Okay, so here are the results of 1.5 years of saving up 50 pounds of mixed integrated chips (including BGAs).
Before you read the result below, it is important to note that most of the chips (90%) were from 1990s to early 2000s automotive electronics. Meaning these were not super modern electronics and most likely were higher component quality.
Roughly 50 pounds of mixed chips yielded 83 grams of gold.
Below are the exact amounts (quantity and weight) of different styles of ICs. The 'Gold Return' column is estimated. Keep in mind, I did not weigh each individual yield after burning, sieving on a shaker table, and thereafter collecting ash and using a blue bowl. Instead, I completed the entire process of 50 pounds and weighed the results at the end. What I’m saying is, I initially had an estimated yield for each style of chip based on internet resources, and after getting the result of 83 grams, I fixed my estimates to equal the true 83-gram result. The total result in the table is slightly over the actual result as there were most likely losses in the blue bowl portion of the process.
I decided to go the Burning method as this was safer than using chemicals. Burning off the volatiles to “reduce” the epoxy to carbon. I wanted not to disturb the bonding wires as much as possible along the way of liberating them from the wafers/pins. I know ball mills and coffee grinders would work, but the sieve and shaker system seemed best for minimal losses.
Before getting into how I processed the chips, some notes on what I learned along the way.
1. First, incineration of ICs (combustion, presence of oxygen) in a controlled combustion using a propane torch - the kind for burning weeds. Burn chips in stainless steel, high-sided cake pan, in a simple fire brick box. Continue to heat while gently mixing until all visible black carbon turns white, and smoking stops. Burn a little at a time to ensure smoke does not escape the burning vessel. I always burned 1 kg of chips at a time, starting with a few handfuls in the pan and throwing in small handfuls as I burned. I used a military issued gas mask during this process and would do it with nothing of lesser quality. Usually takes about 15 minutes and very little smoke if you take your time and have a hot propane torch.
2. Put the burned chips in a large glass container and manually shake like hell (about 3 mins of shaking).
3. Sieve using 8 in diameter sieves. Below are the only sizes needed for this process. Place IC ash into top test sieve in stack and put on small shaker table (bought from Amazon - Vibro Pro Kinetic - works well for this process but pricey). The stack of sieves is held still on the shaker table using a large wood working clamp. Its kind of loud but not too bad.
-18 mesh - 1mm
-35 mesh - 500 um
-120 mesh- 125 um
-Catch Pan
4. Use a hobby glass kiln to further pyrolyze pieces of chips that do not break into ash. Begin picking out metallic parts (pins and heatsinks) out of top sieve. After that, pull out the larger pieces of ICs and place into small stainless-steel dish and place the dish into the kiln (small hobby glass kiln bought from Amazon). Pyrolyze pieces of chips that do not pass through the sieve and shake in a glass container once again before putting ash back into the sieve set on the shaker table. Repeat this process until everything passes through each sieve and the bottom catch pan of the sieve set has nothing but ash and bonding wires. You will have picked out most of the larger metallic pieces along the way. At certain points you can just empty the sieve of metallic pieces when all ash passes through. Know that, not all pieces of chips will make it through 120 mesh sieve, for example, after going through 50 pounds of chips, I was left with about 2 cups of ‘ash’ that would simply not break apart small enough to pass through the 120 mesh sieve regardless of pyrolyzing and shaking. I will probably need to actually grind that up in a coffee grinder (which I haven't done yet)
5. Wash off the fine (ash) by method of choice to provide a “concentrate” before using a final common method to wash/separate ash from gold bonding wires (panning, blue bowl, sluice box/table, etc.). I used Successful Engineer’s method in one of his last videos on YouTube regarding gold recovery as his method was the best I'd come across. I used a 7-gallon drywall bucket to hold the water mixed with ash with a small cement mixer on my cordless drill and a little Jetdry. A spigot placed 1 inch up from the bottom of the bucket, draining via small hose to a small handheld sluice, leading to another smaller bucket with excess water spilling over second buckets edge. I processed roughly one gallon of ash each time I used this method, I probably could have done more at a time - but wanted to play it safe. Most importantly, were the time intervals after mixing the ash in water to let gold settle to the bottom - 30 mins, 20 mins, 10 mins, 5 mins. Watch his videos for the details. I pretty much did the same as him, but used a bigger drywall bucket and different style mini sluice between the buckets. I found very little gold losses in second bucket using his method. Seriously great idea on Successful Engineer's behalf. I can’t help but to facepalm when I see people doing the other bucket method, pouring from one bucket to the other. Yikes.
