Analog Switch and Multiplexer Circuit Design An analogue switch is a pair of MOSFETs that connects or disconnects a signal path, and it behaves quite differently from the mechanical switch it replaces. It has a resistance that varies with the signal, it injects a small charge every time it changes…

Panelisation Design and Depaneling Method Choice for SMT Panelisation is the practice of building several copies of a board in one panel so that the assembly line has something large enough to handle, and the way that panel is designed decides how the boards behave when they are finally separated.…

Flexible Circuit Assembly: What Changes On A Flex Board Assembling components onto a flexible circuit is not the same job as assembling them onto a rigid board, even though the equipment and the solder are the same. The substrate bends, absorbs moisture, changes size during processing and cannot support the…

Difficult Board Prototypes: Layout and System Test Some boards are difficult for reasons that have nothing to do with the circuit diagram. Fine pitch devices, controlled impedance, mixed analogue and digital sections and tight mechanical constraints all push the design outside what a generic layout can support. Building one successfully…

Sequential Lamination HDI Stackup Design In a conventional multilayer board every via passes through the whole stack. As density rises, those through vias consume space on every layer they cross, and the space they take becomes the limiting factor in the layout. Sequential lamination solves the problem by building the…

Measuring Flatness and Coplanarity on Flexible Circuits The flatness of a flexible circuit matters at the interfaces where it has to make contact. A flex tail that plugs into a connector must be flat so that all of its contacts touch their counterparts, a flex that is bonded to a…

PCB Non Disclosure for Gerber: Design, Process, and Quality Notes 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 non disclosure for Gerber from the perspective of a…

FPC Design Mistakes That Break Handheld Products A portable product puts a flexible circuit into a space that is shrinking every generation. The cable has to pass a hinge or a sliding mechanism, follow the curve of a battery or a display module, and end in a connector that is…

FPC Design Parameters For Appliance Electronics An appliance is a difficult environment for an interconnect. The inside of a washing machine, a refrigerator or a kitchen appliance is a three dimensional space occupied by motors, heaters, sensors and a control board, and the connections have to run between them without…

Embedded Resistor and Buried Component Design An embedded resistor is formed from a resistive layer inside the board rather than from a component placed on the surface. The technique removes parts from the surface, shortens the connection to the layer it terminates, and improves the behaviour of high speed nets…