A few quick questions

[huntersarrow]

Right, so I've recently come across a few more sources of scrap and am now build up a nice small stockpile to process.

In the mean time I've gotten a little impatient. Wanted to do a very small test run so the quantities im using at the moment are less than a gram and about 5-6mls of hlc.

1st test. CPU's...

Using 2 flat cpus as a sample run i submerged both in straight hlc. I Have no heat source at the moment so just sitting at room temp. Had removed copper heat sink off the backs of both. One i left complete and the other I removed the center bits (not sure what their called) with a heat gun and it left a small amount of solder on the cpu. Left overnight and checked in the morning. The one with center bits removed seemed to also be free of solder and on the other one the center bits had loosened themselves nicely and didn't see solder underneath either. Few small dots of gold were also floating. Should be able to easily separate from the loose center bit with a magnet. Any thoughts on using this as a depopulation method before ap?

2nd Test. PINS..

Used a heat gun to remove pins from green fiber cpu and collected, Naturally some solder remained on the pics and is in the mix. Have read here for a fair bit, I (like many others) wanted to give the cpu pins a hlc bath to dissolve base metals before ap. I know a heat source would be good and speed up the process but have time at the moment so just using hlc. Used a sample so small i likely wont see any recovery but as this is a experiment / test for cleaning not worried. Very quickly i saw a bubbling reaction and the hlc turned a light purple / violet color. My thoughts are that some gold has dissolved in the hlc. The hlc has also eaten some tin (from the solder) and made stannous in the solution and is the violet color is a positive result for gold (gold cuplric? Hopefully the word i'm trying to remember )in the solution. Showing my novice here but if i add some copper (wire) gold should cement back on to copper as black powder?

3rd Test. Phone PCB.

Removed as many parts as i could by hand, small ic chips and other tiny bit left on and just dropped the thing in a jar of hlc. No visible result yet.

Happy to keep learning from research but if I've made and major errors in my thought process would be grateful for a few tips on what to sty away from

 

[glorycloud]

"In the mean time I've gotten a little impatient. Wanted to do a very small test run so the quantities im using at the moment are less than a gram and about 5-6mls of hlc."

We all get impatient. It looks all golden and shiny. 8)

May I ask, what is the purpose of your test? What are you hoping to accomplish or to see?

 

[huntersarrow]

Mostly depopulation at the moment. Want to have all boards i use ap for as clean as possible so less contaminants when i get to ap.

As an update..

Cpu batch has turned a nice golden yellow, but i've read hlc turns yellow when exposed to oxygen so not getting excited there.. seems to be the best run so far with the gold dots coming off slowly but nice and clean..

Cpu pins don't look like the base metals are dissolving so am looking at a heat source..

Phone pcb has turned clear hlc into a bright purple, removed some ic chips and bits off the board but also looks like its eating away at the gold or removing it like ap would, however that leaves the problem of sorting it with all the other bits that come off... might visit the sand bath idea first to remove most of whats on the phone pcbs..


Have some tin i need to melt to make stannous for testing but finding time is an issue...