Measling, Weave Exposure and Laminate Cosmetic Defects Open a batch of boards and everything works, yet the surface looks wrong: pale crosshatched patches, faint fabric texture, or whitish spots that appear only after soldering. These are laminate cosmetic defects, and they generate more arguments between fabricators and customers than almost…

Via Filling and Plugging: Tenting, Fill and Planarisation A via does not have to be open. It can be covered, plugged or completely filled, and the choice is decided by what sits above the via and by what the via has to survive. The words are often used interchangeably, and…

Land Pattern Design: Pads, Fillets and Density Levels The land pattern is the copper the component sits on. It decides how much solder forms the joint, how much the component can move, and how much of the joint an inspector can see. It is defined once and then inherited by…

Wireless Charging Circuit Design for 15 W Systems Inductive charging at fifteen watts is a mature technology with a well defined architecture, and the design effort goes into the details: the coil, the resonant network, the control loop and the thermal path, not into the principle. How Inductive Charging Works…

Motor Driver Circuit Design From Requirement to Board A motor drive is designed backwards from the mechanical requirement. The torque, the speed and the acceleration profile decide the current, and the current decides the topology, the devices and the copper on the board. Requirements Before Topology The first document is…

Tin Pest: Low Temperature Failure in Solder Joints Tin is one of the most useful metals in electronics and one of the least stable. Below a well-known threshold it slowly transforms from the familiar silvery metal into a grey, crumbly powder, and the joints it forms begin to disintegrate from…

PCB Depaneling: V-Score, Routing and Laser Depaneling separates the individual boards from the production panel. It looks like a simple mechanical step, but it is where a finished assembly can be damaged by stress that leaves no immediate sign and appears later as a cracked joint or a delaminated corner.…

Press-Fit Connector Assembly: Compliant Pins and Hole Fit A press-fit connector is attached to a board by forcing a compliant pin into a plated hole. There is no solder, no reflow and no thermal excursion, which is why the technology is used on thick backplanes where soldering would be difficult…

Scanning Acoustic Microscopy for Package Delamination Some of the most damaging defects in a plastic package are invisible from the outside and completely transparent to X-ray. A thin layer of air between the mould compound and the die pad, or between a solder mask and a copper plane, changes almost…

SMD Aluminium Electrolytic Capacitor For Reflow A radial aluminium electrolytic capacitor is one of the last through hole components on many boards. It cannot be placed by a machine that expects a flat body with solderable pads, so it is inserted by hand, clinched, and soldered in a wave. That…