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

Estimated reading time: 8 minutes

Goldman:

Nable: Exactly. We put it out there to show it to the industry and say, “Yes, we do have an alternative. If you're willing to work with us, come and talk to us in person.”

Goldman: That helps, especially if they ask their PCB supplier, "Could you use this?" I think that would be beneficial for you and MacDermid.

Nable: We've done our rigorous testing, but of course, everything can’t be done in our labs. We need to get out into the real world and qualify it there. That hasn't happened just yet, but there is interest and there have been talks, but in the very early stages.

Santos: We're in the stage of marketing it and letting the customer know the benefits and performance similarities with the existing cyanide-based finish.

Goldman: A chance to work with them and see what questions they have about it. About how long does it take to get the proper amount of thickness?

Nable: Just to give you a perspective, for ENIG applications it deposits about two micro-inches of gold in about ten minutes, which is similar to that with cyanide versions.

Goldman: So, it's not a time-saver, not that it would be, but with the reduced waste treatment, improved safety, and the lower temperature—these are all important things. And even their customers would be interested in the cyanide-free part, I would think.

Santos: Yes, because they pay a lot of money for the waste treatment, permit application, etc.

Goldman: We talk about value-add processes and, of course, waste treatment is not considered value-add. It's an extra expense. So, to reduce the extra expense is very important. And Cherry, you have your own poster?

Santos: Yes, I have a poster on immersion tin. Immersion tin is not a new process. It's been around for years and has been successfully used as a final finish for the automotive industry.

Goldman: Not as glamorous. Not as pretty as gold.

Santos: No (laughs). The challenge for immersion tin is the deterioration of solderability performance after heat treatment. As it goes through heat treatment, it loses thickness due to the formation of copper-tin intermetallic compound between the tin finish and the Cu metal substrate. For this to be solderable, there has to be a free tin layer left after the heat process because the copper-tin IMC has inferior solder wetting. We just listened to a talk that discussed the different final finishes, and there is no ideal finish. There is no perfect finish.

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