ESD Audit for PCB Assembly: What to Measure and Where An esd audit is a measurement exercise, and it fails when it turns into a paperwork exercise. The written program, the signs and the training records are necessary, but they do not protect a board. What protects the board is…

Electrical Test Fixture Design: Probe Pitch and Grid Density An electrical test fixture holds a bare board and presses a bed of probes onto its test points so that every net can be checked for continuity and isolation in a single pass. The fixture is where the electrical test either…

PCB Etch Factor Plan: Laying It Out First Buyers and engineers often focus on the finished product and forget the production line behind it. In practice, most field failures can be traced back to process decisions made during assembly. Understanding PCB etch factor plan gives you a practical advantage when…

Oxygen Concentration: Design Rules and Process Limits The oxygen concentration inside a reflow oven decides how much of the flux is consumed by the atmosphere rather than by the solder. At the 210,000 ppm of ordinary air, oxidation competes with wetting throughout the profile; at 1,000 ppm in a nitrogen…

Anodic Bleed Under Conformal Coating: Causes and Controls Anodic bleed is the dark, sometimes glassy track that appears along a conductor on a coated assembly after the board has spent time under bias in humid air. It is a corrosion product rather than a coating defect, and it belongs to…

Solder Resist Dam Design: Dam Width and Component Spacing A solder resist dam is the strip of mask that separates two adjacent openings on a board. It prevents solder from bridging between pads during assembly, keeps the paste on the pad during printing, and provides the electrical isolation the design…

Copper Contamination in the Solder Pot: Signs and Limits Copper contamination is the slowest and most predictable way for a wave soldering bath to drift out of specification. Copper dissolves into the molten alloy from every plated through-hole, every exposed pad and every tinned lead that passes over the wave,…

Panel Utilization and Routing Margin in PCB Fabrication Panel utilization is the share of the panel area that ends up as delivered boards, and it is set at the moment the board outlines are nested. Everything else on the panel, the process edge, the gaps between boards, the tabs, the…

Surface Finish Shelf Life: Storage and Solderability Control Every board finish changes from the day it is applied. Oxide grows on the surface, intermetallic compounds grow between the finish and the copper beneath it, and the result is a surface that solders less readily than it did on the day…

Reflow Conveyor Vibration: Where Components Move Conveyor vibration is one of the few reflow variables that leaves no trace in the profile. The thermocouple records the peak temperature, the zones hold their setpoints and the boards come out at the right rate, yet a handful of small parts have moved…