Second Source Component Strategy Guide A second source is an alternate part that can be substituted for the primary one without changing the board. It protects a product from a supply interruption, from an allocation and from a quality problem at one vendor. The work is done at the design…

Strain Relief And Lead Forming For Through Hole Parts A through hole component is held by its leads, and those leads have to do two jobs that pull in opposite directions. They have to hold the part in position during handling and soldering, and they have to absorb the movement…

Component Package Selection Guide Component package selection happens early and is decided by whoever is buying the parts, the engineer who designed the circuit, or the person who has to fit it on the board. The choice sets the footprint, the thermal path, the parasitic inductance and the supply risk,…

First Article Inspection For PCB Assembly The first board that comes off a line after a setup is the only one that can be examined without any assumption about the process having worked. Everything after it is a copy, and if the setup was wrong, the copies carry the same…

Solder Sphere Quality and Ball Diameter Control for BGA The solder sphere is the smallest component in a ball grid array package and the one that decides whether the package can be assembled at all. Diameter variation, poor sphericity and surface oxide all surface later as bridging, opens or voids,…

Thermal Via Array Layout and Plugging Selection in High-Power PCB Design Thermal Via Array Layout and Plugging Process Selection in High Power PCB Design In high power PCB design, the thermal via array is not a simple stack of conductive holes. It is the core execution unit of the thermal…

Moisture Sensitivity Levels: Floor Life, Baking and Storage Rules The moisture sensitivity level of a package is a number from one to six that describes how long it can be exposed to air before it must be baked. It exists because a plastic package absorbs moisture from the air, and…

Drill Bit Regrind And Hit Count Management A carbide drill bit for a printed circuit board is a precision tool made to a tolerance of a few microns, and it wears out long before it breaks. The cutting edge rounds, the margin wears, the diameter changes and the surface of…

Copper Voids And Plating Quality In PCB Barrels The copper that lines a plated hole is deposited atom by atom from a bath, and it is possible for the deposit to grow with a gap inside it. A copper void is a cavity in the plating, usually at the corner…

Vacuum Lamination And Void Control In Multilayer Boards A multilayer board is made by pressing several layers of copper and prepreg together until the resin flows, fills the gaps around the copper and cures into a solid block. If the resin does not fill a gap, the result is a…