6. I used a Blue Bowl setup exactly like Successful Engineer’s setup. In his videos, he had to deal with some metallic pins as he did not use the 120-mesh sieve which would have caught all metallic pins. Since I did, I only had to deal with ash and gold in the blue bowl. Some tips: You must concentrate the IC ash, or you will be at the blue bowl forever haha. Do not remove the gold bonding wires/dust from blue bowl as you go along – I found that keeping them in the bowl helped keep other bonding wires from washing out of the bowl, especially the longer bonding wires from gold corner BGAs. Take your time. If your in a rush, you have the wrong hobby
Hope this helps the community. Bye!
Before you read the result below, it is important to note that most of the chips (90%) were from 1990s to early 2000s automotive electronics. Meaning these were not super modern electronics and most likely were higher component quality.
Roughly 50 pounds of mixed chips yielded 83 grams of gold.
Below are the exact amounts (quantity and weight) of different styles of ICs. The 'Gold Return' column is estimated. Keep in mind, I did not weigh each individual yield after burning, sieving on a shaker table, and thereafter collecting ash and using a blue bowl. Instead, I completed the entire process of 50 pounds and weighed the results at the end. What I’m saying is, I initially had an estimated yield for each style of chip based on internet resources, and after getting the result of 83 grams, I fixed my estimates to equal the true 83-gram result. The total result in the table is slightly over the actual result as there were most likely losses in the blue bowl portion of the process.
| Pins per side | Thickness | Style (Size & Thickness) | Est. Gold Per Kg | Total Weight (Kilograms) | Gold Return (Grams) |
| 1S | Thick | Through-hole Chips | 1.5 | 2.5 | 3.75 |
| 2S | Thick | Legacy 2-sided Chips | 2.5 | 1.5 | 3.75 |
| 2S | Thick | Medium to Large sized thick 2-sided chips | 3 | 4 | 12 |
| 4S | Thick | Medium to Large sized Legacy Flatpack/PLCC CPUs | 3.5 | 6.7 | 23.45 |
| 2S & 4S | Thin | Small Mixed ICs & Transistors | 4 | 2 | 8 |
| 4S | Thick | Medium-size, Thick Rectangular & Square Chips | 4.5 | 2.5 | 11.25 |
| 2S & 4S | Thin | Small to Medium sized, Thin mixed Chips | 6 | 1 | 6 |
| 4S | Thin | Large sized, Thin Flatpack CPUs | 8.5 | 0.5 | 4.25 |
| BGA | BGA | Small BGA & RAM Chips (AP to remove tin) | 10.5 | 0.5 | 5.25 |
| BGA | BGA | Gold Corner BGA Chips (tops only) | 14.5 | 0.5 | 7.25 |
| 21.7 | 84.95 |
I decided to go the Burning method as this was safer than using chemicals. Burning off the volatiles to “reduce” the epoxy to carbon. I wanted not to disturb the bonding wires as much as possible along the way of liberating them from the wafers/pins. I know ball mills and coffee grinders would work, but the sieve and shaker system seemed best for minimal losses.
Before getting into how I processed the chips, some notes on what I learned along the way.
- If using the shaker table/sieving process, there is no need to use AP to remove pins/legs from chips as sieving will do the work. I found that NO pins were able to pass through the 120 mesh (125um) sieve.
- Most pins will be trapped in the 18 and 35 mesh sieves.
- I did use AP on small BGA chips to get rid of tin.
- Shaker table and sieving seemed to liberate even the smallest amounts of gold as large quantities of gold dust was found in the blue bowl along with bonding wires. This dust was not something I've seen people get in all the videos of other methods.
- A small hobby kiln for glass is key to completely pyrolyzing chips that don't fall apart after shaking in glass jar.
