Issue link: https://iconnect007.uberflip.com/i/1536435
22 PCB007 MAGAZINE I JUNE 2025 Feature Article by Bob Neves RELIABILITY ASSESSMENT SOLUTIONS, INC. I got my start out of college grinding and polishing PCB microsections. My thumbs are a bit arthritic today because of the experience (microsection grinders know what I mean). Back then, via structures were rather large, and getting to the center in six steps of grind- ing and polishing was easy compared to what my team has been doing recently at the lab. HDI, ultra HDI, substrates, embedded com- ponents, and the plethora of (tiny) via struc- tures (micro, stacked, buried, staggered, etc.) that connect everything in today's "boards" make arriving at a via structure's center using a microsection a true nightmare—and a mir- acle for the lab technician if attained. Our historical faith in the microsection stems from the belief that: The Death of the Microsection • Evaluating the visible attributes of the via structure will demonstrate the quality and reliability that the PCB represents • Looking at the two sidewalls at the cen- ter of a 360-degree via structure will dem- onstrate the quality and reliability of the entire structure • Looking at a few via structures from the many thousands on a panel will demon- strate the quality and reliability of all the structures on a panel You can likely discern that more "faith and belief " are involved in interpreting the results from the microsectioning process than in sta- tistical significance. In addition to looking at the visual attri-