Gold recovery from multilayer PCB

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wkvisual

New member
Joined
Mar 26, 2021
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2
Hello,

I'm looking for help determining the best path for refinement of the gold within multilayered RF boards. These boards are no expense spared microwave communication related boards, and used gold for all connections and throughout the board for the RF characteristics. There are 2 outer layers of gold traces and contacts, as well as 4 inner layers of traces. I have no experience with refinement but I am fortunate to have access to a large high temperature electric furnace, if that can be used for the process.

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wkvisual said:
Hello,

I'm looking for help determining the best path for refinement of the gold within multilayered RF boards. These boards are no expense spared microwave communication related boards, and used gold for all connections and throughout the board for the RF characteristics. There are 2 outer layers of gold traces and contacts, as well as 4 inner layers of traces. I have no experience with refinement but I am fortunate to have access to a large high temperature electric furnace, if that can be used for the process.

Photos attached

Hi

First you need to remove those iron or aluminum pieces, then I would leave them in hcl to dissolve solders and release the components.

Then wash the components and boards using 10 percent lye solution.

You can dry and sort the components and process them accordingly.
 
wkvisual said:
Will HCL work to liberate the gold contained within the inner layers of the pcb?

Hi

Hcl only removes the solders and any ferrous or aluminum from boards, that is why you need to manually remove that aluminum or steel wall shaped piece before doing any hcl.

If there is any gold plating on board, hcl and solders cause galvanic reaction that may turn your gold plating to change color to silver.

After hcl bath you can wash them, then dissolve in nitric all the gold layer comes back.
 
g_axelsson said:
How do you know there is gold on the inner layers?

Göran

My thoughts too.

There is really no reason to have the gold in the layers. I would also be surprised if the gold layer on top is even that thick too. Some of the RF boards will have a varnish over the gold to protect it from wearing that makes it seem thicker than it really is.

they look like good boards for components to say the least.

Eric
 
Very unlikely there is gold on the inner layers. I've had satellite boards/assemblies were everything is required to be gold plated but was never a requirement for internal layers of boards. They are always copper. If any board was to have this it would be the "weather" satellites the DOD ordered.
 
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