Smoke Detector PCB: Sensor, Power and Reliability Design A smoke detector is a product with an unusual set of constraints. It must run for years on a single battery, detect a signal that changes slowly and slightly, resist false alarms from cooking and steam, and be trusted to work when…

Hard Gold versus Soft Gold PCB Plating: Which to Use Gold finishes on a board are not interchangeable. A gold finish chosen for a soldering surface behaves differently from one chosen for a connector that will be inserted a thousand times, and using the wrong one produces either a finish…

Designing for the Soldering Process: What the Layout Should Provide Most solder defects are designed in rather than produced. The stencil, the placement machine and the reflow oven all operate on what the layout gives them, and when the layout gives them something awkward, the process has to compensate. Understanding…

FPC Production: Five Panelisation Principles Flexible circuits are almost never produced one at a time. A single FPC is too small for the handling equipment and too wasteful of material, so production starts from a panel that carries many units. How that panel is arranged, the panelisation of the design,…

PCB Dimensions: Units, Footprints and Enclosure Fit A designer who knows the tool but not the numbers will still produce a board that cannot be assembled. Software facility is a means of expressing a decision about size, and the decision is where the engineering sits: a part placed at the…

MCPCB Price: What a Metal Core Board Really Costs A metal core board solves a problem that ordinary laminate cannot: it moves heat sideways and out of the assembly rather than letting it accumulate under the die. That capability comes from a metal base plate bonded to a thin thermal…

Set-Top Box PCB Design: Blocks and Signal Flow A set-top box board looks busy for its size, and the reason is that it contains three or four different kinds of circuit on one substrate: a radio frequency front end, a high-speed digital core with its memory, and analogue audio and…

BGA Soldering and Rework: Controlling Temperature and the Profile Ball grid array packages fail in a narrow temperature window that is easy to miss and hard to diagnose. The solder balls are underneath the package, so the joint cannot be inspected visually, and the difference between a good joint and…

PCB Assembly and Box Build: Scope, Testing and Handover Printed circuit board assembly ends with a tested board. Box build ends with a product that can be shipped, including the enclosure, the cables, the labels and the packaging. The two are separate services, and the boundary between them is one…

High-Frequency PCB and Microwave PCB: Where the Line Is The two terms are used interchangeably in conversation and they describe overlapping sets of boards. A high-frequency board operates where the interconnect must be treated as a transmission line; a microwave board operates where the wavelength is short enough that distributed…