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DECEMBER 2025 I PCB007 MAGAZINE 59 The Printed Circuit Designer's Guide to... DFM Essentials by Anaya Vardya Chapter 8: Final Finishes and Design Guidelines Final finishes p rovide a s urface f or t he c ompo- nent assembler to either solder, wire bond, or conductively attach a component terminal or lead to a pad, hole, or area of a PCB. The other use for a final finish is to provide a known contact resistance and life cycle for connectors, keys, or switches, and also provides protection against oxidation for the exposed copper. The primary purpose of a final finish is to create electrical and thermal continuity with a surface of the PCB. Pb-free PCBs require that the standard HASL surface finish cannot be used. There is still a sig- nificant a mount of discussion o n what t he long- term surface finishes will be. Currently, the immer- sion silver and OSP surface finishes are the most prevalently specified surface finishes for solder- able PCBs. Immersion tin is the prevalent surface finish for press-fit backplanes. Please contact your PCB fabricator for current information on where industry specifications are heading. Design Guidelines Designing a printed circuit board surface finish is crucial for ensuring the reliability and performance of electronic devices. Functionality and Application Understand the require- ments of your PCB in terms of functionality, environment, and applica- tion. Different surface fin- ishes offer various advan- tages and are suitable for different scenarios. Continue reading... My business philosophy and our success has a lot to do with assembling the right team of people. Building circuit boards is not a one-person process; it requires a whole team to buy into what you are doing and work together to make it happen. We have been successful with developing and nurtur- ing a highly skilled and invested team that really wants to grow the technology, and that knows how to work together to create results. Next, we want to grow with our customers, so we take the lead from what they want to do. When I came here, the bulk of the work was RF, and we were really good at it. We had some metal-backed offerings and FR-4, but not a lot. Our customer base was relatively small, and I wanted it to grow. I also wanted to expand our technology offering. Because we were already building very thin PTFE boards—0.004" and 0.005" double-sided thick boards—diversifying our technology offering with flex circuits felt quite natural. That was our first big diversification. At that time, ASC had two facilities. We merged them into this single facility and focused on expand- ing our quality certifications, which is very important. We have continuously migrated up the technology curve, continually improving our capabilities and expertise. Ultimately, through a continuous focus on ramping up technology and not losing focus on having the right team in place at all times, we have all the pieces needed to be a successful HDI facility. Over the past few years, we've pushed even harder into HDI and UHDI technology, something that must be undertaken slowly and securely. We are building boards today that, a year and a half ago, the overwhelming response would have been, "Are you nuts?" Finally, it is important to invest in the right soft- ware. So, you must have the equipment, the people, the refined and controlled processes, and then the right software and all the efficiencies you can gain from that. Success requires pulling it all together. Anaya, thank you for the tour and this important discussion. My pleasure, Marcy. PCB007 BOOK EXCERPT