PCB Panel Storage Rack Design: Standing Them Up Safely 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…

Choosing A Flex Substrate Or A Rigid Board The material at the bottom of a board is usually decided by the layout engineer on the basis of what the previous design used. That habit is reasonable for a product that has not changed, and it is a source of avoidable…

Military Grade Chip Resistor Screening And Reliability A chip resistor bought on price and a chip resistor bought against a military specification look the same and measure the same on the bench. The difference appears in the qualification data behind them, in the screening that each unit has passed, and…

Load Switch and eFuse Circuit Design Almost every board has at least one rail that has to be turned on and off under software control, or protected against a fault on a downstream module. A load switch does the first, an eFuse does the second, and the two are often…

Solder Paste Storage, Working Life and Handling Solder paste is a chemical product with a shelf life, a working window and a sensitivity to how it is handled. Most of the variation that appears in a print between the start and the end of a shift comes from the paste…

Stencil Cleaning, Storage and Inspection A stencil is a consumable that behaves like a precision tool, and it is treated as neither. Most paste volume problems that are blamed on the printer or the profile begin with a stencil that was not cleaned, not stored or not inspected. Why Cleanliness…

Instant Water Heater: Design Rules and Process Limits An instantaneous water heater switches several kilowatts of resistive load under the control of a small electronic board, and it does so in a wet environment with a person standing next to it. Almost every design decision follows from that sentence. What…

Spirometer Circuit Design: Pressure to Flow A spirometer turns a pressure difference into a flow, and a flow into a volume. The electronics are simple in principle, and the accuracy of the instrument depends almost entirely on the sensor, the conditioning around it and the calibration of the whole path.…

High Speed BLDC Motor Control in a Handheld Product A handheld dryer with a motor spinning at a hundred thousand revolutions per minute is a power electronics problem in a small plastic case. The inverter, the bus, the sensing and the thermal path all have to fit into a handle.…

Radiation Detector Circuit Design With a Geiger Tube A radiation detector built around a Geiger tube is a small system with three difficult parts: generating a stable high voltage from a battery, shaping a very small pulse without losing it in noise, and converting a count rate into a dose…