PCB Traceability From Panel to Box: Following One Board 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…

Depaneling: Preparation, Placement and Process Control A panel exists so that the assembly line has something large enough to handle, and the boards have to be separated again before the product is finished. The separation step is where a surprising amount of damage is done, because the operation that breaks…

Silver Migration and Electrochemical Failure Paths A board that passes every test in a dry factory can fail in a humid enclosure with no component having degraded at all. The culprit is often an invisible conductive path that grew between two conductors over weeks or months, fed by moisture, contamination…

Stencil Aperture Design And Area Ratio The printed circuit board gets the solder paste from a stencil, and the stencil is a sheet of metal with a hole for every pad. The volume of paste that ends up on the pad is set by the geometry of that hole, and…

Copper Surface Roughness and Its Effect on Signal Loss At low frequencies the surface of a copper trace can be rough without consequence, because the current uses the whole cross section of the conductor. As the frequency rises the current crowds into a thin layer at the surface, and that…

Paste in Hole Solder Filling for Through Hole Joints Paste in hole is the technique of printing solder paste into a through hole so that the joint can be formed during the same reflow step that solders the surface mount parts on the board. It removes a wave soldering or…

Silkscreen Design Rules for Assembly and Repair Silkscreen is the only part of the board that explains itself to a person. It carries the reference designators, the polarity marks, the connector pin numbering and the warnings, and it is usually the last item to be considered in the layout. What…

Glass Transition Temperature Effects in PCB Laminates Every laminate datasheet lists a glass transition temperature, and every engineer nods at it without always knowing what it controls. It is not a melting point, and crossing it does not destroy a board. It is the temperature at which the cured resin…

Board-to-Board and Wire-to-Board Connector Selection Every product has at least one place where two boards or a board and a cable have to connect and still be separable. That interface carries the signal integrity, the mechanical retention and the serviceability of the product, and it is usually chosen from a…

PCB Document Distribution: The Right Sheet on the Line 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 document distribution gives you a practical advantage when…