AOI Programming and Escape Prevention What AOI Does An automated optical inspection system photographs the board after reflow and compares what it sees with a reference, using a mixture of image processing and measurements to decide whether each component and joint is acceptable. It finds missing parts, reversed parts, shifted…

PCB Copper Trace Etching Factor: How Sharp the Etch Cuts 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 copper trace etching factor from the perspective of a…

Laser-Cut Versus Electroformed Stencils How a Stencil Is Made A stencil is a thin metal sheet with apertures through which paste is printed onto the pads. Two processes dominate: laser cutting, in which each aperture is cut from a rolled stainless sheet, and electroforming, in which the sheet is grown…

SMT Reflow Solder Joint Ball Shear: Pushing the Ball Sideways 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 SMT reflow solder joint ball shear from the perspective of…

Clock Trace Routing: Length and Termination Why a Clock Is Different A clock is a periodic signal that runs at a single frequency, and that changes how it behaves compared with a data line. Its energy is concentrated at the fundamental and its harmonics rather than spread over a band,…

Decoupling Capacitor Placement and Loop Area What Decoupling Does A decoupling capacitor is a local reservoir of charge that supplies a switching device while the power distribution network is still responding. When a logic gate switches, it draws a current pulse in a few hundred picoseconds, and the inductance of…

PCB Surface Finish Solderability Test: Checking the Pad Wets 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. The same discipline applies to PCB Surface Finish Solderability Test, where a small process drift…

Burn-In and Aging Tests for Assemblies What an Aging Test Screens Every population of manufactured assemblies contains a small number of units with a latent defect that will fail early. The distribution of failures over time follows a curve with three regions: a decreasing failure rate at the start, caused…

Incoming Inspection of Bare Boards Why Inspect on Receipt An incoming inspection is the last opportunity to reject a board before value is added to it. Once components are placed and reflowed, a fault that came from the bare board is indistinguishable from an assembly fault until a considerable amount…

SMT Component Reel Change: Loading a Fresh Reel Modern electronics depend on boards that are assembled correctly the first time. Every product – a phone, a charger, a medical instrument or an industrial controller – relies on thousands of solder joints that must conduct current for years. This article explains…