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How to remove gold from circuit boards?

If you are into circuit boards, then you already know that we include some fine metals like steel, iron, and gold in their structure for different purposes. We are not going to dig deeper into their purposes since we will be off-topic. Instead, in this post, we are going to see some of the easiest and most effective methods for gold removal from sensitive circuit boards.

Make sure to stick to the tips given in this guide so that you can have a better understanding of performing this in the time of need without relying on external help and expensive tools.

So let’s see how it’s done! 

How to remove gold from circuit boards?

Remove gold from PCB
Remove gold from PCB

1.     Be Careful 

When we need to remove gold from the circuit boards, it is better to become highly choosy for chemical selection. There are some considerations to follow while doing this. For example, carefully storing the chemicals and revising protective ways to handle them to avoid compromising the environment at all. If you are using cyanide, then it is better to not only check its shelf life but also wear protective wearables while working with it since it is a highly dangerous chemical for usage. 

2.     Prepare Materials & Safety Equipment

The next thing that we need to do is to keep our materials and safety tools ready at hand. This type of gear comes in handy when you are handling hazardous materials and want to protect yourself from them as well. Take masks, goggles, protective suits, and gloves, for example. All of these serve the purpose of complete protection of workers when they interact with harmful chemicals and acids for gold removal.

3.     Follow Safe Handling Instructions

It is better to always stick to safe handling procedures, and these always come in handy to prevent mishaps and emergencies during work. There is no doubt that personal protective equipment is crucial, but there are some other protective measures that are important to consider to ensure complete safety. For example, covering your eyes, face, and body parts while working with chemicals and acids. Ensuring proper air ventilation where you are dealing with chemicals and gold removal from circuit boards. Once you are done, then wash your hands with cleaning agents and use sanitizers before eating or shaking hands with someone. Other than this, there is still a chance of seeking professional help from experts to avoid mishaps on all counts. 

4.     Prepare Electronics for Gold Extraction

The next step is to prepare your electronics that need gold removal. It is better to detach the components of these devices and divide them into three categories of plastic, metal, and glass. You can even isolate flammable materials during this process and carefully dispose of them to avoid any sort of complications. 

5.     Clean Off PCBs

Now we need to start the cleaning and see if there are any fragments of plastic, glass, and metal on the PCBs or not. There are some residues that we can take out with our hands, while others need specialized equipment. Acetone comes in handy for this purpose. It easily melts down stubborn metal shards on the circuit boards. However, while using acetone, you need to be cautious with its handling and protect your skin and sensitive circuit board components from it as well. 

6.     Create The Etching Solution

At this point, we need to use the etching solution that assists in complete gold removal from the circuit boards. We can even use a cyanide and water mixture for this purpose, but it is better to wear a protective suit and cover yourself properly while doing it. The amount of gold removed from the circuit board depends on the concentration of cyanide that we use in this mixture. In case when we are using high cyanide concentration, we need to handle it with extra care to avoid problems. 

7.     Extract the Gold Foils

Here comes the step when we perform gould foil extraction. Before we do this, it is important to dip the PCBs in the etching solution and take them out after waiting for a while. By relying on a metal brush, we can easily remove the gold from the circuit boards. All of this happens under professional supervision and without wearing protecting suits and using protective equipment; experts don’t recommend performing this step at all. 

8.     Filter Out Gold Foils

The next step is to filter the gold foils after removing them from the circuit boards. We can filter them by using the same etching solution. The better way is to pour the solution into a plastic glass or container. It immerses the foils in the bottom of whatever you are using. After settling, it becomes easier for us to take them out of the container with a spoon and let them dry completely.  

9.     Remove the Gold Foils Sticking to the Coffee Filter

In some cases, gold foils often stick to the coffee filter, but we can remove them easily. We can position the coffee filter in a suitable plastic container and start putting acetone on it. The purpose of acetone here is to melt down the adhesive that is causing the gold to stick to the filter. After melting down, the foil will detach from the filter and will fall into the container that we are using. Since we are using acetone, we need to cover our skin properly for this step. 

10. Use Nitric Acid

Nitric acid also comes in handy when we want to remove gold foil from circuit boards. The acid will melt down the metallic circuit board parts, and the non-metallic components will remain intact. Also, with nitric acid, it is important to use protective equipment for your safety. We can use a beaker or a similar receptacle for this purpose and use nitric acid for immersing the beaker with it. Now we need to wait for 10-15 minutes and start stirring the acid carefully. We will see that the gold will leave the solution and settles down in the receptacle that we are using. The last thing to do is to wash the circuit board completely to remove excess acid present on it. 

11. Use Fire Assay

Relying on fire assay is a good option when it comes to bulk gold removal from circuit boards. The metal melts down and can gather it in special molds and ingots made of steel as well. For small-scale removal, we can use ingots made of clay and sand. 

12. Use a Gold Leaching Process

Gold leaching is also a good option for this purpose. Cyanidation and mercury amalgamation come under this process. We often perform this process on less valuable metals, which promises quick meltdown for the metals as well. 

Step-by-Step Procedure to remove gold from circuit boards

PCB Manufacturing with Immersion Gold-ENIG Surface Finish
PCB Manufacturing with Immersion Gold-ENIG Surface Finish

Step 1: Safety Precautions: Wear your protective suit and perform the process in a fully ventilated area to avoid inhaling harmful fumes and intoxicated air. 

Step 2: Circuit Board Preparation: Now prepare the circuit boards that need to undergo gold removal. For this, gentle and less invasive cleaning agents will prove to be beneficial on all counts. 

Step 3: Chemical Preparation: We can use aqua Regina in adequate amounts as well. It includes hydrochloric acid and nitric acid in a mixture and is a crucial part of the gold extraction process. 

Step 4: Gold Dissolution: Now is the time for gold dissolution. It takes place by putting circuit boards in a chemical so that they can detach the gold from the surface of the boards easily. We can even speed up the process by using a Bunsen burner as well.    

Step 5: Precipitation of Gold: After the gold dissolution. We have to use a precipitant so that the gold can gain a solid form through it, and we can take it out of the solution easily. After cooling the solution, we can do this step since it will settle down the gold in the bottom after some while.

Step 6: Filtration: By using a strainer or filter paper, we can easily isolate the appreciated gold. Then we need to wash this gold with the help of distilled water to remove chemical residue as well. 

Step 7: Drying & Collection: The last step is to dry the rinsed gold particles. Collect them in a suitable container so that they can undergo further cutting and scaling.   


We hope that now you can easily remove gold from the circuit boards without damaging them even a little bit. In this guide, you will get all the necessary tips for performing this procedure safely and securely on all counts. You can even do further research on the process. Also, find out how you can improve the results in different ways.  




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