- If you use a hobby kiln to pyrolyze chip pieces that do not break apart during shaking/sieving, make sure to not heat for too long or you will melt copper pins and make a mess and possibly fuse bonding wires to metallics. The kiln I used had a timer, I always put it to 8 minutes.
1. First, incineration of ICs (combustion, presence of oxygen) in a controlled combustion using a propane torch - the kind for burning weeds. Burn chips in stainless steel, high-sided cake pan, in a simple fire brick box. Continue to heat while gently mixing until all visible black carbon turns white, and smoking stops. Burn a little at a time to ensure smoke does not escape the burning vessel. I always burned 1 kg of chips at a time, starting with a few handfuls in the pan and throwing in small handfuls as I burned. I used a military issued gas mask during this process and would do it with nothing of lesser quality. Usually takes about 15 minutes and very little smoke if you take your time and have a hot propane torch.
2. Put the burned chips in a large glass container and manually shake like hell (about 3 mins of shaking).
3. Sieve using 8 in diameter sieves. Below are the only sizes needed for this process. Place IC ash into top test sieve in stack and put on small shaker table (bought from Amazon - Vibro Pro Kinetic - works well for this process but pricey). The stack of sieves is held still on the shaker table using a large wood working clamp. Its kind of loud but not too bad.
-18 mesh - 1mm
-35 mesh - 500 um
-120 mesh- 125 um
-Catch Pan
4. Use a hobby glass kiln to further pyrolyze pieces of chips that do not break into ash. Begin picking out metallic parts (pins and heatsinks) out of top sieve. After that, pull out the larger pieces of ICs and place into small stainless-steel dish and place the dish into the kiln (small hobby glass kiln bought from Amazon). Pyrolyze pieces of chips that do not pass through the sieve and shake in a glass container once again before putting ash back into the sieve set on the shaker table. Repeat this process until everything passes through each sieve and the bottom catch pan of the sieve set has nothing but ash and bonding wires. You will have picked out most of the larger metallic pieces along the way. At certain points you can just empty the sieve of metallic pieces when all ash passes through. Know that, not all pieces of chips will make it through 120 mesh sieve, for example, after going through 50 pounds of chips, I was left with about 2 cups of ‘ash’ that would simply not break apart small enough to pass through the 120 mesh sieve regardless of pyrolyzing and shaking. I will probably need to actually grind that up in a coffee grinder (which I haven't done yet)
5. Wash off the fine (ash) by method of choice to provide a “concentrate” before using a final common method to wash/separate ash from gold bonding wires (panning, blue bowl, sluice box/table, etc.). I used Successful Engineer’s method in one of his last videos on YouTube regarding gold recovery as his method was the best I'd come across. I used a 7-gallon drywall bucket to hold the water mixed with ash with a small cement mixer on my cordless drill and a little Jetdry. A spigot placed 1 inch up from the bottom of the bucket, draining via small hose to a small handheld sluice, leading to another smaller bucket with excess water spilling over second buckets edge. I processed roughly one gallon of ash each time I used this method, I probably could have done more at a time - but wanted to play it safe. Most importantly, were the time intervals after mixing the ash in water to let gold settle to the bottom - 30 mins, 20 mins, 10 mins, 5 mins. Watch his videos for the details. I pretty much did the same as him, but used a bigger drywall bucket and different style mini sluice between the buckets. I found very little gold losses in second bucket using his method. Seriously great idea on Successful Engineer's behalf. I can’t help but to facepalm when I see people doing the other bucket method, pouring from one bucket to the other. Yikes.
6. I used a Blue Bowl setup exactly like Successful Engineer’s setup. In his videos, he had to deal with some metallic pins as he did not use the 120-mesh sieve which would have caught all metallic pins. Since I did, I only had to deal with ash and gold in the blue bowl. Some tips: You must concentrate the IC ash, or you will be at the blue bowl forever haha. Do not remove the gold bonding wires/dust from blue bowl as you go along – I found that keeping them in the bowl helped keep other bonding wires from washing out of the bowl, especially the longer bonding wires from gold corner BGAs. Take your time. If your in a rush, you have the wrong hobby
Hope this helps the community. Bye!
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