Vacuum Coating System Shields - Copper

Challenge

Clean vacuum coating shields for a thin film coating systems manufacturer in order to recover specific precious metals and to recycle the same shields for use again in their coating systems.

 

Deposition

Gold, Platinum and Titanium

 

Substrate

Copper

 

Results

Copper substrate was processed together with our new solution, and it was successful. We were able to yield gold bullions and platinum sponge to our client’s customer. 

 

One of the largest producers of LED’s lighting products was sending physical vapor deposition (PVD) chamber precision shields and components that were coated with gold, platinum, and titanium depositions to a refiner.

 

The refiner was not able to clean copper parts coated with the precious and non-precious metals.

 

The parts were received with deep grooves. The grooves that were left on the parts by the personnel, located on-site at the LED facility, using screwdrivers to remove the precious metals and we were called to try to improve the situation.

 

Since the copper surface is very sensitive (it can be damaged) by most of the chemicals, the task was very difficult. Gold, titanium and platinum especially require really strong chemicals to dissolve. We realized that to dissolve all of coated materials at the same time, the currently used aqua regia solution needed to be used.

 

However, we could not use it, as the standard aqua regia would dissolve copper within minutes.

 

So again, we reviewed what other existing technologies may be available to solve this:

• The cyanides could not be used because they would not work on titanium. Their action on platinum is either very slow or almost none and requires higher temperatures;

• The current aqua regia would dissolve the copper, so the customer would have to keep buying the shields and components over and over again.

• Blasting by blasting media would require the consequent extraction (dissolution of metals from the media in liquid chemicals) most probably by the current state-of-the-art aqua regia. Since this type of blasting media process yields huge loss of precious metals as well, so we had ruled this possibility out.

• We had data on all the other available technologies that we had tested like weaker aqua regia, potassium iodide/iodine, thiourea/sulfuric acid/iron (III) sulfate and some other processes. All of them were ruled out, because they would dissolve the copper parts, and most of them would not dissolve titanium.

 

We were ideally looking for a technology that would:

• Visibly dissolve all of the deposited metals at the same time, and

• Preserve the copper precision parts to recycle and re-use.

 

Our past research and development provided a novel technology that we developed for another situation. This key technology “allows us use the strong chemicals that are known to dissolve the coating deposition alloys and elements together with a SURFACE PROTECTANT that would protect the sensitive surface of the copper substrate.”

 

So we combined the current aqua regia with our unique surface protectant and were successful in cleaning the copper part and ultimately recycling the gold and platinum from the solution. 

This new patented solution can be mixed in different ways to be more on the “protective” side of the wet etching scale or on the “strong etching action” side of the etching scale, as the copper surface demanded the most protective approach.

We demonstrated this technology to the refiner as complete solution for this specific application.