Amount of A/R for fibre/ceramic cpus

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martymcfly

Well-known member
Joined
Jul 20, 2013
Messages
64
Location
Scotland
Currently im going to try to put 12 black fibre amds through A/R. I beleive these can be done the same way as ceramic processors using A/R @ 4 parts HCL to 1 part HN03 and using the calculation that 3.8ml of HCL + .95ml HN03 dissolves 1g of gold how do i work out how much i should use for my processors? my total weight is 150g with lids removed but obviously this is not all gold as i have fibre and kovar i think.

So would you recommend doing my calculation for this total weight of 150g or just cover processors with HCL and then add HN03 in drops of 3ml at a time untill reaction stops?

i feel that covering them completely and then just adding drops of nitric will do the job but would be grateful if someone with more experience can tell me if this is the best way to go about it?

My second question is, can i just sit them in HCL to dissolve what solder is left on them and then stick them to A/R or just go straight to A/R?

thanks
 
unless you are experienced (and even if your not) you should start with and excess of hcl and add the nitrate in small increments until all the metal is dissolved. very important to make sure all metal is dissolved. ceramic bodies should be smooth with small green dots and black processors should have hollow holes where the legs were. premixing AR solution is not a very good process to follow. trying to add the exact amounts of acids without knowing the exact amount of metal is nearly if not totally impossible.
 
Thanks,

Thats what i was thinking. Do you think the solder from where the lids were held on will be an issue or is it ok to send these straight to A/R?
 
on the black fiber CPU's, remove the lids with heat and send the bodies through a hcl bath to remove as much tin solder as possible before the AR dissolution. crap, cant get the video to show. https://www.youtube.com/watch?v=26q6ILMFe4k
 
Yep, remove as much non-PM parts as possible first. Use mechinal, chemical or thermal processes before AR, it will save you lots of trouble later trying to get that junk out of your PM's.

I always soak anything that had a soldered part on it in HCL first. The cleaner you can keep the AR the higher purity of PM you will get later. Not to mention it will be easier too.
 
martymcfly said:
Currently im going to try to put 12 black fibre amds through A/R. I beleive these can be done the same way as ceramic processors using A/R @ 4 parts HCL to 1 part HN03 and using the calculation that 3.8ml of HCL + .95ml HN03 dissolves 1g of gold how do i work out how much i should use for my processors? my total weight is 150g with lids removed but obviously this is not all gold as i have fibre and kovar i think.
Click to expand...
I wouldn't recommend doing fiber CPU:s in AR. The reason is in this thread.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=60&t=17697

The buried copper traces inside the CPU will cement gold and if the chip is buried in epoxy then it needs incineration to free the bonding wires.

I would use straight HCl or AP to dissolve the pins and recover the gold plate, then incinerate the chips to get the bond wires.

Disclaimer: I don't have any black AMD cpus right now so I could be wrong about how the chips are built.

Göran
 
the black fiber CPU's are different from the green or brown bases. while i agree that the green and brown should not be processed in AR, personally, i would prefer to process the black bases with my ceramics. this is my opinion and it seems to work well for me. ive incinerated the bases after processing and didnt reclaim any more gold. im not saying that trace amounts didnt get tied up in the base but for the trouble, ill take the easier route.
 
My bad, I take it as a man and putting the blame on something else. As I don't have a wife I have to blame my memory. 8)

Göran
 
Lasersteve,
Thank you for those pictures. I have often wondered if the gold bonding wires extended from the chip all the way to the pins. In the end, that could present a lot more PM's.

Göran,
Get a dog. That way you can always say the dog got loose and messed something up. No blaming the wife, kids, or other family members or friends. Dogs ALWAYS forgive you.

MartyMcFly,
Have you considered pyrolyzing or incinerating your chips. Although other problems will present themselves, the processes using heat will make it easier to get to the gold, and once the pins have been removed and processed, the fine ash shouldn't be too hard to work with.
 
Hi bswartzwelder,

I have considered incineration since ive got a load of IC s to do soon but i havent yet made an incinerator so for now ive just used hcl to leech the solder and i have put them into A/R and all pins are gone so just need to get my solution filtered and then precipitate.

Im currently using my only funnel to filter some fingers done in A/P. As im just doing it with gravity its taking a while though. Need to invest in a pump. :lol:
 
bswartzwelder said:
Lasersteve,
Thank you for those pictures. I have often wondered if the gold bonding wires extended from the chip all the way to the pins. In the end, that could present a lot more PM's.
Click to expand...
Bond wires NEVER goes from the die all the way to the pin. I know of three different technologies with bond wire between pins and die.
1. The oldest with ceramic capsule, tungsten conductors inside the ceramic connects the pins with a landing pad where the bond wire is attached and then up on the landing pad on the die. Pins are usually brazed on the bottom or on the side of the capsule. The landing pads and the pads where the pins are mounted are gold plated. Only tungsten inside the ceramic.
2. Metallic lead frame that both offers mechanical strength, cooling and a cheap way to package IC:s. Both ceramic capsules (for example EPROM) or molded plastic resin is used. The tip or the whole of the lead frame could be plated with gold, nickle, silver or palladium-silver when gold bonding wires are used.
3. A small circuit board carrier with the chip bonded to the conductors in a cavity (for example Intel fiber CPU with black resin) or sitting on top of the PCB (BGA capsules, for example north bridge chipset). Only surface elements are gold plated, only copper conductors inside the small PCB. The die and the bond wires is protected by epoxy resin.

Speed is money and gold is money in the IC packaging industry. Longer bond wires takes longer time and costs more than shorter so they try to keep down the length of the wires. It is cheaper to make the conductor on the carrier substrate longer than using longer bonding wires. That is why you will never find a chip with bond wires all the way between the pin and the die.

Wire bonding in real time...
[youtube]http://www.youtube.com/watch?v=6-iuT_o8f00[/youtube]

Göran
 

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