photo plotter apertures for traces

[sycochkn]

Does anybody use other than round apertures for traces?

Bob

 

[James Beck]

Does anybody use other than round apertures for traces?

Bob

Since my CAD package pretty much handles the code generation for FLASH
and DRAW I couldn't say for sure without looking in the output file, BUT
I doubt it. I do know that CADStar can optimize route T's and other
junctures so there isn't an overshoot bulge on the far side. Kinda'
does a little pull back on the gerber data.

Jim

 

[Hal Murray]

Since my CAD package pretty much handles the code generation for FLASH

and DRAW I couldn't say for sure without looking in the output file, BUT
I doubt it. I do know that CADStar can optimize route T's and other
junctures so there isn't an overshoot bulge on the far side. Kinda'
does a little pull back on the gerber data.

Where does that "overshoot bulge" come from?

If I draw a T with 3 lines using the same dia round pen,
it comes out clean. I'm drawing the lines so they all meet
at the same point which is the middle of each line.

The circle from the left matches the circle from the right.
At the junction, there is a circle that gets painted twice.

If I bring the bottom line up to the exact same point, it
doesn't overshoot at all. The circle at the end point overpaints
the same circle that was already painted twice. The new line
adds a pair of small sections to the area that gets painted
twice. They are the corners from the circle SW and SE to the
edges of the lines.

 

[Marra]

Does anybody use other than round apertures for traces?

Bob

I only use round traces for tracks.

Clearly pads can be round, square, rectangular or numerous other
shapes.

 

[sycochkn]

Does anybody use other than round apertures for traces?

Bob

I only use round traces for tracks.

Clearly pads can be round, square, rectangular or numerous other
shapes.

Actually there are 5 types of apertures circular, rectangular, oblong,
diamond and drawn.
all except the drawn can be used for traces. only the round one will give
you the same width in all directions and gurantee no overshoot from the
traces.

Bob

 

[Geo]

Actually there are 5 types of apertures circular, rectangular, oblong,
diamond and drawn.
all except the drawn can be used for traces. only the round one will give
you the same width in all directions and gurantee no overshoot from the
traces.

Cadstar specifies an annular ring to draw traces. Apparently the idea was to
prevent overexposure by the overlap of a solid circle.

Geo

 

[Chuck Harris]

Cadstar specifies an annular ring to draw traces. Apparently the idea was to
prevent overexposure by the overlap of a solid circle.

PCB film exposure is an all or nothing process. It is either fully exposed to
light, or not exposed at all. There is no chemical difference in the emulsion
between fully exposed, and fully-fully-fully exposed. The only way to overexpose
PCB photographic film is to burn a hole in it, which isn't going to happen.

-Chuck

 

[RHRRC]

Cadstar specifies an annular ring to draw traces. Apparently the idea was to
prevent overexposure by the overlap of a solid circle.

Geo

There is but little in Cadstar that isn't targeted at those who know
little about the electronic design and manufacture processes.

 

[James Beck]

Where does that "overshoot bulge" come from?

If I draw a T with 3 lines using the same dia round pen,
it comes out clean. I'm drawing the lines so they all meet
at the same point which is the middle of each line.

The circle from the left matches the circle from the right.
At the junction, there is a circle that gets painted twice.

If I bring the bottom line up to the exact same point, it
doesn't overshoot at all. The circle at the end point overpaints
the same circle that was already painted twice. The new line
adds a pair of small sections to the area that gets painted
twice. They are the corners from the circle SW and SE to the
edges of the lines.

If all the routes are of the same diameter then yes, no bulge, but not
all intersections are from the same DRAW code. You, obviously, don't
need to optimize out a bulge that isn't there. You can also get a bulge
when a DRAW and a FLASH overlap/end on each other. Big DRAW aperture
onto a smaller rectangular FLASH and you get a little overshoot.

Jim

 

[sycochkn]

If all the routes are of the same diameter then yes, no bulge, but not
all intersections are from the same DRAW code. You, obviously, don't
need to optimize out a bulge that isn't there. You can also get a bulge
when a DRAW and a FLASH overlap/end on each other. Big DRAW aperture
onto a smaller rectangular FLASH and you get a little overshoot.

Jim