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Some Commen PCB Terms-C
Jun 25, 2018
C-Stage ResinThis is the final hardened stage of the resin used during the lamination process of the multi-layer PCB.
CAD (Computer Aided Design) CAD refers to the software used by a PCB designer to create the files and needed data that is used to manufacture and assemble the circuit board and components.
CAM (Computer Aided Manufacturing)CAM refers to the software used by PCB manufacturers to prepare customers engineering files (See Gerber Files Blog Post) for the final manufacturing process.
CAM Files These are the files that provide the needed information for the manufacturing of the printed circuit board.
CapacitanceThe ability to store energy in an electrostatic field. In relation to the impedance of a circuit board it is the relationship between dielectrics and the location and size of conductors. 
Castellated Holes When a hole is drilled at the edge of the board and plated, leaving an open half circle at the edge of the board. This is often used in a board design for a circuit that will be used to test microchips.
Check Plots Check Plots are typically a PDF file that depicts the Gerber files once they have been through the CAM process.  The plots can be reviewed by the customer to make sure that the data is correct and ready for manufacturing.
CladClad references the material used in manufacturing PCBs.  Fiberglass material is “clad” with copper and is used as the starting place for manufacturing of the PCB.
Class 3For commercial PCBs this is the highest standard for manufacturing for high reliability circuits that would be used in flight controls or for some type of life support function.
Clearances A clearance (also called isolation) is space used to create a separation from a power or ground layer near a plated hole on an inner layer.   A clearance will prevent a short from the plated hole to either the power or ground plane. 
Coefficient of Thermal Expansion (CTE)A measurement of the amount the PCB material will change per degree of temperature.  This is a key factor in when determining which material is the best one to use for a given circuit design.  Material manufacturers will provide these details in their material specifications sheet.  
Comparative Tracking Index (CTI)Is used to measure the electrical breakdown properties of the insulating material used in PCBs.  It is primarily used to assess electrical safety especially for human users of electrical devices.  Material manufacturers will provide these details in their material specifications sheet. 
Component HoleA plated hole on the circuit board that is intended to have a component pin placed in it. This could include the component pin, terminations or wires.  It is good to designate if a hole is a component hole or not because the size of a component hole is more critical than a hole that will not have a component placed in it.
Component SideThis is typically the top side of the circuit board. Most often is labeled in the data files as component side, layer 1 or top side.  It is important when submitting your files that the component side of the board is clearly labeled to ensure the CAM and manufacturing process is done correctly.
Conductive Pattern This is the pattern of the copper on the final circuit board.  This would include the traces, pads, etc. that make up the circuit on the board.
Computer Numerical Control (CNC) Refers to the computer control that is used with modern day machinery.  It is most often used in the PCB manufacturing process with CNC Drill Machines as well as Rout machines that cut the individual boards away from the production panels.
Conductor Spacing The space between the copper traces on a PCB.  Spacing may vary greatly on any individual board.  Typical minimum spacing would be 0.007″ but could go down to extremes of 0.003″.
Conductor Thickness The thickness of the copper traces on a PCB.  The most common thickness would be 1oz or 0.014″.  1oz refers to the amount of copper that would cover one square foot area.
Conformal Coating A coating that is added over the printed circuit board and the installed components on the circuit board in order to provide protection to the circuitry.  The protection could be against weather, water, dirt, etc.
Continuity Refers to the uninterrupted flow of the electrical current in a circuit. Most often referred to as a part of the electrical test of a circuit. 
Controlled Dielectric Adjusting the thickness of the circuit boards materials (fiberglass) in order to create a specific electrical effect.  Most often used in multi-layer boards in order to obtain the desired impedance.  
Controlled ImpedanceElectrical impedance is the measure of the opposition (resistance) that a circuit presents to the passage of a current when a voltage is applied in an alternating current circuit.  Controlled Impedance is the process of manufacturing a PCB to meet a specific impedance requirement.
Copper WeightThe Copper Weight (also called Finished Copper Weight) is the total thickness of copper on the surface of a PCB.  There are several processes that effect the final copper thickness.  It is measured in oz/sq ft.  For example 1 oz = a thickness of 0.0012″. 
Core ThicknessA multi-layer circuit board is made up of a core, prepreg and copper foil.  The core is fiberglass material that has copper clad to it and will vary in thickness depending on the number of layers and the final PCB thickness required.
CounterboreA counterbore is cylindrical flat-bottom hole that enlarges another drilled hole.  It is typically used when a fastener, such as a socket head cap screw, is required to sit flush with the surface of the PCB.  
CountersinkA countersink is a conical hole added to a drilled hole to allow the head of a countersunk screw to sit flush with the surface of the PCB. 
CrosshatchingA reference to a technique used in drawing to fill an area with with volume or shading.  Used in some cases with larger copper areas on the PCB.  Leaves the copper with voided spaces instead of being a solid area of copper.
CuringThe process of polymerizing (chemically hardening) the epoxy based soldermask and/or silkscreen using a set temperature for a specified amount of time. This ensures the mask and silk will adhere to the rest of the material.  Once the mask and silk are cured on the base material they cannot be removed.

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