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Q: whats the cheapest way to strip the conductive film off bakelite (circuit boards)? Answered

hi, when i was apprentice 40 years ago we use bakelite a lot (before plastic etc became all the rage) - great stuff, nice to work with. when i dismantle old electronic gadgets i always keep the board, too. in some future applications, however, they need to be rendered non-conductive. we used acid to etch boards.... is there a very cheap and simple way to strip off the conductive layer - short of sanding it off, etc. cheers, and have a good one, but not too good either.

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Jack A Lopez

5 weeks ago

By the way, your ideas for stripping the components, and everything else, off of old printed circuit boards, reminded me of this old mini-documentary from like ten years ago, titled, "Ghana: Digital Dumping ground" I found a copy of it on Youtube, here:




If you can get past the foreboding tone, bombastic language, and creepy music, I think this documentary might actually have some helpful hints for your plans for stripping down old circuit boards, cheaply.

The first ten minutes, filmed in Ghana, DOES NOT have any methods worth considering, besides open air pyrolysis of old computers and TVs, including the plastic case, plus other plastic (e.g. plastic foam) to help it burn.

I really do not think this is a good method.

1m+35s
"The smell comes from the burning of plastic from old computers and TVs. In the last few years, Agbogbloshie [,Ghana] has become one of the World's digital dumping grounds..."

2m+34s
"Some of the boys burn old foam on top of computers to melt away the plastic, leaving behind scraps of copper and iron, they can collect to sell."

However, at 13m+24s (in Guiyu, China), we see a big solder pot being used to pull components off a circuit board.

Also at 18m+35, we see some dude in Bangalore, India, messing with some big plastic drums and buckets, filled with sulfuric acid.

It is not really obvious to me what practical things are happening with this acid bath. Obviously the producers included it because it looks toxic and dangerous, fitting with the overall theme of the docu.

My best wild-ass guess for what this method is actually doing is leaching out metals into a solution, where they can be recovered later via electrowinning.

https://en.wikipedia.org/wiki/Solvent_extraction_a...

The remainder of my piecemeal transcript continues below.

11m+30s
[Guiyu, (Guangdong Province), China]
"...miles and miles of nothing but old electronics."

"...toxic trade" "...apocalyptic" "...disturbing"

13m+12s
"...taking place behind closed doors, women literally cooking circuit boards."

13m+24s
"They're slowly poisoning themselves with lead fumes."

18m+35s
"Before leaving (Bangalore?) India, the students find some tell-tale signs of back alley e-waste work. A trail of stripped circuit boards, which brings us to this locked courtyard. Inside the toxic trade continues."


19m+07s
"India may have banned these sulfuric acid baths, but it's hard to enforce, and for this 19 year old, and countless others around the world,the economics of e-waste won't be easily changed."

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la xerraJack A Lopez

Reply 5 weeks ago

interesting... will check that video out when i get down to the valley ("civilization") with internet-showers

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Jack A Lopezla xerra

Reply 5 weeks ago

Well, I suggest downloading a copy

(e.g. using youtube-dl)
https://ytdl-org.github.io/youtube-dl/index.html

(or using a web based downloader like deturl or pwnyoutube, or other)
http://deturl.com/

so you can skip right to the few seconds of human activity that might be useful to your application. E.g. the Chinese woman cooking circuit boards over a solder pot. Or the young man in India soaking circuit boards in acid.

Taken as a whole, this film is mostly just a moralizing guilt-fest, made to make people in the West feel guilty for dumping all their broken electronics onto people in the East.

Of course I think this film's producers have mostly failed in placing blame where it belongs; i.e. on the manufacturers who make products designed to fail quickly, and to be difficult to tear down and recycle, especially in the locations where the products are sold.

