IPC International Community magazine an association member publication
Issue link: https://iconnect007.uberflip.com/i/1544398
52 I-CONNECT007 MAGAZINE I APRIL 2026 material, as printed conductive materials are typi- cally not pure crystalline lattice metals like copper foil but instead are copper- or silver-impregnated inks or resins. This means that the conductivity of the material, while sufficient for electrical signal propagation, may not be as good as a pure con- ductor. This means that there may be a greater IR drop on a printed conductive path compared to a pure conductor path. Additionally, a resin structure without the rein- forcement materials in traditional PCBs will exhibit different CTE rates, and the CTE will be significant in all three axes simultaneously. This means that a different approach to thermal expansion must be considered for these designs. Typical Z-axis copper-balancing techniques do not necessarily work when the conductor material is placed in all three axes. Manufacturing file generation is also different in these designs. Rather than traditional layer data formats like Gerber or ODB++, new designs for additive manufacturing will need 3D modeling file formats, such as STEP (Standard for the Exchange of Product model data, ISO 10303), to define the data to be 3D printed. Tolerances and other fabrication limits must also be re-evaluated by the designer. When using ad- ditive processes for large-scale design features like these, the deposition and feature registration controls now have three simultaneous axes of tolerance rather than a 2+1 tolerance. In traditional designs, the feature registration along the X-Y axis on the same layer is controlled during the etching process. On the other hand, the layer-to-layer Z-axis registration is controlled during the lamina- tion process. In 3D printed electronics, you are concerned not only with the shape of the design but also with the 3D support structures that provide mechanical support during the printing process (and that are removed after printing). Removal of the structures usually leaves an artifact or imperfection on the surface of the board, which will require additional cleaning and shaping of these sites to ensure the surface profile requirements are met. Parts placement is an additional challenge. In a traditional two-sided PCB, parts are placed on the top surface or bottom surface. Whatever orientation the PCB is mounted in will produce physical forces on the board in only two orientations, from the top or from the bottom. These forces include load and pressure applied to the surface of the board due to the mass of the parts, torque from cantilevered parts off the board, and thermal stresses from the thermal energy transferred to the PCB. With parts mounted on only two flat surfaces, the magnitude and directionality of these forces are relatively straightforward to calculate. For a three-dimensional structure, with parts mounted at any angle and on any surface or orientation, the complexity and difficulty of these calculations and determinations increase by an exponential order of magnitude. So, as this one example shows, the rulebook for PCB design that has been so successful for design engineers for so long is no longer the only approach. Instead, the next generation of design- ers will need a thorough understanding of all the scientific disciplines to grasp everything that will go into the design process. The flowchart of the PCB design process will need to be significantly expanded to account for all these new processes and effects. Design will no longer have a rulebook to follow; instead, it will use a multidisciplinary decision tree to help the designer ensure a successful design, the first and every time, regardless of the unique requirements of the design. I-CONNECT007 Kristin Moyer is an instructor for the Global Electronics Association. " So, as this one example shows, the rulebook for PCB design that has been so successful for design engineers for so long is no longer the only approach."