The command DRC performs a design rule check. It checks:
What is Checked?
The following layers are checked: Top, Bottom, ROUTE2...15, Pads, and Vias - but only the displayed layers. At least one of the layers Top, Bottom, and ROUTE2...15 must be displayed. If all of them are displayed, they are checked individually (separately). The overlapping of a polygon with other polygons is not checked!
How to Perform the DRC
If you want to make sure that a pc board is okay, the following steps should be performed:
DRC;
The DRC command writes its results into a (non-text) file boardname.DRC.
Examples
Drc SetParameter MaxErrors=9999 MinDist=20 Angle;
increases the maximum number of errors to 9999, defines minimum distance
between signals as 20 mil and activates the angle check. (The design
rule check is not started if the keyword SetParameter shows up in
the command - only parameters are defined.)
DRC;
starts the DRC with the predefined parameters.
DRC
starts the DRC in the rectangle defined with the two mouse clicks.
GRID mm;
DRC Signal = GND MinDist = 7 MinWidth = 5 Angle;
starts the DRC for the signal "GND"; checks if GND has a minimum
distance of 7 mm to any other signal (see GRID command) and if any
wire, belonging to the GND signal, has a minimum width of 5 mm; the
DRC checks also if there are wires (tracks) at an angle that is not
a multiple of 45 degrees and if there are different signals overlapping
each other (overlap check is always on if distance check is on).
DRC MinDist MinDiameter MaxDiameter ;
starts the DRC and checks minimum spacing as well as minimum and maximum
pad/via diameter. Default values are used because the parameters are
defined without special values.
Delete Error Polygons
DRC Clear ;
deletes all DRC error polygons from the screen as well as the related
*.DRC file.
Parameters
SetParameter: The specified parameters are set but no DRC is started. Succeeding DRC commands use these parameters. SetParameter is especially useful for script files.
MaxErrors: Defines the maximum number of errors per layer. If this number is exceeded the DRC is stopped. Default: 50 errors.
MinDist: Defines the minimum distance between different signals. Specify this value in the current grid unit (Inch, mm, mil, mic). "MinDist" without a value turns the minimum distance check on without changing the predefined value (this is also true for all other Min/Max parameters). The minimum distance check always performs an additional overlap check. Default: 10 mil.
Overlap: Turns on the overlap check.
Angle: Turns on the angle check. All wires (tracks) not placed in multiples of 45 degrees cause an error (see "SET SNAP_BENDED").
MinDiameter: Defines the minimum diameter of pads and vias (see MinDist). Default: 40 mil.
MaxDiameter: Defines the maximum diameter of pads and vias (see MinDist). Default: 255 mil.
MinDrill: Defines the minimum drill diameter of pads and vias (see MinDist). Default: 24 mil.
MaxDrill: Defines the maximum drill diameter of pads and vias (see MinDist). Default: 255 mil.
MinWidth: Defines the minimum width of wires (see MinDist). Default: 10 mil.
MaxWidth: Defines the maximum width of wires (see MinDist). Default: 255 mil.
MinPad: Defines the maximum width of the area which must remain around pads and vias after drilling (see MinDist). Default: 8 mil.
MinSmd: Defines the minimum dimension of an smd pad. (see MinDist). Default: 10 mil.
OffGrid: Turns the grid check on. All elements not placed on the current grid cause an error.
Clear: Clears all DRC error polygons and error messages in the pop-up menu. This is also done automatically if a new DRC is performed.
Signal: Defines the name of a signal to be checked. That allows you for instance to check a certain signal against all others. If a signal name is specified all checks are performed only for this signal.
: Two mouse clicks define a rectangular area in which the DRC is to be performed. Only errors that occur (at least partly) in this area are found. After the second mouse click the DRC is immediately started.
;: The terminating semicolon starts the DRC for the whole board if a defined area has not been indicated.
Related SET commands
The SET command can be used to change the behavior of the DRC command:
SET DRC_SHOW ON | OFF;
Switches the display of the currently checked area on/off while the
DRC is in progress.
SET DRC_COLOR color_word;
Defines the color for the above mentioned rectangle.
Default for color_word: LGray.
SET DRC_FILL fill_name;
Defines the fill style used for the DRC error polygons.
Default for color_word: LtSlash.
Finding the Errors
The command
ERRORS
is used to show the DRC errors. If selected, a
popup menu is opened in which all errors found in the current window
area are listed. Moving the mouse cursor through the list causes the
errors to be marked with a rectangle. Pressing the left mouse button
zooms in to that error with the error in the center of the screen
window. The command
SET MAX_ERROR_ZOOM value;
defines the limit of magnification. Default is 1 inch which means
that the screen shows an area of at least 1 inch horizontal length.
The ERRORS command can be activated directly or via the DRC command menu by clicking on the "ERRORS" button.
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