Termination Impedance: 50 Ohm Versus 1 Megohm A measurement is only as good as the load the instrument sees. Signal generators, spectrum analysers and network analysers are calibrated to drive and to sense a defined impedance, and when the load at the end of the cable does not match the…

PCB Tolerances: Where They Come From and What They Cost An engineering drawing is a contract, and the tolerances on it are the terms. A tolerance that is stated without a reason is either too tight, which costs money, or too loose, which costs yield, and both are avoidable. What…

PCB Chassis Ground Connection: A Factory-Floor Review Electronics manufacturing has become a discipline of small details. Solder paste volumes, placement accuracy, temperature profiles and inspection limits all add up to the final result. This guide looks at PCB chassis ground connection from the perspective of a PCBA factory floor, covering…

SMT Production Material Management: Practical Controls Material management is the part of smt production that receives the least attention and causes a disproportionate share of the problems. A reel in the wrong place, a moisture sensitive package opened too early or a part consumed without recording turns into a stopped…

Digital Isolator Creepage and Clearance A digital isolator carries logic signals across a barrier that must survive thousands of volts, so the package rating is only half of the story. The creepage across the board surface, the clearance through the air, and the way the two grounds are separated all…

PCB Loop Inductance: The Area That Matters Loop inductance is set by geometry, not by the component you solder onto the board. Current leaves a driver, travels along a trace, and returns through a plane or a second trace. The area enclosed by that round trip decides how much inductance…

Footprint Library: Lessons From the Last Product: A Design Review Input The cheapest improvement available to most hardware programs is a short review of the previous product, and it is the one most often skipped because the schedule has already started. The findings are consistent, and they fall into a…

Edge Plating Process Window: Design and Quality Control Edge plating turns the outside wall of a circuit board into part of the electrical and mechanical design. Instead of stopping at the copper layers, the plating wraps around the routed edge and connects the top, bottom and inner planes into one…

Optocoupler CTR Degradation and Design An optocoupler is often chosen as a fit and forget isolation device, but its transfer efficiency falls steadily from the day it is first powered. A design that works perfectly on the bench can fail in the field after a few years because the current…

Flexible Printed Circuits in Electric Vehicle Harnesses A modern vehicle contains more copper than most people expect, and a growing share of it is not round wire. A flexible printed circuit replaces a bundle of individual wires with a flat laminated conductor pattern that follows the shape of the space…