These metal Processor chips have me stumped! Over 18 lbs of them!

[J&D]

Hi all. My name is Jason. Earlier this week I found about 18 lbs of manufacturer scrap processor chips. Still in strips of 4-6. Hundreds of strips of 4-6. They are beautiful. Packed with gold bonding wires and all, exposed already.
BUT the strips and the wafer the chips are on is made of aluminum.
I have never heard of aluminum wafers for a chip. I have no idea how best to process these!
I can recover the gold from printed circuit boards, ceramic chips, etc. But those materials are not on AL.....all of my acids will just work against me dealing with aluminum, right?
I am kind of stumped. I'm going to include some pics of this material. If anyone has an idea how best to process these, I would be very grateful to hear it. I have all of my acids, glassware, 10 years of experience, a proper workshop, fume hood, etc....I just wasn't expecting this curve ball!
Metal chips.....and so so many of them!
In the following pics, you can see a yardstick for reference to the scale of these. Its over a cubic yard of these buggers laid out, and there was probably 4 pounds left in a bin, I just got tired of making the cube there were so many

 

[Yggdrasil]

Hi all. My name is Jason. Earlier this week I found about 18 lbs of manufacturer scrap processor chips. Still in strips of 4-6. Hundreds of strips of 4-6. They are beautiful. Packed with gold bonding wires and all, exposed already.
BUT the strips and the wafer the chips are on is made of aluminum.
I have never heard of aluminum wafers for a chip. I have no idea how best to process these!
I can recover the gold from printed circuit boards, ceramic chips, etc. But those materials are not on AL.....all of my acids will just work against me dealing with aluminum, right?
I am kind of stumped. I'm going to include some pics of this material. If anyone has an idea how best to process these, I would be very grateful to hear it. I have all of my acids, glassware, 10 years of experience, a proper workshop, fume hood, etc....I just wasn't expecting this curve ball!
Metal chips.....and so so many of them!
In the following pics, you can see a yardstick for reference to the scale of these. Its over a cubic yard of these buggers laid out, and there was probably 4 pounds left in a bin, I just got tired of making the cube there were so many

HCl eats Aluminum fast and efficient, but it can create a gooish slime that will lock up the foils.
Maybe a Sulfuric stripping cell will fix this?

 

[MicheleM]

Is the chip side with the gold wires protected by some kind of plastic ?

 

[J&D]

HCl eats Aluminum fast and efficient, but it can create a gooish slime that will lock up the foils.
Maybe a Sulfuric stripping cell will fix this?

thx, yes I remember that about HCI. Would a sulfuric cell work on the tiny gold bonding wires?

 

[J&D]

Is the chip side with the gold wires protected by some kind of plastic ?

On most of the chips, I can see plainly, there is no coating, as the bonding wires are exposed.
On some of the chips, like a small portion, the actual center of the chip has a glob of epoxy-kind of serving as a cap for the bonding wires and die in the center. On most, this epoxy glob is not present. As for the foils along the outside edges, so far as I can tell, there is no coating.

 

[snoman701]

These look like in process BGA chips without the epoxy added to protect the die and wires.

Can't you just remove the chips from their aluminum carrier?

 

[rickbb]

What about a sodium hydroxide solution to dissolve the Al first?

 

[J&D]

hi, thx for the idea....the chips can be removed from their carrier, but the wafers themselves are also made of aluminum! So, they will be removed when I figure how to process them, just to eliminate the excess 5 or 10% AL

 

[Lou]

I myself would just use 20% NaOH and be prepared for a lot of hydrogen and a very vigorous reaction. Sometimes those things catch on fire if they're not submerged and scrubbed properly.

 

[J&D]

I have not ever worked with sodium hydroxide.....
NaOh? is that lye? My concern with something like trying to dissolve away 18 pounds of aluminum is that I would think the weight of all these chips is 18 pounds, so 99.998 or so percent of that is not gold....I would hate to lose my .002% in all of that waste! What could attack just the gold? Ive imagined dilute nitric, Yggdrasil suggested sulfuric cell....

 

[J&D]

NaOh is relatively inexpensive yes? compared to sulfuric and nitric? And when you suggest a 20% solution, do you mean by diluting 5 to 1 with distilled water? I did look up some bottles of it, and it seems to come in a 99% conc.
I am up for a vigorous reaction, but I certainly wouldnt want any chemical fires going on!
Small test run to start would be best I take it!

 

[J&D]

I myself would just use 20% NaOH and be prepared for a lot of hydrogen and a very vigorous reaction. Sometimes those things catch on fire if they're not submerged and scrubbed properly.

Hi Lou, I just did a tiny amount of research on using NaOH (watched a Youtube video) It looks like the solution turns black with the dissolved aluminum....does that completely dissolve? Or just break down? If its totally dissolved, it would just work to filter and rinse the remaining gold?

 

[J&D]

These look like in process BGA chips without the epoxy added to protect the die and wires.

Can't you just remove the chips from their aluminum carrier?

Can and willo, but the wafers themselves are made of AL too. Removing them would eliminate 5-10% of the weight, which I would do

 

[J&D]

What about a sodium hydroxide solution to dissolve the Al first?

I think I will try this. On a tiny amount

 

[Yggdrasil]

I have not ever worked with sodium hydroxide.....
NaOh? is that lye? My concern with something like trying to dissolve away 18 pounds of aluminum is that I would think the weight of all these chips is 18 pounds, so 99.998 or so percent of that is not gold....I would hate to lose my .002% in all of that waste! What could attack just the gold? Ive imagined dilute nitric, Yggdrasil suggested sulfuric cell....

Nitric do not dissolve Gold or Aluminum.
I don't know what AR does to Aluminum though.
The Sodium Hydroxide route may be the cheapest.
Just add 200g of powder to 1L of water. this will give 17% or so solution.
Strip the majority of the Al from the items first, it will save time and cost.

 

[J&D]

I am ordering a bottle this morning of NaOH this morning. I will try on a test batch and post my results. Thank u for the suggestions

 

[J&D]

Nitric do not dissolve Gold or Aluminum.
I don't know what AR does to Aluminum though.
The Sodium Hydroxide route may be the cheapest.
Just add 200g of powder to 1L of water. this will give 17% or so solution.
Strip the majority of the Al from the items first, it will save time and cost.

Does it need to be heated? Or does it produce it's own heat?

 

[Yggdrasil]

Does it need to be heated? Or does it produce it's own heat?

If you use powder, you need to be cautious. Mixing NaOH with water is exotermic.
The bottles used for drain opening should be around 60-80ish%.
Mix it with about 3-4 times as much water, depending on concentration.
When you put in the Al it will bubble strongly and create Hydrogen gas and possibly heat, I really do not know since I have only used HCl for Al.

 

[MicheleM]

First of all i would remove the bonding wires manually (using a appropriate container) , they are about 90 pct of all gold. After that I would break each single "square" and i would put them in HCl, in my opinion too much Al for NaOH

 

[Yggdrasil]

First of all i would remove the bonding wires manually (using a appropriate container) , they are about 90 pct of all gold

Is that even possible to do in a practical way?
They are usually way to small and thin.