Processing bga chips

[Mitch2580]

DIP or dual inline package. Using "dual inline package" for a search term finds a lot of information. This was one of the first questions I ask.

Edited for clarity

Thank you guys for the info

 

[kjavanb123]

Hi

I tried the method described here by spaceships and might add the following to it.

I had a 100ml hcl added to some gold foils from relays and added 1ml when it was hot not boiling just hot.

It dissolved the gold and got this orange solution which I kept at the same temperature.

Prepared saturated sulfamic acid solution per instruction in his post, also kept this hot and not boiling.

Added 1ml using a dropper to AR solution and got no reaction, repeated it and still no foaming or any reaction.

So thinking I didnt have excessive nitric acid in my gold solution I let solution on hot plate for 20 minutes then cool to room temperature.

Added half a teaspoon SMB and got the red foams which is an indication of excessive nitiric acid.

I put the gold solution on hot plate and got it to near boiling, added a ml of saturated sulfamic solution, only then I got the foaming up.

So I guess the right temperature as it was once mentioned by Geo is near boiling

 

[anachronism]

Did you add the sulphamic solution to the pregnant solution when the pregnant solution was hot? Sorry I couldn't work that out from what you typed.

 

[anachronism]

Here's a process I have learned and modified to get the best results for denoxing AR solutions.



Add 150ml of water to the beaker, and place on the hot plate. You want this solution to be warm to hot, not boiling.
Add a couple of teaspoons of the crystals to the water, stir and let it dissolve- this will happen relatively quickly to start with.
Keep repeating this process until your solution leaves some crystals in the bottom even after plenty of stirring. Your solution is now close to being saturated. It doesn't HAVE to be this strong but experience will help you learn the required amounts.

In order to learn this properly without any risk of losing gold, I would suggest that you prepare a dummy solution of AR. Remember the purpose of the tutorial is to help you learn to denox a solution so why risk your money if it can be learned without financial risk?

Preparation of "dummy" AR.

Put 100ml of HCl in a 1 litre beaker.
Add 100ml to 150ml of water - tap water is absolutely fine for this.
Add 3ml of Nitric acid (70%) or 6ml of Nitric acid (35%) or the equivalent of "poor man's Nitric."
Put this on a hotplate (WITH A CATCH PAN) and warm up. Again you want a warm to hot solution - as if you were truly dissolving gold but no need to boil.

Spaceships *cough cough* did say hot 8) 8) 8)

 

[kjavanb123]

Yes hot saturated sulfamic acid solution was added first to hot AR solution and nothing happened.

So I added SMB and since it indicated excessive nitric (red foams), I got the AR which now SMB also added to near boil, then addee saturated sulfamic solution and could see bubbling and foaming only at this state.

Best regards
Kj

 

[Shark]

Just curious, but how dirty was your AR?

It seems to be more of a problem to me when the AR is heavily contaminated with copper. I read somewhere that copper in solution could, under the right conditions, rejuvenate the nitric acid. Wish I had kept that as link as I can't seem to find it now.

 

[kernels]

I think I may generally accidentally avoid this problem since I always cement Gold out of very dirty solutions, Sulfamic is only used for the final clean(ish) solution and I always just add it in powder form (slowly). You also want to add it to a less concentrated solution, so I usually just add some boiling water to my solution before I add the Sulfamic. I aim for a temperature around 90deg C when adding the Sulfamic (slowly)

 

[anachronism]

I think I may generally accidentally avoid this problem since I always cement Gold out of very dirty solutions, Sulfamic is only used for the final clean(ish) solution and I always just add it in powder form (slowly). You also want to add it to a less concentrated solution, so I usually just add some boiling water to my solution before I add the Sulfamic. I aim for a temperature around 90deg C when adding the Sulfamic (slowly)

It was written for people who were getting started and like you Kernels I use now the solid form too.