Set Top Box Mainboard Design With GPS Positioning A set top box that reports its own position combines a video platform with a radio receiver, and the two have to share one board without interfering. Set top box mainboard design in this case is mostly a question of where the…

PCB Acceptance Classes 1, 2 And 3 Explained Fabrication and assembly standards divide products into three classes, and the class is a statement about the consequences of failure rather than a general comment on quality. A class one product is one where a failure is not a hazard and the…

Thermal Shock Testing for PCB Assemblies Explained An assembly that works perfectly on a bench may still fail after a few hundred temperature swings, because the materials it is built from expand and contract by different amounts. Thermal shock testing exists to compress years of that behaviour into weeks, and…

Battery Cell Balancing Circuit Design A series string of cells can only deliver as much as its weakest member, and the members drift apart with every cycle. Balancing is the function that keeps them together, and it is one of several jobs a battery management board performs. Why Cells Drift…

Copper Balance And Etch Uniformity On Inner Layers An inner layer is not etched as a collection of individual traces. The whole panel passes through the etcher at once, and the etchant removes copper at a rate that depends on how much copper it has to dissolve in each area.…

ESD Control on the Electronic Assembly Line Static electricity is generated by movement and it is invisible. A person walking across a floor can accumulate a charge of several thousand volts, and the discharge that follows when a hand approaches a board is fast enough to damage a semiconductor junction…

Component Lead Coplanarity and Placement Force A component can only be soldered if its leads reach the paste. On a fine pitch part the difference between a lead that touches and one that floats above the deposit is a few tens of microns, and it is a property of the…

Energy Harvesting Circuit Design Guide An energy harvesting circuit takes a source that produces microwatts or milliwatts and turns it into something a sensor node can use. The source is weak, intermittent and has a high internal resistance, so the design is about matching, storing and budgeting rather than about…

Thermal Pad Voiding: Causes and Control A thermal pad is soldered like any other joint and judged differently. Instead of a fillet that can be inspected from the side, the connection is a large area under a package, and the quality of the joint is expressed as the proportion of…

Nitrogen Reflow: What the Inert Atmosphere Buys Air is mostly nitrogen, and the oxygen in it is the part that matters to a soldering process. At reflow temperature that oxygen reacts with the metal surfaces and with the solder, forming oxides that resist wetting and that change the way the…