Solder Paste Jetting vs Stencil Printing: Deposit Method Selection Stencil printing and solder paste jetting both put a controlled volume of alloy on a pad, but they do it by different physical mechanisms and they fail in different ways. The choice follows from the smallest aperture on the board, the…

Moisture Sensitivity Level: Design Rules and Process Limits Moisture that a plastic package absorbs before reflow turns to steam at the peak of the profile, and the pressure it develops is what cracks the body or delaminates the die attach. The moisture sensitivity level printed on the bag says how…

Copper Thieving Density: Balancing Panels for Lamination and Warp Control Copper thieving is not decoration. It is the copper added to areas that carry no signal so that the press sees a similar amount of metal across the panel, and the amount and distribution of that copper decide whether the…

Thermal Relief Spoke Geometry for Through-Hole Wave Soldering A thermal relief is a deliberate interruption of copper between a pad and the plane it belongs to, and every dimension of that interruption changes how the joint fills in the wave. This article sets out the spoke count, spoke width and…

Tape and Reel Packaging Requirements for SMT Feeders Packaging is the part of a component delivery that the line interacts with as a mechanism rather than as a product, and a tape that is slightly out of specification stops a feeder rather than failing an inspection. The requirements are published…

Electrical Test Coverage: Continuity and Isolation Design Electrical test is measured in coverage, and coverage is a property of the design rather than of the tester. A board with inaccessible nets cannot be tested however good the equipment is, and a board whose coverage is not documented cannot be shown…

Reflow Oven Exhaust and Flux Condensate Management The exhaust system is the part of a reflow oven that nobody profiles until something changes. It removes flux vapour and volatile organics from the heated zones, and it also removes heat, which means a change in airflow changes the profile at the…

Flying Probe Test Point Design and Accessibility Flying probe testing needs no fixture, which makes it attractive for prototypes and low volume, but it needs physical access that a bed of nails fixture would have provided through its own pins. Test points that are too small, too close together or…

Placement Nozzle Selection and Wear in SMT The nozzle is the only part of a placement machine that touches the component, and it is usually the last item considered when placement accuracy is reviewed. Its diameter decides how the part is held, its material decides how long it holds it…

PCB Serialisation and Panel Level Traceability Marking Serialisation is only useful if the mark survives every process the board goes through and can be read at the point where the information is needed. That means the marking method, the position, the symbology and the reading equipment are one design decision…