This weekends project...6kg :-)

[Brett Novak]

cleaned out my desk.

Silvers are Au + Ag

Have another 15#'s of Ag + CuPdAu to sort out.

 

[eaglekeeper]

cleaned out my desk.

Silvers are Au + Ag

Have another 15#'s of Ag + CuPdAu to sort out.

I just finished processing 110 of those ceramic Proms (Motorola), all had gold bonding wires. I did the lids separately because of the iron residue they produce. After many, many rinses I managed to clean the foils of the iron. Then I did the bodies, which was uneventful and went as expected. In the end I recovered 5+ grams of gold.

I did not detect any other PM's through out many stannous tests....your mix maybe different.

 

[Brett Novak]

Yeah there isn't much else in these.

What did you use to mechanically seperate the lids? I've done nitric boils (usually takes like 6 of them) but seems wasteful.

I also have about 3#'s that I already smashed up in the mortar & pestil - maybe I'll go through that and pull as many lids out as I can.

 

[eaglekeeper]

Yeah there isn't much else in these.

What did you use to mechanically seperate the lids? I've done nitric boils (usually takes like 6 of them) but seems wasteful.

I also have about 3#'s that I already smashed up in the mortar & pestil - maybe I'll go through that and pull as many lids out as I can.

You can use a propane torch to heat the lids to melt the solder and they can be pick off (at least the ones I had). Once the lids are off I cut them in half to allow the nitric to get in to do it's thing. The lids produce a lot of iron slim, but with careful rinsing and decanting you can clean the foils up good enough to go to AR.

I usually don't crush them up because there's nothing inside the ceramic and it's much easier to rinse several large pieces then to rinse off thousands of small pieces....personal preference.

 

[kurtak]

I did the lids separately because of the iron residue they produce. After many, many rinses I managed to clean the foils of the iron.

Once the lids are off I cut them in half to allow the nitric to get in to do it's thing. The lids produce a lot of iron slim, but with careful rinsing and decanting you can clean the foils up good enough to go to AR.

Ceramic ICs with Kovar lids - why spend all that time separating the lids to process separate ?

Why not just process the WHOLE chips - as they are - directly in AR ?

Thats how I process ceramic ICs with Kovar lids

Kovar is an alloy of iron nickel & cobalt & is resistant to both nitric & HCl (both will dissolve Kovar - but - is very slow at doing so even with lots of heat)

Per the bold print - that is the problem with nitric - it produces an "iron oxide slim" that is then mixed in with the gold foils - pain in the butt to then try to wash out

HCl will dissolve the Kovar without producing that iron oxide slim - BUT - it is VERY slow at doing so (can take as much as a couple days) & it needs to run VERY HOT - like boiling hot

HOT - AR - will dissolve EVERYTHING - the Kovar - the gold plating & the bond wires & do so in a day - & it will not produce the iron oxide problem

You need to be sure to run the HOT AR long enough that it releases the silicon die in the ceramic housing cavity so that the gold plating "under" the silicon die also dissolves & goes into solution

You know that the leaching is done when you see that the silicon dies have released from the ceramic cavity --- (edit to add; - & see that - that gold plating has dissolved)

Drop your gold as normal (SMB or iron sulfate)

Here is a pic of a couple kilos of ceramic ICs with Kovar lids I processed (just as you see them in the pic) "direct" in AR - dropped 52 grams of gold from that batch "at the end of that day" running direct in HOT AR --- did the washes of the gold sponge - dried it & melted it the next day resulting in 52 grams of 999 gold

Kurt

 

[eaglekeeper]

Ceramic ICs with Kovar lids - why spend all that time separating the lids to process separate ?

Why not just process the WHOLE chips - as they are - directly in AR ?

