Special coat on printed circuitboards?

[9kuuby9]

Hello guys,

I hope you all had a lovely summer :mrgreen:


I've got a question, I have some PCB's laying around here and I wanted to process them but I think i ran across a special type of PCB's, So I tought I'd ask you guys if you now anything about these coatings on these PCB's.


Now I looked on the site of the manufacturer (http://www.nrielectronics.com/pcb-printedcircuitboard.aspx) and the coating could be could be composed of the following : Conformal Coating, Encapsulation, RTV / Epoxy Application.

Here are some pics to make it easier :mrgreen:

and I also tried caustic on it (3moles), no go.

Any help is appreciated!

 

[SFC]

9kubby9, you might want to check out Laser Steve's web page at URL: http://www.goldrecovery.us/goldrecovery/videos/ShowVideo.aspx?id=soldermask&yt=0

It might or might not be the same type of green mask.

 

[butcher]

This looks like an epoxy coating over the circuit board from your picture, the epoxy coating looks to be over the circuit components as well as the solder mask, the sodium hydroxide would most likely have a hard time penetrating the epoxy much less get to the solder mask, you might try and see if acetone, or paint strippers, would effect the epoxy, I know fire would, but the toxic smoke danger to your and others health is not worth the few penny's of values underneath.

 

[rshartjr]

I am an avionics technician by trade and that board appears lacquered, to me. Lacquer is cheaper and easier for manufacturers to apply, and is, therefore, much more common.

I perform a simple test before I attempt to solder on conformal-coated boards.

Dip a q-tip in rubbing alcohol (isopropyl, any strength) and rub a small spot on the surface. If the coating softens, or comes off of the test spot entirely, you can use far less harsh methods.

If it is only lacquer, you can remove it with a scrub brush and alcohol or very hot tap water and dish soap. (Either will require a judicious application of elbow grease)

I'm a "keep it simple" kind of guy. The simplest solution always works best.

Scott

 

[butcher]

Thanks Scott for the good tip.

 

[9kuuby9]

Thank u guys for helping me out :mrgreen:

I have tried the the method as rshartjr suggested, it seems to me that it is an epoxy coating.

I have used 96° rubbing alcohol seems like nothing happened, I also tried to scratch it off with a knife on the same spot i used the alcohol and it barely comes off. And it is also very resistant to flames/heat.


Does anyone have an idea how to soften or remove the epoxy coating?

Normally i would not mess with such PCB's but since I have over a 100's of them I thought it maybe worth it's while.

(i'm going to get some acetone and see what happens :d)

 

[Geo]

have you tried "Goof-Off". its a name brand solvent that will dissolve most any organic based epoxy or paint or glue. if all else fails, this is something i would never recommend on a large scale, as an experiment, try soaking a board in gasoline.in a safe place in the open and away from structures, on the ground, place a flat container big enough to fit one board in and cover in gasoline and cover the container but do not seal. give it a day and see if the epoxy has melted.

 

[rshartjr]

It could be the lighting, but I don't see a much gold on the board. I do see some nice chips and lots of capacitors, though.

If it your intent to depopulate the board, I have an idea. It's a little time consuming, but it will work.

You need only chip or scratch the coating from the solder fillet to expose it to the HCl bath. This can be done with an old dental tool, scribe, scratch awl, or a Dremmel tool with a ball mill or cutting disk. Be sure to get both sides for through-the-board pins like the connector pins.

Once the HCl has done its job, you should be able to scrape everything off with a putty knife. Depending on the strength of the remaining epoxy, some minor "coaxing" with a mallet might help.

Scott

 

[9kuuby9]

Thanks scott!

I will experiment and see how I can depopulate the board accordingly.


Thanks for all the ideas guys 8)

I'll post the results in the weekend


If anyone still has a suggestion(s) just shoot it out :mrgreen:

 

[9kuuby9]

It could be the lighting, but I don't see a much gold on the board. I do see some nice chips and lots of capacitors, though.

If it your intent to depopulate the board, I have an idea. It's a little time consuming, but it will work.

You need only chip or scratch the coating from the solder fillet to expose it to the HCl bath. This can be done with an old dental tool, scribe, scratch awl, or a Dremmel tool with a ball mill or cutting disk. Be sure to get both sides for through-the-board pins like the connector pins.

Once the HCl has done its job, you should be able to scrape everything off with a putty knife. Depending on the strength of the remaining epoxy, some minor "coaxing" with a mallet might help.

Scott

These switches have thick plated gold balls, and the rest is namely MLCC's

 

[butcher]

In repairing circuit boards, a long time ago I bought a chemical to remove the epoxy, it would dissolve it,so I could troubleshoot and replace the bad components, I really do not know what the name of the product was, but do remember it was flamable, (search dimethal sulfur oxide glycol ether epoxy removerfor circuit boards), it also needed heated to 300 degrees F.



http://www.google.com/#sclient=psy-ab&hl=en&rlz=1R2RNQN_enUS457&q=dimethal+sulfur+oxide+glycol+ether+epoxy+remover+for+circuit+boards&btnK=Google+Search&rlz=1R2RNQN_enUS457&oq=dimethal+sulfur+oxide+glycol+ether+epoxy+remover+for+circuit+boards&gs_l=hp.12...24204.34250.2.37110.19.18.0.0.0.2.2281.18921.2-3j1j0j3j1j5j4j1.18.0.les%3B..0.0...1c._GyI7i_2L5Q&psj=1&bav=on.2,or.r_gc.r_pw.&fp=baef827db5508c9b&biw=1024&bih=583,


Maybe checking this out, or searching for epoxy composition and removers from circuit boards and then seaching the MSDS you can find something you can mix up from cheaper ingrediants, reading is not dangerous, but be very careful with expierimenting.

http://www.faqs.org/patents/app/20110303446

 

[Palladium]

Goof off is nothing but xylene and can be purchased at Lowes. Try denatured alcohol first and then lacquer thinner and see what that does. The next highest thing up the ladder is acetone. This stuff is like jet fuel actually more flammable i think so be very aware that it can self combust.

 

[qst42know]

There are several types of conformal coatings. This tech bulletin covers several types and techniques for removal.

http://www.paryleneengineering.com/pdf/conformal_coating_removal_techiques.pdf

 

[silversaddle1]

Just flip the boards to Boardsort and move on to bigger and better things.