Non-Chemical Any Bonding wires here?!

[Liquidau]

So I properly incinerated some flatpaks and miscellaneous chips taken off PCBs; only white ash left; sifted through the ash, and put under my new digital microscope.
Pics attached. Can someone please identify the elusive gold bonding wires, assuming they are there? There are several plated regions, but I'm trying to find the wires.
Thanks in advance.

 

[Yggdrasil]

The "broken open" images are from chips not incinerated?

 

[Liquidau]

The "broken open" images are from chips not incinerated?

Yes correct. I wanted to look for the wires there too to identify them properly….

 

[Yggdrasil]

Yes correct. I wanted to look for the wires there too to identify them properly….

The bonding wires are connected to the end of the ones in "broken open" to the silicon die inside.
Very thin hair like whiskers.

 

[Liquidau]

So none visible in the other images?

 

[Liquidau]

And I hope these are gold wires?
And what are those pins?

 

[Martijn]

Those on the first picture are gold bonding wires.

 

[manorman]

And the next to the last pic looks like bond wire on bottom left hand side

 

[Liquidau]

So I've incinerated a kilo of misc. ICs (from RAM cards and medium grade boards) to white ash; milled them in my cement mixer to a fine powder mixed with metallic parts; and sieved them with an 80 mesh sieve. Magnetic separation is tricky now due to the load of powder.
First two images show the powders. The next two are unsieved ash.
Questions:
Might it be better to use the magnets BEFORE milling to a powder but after incineration? Maybe after a quick crushing only?
Do the elusive gold bonding wires go through the sieve? I don't see any wires in the powder through my microscope, nor in the coarser fraction either. Have they been reduced in size rendering them invisible?
Is this now the best time to put the powder through the blue bowl, and or a gold cube?
Or is the next step at any rate to process the powder with HCl, filter, wash, burn off chlorides (is this step necessary?), then use AR?
I know it's recommended to assay the coarse fraction before discarding it. How likely are there to be values in there?

Thanks to all Well-knowns and Moderators for the invaluable shared expertise!

 

[vgecas]

Hi,
Theoretically, after sifting, gold wires should be in ash dust, but a kilo of chips in a concrete mixer... they could be left in various corners in the mixer, unless you washed it and saved the washings. Put ash in a container and shake it not very vigorously for a while, then try to get a spoon of ash from the bottom of the container and put it in a jar. Fill the jar with water and mix well, you should be able to see gold wires through the bottom.
I would also burn coarse material one more time and crash it to powder cause the can be some gold left.
And don't forget that magnetic material also has gold attached (not so much but...) and it can have some silver.

 

[Geo]

Some examples.
First a bga memory chip with bonding wires attached.
Next is a small pile of bonding wires at 60X mag.
Next is a single bonding wire at 100X mag.

 

[Geo]

The ash should be milled until it can pass through 100# sieve. That's really small but the wires are so small that they will pass through the 100# mesh with no problem.

 

[Liquidau]

Thanks Geo. I see a few here and there but not in that quantity! This is a typical look at around 100X mag.....

 

[manorman]

Thanks Geo. I see a few here and there but not in that quantity! This is a typical look at around 100X mag.....View attachment 48129

Not much to see until you concentrate them down to a smaller amount of material.

 

[Liquidau]

Geo, is that first image typical of BGA chips? That is a remarkable amount of gold wires.....

 

[Geo]

Geo, is that first image typical of BGA chips? That is a remarkable amount of gold wires.....

No. That is a bga type of ram chip that appears to be just the silica glass die. The tiny base that is between the glass and the printed circuit board is where these are found. They are greatly magnified. I can't remember the setting but they are really small.

 

[Geo]

They normally have some sort of heat sink that sits against the chips. Usually aluminum.

 

[Liquidau]

They normally have some sort of heat sink that sits against the chips. Usually aluminum.

Ok thanks. Imagine if those were actual size….

 

[Liquidau]

So I incinerated half a kilo of RAM card chips to white ash, washed them, and floated off most of the white paper-like covers. Left with all the silicon dies and some crushed bits. Removing iron with magnet. Is it best to crush the dies, or to just remove them? Where would the gold be from these (mini)-chips?

 

[Liquidau]

Here is an image of the powdered material after incineration, washing, magnet removal of pins/legs, grinding, and sieving to 80 mesh. Can you see any bonding wires? What are all of those thin wire looking lines?