Thats how I process ceramic ICs with Kovar lids

Kovar is an alloy of iron nickel & cobalt & is resistant to both nitric & HCl (both will dissolve Kovar - but - is very slow at doing so even with lots of heat)

Per the bold print - that is the problem with nitric - it produces an "iron oxide slim" that is then mixed in with the gold foils - pain in the butt to then try to wash out

HCl will dissolve the Kovar without producing that iron oxide slim - BUT - it is VERY slow at doing so (can take as much as a couple days) & it needs to run VERY HOT - like boiling hot

HOT - AR - will dissolve EVERYTHING - the Kovar - the gold plating & the bond wires & do so in a day - & it will not produce the iron oxide problem

You need to be sure to run the HOT AR long enough that it releases the silicon die in the ceramic housing cavity so that the gold plating "under" the silicon die also dissolves & goes into solution

You know that the leaching is done when you see that the silicon dies have released from the ceramic cavity --- (edit to add; - & see that - that gold plating has dissolved)

Drop your gold as normal (SMB or iron sulfate)

Here is a pic of a couple kilos of ceramic ICs with Kovar lids I processed (just as you see them in the pic) "direct" in AR - dropped 52 grams of gold from that batch "at the end of that day" running direct in HOT AR --- did the washes of the gold sponge - dried it & melted it the next day resulting in 52 grams of 999 gold

Kurt

With kilo's of chips that's shown in your picture, you're absolutely right....AR is the only way to go. There's no way I would sit down and remove the caps from that many. But if it's manageable I like to remove as much base metals as I can prior to the recovery drop. I had just 110 pieces and it only took an hour or so to remove the caps. I don't know how many pieces Brett Novak has, but they look similar to what I had.

Besides that, I had to remove the chips off of the boards.., so I already had the heat gun out. I figured if I'm already butt deep into this far....why not.

Putting the caps in nitric, some of the times (but not always) the gold foils will release from the plate. Then the excess Kovar plate can be picked out and I wouldn't have to dissolve everything. The iron is a pain, but it's not overly complicated to deal with.

For me it's just a personal preference, I really don't like dropping from an extremely dirty solution if I can help it.

Assuming his ceramic chips have gold bonding wires, Brett should have a descent recovery....As far as for the other chips....we'll see.

 

[kurtak]

With kilo's of chips that's shown in your picture, you're absolutely right....AR is the only way to go. There's no way I would sit down and remove the caps from that many. But if it's manageable I like to remove as much base metals as I can prior to the recovery drop. I had just 110 pieces and it only took an hour or so to remove the caps. I don't know how many pieces Brett Novak has, but they look similar to what I had.

Besides that, I had to remove the chips off of the boards.., so I already had the heat gun out. I figured if I'm already butt deep into this far....why not.

Putting the caps in nitric, some of the times (but not always) the gold foils will release from the plate. Then the excess Kovar plate can be picked out and I wouldn't have to dissolve everything. The iron is a pain, but it's not overly complicated to deal with.

For me it's just a personal preference, I really don't like dropping from an extremely dirty solution if I can help it.

Assuming his ceramic chips have gold bonding wires, Brett should have a descent recovery....As far as for the other chips....we'll see.

Of course - or as the saying goes --- there us more then one way to skin a cat

Kurt

 

[eaglekeeper]

cleaned out my desk.

Silvers are Au + Ag

Have another 15#'s of Ag + CuPdAu to sort out.

If you can....would you be able to post yield data on the ceramic and non-ceramic chips?

It would be nice to see the yield data on the non-ceramic chips.

 

[Brett Novak]

Yes - I'll do another measured test on both.

I ended up de-lidding about a kg of them. Basically, smash them up in a mortar & pestle, then peel the lid off. Easier than it looks, time consuming, but hey I was just watching football drinking beer anyway so why not.

As far as treating them - I kept them separate from the rest of the batch and tried

1 - Boiling Citric Acid - didn't work, but I was using powdered citric and water, may get some lemon juice and try that next.
2 - AP solution - actually worked really well getting everything to foil, then a ton of water washes to get rid of the orange goo.

Then dissolved in AP and dropped with SMB - waiting to get home to see the yield. I know I started with 125g of lids, but not sure how many bodies I threw in also so it's not a good measurement.