especially in the Spring and Summer Months with all the other stuff I have to do.

I am actually considering Shutting it all down.

QUOTE: 3v0
I agree with that. But I like chemelec and I think there is a place for him here. He is the only one I know who has instructions for building electrostatic filters and even sources some of the needed part(s). Just sort of wished that you growled a bit less loudly.

Thanks, Glad you liked that one.
I Growl?
Sorry if I do.

Take care all........Gary

 

[3v0]

So I Don't always use the Correct Terms, Sorry about that.
I Do Know it is "Electroless" nickel.
But Brain doesn't always work as needed.