Etching PCB's - don't tell the wife pls!

yes, my wife's good extra large Farberware frypan is used as a water bath to heat the FeCl to about 145 degrees. The etchant is in a Corning Wear dish, and as you can see, repeated uses have turned it a brownish yellow. I use a darkroom spatula/stirrer to rock the board. This method only takes a few minutes. After the board is cooked I wash it thoroughly, remove the protective ink with MEK (outdoors of course), clean it again with a rough cloth in running water, and give it a dip in LiquidTin:


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MEK and exposure

I use fiberglas cleaning solvent or laquer thinner we occasionally have to patch the boat up after the summer -- these are mostly MEK or methyl isobutyl ketone with acetone or isopropyl alcohol.

For this board, which is 3 X 6 inches, I used an Avery 8665 clear full sheet label, printed the traces in "reflected mode", and slapped it on the board. Exposure was exactly 6 minutes on my lightbox (used for negatives and transparencies.) Development was about a minute in 1% NaOH. The Avery Label method works much better than mylar sheets in my Laser printer, the 10 mil traces came out fine with no breaks whatsoever.
Speed etching

Do you want a faster etching?

Here is the recipe:

1 part concentrated HCl Acid :skull:
1 part 30% H2O2, hydrogene peroxid (hair bleech) :skull:
3-5 parts water

Etching time 1-5 minutes at room temperature and normal 35µm (1 oz?) copper laminate.

:skull: ********************************************
Be outside!!! Or in a lab with good ventilation.
Dangerous gases, Cl2! Keep away any iron/steel, rusts!
:skull: ******************************************

It's important to have equal parts of acid and H2O2. If you have too much acid, nothing happens, too much of H2O2, nothing happens. Less waters faster reaction and heat!! The solution gets hot if the reaction is fast.

This isn't so dangerous if you take precations with glasses, gloves and non-metallic bowl. Plastic or glass will do fine.

You can't save the solution. Prepare as much you need.
I don't know if I would do this at home:

WE3: Residual Co etch with HCl-H2O2
1) Take 3 parts of a 37% HCl solution in water and 1 part of a 30% H2O2 solution in water.

2) Add the H2O2 slowly to the HCl, be careful that the mixture doesn't boil over.

3) When all the H2O2 is added the mixture should have a higher temperature, (60-80 °C) now

immediately etch the substrate for 10 s.

4) Rinsing in water for more then 10 min and spin dry.


2002-05-17 8:48 pm
jackinnj said:
yes, my wife's good extra large Farberware frypan is used as a water bath to heat the FeCl to about 145 degrees. The etchant is in a Corning Wear dish, and as you can see, repeated uses have turned it a brownish yellow.

I am putting you on my list of people from whom I will NEVER accept a dinner invitation... ;)



2002-05-17 8:48 pm
Back when I was etching boards I used to use a plastic tank. I used an aquarium heater to get the temperature up a little, and an aquarium air pump and stone to bubble air through the liquid. The air does the agitating so I got nice, evenly etched boards and I didn't have to stand around watching the thing and agitating it for what always seems like hours (a watched pot never boils, as they say).

These days I cut boards in a T-Tech milling machine (sometimes it pays to work for a big technology company). It's a lot of up-front work to lay out the board in CAD and squirt out Gerber files, but it makes it real easy to make multiple boards. No nasty chemicals except the optional tin plate solution.

my most sincere apologies "les gourmands" de Plano

Plano has never been the same since JCPenney moved down there. Sixth Avenue's loss was your gain. :)

The CNC milling machine arrival down the block was a disaster. It fell off the lift gate of the truck and was sent back -- probably a product of the public education system in the us, and of course this occurred after Con Freight went bust and left everyone stranded including the awaiting recipient who had to arrange alternate transportation. Yes, I look forward to milling the boards !!!! until then it's Avery labels, NaOH and FeCl.
That sounds like the formula for the rocket fuel they use on the shuttle!! dangerous stuff they say.

Here are some amazing facts about the SSME from the Rocketdyne/Boeing site"

Rocketdyne's Space Shuttle Main Engine operates at greater temperature extremes than any mechanical system in common use today. The liquid hydrogen fuel is -423 degrees Fahrenheit, the second coldest liquid on Earth. When the hydrogen is burned with liquid oxygen, the temperature in the engine's combustion chamber reaches +6000 degrees Fahrenheit - that's higher than the boiling point of Iron.

The maximum equivalent horsepower developed by the three SSMEs is just over 37 million horsepower.

The energy released by three of Rocketdyne's Space Shuttle Main engines is equivalent to the output of 23 Hoover Dams.

Although not much larger than an automobile engine, the SSME high-pressure fuel turbopump generates 100 horsepower for each pound of its weight, while an automobile engine generates about one-half horsepower for each pound of its weight.

Even though Rocketdyne's SSME weighs one-seventh as much as a locomotive engine, its high-pressure fuel pump alone delivers as much horsepower as 28 locomotives, while its high-pressure oxidizer pump delivers the equivalent horsepower for 11 more.

If water, instead of fuel, were pumped by the three Space Shuttle Main Engines, an average family-sized swimming pool could be drained in 25 seconds.

The SSME high-pressure fuel turbopump main shaft rotates at 37,000 rpm compared to about 3,000 rpm for an automobile operating at 60 mph.

The discharge pressure of an SSME high-pressure fuel turbopump could send a column of liquid hydrogen 36 miles in the air "

Now this would make one heck of a speedy echant machine!!!

till said:
Last weekend i made PCB for Zen V4, using 30% HCl and as much H2O2 as it begins to make bubbles, took about 2 min. i made it outdoors because of the gas coming out of the solution. No problems, very good PCB.

Of course you can skip the water but for a newbeginner, I think it's unsuitable. Be a little careful at first and then reduce the amount of water. Pure acid + H2O2 is like rocket fuel, very fast reaction, in fact you can etch a board within 15-30 seconds!
Whoa... You must be <i>very</i> careful working with concentrated acid...

:att'n: for safety, you must slowly add the acid TO the dilutant (water, H2O2) never vice-versa! This is especially important with concentrated acids, as they can get very hot very quickly, even boil explosivley, spraying you with concentrated acid!!!

Be careful fellas... full coverage goggles or face shield is a good idea, as is a chemical respirator, good ventilation, and first-aid supplies on hand, especially and eye-wash method of some sort. Chemicals, especially acids, are no joke... I used to work in materials engineering, and we had one bad accident and several close calls, even with all the safety equipment and procedures of a properly equipped and staffed lab...

Of course we worked with some serious stuff... Nitric acid, Hydro-Flouric Acid and a bunch of other metal etchants, mostly for preparing samples for microscopy. Still, HCl isn't friendly stuff.

I just to make sure all the newbies who read this understand the nature of this stuff!

I don't etch my own boards any more, but I recall being very frustrated with the painfully slow FeCl method. I would've jumped to try a high-speed etching technique with simple ingredients like this.

Anyway, I'm sure it works really well. Maybe if I decide to do my own boards again, I'll try it out.

Safe etching fellas...
Sign for your lab

I wouldn't think of keeping hydrofluoric acid in the house. a couple years ago a sanit-man in NYC burned to death from someone's negligence placing the stuff in the trash. Hydrofluoric acid is used to etch glass, among other things. All t hese are nasty (how many of you audio DIY'rs have pH meters like me?)<p>found the following on the wwwwwwww:


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