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Some Common PCB Terms-F&G&H
Jun 25, 2018
Fabrication Drawing A drawing that is used to provide additional information for the correct manufacturing of the PCB.  It may include the location of holes, sizes and tolerances, board dimensions, material to be used, finish choice and any other important information not included in the gerber files.
Fiducial Mark The fiducial is a circle that is a copper pad with the same finish as the rest of the board and provides alignment targets for automated assembly equipment.  A fiducial may be on the rails of the array, on individual boards or next to special components.  Typically three fiducials are needed on an array and the ideal size is 0.050”. 
First Article A first article is a test run of a particular manufacturing process. It is useful to verify that all manufacturing parameters are correctly in place. For example when routing PCBs away from a production panel a single board will be routed out first to verify the rout program is correct. 
Flash GoldFlash gold is hard gold with a maximum thickness of 3 micro inches.  It is very thin and requires special handling. 
Flying ProbeThis is an electrical test method of bare circuit boards.  The flying probe machine uses several arms with probes on the end that work together to touch the test points on the circuit board to determine if there are any opens or shorts on the board. 
Fixed Frame Stencil A fixed frame stencil is a laser cut stencil that is permanently attached to an aluminum frame. 
FR-4FR-4 is fiberglass material that has a specific standard for flammability.  It is the most common material used in the manufacturing of printed circuit boards. 
Frameless StencilA laser cut stencil that will be placed inside a universal frame.  A frameless stencil will have holes cutout along the each edge of the stencil so that it can be attached to a universal frame. 

G

Gold FingersGold Fingers are gold plated connectors on an edge of the PCB.  The hard gold plating allows for the PCB to be inserted into a connector without damaging the surface of the connections.  An example would be a PCI card inserted into a PCI slot in PC. 
Ground Plane

 In PCBs this is a conductive area of the board, often an entire layer, that is usually connected to the power supply ground of the circuit. 

Hard GoldHard Gold is an electrolytic process and has hardeners in it for durability.  It is plated over a nickel finish and may also be referred to as Deep Gold.  (The term Deep Gold is used to indicate that full panels are placed in the plating tank prior to the application of soldermask.) 
HASL FinishHASL, Hot Air Solder Level is a common finish type for PCBs.  The PCB panel with exposed copper is lowered into a liquid bath of solder then quickly raised out of the bath and moved passed jets of hot air that clear off the excess solder leaving only the solder on the exposed copper areas. 
Home Base Apertures Home base apertures are the shape of the aperture used in laser cut stencils that will control solder balling and tomb-stoning of chip components. 

 




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