PCB Reballing BGA: New Balls for an Old Package 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 reballing BGA from the perspective of a PCBA factory floor,…

PCB Rework Hot Air Profile: Process Details and Inspection Points Buyers and engineers often focus on the finished product and forget the production line behind it. In practice, most field failures can be traced back to process decisions made during assembly. Understanding PCB rework hot air profile gives you a…

Stackup Symmetry: Keeping a Multilayer Board Flat Most stackup discussions are about impedance, layer count and material. Symmetry rarely comes up until a board comes back bowed, and then it becomes the only thing that matters. A multilayer board is a sandwich of materials with different thermal expansion, pressed under…

Crystal and Oscillator Layout: Rules for a Stable Clock The crystal circuit is a handful of components that takes almost no board area and is responsible for whether the product works at all. A badly placed crystal can fail to start at low temperature, drift enough that a radio will…

Flex Stiffeners: Adding Rigidity Where It Is Needed A stiffener is a piece of rigid material bonded to part of a flexible circuit to stop it flexing where it should not. It is a small addition that solves a large class of problems: a connector that cannot be soldered to…

Gold Fingers on a PCB: Design Rules for Edge Contacts Gold fingers are the plated contacts on the edge of a board that slide into a socket. They are one of the few parts of a circuit board designed for mechanical wear, and they fail for mechanical reasons: worn plating,…

Choosing a PCB Surface Finish: Five Options Compared The surface finish is a thin layer of metal or organic material that protects the copper from oxidation and provides a solderable surface. It is chosen in seconds on most projects and it decides whether the assembly process runs smoothly, how long…

Thermal Via Arrays: Moving Heat Through the Board A thermal via array is the simplest thermal management tool available on a printed circuit board: a group of small vias under a component that carries heat from the pad into the copper layers below. It costs almost nothing in material and…

Power Integrity on a PCB: The PDN From Bulk to Die Power integrity is the least visible part of signal integrity and the most common cause of intermittent failures. A board can pass every eye diagram test and still reset a processor when an FPGA switches a thousand outputs at…

Backplane Design: Long Traces, Many Slots and Heavy Power A backplane is the board that carries the connectors for every card in a system. It usually has no active components of its own, it is physically large, and it is the most demanding board in the chassis in terms of…