ASM 502 and ASM 500 Filling Routine

Why do ASM 502 and ASM 500 cost substantially more than ASM 501? One important feature is the area fill routines. Microwave, RF, analog and package designers often require that complex areas designed using AutoCAD be filled black on the film. There are a couple of ways to achieve this:

Hatching

You can always use AutoCAD's hatch command to fill each area with hundreds or thousands of closely spaced lines. How close? Depends on the resolution you need. Unfortunately for many microelectronics circuits you will need to space the lines 0.001 inch apart generating thousands of lines per area.

AutoCAD actually stores all of these lines in its database and your display, load, save and regen times will become enormous. Not very practical if your circuit is at all complex.

There is also the problem of endpoint compensation which I won't even go into here.

Fill-on-the-Fly

ASM 502 and ASM 500 have powerful fill-on-the-Fly routines. They recognize certain objects as fillable - circles, solids and either polylines with width or zero width closed polylines and automatically fill these entities during the translation.

Your AutoCAD file stays small but your film looks correct.

Furthermore, they don't use a single small pen to fill the figures - Both programs use a sophisticated multi-aperture fill routine. A small pen is used around the edge of the polygon and larger pens are used to paint the interior region.

The microwave circuit (right) is very typical of a design that will benefit from ASM 502's filling routine. The designer used zero width closed polylines to "surround" the areas he wants dark on his film. He need not worry about compensating for pen width since ASM 502 only fills inside the boundary and not right on the boundary line.

If you run ASM 502 or ASM 500 with the fill option turned on and you give the program some reasonable apertures to use:

d10  round  0.001
d11  round  0.002
d12  round  0.004
d13  round  0.008
d14  round  0.015

You will find that the resulting Gerber file, metal3.gbr is reasonable in size (about 79K) and that the area is solid black.

The small file size with high resolution is achieved by using a 1 mil aperture around the edges of the polygons and larger apertures in the interior.

If we zoom in real tight with our GBRVU program and set the aperture width's equal to zero we can see how ASM 502 steps from the smallest aperture to much larger ones to fill the interior areas.

It's difficult to see in the low res GIF file but around the inner edge of the figure ASM 502 uses a couple of overlapping 0.001 inch apertures resulting in very precise corners. The interior is filled using .015 in. apertures. Net result is a file that is 10-15X smaller than if we had used a single 0.001 inch aperture with the same sharpness.