A known good PCB by which quality levels may be compared when considering other PCBs for rework.
Gull wing Lead
A lead configuration typically used on small outline packages where leads bend and out. An end view of the package resembles a gull in flight.
IC, Integrated Circuit
An assembly of miniature electronic components simultaneously produced in batch processing, on or within a single substrate to perform an electronic circuit function.
A sharp point of solder that protrudes out of a solder joint, but does not make contact with another conductor. Icicles are not acceptable.
An electrical test of an assembly in which each component is tested individually, even though many components are soldered to the board.
The band of electromagnetic wavelengths existing between the extreme of the visible and the shortest microwaves/ The strong absorption of infrared by many substances renders it a useful means of applying heat energy.
Infrared Reflow Soldering
Soldering A reflow soldering furnace using infrared heating as the primary source of heat introduction in the furnace environment.
Process residues such as flux activators, fingerprints etching and plating salts, etc., that exist as ions or when dissolved , increase electrical conductivity.
A lead configuration typically used on plastic chip carrier packages which have leads that are bent underneath the package body . A aide view of the formed lead resembles the shape of the letter “J”.
A portion of a conductive pattern usually, but not exclusively, used for the connection , or attachment, or both of components. (Also called “pad”)
Component mounting sites located on the substrate that are intended for the interconnection of a compatible surface mount component. Land patterns are also referred to as “lands” or “pads”.
LCCC, Leadless Ceramic Chip Carrier
A ceramic, hermetically sealed, integrated circuit package commonly used for military applications, The package has metallized castellations on four sides for interconnecting to the substrate.(Also known as LCC).
The dissolution of a metal coating, such as silver and gold into liquid solder. Nickel barrier underplating is used to pre vent leaching.
The solid formed conductors that extend from a component and serve as a mechanical and electrical connection that is readily formed to desired configuration. The gull wind and the J-lead are the most common surface mount lead configurations. Less common are butt leads formed by cutting standard DIP package leads at the knee. See also Butt Joint.
The distance between successive centers of the leads of a component package. The lower the lead pitch, the smaller the package area for a given pin count in a package. In DIP, the lead pitch is 100 mil; in surface mount packages it is 50 mil. For fine pitch, commonly used lead pitches are 33 (Japanese),25, and 20mils. In tape automated bonding, generally 10 mil pitches are used.
A format of letters, numbers, symbols, and/or patterns on the printed board that are primarily used to identify component locations and orientation for convenience in assembly and replacement operations.
A fiducial mark to locate the position of land patterns for components on a PCB.