Removing silicon die ceramic ic

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Slochteren

Slochteren

Well-known member
Joined
Apr 3, 2015
Messages
168
Location
Netherlands
I process a lot of ceramic ic's/processors lately, AR works fine but +/- 10% of the silicon die's are still stuck to the ceramic and leaving somme gold.
Is there a way to remove these?
 

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Slochteren said:
I process a lot of ceramic ic's/processors lately, AR works fine but +/- 10% of the silicon die's are still stuck to the ceramic and leaving somme gold.
Is there a way to remove these?
Click to expand...

I have a handful of these as well, I'm not sure if they're worthy of reprocessing just for that little amount. You could either leave them in very hot AR for longer or I just throw them in the next batch of ceramics.
 
Slochteren said:
I process a lot of ceramic ic's/processors lately, AR works fine but +/- 10% of the silicon die's are still stuck to the ceramic and leaving somme gold.
Is there a way to remove these?
Click to expand...
I usually heat the chip to release the cap. Once the cap is removed I continue with heating in the chip until that die can be picked right off with pliers or tweezers.
Thats how I remove them.
 
In a commercial refinery, one which see's a lot of these processors sent in as a separate scrap type, would granulate this material before processing them in aqua regia. The theory being the smaller pieces allow better penetration of the acids and digest more of the values.

Also note that the refiners processing this material in aqua regia also save the residues because they can never be totally stripped of all of their values in AR. (If properly granulated to small enough pieces you will get most of the gold but some remains.) The residues are melted in a furnace with copper and cryolite which will dissolve the ceramic. It is a slow process requiring a long heat to melt the ceramics. And it eats up crucibles as well.
 
4metals said:
In a commercial refinery, one which see's a lot of these processors sent in as a separate scrap type, would granulate this material before processing them in aqua regia. The theory being the smaller pieces allow better penetration of the acids and digest more of the values.

Also note that the refiners processing this material in aqua regia also save the residues because they can never be totally stripped of all of their values in AR. (If properly granulated to small enough pieces you will get most of the gold but some remains.) The residues are melted in a furnace with copper and cryolite which will dissolve the ceramic. It is a slow process requiring a long heat to melt the ceramics. And it eats up crucibles as well.
Click to expand...
From the legs to the die inside the ceramic is that also gold plated? That would be a reason to granulated I guess...
 
Slochteren said:
From the legs to the die inside the ceramic is that also gold plated? That would be a reason to granulated I guess...
Click to expand...
If you think for one minute a commercial refiner has the chip by chip specifics about these circuits that a lot of members here have you are mistaken. Commercial refiners will not pick through the chips they simply toss tbe lot in the granulator.
 
I have no idea how commercial refiners do things, they will have their reasons how to process things.

But I was wondering in general how the connection runs from the legs thru the ceramic to the silicon die, I broke some but cannot see any connection wire... The normal dip ceramics are made of 2 parts "glued" together and breaking the parts you can see the connection. But for the ons that look as 1 piece I don't know.
 
you aren't losing anything. There is no gold underneath the die - just bonding glue. The gold is in the wires that come off the top of the die, a trace from the legs and a trace from the "paddle" inside the package.

I usually break mine in half to get the stupid metal cap off (has a lot of nickel in it and makes a mess) but other than that, the die just get tossed with the trash at the end, stuck to the package or not.
 
Brett Novak said:
you aren't losing anything. There is no gold underneath the die - just bonding glue. The gold is in the wires that come off the top of the die, a trace from the legs and a trace from the "paddle" inside the package.

I usually break mine in half to get the stupid metal cap off (has a lot of nickel in it and makes a mess) but other than that, the die just get tossed with the trash at the end, stuck to the package or not.
Click to expand...
Agreed. I usually make sure the die is cracked and then process in AR. The gold plated lids are pretty awesome though.
 
Brett Novak said:
you aren't losing anything. There is no gold underneath the die - just bonding glue. The gold is in the wires that come off the top of the die, a trace from the legs and a trace from the "paddle" inside the package.

I usually break mine in half to get the stupid metal cap off (has a lot of nickel in it and makes a mess) but other than that, the die just get tossed with the trash at the end, stuck to the package or not.
Click to expand...
I disagree strongly!

A classical way to attach the die in the cavity of a ceramic body is to use a gold silicon braze. It's not the only way to attach the die, other ways are silver or palladium based braze or even glue (possible silver filled to make it conductive). Gold braze is expensive so naturally people have tried to come up with cheaper alternatives.

As a rule of thumb, pale yellow metal around the die is gold silicon braze.

I always run my ceramic dies with gold braze until the dies falls off or can be pushed off with a glass or plastic rod. Any dies that I missed goes back in the next batch so I'll get it eventually.

Here is a patent that discuss different braze and solder alloys. :
https://patents.google.com/patent/US4214904A/en

Here is a manufacturer of silver filled epoxy and other bonding materials. :
https://tanaka-preciousmetals.com/en/products/detail/silver-adhesive/?nav=use

And finally a pdf with examples of gold - tin alloys used for mounting dies.
https://www.indium.com/media/documents/0424/au-based-precision-die-attach-preforms-pds-99990-r2.pdf

There is a huge amount of other information sources on the net so you can spend hours just digging in on this topic.

Göran
 
g_axelsson said:
I disagree strongly!

A classical way to attach the die in the cavity of a ceramic body is to use a gold silicon braze. It's not the only way to attach the die, other ways are silver or palladium based braze or even glue (possible silver filled to make it conductive). Gold braze is expensive so naturally people have tried to come up with cheaper alternatives.

As a rule of thumb, pale yellow metal around the die is gold silicon braze.

I always run my ceramic dies with gold braze until the dies falls off or can be pushed off with a glass or plastic rod. Any dies that I missed goes back in the next batch so I'll get it eventually.

Here is a patent that discuss different braze and solder alloys. :
https://patents.google.com/patent/US4214904A/en

Here is a manufacturer of silver filled epoxy and other bonding materials. :
https://tanaka-preciousmetals.com/en/products/detail/silver-adhesive/?nav=use

And finally a pdf with examples of gold - tin alloys used for mounting dies.
https://www.indium.com/media/documents/0424/au-based-precision-die-attach-preforms-pds-99990-r2.pdf

There is a huge amount of other information sources on the net so you can spend hours just digging in on this topic.

Göran
Click to expand...
How hard do you drive the reaction to get this to happen Goran?
 

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