Etch Compensation

Etch Compensation grows the copper features of a Gerber object by the lateral etch. Etching removes copper from the side of a trace as well as from the top, so the trace becomes narrower. The tool adds the lateral etch back to the copper. It creates a new Gerber object and leaves the source object unchanged.

Where to find it

• Menu: Plugins > Etch Compensation.
• Keyboard: none.
• The panel opens in a tab next to Project and Properties. The tab shows the plugin name.

Screenshot placeholder: images/Etch-Compensation-1.png — the Etch Compensation panel with the Source, Utilities and Parameters frames visible.

Quick start

1. Select the copper Gerber object in Source.
2. Set Copper Thickness to the foil thickness in microns (um). A 1 oz foil is about 35 um.
3. Keep Ratio as Etch Factor. Keep Etch Factor at 3.0 (or set your own value).
4. Read the Lateral offset field. It shows the offset in um and in mm.
5. Click Preview to draw the result on the canvas. Nothing is created.
6. Click Compensate. A new object named <source name>_comp is created.

Screenshot placeholder: images/Etch-Compensation-2.png — the canvas with the preview outline of the compensated copper drawn over the source copper.

Parameters

Source

Parameter	Description	Selected by default
Source	The Gerber object that is compensated.	—
Use all selected Gerber objects	When checked, every selected Gerber object is compensated. Each one goes into its own new object. When unchecked, only the object in Source is compensated.	Unchecked

Utilities

Two converters. Type a value in the left field. The converted value appears in the right field. Both fields accept formulas with the operators /, *, +, -, %, and the dot as decimal separator.

Parameter	Description	Selected by default
Oz to Microns input	The copper weight in oz. Multiplied by 34.798 to get microns (1 oz is 1.37 mil).	—
Oz to Microns output	Read-only. The thickness in microns.	—
Mils to Microns input	The thickness in mils. Multiplied by 25.4 to get microns.	—
Mils to Microns output	Read-only. The thickness in microns.	—

Parameters

Parameter	Description	Selected by default
Copper Thickness	The thickness of the copper foil. Unit: um.	18.0 um
Ratio = Etch Factor	The lateral offset is the copper thickness divided by the etch factor that you enter.	Selected by default
Ratio = Etchants list	The lateral offset is the copper thickness divided by the etch factor of the chosen etchant.	—
Ratio = Manual offset	You enter the lateral offset directly.	—
Etchants	The etchant list. Shown when Ratio is Etchants list. Choices below.	CuCl2
Etchants = CuCl2	Copper chloride. Etch factor F = 3.0.	—
Etchants = FeCl3	Iron chloride. Etch factor F = 2.5.	—
Etchants = Alkaline baths	Alkaline etchant baths. Etch factor F = 4.0.	—
Etch Factor	The etch factor F, the ratio between the depth etch and the lateral etch. Must be above zero. Accepts a real number or a formula. Shown when Ratio is Etch Factor.	3.0
Offset	The value by which the copper is grown (positive) or shrunk (negative). Unit: um. Shown when Ratio is Manual offset. Range: -10000 to 10000.	0.0 um
Lateral offset	Read-only. The offset that Compensate applies, in um and in mm.	—
Preview	Draws the outline of the compensated copper on the canvas. Nothing is created.	—
Compensate	Grows the copper features by the lateral offset. A negative manual offset shrinks the copper. The source object is not changed.	—
Reset Tool	Resets the tool parameters to their default values.	—

Screenshot placeholder: images/Etch-Compensation-3.png — the Ratio set to Etchants list with the Etchants combo open.

Advanced

• The lateral offset is the copper thickness divided by the etch factor. The Etch Factor and Etchants modes both use this formula. The Manual offset mode skips it.
• The copper polygons grow by the offset on each side. Each aperture grows by twice the offset. Clear features shrink by the offset.
• When the lateral offset is zero, Compensate creates nothing and shows a warning.
• The name of the new object is the source name with the suffix from the preference tools_etch_suffix (default _comp). The suffix is not on the panel.
• The command-line version is etch_compensate. See Tcl Command Reference.

See also

• Gerber Object
• Invert Gerber
• Isolation Routing
• Tcl Command Reference
• Preferences Plugins