Battery FPC Materials: Building a Reliable Battery Flex A battery flex is one of the few circuits that carries current, moves and connects to a welded interface at the same time. That combination sets the material list far more tightly than a signal flex, because the film, the copper, the…

Signal Reflection In Transmission Lines: Causes And Termination Every discontinuity on a transmission line sends part of the incident wave back toward the source. The mechanism is not mysterious: the wave carries a ratio of voltage to current set by the line, and when it reaches a region where that…

Laser Marking on PCB Assemblies: Date Codes and UID Assembled boards are increasingly marked by laser rather than by ink, because a laser can write a unique identifier on every unit without a stencil or a print cycle. The change brings new questions about contrast, substrate damage, and how the…

PCB Prototyping Risk: Checks That Prevent a Bad First Build Most prototype failures are not caused by a clever circuit that did not work. They are caused by a footprint that was wrong, a tolerance that was assumed, or a component that was not available when the board arrived. Those…

Etch Factor and Undercut Control in PCB Etching Every wet-etched trace ends up slightly narrower at the top than the artwork that defined it, and slightly narrower again at the base. That geometry is described by the etch factor, and it sets the limit on how fine a line a…

PCB Assembly Fixture and Pallet Design Best Practices A pallet or fixture is the interface between a bare panel and the machine that will process it, and it quietly sets the limit on how thin a board you can run, how flat it stays at reflow, and how repeatably the…

Why 50 Ohm Impedance Is Hard To Hold Ask a fabricator to hold fifty ohms and the answer will be a tolerance, not a number. That is honest, because the impedance of a trace on a real board is the product of four variables, each with its own process window,…

Industrial Data Acquisition Board Design: Pitfalls and Fixes An industrial data acquisition board is judged by measurement quality rather than by feature count. A design that samples quickly and offers many channels but cannot hold an accurate reading in a noisy plant environment has solved the wrong problem. Most of…

Star Ground: Preparation, Placement and Process Control The <a href="https://www.gopcba.com/mixed-signal-pcb-design-guidelines/” title=”star ground”>star ground is one of the most repeated pieces of layout advice and one of the most frequently misapplied. It solves a real problem, but only in circuits where that problem exists, and it creates new ones when a…

Flexible Circuit Design Steps: How a Flex Board Is Built A flexible circuit is designed around movement rather than around area, and that changes the order in which decisions have to be made. The bend comes first, the stackup follows, and the conductor geometry is derived from both. This guide…