antimon
Harmless
Posts: 33
Registered: 24-6-2015
Member Is Offline
Mood: No Mood
|
|
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]
|
|
|
diddi
National Hazard
Posts: 723
Registered: 23-9-2014
Location: Victoria, Australia
Member Is Offline
Mood: Fluorescent
|
|
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
|
|
|
agent_entropy
Hazard to Self
Posts: 91
Registered: 17-7-2006
Location: U.S.
Member Is Offline
Mood: No Mood
|
|
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.
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
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.
|
|
|
WGTR
National Hazard
Posts: 971
Registered: 29-9-2013
Location: Online
Member Is Offline
Mood: Outline
|
|
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.
|
|
|
battoussai114
Hazard to Others
Posts: 235
Registered: 18-2-2015
Member Is Offline
Mood: Not bad.... Not bad.
|
|
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.
|
|
|
Nicodem
|
Thread Moved
24-6-2015 at 14:14 |
innervision
Harmless
Posts: 49
Registered: 6-2-2006
Member Is Offline
Mood: eh.
|
|
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 
|
|
|
battoussai114
Hazard to Others
Posts: 235
Registered: 18-2-2015
Member Is Offline
Mood: Not bad.... Not bad.
|
|
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?
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
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).
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
