IPC International Community magazine an association member publication
Issue link: https://iconnect007.uberflip.com/i/1546580
SEPTEMBER 2026 I I-CONNECT007 MAGAZINE 81 • Daisy chain electrical reliability (four immer- sions at 288°C of 10 seconds followed by 4-wire Kelvin measure) • First drilled hole of multiple diameters/last drilled hole of multiple diameters (inspection if present) • Layer-order windows (inspection if present) • CAF reliability (CAF test chamber) HDI and UHDI fabrication will continue to push the limits of PCB manufacturing as circuit densities increase and feature sizes shrink. For the fabricator, success will depend on much more than having the equipment to produce smaller features. Via formation, process control, testing, and the proper use of panel coupons all become important as tolerances tighten. In the next installment, I'll take a closer look at process control for HDI and UHDI fabrication. I-CONNECT007 Michael Carano brings over 40 years of electronics industry experience with special expertise in manufacturing, performance chemicals, metals, semiconduc- tors, medical devices, and advanced packaging. To read past columns, click here. square inch. This fact requires the test equipment to navigate fine pitch HDI boards below 50-micron lines and spacing and 0.4mm pitch. The good news is that traditional flying probe and bed-of-nails test equipment are being supple- mented with a multitude of advanced electrical test technologies. These include very high speed flying probe testers that not only are capable of testing fine pitch designs, but are able to perform imped- ance measurements and detect intermittent opens and current leakage. Panel Coupons Special artwork designed into the panel edges or in unused space on the panel is essential. For addi- tional traceability, if the artwork shares common fea- tures on the assembly sub-panel, there is continuity for whoever performs the SMT assembly. Figure 2 shows a small coupon design that can be used on fabrication panels and assembly sub-panel carriers. The coupons are detachable and can be tested by production personnel during the fabrication process. These coupons test for: • Desmear-metallization-plating quality (10 immersions of 10 sec in 288°C solder pot inspection) • Layer-to-layer registration and movement directions (continuity and cross-section) T RO U B L E I N YO U R TA N K T RO U B L E I N YO U R TA N K