Low Power Wake Up Circuit Design A battery powered product spends most of its life asleep, and the circuit that wakes it up decides both how long the battery lasts and how quickly the product responds. The two requirements pull in opposite directions, and the design is the reconciliation of…

Industrial Control Board Selection for Embedded Systems An industrial control board is bought to run a machine for years, not to win a benchmark. Selecting one therefore means comparing service life, thermal behaviour and interface availability rather than processor speed alone. What Makes a Board Industrial The industrial version of…

Creep Corrosion Growth on Immersion Silver Surfaces Corrosion on an electronic assembly is usually a local phenomenon: a pad darkens, a joint discolours, a region of a trace changes colour. Creep corrosion is different. The corrosion product migrates across a surface, away from the metal that produced it, and it…

Crystal Oscillator: Design Rules and Process Limits A crystal oscillator is a mechanical resonator with a very high quality factor, and the circuit around it is an amplifier that has to keep it running. It is also one of the few analog circuits left on a digital board, and the…

PCB Baking Schedule Before Assembly Circuit board laminate absorbs water from the air, and the amount it holds depends on the material, on the humidity, and on how long the board has been exposed. That moisture becomes a problem at reflow temperature, because water turns to vapour and expands, and…

Tin Whisker Growth and Mitigation on Plated Surfaces A thin filament of metal growing out of a plated surface, apparently spontaneously, is one of the strangest reliability problems in electronics. Tin whiskers can grow several millimetres long, they conduct electricity, and they can bridge gaps that were designed with generous…

AOI Program Setup and the Defect Library Automated optical inspection is a camera and a decision. The camera is reliable; the decision depends on how the AOI program was written and on what it was taught to accept. Two machines with identical hardware will find very different numbers of defects…

Development Board PCB Design for Embedded Platforms A development board exists to expose every interface of a processor, which makes it a different design problem from a product. Development board pcb design is judged by how many interfaces reach a connector and how easily the software team can reach them.…

Reflow Profile: Reflow Profiling with a Thermal Coupon on the Real Board A reflow profile is a claim about what the board experiences, and the claim is only true where it was measured. An oven display shows the air temperature in each zone, which is not the same as the…

Random Vibration Testing for PCB Assemblies and Components A board that survives a drop test can still fail on a shaker table, and a board that survives a shaker table can still fail in a vehicle. Vibration is a cumulative loading process, and the damage it does depends on the…