Or, why is immersion silver the preferred finish in ballistic missile nosecones?
Surface Finishes. What more can be said about circuit board surface finish processes? Perhaps I’m too close to the topic, but I’m continuously bombarded by columns, publications, conferences, technical reports, press releases, and advertising on surface finishes. A portion of these are self-aggrandizing presentations of semi-scientific technical results. Others may contain nuggets of precious information. But in the hallways of the technical conferences and at the bar before the tradeshow, you’ll get the real story on surface finishes. How that OEM in Germany likes to use this surface finish, while that other assembler won’t use such-and-such, ever since they got burned with that terrible failure mode. And why is immersion silver the åpreferred finish in ballistic missile nosecones? I guess there is always more to say about surface finishes. The proof is in the fact that people keep talking about them.
The chatter is not all technology. Pricing. Specification. Operator complaints. Document updates. Phosphorous content. Good service guys. The Japanese market. Waste water. And …failure modes. Did I forget to mention failure modes? The list of topics continues to grow, and now the list will become a series of columns in this magazine. Our charter? To discuss all aspects of surface finishes, not just the same old boring solderability comparison charts, but the whole spectrum of hallway conversations. In this series of columns we will address printed circuit board surface finishes, a.k.a. final finishes or solderable finishes. We will keep the columns fresh, and the subjects diverse.
You may have noticed that this industry is full of technology enthusiasts (geeks). So often, we get all wrapped up in discussions of ohms and thickness distribution and surface analysis equipment. Of course, we will cover plenty of technical jargon, but we will always give the real-life applications view of the technology. Our challenge will be in giving adequate coverage to all the various views on surface finishes.
At MacDermid, I’ve spent the better part of 20 years involved in surface finishes. On the lab bench, I mixed the chemicals. At the EMS site, I soldered the test vehicles. In the board shop, I suffered from “nickel itch.” And back here at my desk, I’ve attempted to coordinate the data from all of these activities into a message to the industry. As I get older, and less able to tend to the lab bench, I’m assisted by lots of more capable people. These people will be sending in reports on specific surface finish topics as we attempt to tackle them. It’s a big project, so let’s get started.
Lao Tze gave us the wisdom; “The journey of a thousand miles begins with just one step.” Taking that first step into the big arena of surface finishes, I plan to divide the topic into "bite-sized" units as outlined in the central figure.
In addition, I hope you’ll embrace the idea of emailing questions that can be handled in the column. Admit it, we’ve all complained at how information is presented in the media. (Just think about politics, nobody likes the news coverage of the presidential campaigns.) Instead of complaining, be part of the solution! Bring us ideas for columns on surface finishing, and we’ll have an honest-to-goodness debate, here in our own small world of PCB manufacturing. On reflection, I guess I do understand why the topic of surface finishes is so widely investigated, and why there are so many articles, conferences, etc on the topic. There is always change in board finishing technology, and there is always news in the surface finish front. I congratulate PCD&F for bringing the spotlight to surface finishes. And I hope you’ll accept the responsibility for helping shape this column. You can send your questions to the magazine or directly to the columnists via the email address of the authors. PCD&F
Don Cullen is the director - OEM and assembly applications for MacDermid, Inc. He will be a regularly featured columnist on the Final Finish Forum. He can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..
