Board Depaneling Selection for Production Assembly Separating finished boards from their panel looks like the simplest step in the process and is responsible for a surprising share of field failures. Board depaneling introduces mechanical stress, and the way that stress is applied decides whether a ceramic capacitor cracks, a solder…

Surface Energy and Wettability Control in PCB Assembly Every soldering, coating and bonding process depends on a liquid wanting to spread over a solid. That tendency is described by the surface energy of the solid and the surface tension of the liquid, and it is easily destroyed by a fingerprint,…

PCB Strain Relief Design Guide PCB strain relief starts from a simple observation: most board failures that arrive as electrical faults began as mechanical ones. A cable is pulled, a connector is levered, a flex tail is bent once too often, and the load ends up at a solder joint…

Board Labelling and Traceability Through Assembly A board that cannot be identified cannot be controlled. Traceability begins with a marking that survives the process, continues with a record that links the board to its build data, and ends with a system that can find every affected unit when something goes…

Stencil Nano Coating and Its Effect on Paste Release A stencil aperture is a small well with vertical walls, and solder paste has to leave it completely when the board separates. As apertures shrink, the paste increasingly prefers to stay where it is, clinging to the walls and to the…

Wave Solder Bath: Design Rules and Process Limits A wave solder bath is a working alloy that accumulates everything the process brings into it. Copper dissolves from the boards, gold from the finishes, iron from the pot and the pump, and flux residues collect on the surface, so the alloy…

Connector Selection Design Guide Connector selection is usually done late, from a catalogue, by whoever has the fewest other tasks. That is the wrong order. The connector sets the pin count, the board outline, the panel height and the assembly method, and a connector chosen at the end of a…

Copper Foil Roughness And High Frequency Loss At low frequencies the resistance of a trace is set by its cross section, and the surface of the copper can be rough or smooth without consequence. As the frequency rises, the current stops using the whole conductor and crowds into a thin…

ESD Safe Handling of Boards and Assemblies Static damage is the defect that leaves no evidence behind. A device that has been exposed to a discharge may fail immediately, may drift slowly, or may pass every test and fail in the field after a month of use, and nothing about…

Solder Mask Exposure And Registration Control Solder mask is applied as a liquid or a dry film over the whole board and then patterned by light. The exposure step decides where the mask stays and where it is removed, and the registration of that pattern to the copper underneath decides…