Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Make pcb etching solution
antimon
Harmless
*




Posts: 33
Registered: 24-6-2015
Member Is Offline

Mood: No Mood

[*] posted on 24-6-2015 at 01:37
Make pcb etching solution


Hi, i am going to make my own pcb etching solution, and i just wonder how i go about doing that?
I have some anhydrous FeCl2 that i can probably use, but i want to make my own from scratch.
Do i use steel wool, and dissolve it in HCl, or what?


If i were to use the dry FeCl2, what do i mix it with to make it a solution?

Do the solutions that you can buy from ebay, and other places contain just FeCl, or are there other chemicals mixed in there too?
I have read that CuCl are also used, or if it may be a side product in the end of the process maybe.

Thanks in advance.

[Edited on 24-6-2015 by antimon]
View user's profile View All Posts By User
diddi
International Hazard
*****




Posts: 723
Registered: 23-9-2014
Location: Victoria, Australia
Member Is Offline

Mood: Fluorescent

[*] posted on 24-6-2015 at 03:26


the best method I found is to remove large areas of cupper with nitric acid (if required) and then use dropwise addition of H2O2 in 5M HCl
you only need a very small amount of HCl. 5mm over the surface. then add drops of H2O2 and agitate. you can see through the solution and observe progress. easy to see problems in etch before it is too late




Beginning construction of periodic table display
View user's profile View All Posts By User
agent_entropy
Hazard to Self
**




Posts: 91
Registered: 17-7-2006
Location: U.S.
Member Is Offline

Mood: No Mood

[*] posted on 24-6-2015 at 04:40


Here's some to try:
http://www.instructables.com/id/Stop-using-Ferric-Chloride-e...
http://www.instructables.com/id/Make-10-Etchants-for-Copper-...

I've made the regenerable HCl and H2O2 one that produces copper (II) chloride as the final etchant and it works pretty well.
View user's profile View All Posts By User
aga
Forum Drunkard
*****




Posts: 7030
Registered: 25-3-2014
Member Is Offline


[*] posted on 24-6-2015 at 04:45


FeCl3 is the etchant i usually use for PCBs.

Dissolve steel wool in 20% HCl (a day or two) then filter.

The solution will be Green FeCl2

Add H2O2 (or bubble air through it for days) and it will go Yellow/Brown FeCl3.




View user's profile View All Posts By User
WGTR
International Hazard
*****




Posts: 963
Registered: 29-9-2013
Location: Online
Member Is Offline

Mood: Outline

[*] posted on 24-6-2015 at 07:13


Here's one I've used that works:

Make up solution to give 2.5L after H2O2 has been added.
React 187g copper (from wire) with 750mL 32% HCl and H2O2 with stirring.
Add H2O2 slowly over several hours (careful, it will get very hot, especially if 30% H2O2 is used). Concentrated H2O2 is preferred, but 3% can also be used. It will just introduce more water.
A clear, green solution should result. If it is dark and opaque, add more H2O2. Don't use excess peroxide. It can attack common organic etch resists. If too much was added, just keep the solution hot for several hours to help decompose it (a good idea anyway). This results in CuCl2, with free HCl. Maintain about 1M free HCl, with 75-200g/L of copper.

This solution works well, but is slower than the traditional ferric chloride etchant. If it's sprayed, it results in finer features with less undercutting than ferric chloride. It is also less troublesome to regenerate, only needing more H2O2 and HCl.

I've made etchant the way that aga suggests, and I've found that it works well. I use it for small jobs, and when I'm doing a class demonstration and need an etchant that works fast. After adding H2O2 it may be necessary to evaporate the solution down a bit to concentrate it. Add extra HCl afterwards if needed, to keep the CuCl soluble, and to dissolve the "rust". The same principle applies here about excess peroxide as before.

Both of these etchants work well with the typical organic photopolymer resists, which usually resist acids well. If an etch resist for through-hole plating is needed, then I use a tin resist (so it can be plated down into the holes). In this case it is necessary to use ammoniacal copper sulfate etch, which does not attack tin.
View user's profile View All Posts By User
battoussai114
Hazard to Others
***




Posts: 235
Registered: 18-2-2015
Member Is Offline

Mood: Not bad.... Not bad.

[*] posted on 24-6-2015 at 10:26


I usually go with a mix of HCl and H2O2 that agent_entropy talked about. It's faster than FeCl3 and overall easier to use albeit you should be more carefull as getting it on your skin will do worse than the stains FeCl3 leave.
I think some people also use ammonium perchlorate due to it being less toxic... but i can't say how well it works.
View user's profile View All Posts By User
Nicodem
Super Moderator
Thread Moved
24-6-2015 at 14:14
innervision
Harmless
*




Posts: 49
Registered: 6-2-2006
Member Is Offline

Mood: eh.

[*] posted on 28-6-2015 at 00:01


I use:

Developer:
700mL H2O
10mL Sodium silicate solution
10g NaOH

Etchant:
100mL HCl
200mL H2O2 3%

I keep the developer in a jug and use what I need. The etchant gets made fresh every session. Now if only I knew what to do with this worthless gallon jug of FeCl3 ;)
View user's profile View All Posts By User
battoussai114
Hazard to Others
***




Posts: 235
Registered: 18-2-2015
Member Is Offline

Mood: Not bad.... Not bad.

[*] posted on 29-6-2015 at 13:45


Quote: Originally posted by innervision  
I use:

Developer:
700mL H2O
10mL Sodium silicate solution
10g NaOH

Etchant:
100mL HCl
200mL H2O2 3%

I keep the developer in a jug and use what I need. The etchant gets made fresh every session. Now if only I knew what to do with this worthless gallon jug of FeCl3 ;)

Reduce it to Fe NanoParticles and make ferrofluid?
View user's profile View All Posts By User
aga
Forum Drunkard
*****




Posts: 7030
Registered: 25-3-2014
Member Is Offline


[*] posted on 29-6-2015 at 14:01


I tried that with magnetite.

FeCl2 + FeCl3 + NaOH, filter, dry, then add 'a surfactant' for which i used Oleic acid.

Worked kind of, in that the 'liquid' followed a magnet, just that it also left a smeary brown slug trail on everything it touched.

Dry magnetite is pretty amazing with a magnet IMHO and is much easier to clean up (unless it hits the magnet).




View user's profile View All Posts By User

  Go To Top