File Size Issues in AutoCAD

Sometimes large GDSII files when translated to DXF and loaded into AutoCAD, will cause the program to crash or stop responding. AutoCAD is not only known for having a hard time displaying large files, but often smaller files with lots of arrayed data will be exploded in AutoCAD, increasing the file size internally and causing the program to crash.

The following example will show a sample GDSII file (test12.gds), which is 11.34 MB in size. When translated to DXF the file size grew to 29.5 MB. After loading this file into AutoCAD, the program stopped responding after about a minute due to the large amount of data contained within it.

First, lets take a look at the sample GDSII file in Artwork's QCKVU and try to determine the best way to reduce the file size without losing any pertinent data.

The Problem

This is a full view of our sample file in QCKVU. Obviously, it's not possible to determine why the file is so large from this view. So, we'll take a closer look at a more specific area of the drawing (highlighted in yellow). Basically what we're looking for are dense areas which contain lots of blocks.

At left is a zoomed view of the highlighted window from the display shown above. Notice the large red areas in the center. These appear to be very dense. We'll zoom in even further, (highlighted in yellow), to examine this section in greater detail.

From this view it becomes clear that this area, (and others like it in the drawing), are filled with numerous blocks which are extremely small in size. This is also the reason why the file size is so large. Since this data is basically useless to the package designer, we can filter out what we don't need, preserve the necessary elements, and drastically reduce the size of this file.

The Solution

Close down QCKVU and open the GDSFilt Program. From the Main Menu, press the Select GDS File button. First, make sure to set the Working Directory to the same one where the file is located. Then, choose your file (test12.gds) and press open.

Check the Polygon Filtering option and Click the Polygon Filtering button to open the menu.

From the Polygon Filtering Menu we will set the Min. Extents = 1. This will filter out any polygons which are less than one micron. We measured the size of the small blocks in the drawing above and found that they were .4 microns. So, a value of 1 for Min. Extents will filter them out, but leave all the pertinent data we want to keep.

To the contrary, set the Max. Extents = 200,000, or a value so high that no other extents will be filtered out of the file. Press OK to continue.

For more information on Polygon Filtering, see the GDSFILT application note, Filtering by Boundary, Size and Shape.

Now, Click on the Translate button and Save the GDSII File under a new name. Now lets take another look at the Filtered GDSII File we just created in QCKVU.

Although from a full-view it may not look much different than the original, but after the filtering process, the file size dropped to 6.07 MB, a reduciton of nearly half. Let's zoom into the highlighted area again.

From the zoomed view of the same area, you can see that the small .4 micron blocks are no longer there.

This file can now be translated to DXF and opened in AutoCAD without worries of the program crashing or not responding.