Etch Compensation is a read-write DFM action intended to compensate for the etching process while preserving CAD specifications.
Pads and conductors will generally shrink after etching relative to design. To compensate for this shrinking, the action will enlarge features by a certain user-defined amount up to the maximum without violating spacing. If a spacing conflict arises, it may be resolved in one of two ways:
1. Non Shave Mode (Use Shaves = No, in Etch Compensate Action popup)-
copper features are enlarged up to a size less than user-specified value.
2. Shave Mode (Use Shaves =
Yes, in Etch Compensate Action popup)- copper feature will be enlarged up to
the user-specified size but will be shaved with negative features to avoid
spacing violations.
The following guidelines are applicable throughout the action:
*
When a conflict arises between spacing restrictions and optimal
compensation, the system decides for compensation by a margin of 0.01.
*
The action is designed to work on positive features only. If a
negative feature is selected the action will abort.
*
The action processes only the following features:
-
Round and square lines and surfaces
-
Round and square pads
-
Rectangular and oval pads
In some cases, the processing speed of this action is slow when operating in Local Mode. Switch to Global Mode to increase processing speed.
The report lists counts of measurements for each category.
Measurement counts are produced for each category. The standard naming convention is followed:
<layer name>_<category erf name>
When selected features are processed, an additional result attribute selected will be produced. For each processed layer its name will be:
<layer name>_<selected>
This will provide the number of selected features.
To avoid the creation of special symbols with minor differences (by only a fraction of their sizes, such as rect100x200, rect100.0001x200, rect100.0002x199.9999, etc.), a symbol size mechanism provides a solution. It rounds all sizes to the nearest value, exactly divisible by a certain symbol_resolution value.
By default, this value is set to 0.1 mil and it may be changed by changing the aper_res ERF Variable value.
See the example below, a section of an ERF file:
.units inch
...........
...........
...........
aper_res=0.2
This will set symbol_resolution value to 0.2 mil. The resulting conversion is shown in the following table:
Calculated Symbol Size |
Actual Symbol Size |
100.05 |
100.0 |
100.15 |
100.2 |
100.21 |
100.2 |