Non-metal in AP solution

[Cricket]

I'm sure this is an obvious newbie question but I thought I'd ask before I attempt it. When using the AP method of gold plating removal off circuit boards using Muriatic Acid (from Lowe's) and Hydrogen Peroxide 3%... does the board HAVE to be completely depopulated or is it ok if certain plastic connector plug-ins that are very small, but contain gold plated pins within, stay attached or will the plastic cause an issue? That being said... what about other components such as tiny SMD resistors, capacitors, very small IC chips, etc.? I ask because 1... Hot sand baths aren't seeming to work for me and a hot air gun method of removal is extremely time consuming and still not 100% effective. And 2... given the tiny size of the plastic parts containing gold pins, leaving them on would seem to be a time saver as well as leaving on the other very small components. I'm not wanting to overly complicate this step by doing more than is necessary but yet I don't want to ruin any batches either if I can help it. Thanks for any advise!

P.S. - What about solder? Will solder affect the solution to awful much or is it important to remove as much as possible when there appears to be a decent amount? Thanks again!

 

[patnor1011]

Sand bath is the best method for me. Do not use a lot of sand and it will work like charm for you. I barely manage to change boards quick enough to remove components from them. In a steel pan with just about 1cm layer of sand I do 6 ram sticks and as soon as I put last one in I have to remove first one as it is done. When I remove one I always place another in its spot and on and on...

Certain plastic will be affected by acid and will increase mass it will "swell" I try to put none in acid. Pins usually take a long time in acid peroxide to dissolve and with connector housing and other bits of pieces of plastic cleaning stripped material of foils and gold powder will be problematic and some gold may be lost. There is no time saver when doing this type of material. Most of things which appear to be saving you time will cause headache in next steps. This is very time consuming hobby and every time I attempted to cut corners I was actually losing time and money. You will be better off removing pins from their housing.

 

[MarcoP]

Quoting Geo about plastic in CuCl2, source http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=21704&p=224962#p224962

Also remove any PVC parts you can find. Any plastic that bends before it breaks. This type plastic is susceptible to attack from HCl (hydrogen chloride) and can hydrolyze in AP. Any plastic that breaks before it bends will hold up to the acids.

Or, as Pat says above remove it all, otherwise pyrolize it.

Marco

 

[Cricket]

Thanks for the reply patnor1011 and Marco. AH... then maybe that's my problem with a hot sand bath... I been trying to use a couple inches of sand in an electric skillet that goes to 420 degrees F (no access to a grill) instead of a thin layer. I will have to re-visit that method again. I figured as much about the plastics on the boards but thought it couldn't hurt to ask. I have heard and read in many places that one shouldn't go into this thinking it's a quick process so I am fully aware to be patient. It's just that I have loads upon loads to process and would rather try to do it myself if possible instead of selling the boards to some recycle site lol. I have something like 800+ RAM sticks to process (minus the fingers that are cut off for separate processing) that have other gold plating throughout the surfaces but also scrapped other medium-to-small-to tiny sized boards of varying types that have what appears to be gold plating that I'm wanting to AP also and that's why I was asking.

What about if other components are left on like very thin & tiny resistors and such that aren't plastic and won't come off? And should I do the Lye treatment that I saw Moose Scrapper posted on YouTube the remove solder masking or is that usually a time waster?

 

[patnor1011]

I collect resistors and monolithic capacitors they do contain silver and some palladium too. Better to process them separately. I am not a fan of lye and washing solder mask off. Unless you do have super old military/telecom grade material. Gold on some ram stick under solder mask is just flash plating not worth effort, lye, dangers involved or electricity in my opinion. One single IC from ram does have more gold than what is plated under solder mask. Is it worth the effort? For me not, that would be very expensive gold to get.

 

[Cricket]

Thanks again patnor1011. I knew to collect monolithic capacitors to sell on eBay and such but I haven't heard of any processing methods for them to recover silver and/or palladium. Nor have I heard of even collecting the monolithic resistors for anything. But I do also collect the tantalum capacitors and oscillating crystals for either processing later on or outright sell them. And the other odds n ends that come off go into an "unknown" container if I don't recognize them to maybe someday have a value. Thanks for that tip about the monolithic resistors!

I assumed as much about the solder mask but again I thought I'd ask.

I have been collecting the bigger IC chips but didn't know if the small & thin flatpack type were worth saving & processing/selling or not but I do have them in a separate container just in case.

 

[bswartzwelder]

Not only what has been said before, but anything like tin and lead will destroy your Cu2Cl (AP) solution making it unusable. Some members have reported using Cu2Cl for well over a year because they are judicious about what goes in the bucket and what stays out.

 

[Cricket]

Thanks bswartzwelder. But isn't there tin and/or lead in solder? Not to mention trace amounts of silver sometimes? From what I understand... solder can't be completely removed from the boards via hot sand baths and more so via hot hair gun as I've noticed myself. I thought solder is acceptable in the AP since it's suppose to "eat" away base metals including solder where as I also thought gold plating is removed, not dissolved, in AP (if not heated) and then AR for the refining of the gold foils. Is there a step I've overlooked that involves solder removal?

 

[Pantherlikher]

Ok...

Cricket...
You need to put Youtubewillhurtyou away.
Put all questions side as well as any chemicals you think you know enough to use.

Now, got the welcome section of this great forum and begin your journey of extensive learning everything you wish to learn.

Your 1 simple question is turning to more questions which lead to more questions all of which are part of the learning process of this forum.

We all started somewhere and the beginning is always the best for best possible outcome.
And don't skip over the safety section.

B.S.

 

[hoosierdaddy]

First and foremost welcome.
Now, listen to the advice given. Forget what you think you know from youtube. Moose has good "advice" but is not an educator. Do reasearch while gathering material.
When it comes to solder masks, not worth the time, smell, or risk.
When it comeas to plastic remove it all.
If you are worried about solder on your IDE Pins soak them in HCl for 24 hrs to knoch the solder off.
Given the amount and type of questions you have, I feel you are not ready for AR processing. You need to read, build your lab, and make yourself awars before going beyond AP digestion of pins. Not to be a prune, I am a perfectionist who also still makes mistakes.