MacDermid’s Research Team Talks New Cyanide-free Immersion Gold at SMTAI


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While at SMTAI in Chicago recently, I met with two of MacDermid’s research team, Jun Nable, research project manager, who has been with MacDermid since 2007, and Cherry Santos, associate research fellow responsible for formulation work for metal plating solutions. We talked about the posters they were presenting and why they chose SMTAI.

Patty Goldman: I understand that you both presented posters here at SMTA, so why don’t you tell us a little about them.

Jun Nable: The poster that I presented is about a new cyanide-free immersion gold that's suitable for PCB surface finishes. What makes this different is it is cyanide-free. It's more environmentally-friendly, it's easier to handle, and has the advantage of simplified operating parameters. The majority of conventional immersion gold in use right now contains cyanide. When you hear the word cyanide, you know it's toxic. We need to take special precautions when handling it.

Santos: And there are requirements for waste treatment.

Nable: Right, like waste permits and things like that. So, that's the conventional immersion gold generally in use in the industry. We are providing an alternative to that without compromising the performance of the surface finish.

Goldman: That's very important. There must be a lot of interest in cyanide-free. How thick is the final gold finish?

Nable: For ENIG purposes, the target is around two micro-inches. In terms of plating performance like plating rate, the cyanide-free immersion gold is comparable to the conventional immersion gold. It's comparable, if not better in solderability, appearance and uniformity.

Goldman: And how about the controls and lifetime of the bath, things like that?

Nable: I mentioned earlier about simplifying the operating parameters. The advantage of this cyanide-free immersion gold is we can operate at 40°C. Conventional immersion gold operates at a much higher temperature of 80°C. Also the pH is near neutral for this cyanide-free bath. So, it's much more simplified. Not to mention the energy savings as well, by not having to get to that high temperature.

Goldman: That has got to be a nice selling point. A lot of people here are with EMS companies. Has there been a lot of interest in your new process?

Nable: There has been some interest. Every time you give an alternative that has new features, of course, it has to be further qualified.

Santos: There's always that skepticism with any new finish. It has to go through a rigorous qualification process.

Goldman: So, in order for a PCB fabricator to begin using this, it still has to be qualified by their customers?

Santos: Yes, it has to go to trial production and get OEM approval. The customer needs to assess the performance and ensure that it meets the specified standard for their target application. Does the alternative finish perform similarly or better than the current finish?

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