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Some Commen PCB Terms-D&E
Jun 25, 2018
Date Code

 The Date Code is added to the copper or silkscreen of the PCB during the manufacturing process.  The date code shows the week and year that PCB was made.  

Datum A Datum is used in PCB design files to mark the point of the axis or plane used as the origin of the PCB design. 
Delamination When any copper or laminate materials in a PCB begin to separate after the boards have been manufactured. 
Desktop Stencil A desktop stencil is a laser cut stencil that is used to apply solder past to surface mount component pads on a printed circuit board by hand. 
Desmear

 The chemical process of removing drilling debris that is left in the holes of a production PCB panel after being drilled. 

DielectricDielectric refers to the fiberglass material in a PCB.  The material is non-conductive and acts as an insulator for the electrical circuit in the PCB.  The properties of the dielectric material can have an effect on the electrical circuit.
Double Sided PCBA double sided PCB is the most common of all circuit boards.  It has copper on the top and bottom of the board material and includes connections through plated holes. 
DRC (Design Rule Checking) A DRC is performed with CAM software to verify the continuity of all conductors and routing within the manufacturers design rules. 

E

Electrical testElectrical Test is the process of testing the board for continuity and isolation.  (opens and shorts).  Typically the end points of all nets are checked for opens and shorts.   It does not include functionality testing of the PCB.  
Electro DepositionThe process of depositing a conductive material from a plating source using the application of an electrical current. This is used for plating in the hole walls as well as adding plating the copper pattern.
Electroless DepositionThe process of depositing a conductive material from an autocatalytic plating solution without the application of an electrical current.   Used to apply a thin amount of copper prior to copper plating to improve the possible connecting in the hole walls.  Is also used when applying various finishes to the board such as ENIG (Electroless Nickel Immersion Gold).
Electroless Nickel Electroless Palladium Immersion Gold (ENEPIG)Similar to ENIG but applies palladium over the nickel prior to the application of the gold.  This prevents any problems of corrosion between the nickel and gold and makes it a very “universal” surface finish.  Can be used for fine pitched components as well as gold wire bonding.
Electroless Nickel Immersion Gold (ENIG) ENIG is a very thin amount of Gold applied over Nickel.  The nickel is plated onto the copper prior to the application of Gold and acts as a barrier to prevent the Gold and the Copper from migrating into one another. The gold will disappear when soldered, as it is absorbed in the process.  Excellent for very fine pitched components.
Electroplating The electro-deposition of metal coating on a conductive object. The metal may be conductive or non-conductive. The object is placed in an electrolyte and connected to one terminal of a DC voltage source.  The metal to be deposited is similarly immersed and connected to the other terminal.  This creates a current flow from the metal to the conductive material thus depositing the material.  In PCB manufacturing it is used to apply copper to the hole walls and copper conductor pattern.
Etch Compensation Small adjustments are made to normalized Gerber data it compensate for the amount of copper that will be etched from the production panel. This can vary depending on the copper weight and is determined by the CAM operator based on quality controls.
Etchback

 Chemically removing the sidewalls of plated through holes in order to expose conductor areas on inner layers or a multi-layer PCB.

Etching After an image pattern as been applied to a panel of copper clad fiberglass the unwanted copper is chemically etched away.
Excellon Drill File The data file that defines the drill hole sizes, X & Y coordinates, and tool numbers for a circuit board.  Also called a NC (numerically controlled) drill file.


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