Does a Higher PCB Layer Count Mean Better Performance? More layers is a common shorthand for a better board, and it is wrong often enough to be worth examining. Layer count is a design decision that follows from routing density, reference requirements and the number of supply voltages. Beyond the…

Component Usage in Prototyping: Latch-Up, Filters and Spare Inputs Most product failures traced to component choice are not caused by the wrong part number. They are caused by a part that was used correctly on paper and left in a condition the circuit could not tolerate: an input floating, an…

Clean Production Measures in FPC Manufacturing Clean production in circuit board manufacturing means reducing pollution at the source rather than treating it at the outlet: improving the process, choosing less hazardous chemistry, using equipment that contains what it produces, and recovering what would otherwise be discharged. For flexible circuits, whose…

Fine Line Production in PCB Fabrication: Resist, Exposure and Etching Component packages have moved toward ball grid arrays and finer pitches, and the consequence for the board is a steady reduction in conductor width and spacing combined with an increase in layer count. Width and spacing save area; layers save…

Characteristic Impedance Control in PCB Design: Width, Height, Dk Impedance is the property that separates a board that merely conducts from a board that transmits. A design that passes continuity and isolation testing can still fail to carry a fast signal, because what is being conveyed along the trace is…

32.768 kHz Crystal Layout: Load Capacitance and RTC Accuracy A real-time clock keeps time while the rest of the product is powered down, and it does so with a crystal that operates continuously from a small backup supply. That crystal runs at a low frequency and draws very little current,…

Electroless Copper in PCB Holes: Process Steps and Control Every plated through hole in a printed circuit board starts life as an insulating wall. The resin left by the drill does not conduct, and electroplating cannot begin on a surface with nowhere for the current to flow. Electroless copper is…

PCB Prototype Production Flow: Cutting, Drilling and Plating A prototype order moves through the same production line as a volume order, but with different economics. Setup dominates, quantities are small, and the process has to be flexible enough to handle a design that has never been built before. Understanding the…

Resistor Selection for PCB Design: Power, Voltage and 0 Ohm Uses Choosing a resistor looks like the simplest task in a schematic, and it is where a surprising number of reliability problems begin. Two engineers can specify the same 10 k value and end up with one circuit that works…

Panel and Fiducial Design Rules for Automated SMT Assembly An automated surface mount line can place tens of thousands of parts an hour, but only if the board presents itself to the machine in a form the machine can handle. Panel geometry, edge conditions, fiducial placement and tooling holes are…