My results of specific types of IC chips, flatpacks and BGA
- Thread starter Tzoax
- Start date
Help Support Gold Refining Forum:
patnor1011
Well-known member
You need to realize how small and tiny these wires are. There is no way you can accomplish what you want mechanically. Maybe with some use of ultrasound but mechanically it simply can't be done in my opinion and experience. I still do have few metal pots, rods, spoons with gold from bonding wires smeared on them
If you can't get and use cyanide you can try ferrocyanide leach like ecogoldex or straight ferrocyanide. That can be bought freely. Work slower but it does the job. There are some other leach agents I personally not used but are worth exploring as they are much wiser to use than trying to dissolve metallic parts from IC.
If you can't get and use cyanide you can try ferrocyanide leach like ecogoldex or straight ferrocyanide. That can be bought freely. Work slower but it does the job. There are some other leach agents I personally not used but are worth exploring as they are much wiser to use than trying to dissolve metallic parts from IC.
Has anyone considered using liquid nitrogen (if easily obtainable and inexpensive in your area)? I would first freeze the legs (using a standard refrigerator/freezer) in an attempt to lower the ambient temperature of the material so less liquid nitrogen is boiled away when it is first tumbled. This process should make the tin solder fairly brittle, although antimony as an additive to the solder may keep it malleable even at low temperatures. One benefit would be that no extra waste is created. Just thinking here, and I have never tried this process for removing gold wires from legs. One item to consider is the quantity of gold recovered may not justify the cost of the liquid nitrogen.
patnor1011
Well-known member
rickzeien said:
This was always a team effort. I do not hide stuff I have no reason for it I just wanted to share things even if they did not work for me.
Perhaps we all do have different standards - meaning that everyone does have a different approach to question "what is enough" or "when is enough".
The classic procedure we use (incinerating-grinding-washing) liberate most of the gold. If someone wants all of it then going after what was left on metallic parts like legs is a logical step. If you really want all of it then this could be considered as an added cost and in some cases (low-value IC with many legs) cost of recovery may exceed recovered value. In my case and current gold price it was not worth it but they are stashed for later so one day in future me or someone may get what was left behind.
Same goes for wafers from inside, there is some gold on them too.
Dr.xyz said:
Good point. However, it would still stand to reason that the metal(s) used to bond the gold wire to the leg would become more brittle. Remains to be tried and I may look at this when I process my next batch of chips.
patnor1011
Well-known member
I do not think that is a correct statement. Some IC do have just legs (pins) but most of them do have various other stuff in them like some sort of let's call it "shielding" or "placeholders". I have seen tons of various odd-shaped metallic parts inside IC.
The odd formed metal parts found inside chips are either the lead frame or an integrated heat spreader. Heat spreaders are most common in plastic BGA chips and can have all kinds of shapes, squares, rounded, star formed... Lead frames for plastic chips (not the metal lead) are a metallic structure which the chip is first mounted on and then after the plastic is cast around bond wires and the lead frame, the frame is cut off and the legs of the IC is formed from the remaining metal sticking out of the plastic.
Göran
Göran
stella polaris
Well-known member
- Joined
- Sep 11, 2018
- Messages
- 416
patnor1011 said:
Could it be from the crushing of the IC chips? The crushing of the chips can be the reason the gold is smeared out. But if the gold is smeared out during tumbling/shrubbing the legs you have a point. If not then its like comparing apples and pears.
It might be so that crushing is not the way to go. Just because the gold gets smeared out.
Tzoax
Well-known member
I just bought a USB microscope. I made a couple of random photos of gold bonding wires. It is little tricky to make a focus....but it is a huge difference comparing with my previous pictures made with magnifying glass...
Now i can make a couple of tests with them.
Now i can make a couple of tests with them.
Tzoax
Well-known member
Thank you rickzeien! I just made one test to see what would happen when gold bonding wire is detached from leg... I found this one for test:rickzeien said:
The other side of leg:
Different light angles...:
Tzoax
Well-known member
So i tried to take off the gold bonding wire from leg and after this first attempt - the wire braked like in the picture...
After second attempt...
It is clear that gold bonding wire braked again because it could be seen that there is still some small amount of gold left on leg...
"I just bought a USB microscope. I made a couple of random photos of gold bonding wires. It is little tricky to make a focus....but it is a huge difference comparing with my previous pictures made with magnifying glass..."
Welcome to the world of USB microscope photography!
Have you tried playing around with your camera's photograph resolution and image size?
Try using a higher resolution along with a smaller image size.
Good start though!
James
Welcome to the world of USB microscope photography!
Have you tried playing around with your camera's photograph resolution and image size?
Try using a higher resolution along with a smaller image size.
Good start though!
James
glorycloud
Well-known member
Trust the Fin's to rain on someone's parade. :lol:
rickzeien said:
Now I'm in trouble . . . you just added to my "things to try" list.
I recycle, repurpose and refine ewaste (yes, I just melted my first button!
). My wife and I also make jewelry (no, not from ewaste :shock: ).Being retired, I always try to stretch my "for hobby/play" money as far as possible. If for some reason I can't make my own equipment, one thing I always do is buy the best equipment I can and try to have multiple uses for it.
One thing I recently bought was an Extreme Rebel 17 tumbler http://extremetumblers.com/products.html
that was initially designed for use as a brass cartridge tumbler/polisher for those shooters that reload their own ammo.
I am an Industrial Designer and can honestly say that if I was going to design a small tumbler, it would be built like this "beast". I have used it as a mini-ball mill using various diameters of SS ball bearings to crush a load of incinerated ICs. Worked like a charm. Cleaned it (rubber liner can be removed), and then used it to tumble hard stones and crystals for jewelry. For the stones, I use various grades of silicon carbide grit along with ceramic tumbling media. The grit is commercially available in small quantities and sizes. Such as 60/90 grit, 120/220 grit, etc.
When I get done with my current load of stones (it takes 4+ weeks running 24/7 to properly tumble stones to a high polish), I am going to try a small load of incinerated ICs and then a small load of un-incinerated ICs using a coarse silicon carbide grit instead of SS ball bearings.
Legs and lead frames are usually made from a Kovar/Type 41 alloy that has a very high tensile strength. My hypothesis is that the epoxy on the un-incinerated ICs should abrade first then the softer metals and Kovar last. The process could be stopped before the steel is ground leaving only epoxy dust comingled with any Sn, Al, Cu, Au, Ag, Pd, etc. and, of course, fractured SiC. My theory is that the softer metals should be reduced to a "sand" and not "smeared" by any dropping force. The whole process could be done in a dust cabinet to mitigate any free-floating dust which may escape when the tumbler is opened. The tumbler is designed to be used as a wet media tumbler and seals extremely well. Final processed volume should be reduced dramatically thereby making final wet refining less chemically intense.
Go ahead and pick me apart - I'm a "big boy" and can take constructive criticisms and especially constructive suggestions.
Peace all,
James
BTW, never use sand - way too contaminated.
Dr.xyz said:
Sorry, IMHO, no.
You get what you pay for.
Peace,
James
