Common Mode Choke: Design Rules and Process Limits A common mode choke has two windings on one core, arranged so that the current flowing out on one conductor and back on the other produces no net flux. It presents a high impedance to the current that flows on both conductors…

TVS Diode: Design Rules and Process Limits A transient voltage suppressor is a diode that conducts when the voltage across it exceeds a threshold and absorbs the energy of the event. Choosing one is a matter of three numbers, and getting any of them wrong produces a circuit that either…

Fiducial: Design Rules and Process Limits A fiducial is a small mark on the board that exists only to be seen by a camera. It is a patch of copper with a clear area around it, and the vision system of a stencil printer or a placement machine uses its…

PCB Coating Specification: Writing Down the Film 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 explains PCB…

Digital Signage Board Design for Multi Display Players A media player that drives one or two screens around the clock has to be simple, quiet and reliable. Digital signage board design is mostly about the display interfaces and the thermal path, because those two decide whether the product survives its…

Thermal Fuse Protection Circuit Design A thermal fuse is a one time device that opens when its temperature exceeds a set value, and it is the last line of defence in a product that can overheat. Used well, it converts a dangerous failure into a product that stops working; used…

How SMT Line Automation Works in PCB Assembly A modern assembly line turns a bare panel into a tested board with very few people involved. Understanding how an smt line is automated explains which layout decisions help the process and which ones cause stoppages. What Automation Means on the Line…

Thermal Pad Soldering and Void Control in QFN Assembly A QFN package connects to the board through terminals around its perimeter and through a large exposed pad in the centre. The perimeter joints are visible before reflow and inspectable after, but the thermal pad sits underneath the body where nothing…

PCB Warpage, Bow And Twist Control A printed circuit board is a laminate of resin, glass, and copper, and those materials expand at very different rates when they are heated. The result is that a board which looks flat on the bench can bend or twist during assembly, and the…

PCB Laminate Lot Control: Knowing Which Batch Electronics manufacturing has become a discipline of small details. Solder paste volumes, placement accuracy, temperature profiles and inspection limits all add up to the final result. This guide looks at PCB laminate lot control from the perspective of a PCBA factory floor, covering…