Rethinking Stackup, Materials, and Tolerances in Modern Designs

Estimated reading time: 2 minutes

The simple rectangular rigid PCB is becoming increasingly infrequent. This reality necessitates designing with concepts well outside traditional rigid PCB methodologies. For example, the designer of wearable electronics may need to implement conductive fibers integrated into the textile material. Heads-up displays, like those in VR/AR headsets and glasses, require transparent circuitry etched into the display glass. The process of designing without a rule book usually starts with something other than the traditional board design process.

In this process, the complete schematic is sent to the PCB layout tool. The first step is usually to define or import the mechanical board outline from the mechanical design engineer’s or the customer's specification. Next, you define the board stackup and place all the parts into the design, followed by routing and validation. Finally, you have documentation and manufacturing file generation.

In new designs, there are often several steps that differ from this traditional approach. First, when considering modern designs, it may be necessary to select specialty materials with properties that may not have been accounted for in the designs' electrical requirements. You may need to select materials for thermal, chemical, or mechanical needs. In the case of 3D-printed electronics, there is no reinforcement material (glass) like that used in a traditional PCB design.

In this case, conduct a physics study of the materials first, focusing on the conductive material, as printed conductive materials are typically 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 conductor. This means that there may be a greater IR drop on a printed conductive path compared to a pure conductor path.

To continue reading this article from the April 2026 issue of I-Connect007 Magazine, click here.