Issue link: https://iconnect007.uberflip.com/i/1541840
22 DESIGN007 MAGAZINE I DECEMBER 2025 TA RG E T C O N D I T I O N Downstream Impact of 'Counter-flattened' Panels The EMS provider receives the shipment and performs first-arti- cle inspection. The panels are placed on the flat inspection surface. Astonishingly, they appear compliant as the hidden, opposing stresses hold steady. With no way to measure the artificial mechani- cal tension inside the laminate, the boards pass and move onto the production line. ♦ Solder paste printing on Side A: No problem. ♦ Pick-and-place: Still no problem. ♦ The boards behave, for now. But there's something about heat that relaxes most everything. At the end of a PCB designer's day, it's a sauna, hot tub, or maybe those little stick-on heating pads. But for a stressed out, counter-flat- tened PCB? After a long trip riding in a FedEx van, getting inspected, smeared with solder paste, and covered with hundreds of tiny, cold SMT components, nothing beats a nice long run through the 210°C–260°C reflow oven. Figure 3: Engineering EQ for stackup modification concession. Figure 4: Warped panel. Figure 5: Counter-flattening.