My etching process

Thread Starter

cmartinez

Joined Jan 17, 2007
7,312
I was thinking about posting these pictures in this thread, but then I thought I didn't want people to think I was hijacking it. So I'm tagging its main participants here, see if they find it interesting.

@nerdegutta, @DerStrom8, @Lestraveled, @jpanhalt, @atferrari, @JDR04, @A_Maine96, @MrAl, @Dr.killjoy

This is how I start my PCB process. First I draw my circuits in AutoCAD ('cause I'm an expert... and I've been too lazy to learn a specialized software... so maybe I'm just drawing pretty pictures, as @WBahn once said, but what the heck. :rolleyes:)

Then I print the layout using the magic paper that I described in this thread.

01.jpg


After that, I cut the circuit layout to its adequate size, depending on the board size I'll be using. Like here, with a 10 x 15 cm board:

02.jpg



And then I place it on my press iron, using a 1/8" thick of red silicon sheet as a separator so that the paper won't burn. This also helps distribute the pressure more evenly.

03.jpg

After ironing, I cut the excess board and very easily peel the paper off.

05.jpg

06.jpg
The paper will come off very easily if it's out of a new package. As the paper ages, it becomes a little harder to peel, until eventually, after about 18 months, it just won't work anymore and will stubbornly stick to the board, and will even jam at the printer quite often.


You can tell that the transfer was a success if no ink toner was left on the paper.

06b.jpg

It took me several years of trial and error until I came up with a satisfactory design for my etching tank. The tank is made by using 3 layers of sheet glass 1/4" thick, with the middle layer working as the tank's cavity. This helps make sure that the PCB is thoroughly immersed in the etching solution, and it also allows for a 200W halogen light to be placed behind it, so as to warm the whole thing at once and speed things up a bit.

07.jpg

08.jpg



Here you can see the PCB just prior to being dumped into the tank. The PCB is held by a nylon fishing line to make it easy to extract after the process is completed.

09.jpg

If the ferric chloride in the tank is new out of the bottle, and it hasn't been used to etch anything yet, it will allow the light from the halogen lamp to shine right through it.

10.jpg
 
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Thread Starter

cmartinez

Joined Jan 17, 2007
7,312
But the chemical will definitely start looking much darker once a couple of PCBs have been processed.

11.jpg


You can see that I'm using bubbles to shake things up a bit in there. This is done by using an ordinary fish-tank air pump, which I placed in the back of the device.

13.jpg


I also installed a PVC valve in the back, to be able to drain the solution after it becomes too saturated with residue after too many uses. Finding the appropriate valve was a pain the the rear-behind since all the commercial valves that I tried to use had a ball that was made of some OTHER material that was not PVC, and that was eventually eaten through by the FeCl₃
It wasn't until I bought a valve from these guys, that the problem was solved. Kind of expensive for a 1/2" PVC valve (more than $30.00 dlls, if you include S&H) but worth every penny.

12.jpg


Finally, here are some of my results:

14.jpg
 
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Thread Starter

cmartinez

Joined Jan 17, 2007
7,312
And you didn't invite me! I'm hurt!
You're always invited! and besides, you don't need an invitation, you're a moderator so I know you're always LURKING in the background... Emoji Smiley-12.png

Anyway, what do you think of my tank? Maybe I overdid things a little, after I took a look at Lestraveled's economy version. Probably the next thing I'll add is a PWM for the lamp, to control the temperature.
 

Wendy

Joined Mar 24, 2008
22,368
You can never overdo something like that. It works, and probably much better than my Tupperware.

The professional etching tank I worked on heated the FCl to something like 50 degrees C, and sprayed both sides of the PCB. Yours is much easier to work with.

I especially liked the press. I want one.
 

Lestraveled

Joined May 19, 2014
1,946
C
Excellent excellent post!

Wendy, there is a lot of great information on making printed circuit boards on this forum, and the contributions are not stopping. What do you think about a more defined place for this information?
@Wendy

This is my first tag, did it work??
 
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Thread Starter

cmartinez

Joined Jan 17, 2007
7,312
You can never overdo something like that. It works, and probably much better than my Tupperware.

The professional etching tank I worked on heated the FCl to something like 50 degrees C, and sprayed both sides of the PCB. Yours is much easier to work with.

I especially liked the press. I want one.
Thanks... the press is probably the best investment I made. I've never had any problems with it, and I get a perfect print every time. When you get one, make sure that it has an automatic lid-lifting timer. It makes all the difference.
 

Wendy

Joined Mar 24, 2008
22,368
C
Excellent excellent post!

Wendy, there is a lot of great information on making printed circuit boards on this forum, and the contributions are not stopping. What do you think about a more defined place for this information?
@Wendy

This is my first tag, did it work??
Sorry, don't know why it didn't work. I get likes and quotes very reliably though.

I have a couple of 8" 1/4" thick sheets of aluminum. I was thinking of using paper, but the silicon works much better I suspect. My thought was to put it on a hot plate with a phone book on it. Now I'm wondering if I can't make something more similar to the press. While the laminator works, it has problems galore.

How much does a press like that set you back?

I also need to find a source for the silicon sheets. Any thoughts?
 

Art

Joined Sep 10, 2007
806
Ok well they are certainly pretty pictures :D
I am in the process now of developing skill also etching art on brass and copper,
so it’s probably time to invest in some PCB skills which should flow over to art etching too.
 

Thread Starter

cmartinez

Joined Jan 17, 2007
7,312
Hola César,

Worth many lines of text!

What is the original use of the silicon?
Agustín, many thanks!

The silicon is there to spread the heat more evenly, avoiding unbalanced hot spots in the board. And it also distributes the pressure applied by the press equally throughout its area.
 

Thread Starter

cmartinez

Joined Jan 17, 2007
7,312
Sorry, don't know why it didn't work. I get likes and quotes very reliably though.

I have a couple of 8" 1/4" thick sheets of aluminum. I was thinking of using paper, but the silicon works much better I suspect. My thought was to put it on a hot plate with a phone book on it. Now I'm wondering if I can't make something more similar to the press. While the laminator works, it has problems galore.

How much does a press like that set you back?

I also need to find a source for the silicon sheets. Any thoughts?
Give me a few hours and I'll get back to you with that info.
 

Thread Starter

cmartinez

Joined Jan 17, 2007
7,312
Sorry, don't know why it didn't work. I get likes and quotes very reliably though.

I have a couple of 8" 1/4" thick sheets of aluminum. I was thinking of using paper, but the silicon works much better I suspect. My thought was to put it on a hot plate with a phone book on it. Now I'm wondering if I can't make something more similar to the press. While the laminator works, it has problems galore.

How much does a press like that set you back?

I also need to find a source for the silicon sheets. Any thoughts?
Wendy,

I bought the silicon rubber sheet (1/8" thick, 12" x 12") from http://www.superiorseals.com/sheeting.asp . It cost about $30.00 dlls a few years ago.
As for the press, it's a 11"x15" and I bought it from these guys. Let me warn you, it ain't cheap. It sells for $1,000 dlls down here... it's probably around $700 in the U.S. but you're gonna have to ask for a quote... I bought it because of its accurate temperature adjusting capability and its auto-release timer... and also because I'm a spoiled brat Emoji Smiley-16.png

But you can get a pretty decent press of the same capacity out there, brand new, for less than $200.00 dlls. Adding a magnetic auto-release timer mechanism could be a good project to work in this forum, if you're up to it.
 
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