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la xerraJack A Lopez

Reply 4 weeks ago

hey jack, thanks.... definitely will check it out... but,you know, there is a LOT of 3rd-world in this ´our´ 1st-one.... some people get ´their´ water from opening a tap and out it gushed without end it seems... other carry buckets etc to a well.... same with internet.... and this critter here belongs to the bucket-line.... be good, later, pit

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Orngrimm

5 weeks ago

Unsure if i understand what you are trying to do... You want to strip the PCB from all its copper?
If so, the PCB first needs to be stripped of the solderresist (The green stuff). That stuff is notoriously hard to kill. Its its job anyway: Be resistive against mechanical and chemical stuff.
You may google for solvents to strip the solderresist. Unsure if a combination of acetone and a bit PH-raiser (Aka Acid) is helpfull here.
After, you basically just follow PCB-Etching-Guide as found here on Instructables to dissolve the Copper.
My preffered method is CuCl2 (Copper(II) chloride) as it is regenerative and can be done with very simple and free available chemicals (Muriatic acid and Hydrogen Peroxide).

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la xerraOrngrimm

Reply 5 weeks ago

yes, yes, get rid off everything conductive that might cause a short (see link below, of trying to find some simple solution for the nichrome-cutter)

in general, from all your feedbacks, seems like easier to make some explosives than to strip all those tough layers off.... oh well, as often, the pure brute one might be the way... mandankt (frauauch)

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Jack A LopezOrngrimm

Reply 5 weeks ago

Acids have low pH, less than 7, and adding acid to a solution will tend to lower its pH. Conversely, bases have high pH, greater than 7, and adding base to a solution will tend to increase its pH.

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Downunder35m

5 weeks ago

Are we talking about real bakelite or modern circuit boards?
Bakelite won't care much about a strong acid treatment while a standard circuit board of todays times will just fully disappear.
Having said that...
What are we talking about in thickness and flatness here?
I know that all my really old boards are far from straight and even further away from being really clean.
As all conductive stuff is either on top or within the top layer sanding would be the least problematic approach IMHO.
I prefer a glass plate from an old scanner with some sandpaper on it (total flatness ;) ).
I used cheap double layer sticky tape to keep it in place.
Starting with 180 grid I go down as far I need to remove all that is on the surface.
Then I work my way through 200, 400, 600 and so on until the desired finnish is reached.
If it can be coated I stop at 200 as the varnish or paint will fill the fine cracks and marks - plus it help with the adhesion.
A board of 10x15cm with normal circuitry on it takes me about half an hour to have it free of everything, less if I can use paint or varnish....

For an acid treatment you need to be aware that apart from the health and possible enviromental problems you won't be able to get a "clean" finnish.
You will always see the remains of the etched copper traces as the initial copper was usually applied with some heat.
But as said, if it is bakelite and flat than snadpaper on a glass plate won't disappoint you.

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la xerraDownunder35m

Reply 5 weeks ago

i just hate to throw out stuff (worse, stuff others throw out i schlepp home=cabin, if i can)

yes bakelite, any size i can get my hands on... but usually of few mm thickness (the circuit-stuff, at least --- other bakelite i dont come across anymore.... i remember we had big sheets like ply-wood of up to 1 inch or thicker flying about in our workshop when i was an apprentice)

the other day i was just looking for some *buckle* i could rig out of a piece of circuit-board ( https://www.instructables.com/id/How-to-Cut-Glass... ) ... as i mentioned, i like that stuff... its tough, easy to work with, heat-resistant and non-cunductive

thanks 35m

ps, at worst i scrape the sh it off with some knife...

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Jack A Lopez

5 weeks ago

Well, you know, you have roughly three layers to deal with, before getting down to bare, nonconductive, dielectric board.

1) The circuit board is covered with a forest of little electronic components. Those have to be removed first, either by desoldering them one by one with a soldering iron, or by way of a giant pot, or frying pan, full of molten solder, so that large sections of board can be heated all at the same time.

2)The conductive traces are typically covered with a layer of paint-like material, called "solder mask".

https://en.wikipedia.org/wiki/Solder_mask

Removing that stuff will probably require something like a paint stripper type solvent. Unless you want to grind the mask layer off mechanically, like with sandpaper, or scouring pad, or something like this.

http://www.circuitmedic.com/features/514.html

3) Once you have have bare copper traces exposed, there a number of etchants that can dissolve copper. I recall, Youtube chemistry guru, Nurdrage, made a video showing ten different ways to make etchant that could dissolve copper circuitboard traces.

Here is Nurdrage's 'ible for that,

https://www.instructables.com/id/Make-10-Etchants-...

and that 'ible is really just a summary and a link to a Youtube video, that I might as well embed, here: